The Impact on Topographic Mappingof Developments in Land and Air Survey

1900-1939

Peter CollierABSTRACT At the beginning of the twentieth century littleof the orld outside of Europe Indiaand parts of North America had been covered by topographIC mappmg By the end of the centurythere were few areas that were not covered by topographic mapping if only at smal1scales Mos~ofthe technological changes that made this extension of ma~ coverage possible ~vereploneere~ dunngthe period 1900-1939 This paper reviews the technologlCaldeveiopments m land an~ aIr surveythat took place during that period and relates them to the dnve to produce cost-effectn e mappmgfor civil and military purposes

KEYWORDS Topographic mapping twentieth century photogrammetry land survey technologi-cal developments

Introduction

The development of techniques for datagathering and their impact on topo-graphic mapping can be divided into four

phases The first phase before World War I wascharacterized by numerous experiments using newtechniques often carried out by individuals butwith little direct impact on the making of mapsThis phase was also one of considerable cross-national cooperation During the second phaseWorld War I progress was mainly in the develop-ment of simple techniques to assist in the rapidproduction of maps to meet military needs Thethird phase the 1920s was one of conSiderabletechnical development in instrumentation and thefirst use of aerial photogrammetry both instru-mental and graphical to make civilian maps Mostof the developments in the 1920s were nationalwith little attempt at international cooperationDuring the fourth phase the 1930s a start wasmade on large-scale production of civil mappingusing photogrammetric techniques which w~renolonger regarded as experimental In par~ thiSwasthe consequence of two important techmcal devel-opments the introduction of slotted temp lets ~ndmultiplex These techniques were also to providethe basis for most post-war medium-scale topo-graphic mapping

Peter Collier is a principal iecturer in the Department ofGeography at the University of Portsmouth PortsmouthPOl 3HE UK E-mail ltpetercollierportacukgt

Topographic Mapping andTechniques 1900

At the beginning of the twentieth century ~hiletopographic maps of various scales and of vanablequality covered most of Western Europe relativelylittle of the rest of the World (Figure 1)was coveredby topographic mapping even at small scales (1250000 or smaller) It was this dearth of evensmall-scale mapping that led to the proposals forthe 11000000-scale International Map of theWorld (penck 1893)

Within Europe the range of scales used for basicmapping wasa function of the varied istories a~dresponsibilities of the national mappmg agenCIesAt one extreme the Ordnance Survey in GreatBritain had produced topographic mapping forthe entire country at 110000 (Seymour 1980) InFrance by contrast the Service Geographique deIArmee had started working on a new map at 150000 (Type 1900) which was to replace the old180000 Carte de France dEtat-Mlttior The newmap was based on surveys at 1100~0 in lowlan~areas and 120000 in mountain regIOns In addi-tion 120000 Plans Directeurs were produced forborder areas (Service Geographique de IArmee1938)

In Germany each individual state had its ownmapping program The Hapsburg Monarchy(modern Austria Hungary Czech and SlovakRepublics Slovenia Croatia and part of Poland)wasgenerally well mapped as a consequence of theactivities of the Militargeographische Institut The

Cartography and GeograPhic Information Science VOL29 No3 2002 pp 155-174

Figure 1 The state of world topographic mapping about 1900 (after Bartholomew 1890 Robinson projection)

whole Empire had been mapped by plane tablesurvey at 125000 between 1869 and 1887 anda new survey the Prazisionsaufnahme had beeninitiated in 1896 using tacheometry (Kretschmer1991)

Belgium had been mapped at 110000 and TheNetherlands was mapped at 125000 By contrastthe Spanish Instituto Geografico Estadistic hadmade relatively slow progress with the 150000Mapa Topografico Nacional which had beenstarted in 1870 Portugal had also started work on150000 mapping (in 1893) with the first sheetappearing in 1900

In Scandinavia the picture was mixed with 1100000 maps being produced in Norway (althoughcoverage was far from complete) while in Sweden1100000 was used for the southern parts of thecountry and 1200000 for northern parts InDenmark a variety of scales were published fordifferent parts of the country but in 1891 the scaleof 1100000 had been adopted as standard

North America and India were the only otherparts of the world that can be said to have hadproper mapping programs Even in NorthAmerica the volume of mapping available was rel-atively small Mapping at scales of 131680 and 124000 was available in the United States for townsand special projects while settled rural areas weremapped at a scale of 162500 For the rest of theUnited States the largest scales available were 1125000 or 1250000 In total topographic map-ping covered nearly 26 percent of the continental

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United States In Canada the only topographicmaps were at 1190080 reduced from 131680cadastral sheets The first true topographic mapswere not to be produced until 1906

One of the first tasks undertaken by the EastIndia Company when it acquired control of terri-tory in India was to carry out surveywork Much ofthe mapping was for fiscal purposes but admin-istration control and defense all required theproduction of topographic maps In consequencethe Survey of India can claim to be one of theoldest national mapping agencies By the end ofthe nineteenth century most of British India wasmapped at various topographic scales

In the newEuropean colonies ofAfricaalmost nomapping existed In the British Empire this led tothe setting up of the Colonial SurveyCommittee in1905 In the first report of the committee (ColonialSurvey Committee 1906 pp 3-4) the need formapping was set out in the introduction

The purposes for which maps are requiredin the administration of a country (especiallyan undeveloped country such as a protector-ate in Tropical Africa) are many and variedMaps are necessary to define the exact limitsof national territory to show the areas andvillages under the rule of native chiefs theyare essential for land registration and settle-ment for the allotment of mining and forestconcessions and for the organization ofinternal communications Of their necessityin war the experiences of the army in South

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Africa afford an eloquent testimony and eventhe conduct of a small war or a police expe-dition is much simplified by the existence ofreliable maps of the scene of operations

With very few exceptions the topographic map-ping available in 1900 had been produced usingground survey techniques Although the conceptof photogrammetry had been discussed since thelate 1850s (Laussedat 1860) very little had actu-ally been achieved The only extensive mappingundertaken using photographs had been that inCanada by Eduard Deville (1895) Although anumber of Europeans had in the 1890s carriedout alpine mapping using terrestrial techniquesthe equipment necessary to carry out the work costeffectivelywas not yet available in 1900

Indeed the survey techniques being used by landsurveyors in 1900 were little different from thoseused in 1800 Because accurate distance measure-ments were difficult and expensive to acquire allcontrol networks used for medium- and large-scaletopographic mapping were based on triangulationAlthough the discovery of invar (an alloy of steeland nickel with a very low coefficient of expansionwith heat) in 1896 was to make accurate distancemeasurement easier it was not until the develop-ment of electromagnetic distance measurementin the 1950s that alternatives to triangulationbecame possible Traversing for lower-order con-trol networks was used in colonial territories butonly if small-scale mapping was to be producedTraversing was also used for mapping during mili-tary operations (Close 1905)

The theodolite had undergone improvementsduring the nineteenth century These werelargely the result of improvements in the dividingengines used to graduate the horizontal and verti-cal circles Consequently it was possible to makebetter measurements on instruments with lO-inchcircles in 1900 than it had been on instrumentswith 36-inch circles in 1800 Accurate reading oftheodolite angles depended on the use of verni-ers or micrometers Vernier instruments werepreferred for expeditions and surveys in roughconditions because they were lighter and morerobust than the micrometer instruments (Reeves1933) Edward Reeves was to make a significantimprovement in theodolites with the developmentof the tangent micrometer a device which madeaccurate reading of the circles easier and perhapsmost importantly could be retrospectively fitted toexisting instruments (Close 1905 Reeves 1933)Similar devices were to be incorporated into thedesigns of theodolites from the major manufac-turers The most significant improvement in the

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design of theodolites occurred in the twentiethcentury when the lead in design passed fromBritain to Switzerland and Germany

Another development adopted by surveyors wasthe use of the telegraph for the transmission oftime signals This technique became common forthe determination of longitude until supersededby the use of radio time signals in the 1920s

Emerging TechnologyAt the beginning of the twentieth century Themost important emergent technology was with-out doubt the use of photography for surveyingAlthough attempts had been made to captureand use aerial photography the lack of a stableand reliable aerial platform meant that the useof photography was restricted to terrestrial pho-togrammetry In 1893 C B Adams had proposeda method for plotting by intersection from bal-loon photographs (US Patent 510758) Althoughthis approach never led to a practicable mappingtechnique it provided the conceptual basis for theradial-line techniques in vertical aerial photog-raphy To use terrestrial photography cost effec-tively in mapmaking it is necessary to elevate thecamera above the surface to be mapped or place itat a sufficient distance from the surface to permitcoverage of a large area In practice this meantthat terrestrial applications were best carried outwhere there were natural vantage points such asmountains and high hills

Terrestrial photogrammetry had first been dem-onstrated by Aime Laussedat in 1859 (Blachut andBurkhardt 1989) although he was at first limitedby the wet plate process Ignazio Porro in Italyand Dr A Meydenbauer in Germany improvedupon Laussedats work These early attempts allinvolved the use of graphical techniques to plotthe detail and contours from photographs Theprocess of map creation from photographs wasthus slow and laborious and it tended only to beused where difficult terrain made plane table workimpractical For the photogrammetric approach tobecome more cost effective a method of automat-ing the plotting was needed Work on developingsuch a method was being actively pursued in anumber of countries at the turn of the century

The Canadian experience had led to a system-atic use of terrestrial photography for topographicmapping along the Alaska-Canada boundary byboth Canadian and American members of thesurvey party John Flemer ofthe US Coast andGeodetic Survey (USCampGS)was assigned to makea study of European methods which led to the first

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American textbook on photogrammetry (FIemer1906) Even so this did not lead to the widespreadadoption of photogrammetry within the USCampGSas photographic techniques could still not competewith the efficiency of existing techniques (Landen1952) In 1904 the US Geological Survey (USGS)which was also interested in the use of terrestrialphotogrammetry adopted Devilles panoramiccamera approach for mapping in Alaska JamesBagley further developed the technique by rede-signing the camera and producing a panoramicphoto alidade (Bagley 1917)

Photogrammetry to 1914Until the outbreak of World War I the chief focusof photogrammetry remained terrestrial appli-cations In 1901 Henry Fourcade described amachine designed to make measurements fromstereoscopic photographs essentially a stereocom-parator (lltourcade 1901) At about the same timeCarl Pulfrich (1902) produced and described thePulfrich Zeiss stereocomparator During the 1930sthere was considerable debate over the precedencein producing a serviceable design for a stereocom-parator Otto von Gruber (1932) gives precedenceto Pulfrich by citing his 1902 paper and the 1902paper by Fourcade which appeared in Nature Butas noted above the Fourcade design was first dis-cussed in a paper published in 1901 albeit in arelatively obscure journal It is not clear whethereither designer was aware of the work of the othereven if they both produced very similar designsThis notwithstanding it is worth noting that vonGruber was also to dismiss Fourcades claim toprecedence over his own work in the design ofan instrument that employed the concept of thestereogoniometer Martin Hotine (1931) makes astrong case in support of Fourcade s precedence inboth cases Both machines could be used to makeaccurate stereoscopic measurements of pointsbut because the plan positions and heights of thepoints were computed individually maps producedfrom these measurements required interpolation

While these early machines demonstrated thepossibility of making accurate maps from stereo-scopic photographs the technique was extremelytime consuming and only suitable if no othertechnique was available Appropriate conditionsexisted in alpine mapping where ground surveywould have been hazardous or even more timeconsuming than photogrammetry Early examplesof photogrammetrically derived contours were pro-duced in the Tyrol between 1902 and 1907 by theAustrian survey using the Pulfrich stereocompara-

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tor (Kretschmer 1991) Both the Prussian GeneralStaff and later the French Service Geographiquede lArmee adopted the Pulfrich stereocompara-tor for mapping mountainous areas in Pelvoux(Service Geographique de lArmee 1912 1938)However there was general recognition that thetechnique was not cost effective(see the commentsof Major Hills followingThompson 1908)

What was needed to make the use of photogra-phy cost effectivewas the ability to produce topo-graphic details and contour lines directly from thephotographs rather than by manual interpolationIn 1908 Eduard von Orel produced his autoste-reograph (von Ore11910 1911 1912von Gruber1932 Hotine 1931 Kretschmer 1991) and in thesame year Vivian Thompson published details ofhis stereoplotter (Thompson 1908 von Gruber1932 Hotine 1931 Thompson 1974 Petrie 1977Burnside 1995) Both machines were capable ofproducing plotted detail lines and contours fromterrestrial photographs The autostereographwas quickly adopted by the Austrian survey foralpine mapping and was subsequently taken up byother national mapping departments The largestsystematic survey carried out with the autostereo-graph was some 560 km2 of the Tyrol surveyed in1911 by the Militargeographische Institut (Koner1924) Bycontrast the stereoplotter attracted littleinterest in its country of origin Great Britain butwas adopted by the Survey of India for mappingin the Karakorum Range Because these areashave not subsequently been remapped the origi-nal contours from the stereoplotter are still thoseused on the published sheets One plotter was alsoacquired for survey work in Fiji where McCawused it for mapping prior to WorldWarI (ColonialSurvey Committee 1911 1912 1913)

Both machines were suitable for mapping fromterrestrial photographs as were machines devel-oped from von Orels autostereograph (Therewere no developments from the stereoplotter)Howeverbecause both solutions required coplanarphotographs they could not be readily adaptedfor use with aerial photography which is rarely ifever coplanar This fact did not stop many abor-tive attempts to turn terrestrial photogrammetricplotters into machines capable of handling aerialphotographs

A non-technical development that was to havea significant impact on the development of pho-togrammetry was the founding of the AustrianSociety of Photogrammetry in 1907 followedby the publication in 1908 of the first volumeof the lnternationales Archiv flir PhotogrammetrieThe International Society for Photogrammetry

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was founded in Vienna in 1910 Vienna was alsothe setting for the first International Congressfor Photogrammetry in 1913 The Society wasto become one of the main vehicles for the dis-semination of information on photogrammetrywhile the congresses were the main showcases forthe latest equipment Previously the InternationalGeographical Union was the main forum for thedissemination of developments in surveying andphotogrammetry but its importance had contin-ued to decline until after World War II when italmost completely withdrew from the field

World War I (1914-1918)World War I generated an unprecedented demandfor maps at scales from 1200 for detailed trenchmaps (Chasseaud 1999) to 11000000 andsmaller for strategic planning maps (Heffernan1996)At the outbreak of war in 1914 the armies ofEurope were issued with maps at scales of 180000or smaller designed to support a war of rapidmovement in which victory would be achievedby bringing to bear an overwhelming force in adecisive battle Military leaders still believed thatoffensive operations could be successful despitethe precedent of the Russo-Japanese War of 1905which had degenerated into sieges and large bat-tles of encounter in which opposing armies foughtin the open rather than in prepared positionsNeither side could achieve a decisive blowbecauseof the superiority of defense based on rifles andmachine guns

The strength of the defenses meant that if therewas to be any hope of success in offensive opera-tions the attacking troops needed accurate mapsof the enemy defenses This included the positionsof any artillery ammunition dumps and transportinfrastructure Allof these features were difficult orimpossible to map from the front line In the caseof ammunition dumps and transport the targetscould be many miles behind the front What thearmies of both sides needed wasa wayof collectinginformation that could either be added to existingmaps or used to produce entirely new maps Mostimportantly as the artillerymen developed evermore accurate targeting they created a demandfor increasingly precise mapping to locate poten-tial targets As the war progressed the armiesexperimented with a closer integration of artilleryand infantry operations such as the rolling bar-rage (a barrage where the gunner slowlyincreasesthe range while infantry advance slowlybehind thebarrage) Again this required more precise point-ing of guns and locating of targets

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Suneyors were used to fix the position of bothguns and targets The need for secrecy-no pointin alerting the enemy that an attack was beingprepared-also changed the ways in which theguns acquired their targets Early in the war thenormal technique involved the use of rangingshots That is each gun was fired towards a poten-tial target and an observer identified the fall ofshot The obsener then told the gunner to eitherincrease or decrease the range as appropriateand to traverse left or right until the shot was fall-ing on the target The problem with this techniquewas that it revealed that a new gun had been intro-duced into a stretch of the front A large number ofranging shots revealed the introduction of a largenumber of guns and the threat of a forthcomingattack To overcome this dilemma the positions ofthe guns and targets needed to be determined pre-ciselyby surveying From this information artilleryboards were prepared to show the positions of theguns as well as the targets It was then possible todetermine the directions in which the guns neededto fire and the range to the target without reveal-ing that new guns had been positioned

The identification of targets and the accuratepositioning of guns led all the nations to adoptthe use of grids on their mapping In the latenineteenth century John Ardagh had tried toget a grid system adopted by the Survey of Indiabut without much success (Ardagh 1893) Prior toWorld War I therefore almost no maps carriedgrids The exceptions were the squared mapsused by the French artillery on maneuvers atChalons in 1911 (Chasseaud 1999) Increased useof indirect fire underscored the need for griddedmaps Unfortunately grids were adopted on an adhoc basis which led to considerable confusion Forexample the Germans used three different gridsystems with origins at Lille Rheims and Paris(Hinks 1919)The British adopted an imperial gridbased on 1000-yard grid squares even though theentire mapping on the Western Front used metricscales Despite this uncertain start it was quicklyrealized that grids had uses well beyond those ofwarfare and they became a standard feature ofmost post-war topographic mapping

Military mapping in Europe was largely focusedon map revision whereas that in Palestine Sinaiand Mesopotamia involved considerable origi-nal mapping (Collier 1994 Collier and Inkpen2001) In the initial stages of the World War I allthe belligerents used existing pre-war mappingsupplemented by photographic enlargements InFrance this involved the use of 180000 mappingsubsequently enlarged to 140000 When how-

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ever the deficiencies of the enlargements becameevident they were replaced by new mapping Onlythe German survey seems to have continued to useenlargements through to the end of the war aack1920) With the development of positional warfare140000 mapping wassoon found to be inadequateand was successively complemented by mappingat 120000 and 110000 Where necessary evenlarger scales were used (Chasseaud 1999)

Behind the lines revision and new surveys werecarried out using conventional land survey tech-niques trigonometrical control surveys and theplane table to add detail Oack 1920 Winterbotham1919a 1919b Service Geographique de lArmee1938 Albrecht 1969 Chasseaud 1999) For front-line areas and for the enemys rear areas the maindata source was aerial photography

The Development of CamerasInitially photography for intelligence and maprevision involved the acquisition of photographyfrom fairly low flying aircraft using largely impro-vised camera equipment With the development ofanti-aircraft defenses however reconnaissance air-craft were forced to fly higher and higher to avoidbeing shot down To compensate it became neces-sary to devise cameras with longer and longer focallengths if the resultant photography was to be ofuse for analysis and mapping

The earliest cameras were simple devices thatused glass plates and dark slides (devices used tochange glass negatives in a camera without expos-ing the negatives to light) Images were obtainedby observers pointing the cameras over the side ofthe aircraft The cameras were fitted with simplesighting devices to ensure that the target wasactually imaged Recognition that vertical photo-graphs were much better suited to mapping thanthe oblique pictures taken with hand-held camerasled to the cameras being fixed to the side of theaircraft Fairly quickly magazines were providedso that a series of photographs could be taken bythe observer activating a lever to change platesEven so changing the magazines still required theobserver to lean over the side of the aircraft Giventhese difficulties it seems strange that roll filmwas not used earlier especially since panoramiccameras had used it as early as the late nineteenthcentury The Germans did not introduce a filmcamera until 1916 (Albrecht 1969) and the Britishcontinued to use plate cameras until the end ofthe war

Most of the cameras used for military operationshad relatively long focal lengths the standardBritish camera in the early part of World War I had

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a focal length of 8 inches (approximately 200 mm)while the standard German camera had a focallength of 180 mm (Albrecht 1969) By the end ofthe war focal lengths of 500 mm were not uncom-mon-some German cameras had focal lengths aslarge as 1200 mm (Albrecht 1969) These lenseswere designed for reconnaissance rather thanmapping so that each photograph covered only asmall area of ground Cameras needed wide-anglelenses to minimize the amount of control neededfor mapping but none of the high-quality lensesavailable provided a wide field of viewMulti-lenscameras were developed in the nineteenth centuryto obtain broader coverage from each exposurestation but these cameras were generally largeand cumbersome and thus unsuited for militaryoperations

Control for MappingEarly attempts at using aerial photography formap revision experienced considerable difficul-ties As Malcolm MacLeod (1919 pp 382-83)noted though the photographs showed all theprincipal topographical features in great detailthere was no means of determining their exactscale or the amount of distortion due to thecamera not being truly vertical at the moment ofexposure of the plate In the absence of mechani-cal restitution instruments to overcome theseproblems two possible solutions were consideredto develop a device for mechanically determiningthe altitude and tilt of the camera at the momentof exposure or to compare the positions of pointson the photographs with their known ground coor-dinates Although both sides experimented with amechanical solution most work involved the lattertechnique This placed a heavy demand on accessto ground coordinates

The provision of control points both in andbeyond their own front line was a major problemfor all the combatant nations Placing markersover control points in frontline areas and thenfixing them by observation from the rear was notfeasible as this also enabled the enemy to fix theposition of the trenches A number of strategieswere adopted including the use of periscopictheodolites employed from within the trencheswithout exposing observers to enemy fire Thesetheodolites could be used to fix positions withinthe trenches by resection

While resection on the plane table was a com-monly used technique among topographers ithad not been widely used for instrumental obser-vations because of the relative complexity of thecalculations However the conditions of trench

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warfare left few alternatives Once adopted resec-tion remained in common use among surveyorsAn alternative adopted by the Germans was to firea flare vertically from the trenches and obsenTethe flares position from the rear using theodolitesGack 1920)

Locating control points beyond the front line waseven more difficult Where possible the position ofprominent points would be fixed by intersectionHowever in Mesopotamia there were often too fewsuitable features to intersect This led to an inno-vation by Col C P Gunter to fix control pointswithin the Turkish lines using artillery shell burstsFour observers took simultaneous observations ofindividual shell bursts while an observer in anaircraft recorded the position of the explosionson a detailed map of the trenches created from airphotographs On average out of ten shell burststhree good intersected points were observed andthe observer would have accurately marked one ofthese Points observed in this way were then usedto control and adjust the strips of photographyused for mapping (Surveyof India 1925)

Plotting DetailOnce control had been obtained it was necessaryto interpret and plot the information on photo-graphs Initially interpretation was relatively easyas there was little attempt to conceal potentialtargets from aerial observation Camouflage onlystarted to be used systematically around 1916(MacLeod 1919) thereafter photo-interpretationdeveloped into a specialist skill Use of camouflagealso led to the development of new surveyingtechniques such as flash spotting and soundranging

Extraction of detail for revision purposes wasdone by some form of graphic intersection orthrough the use of optical projection Despite someuse of more rigorous methods involving compara-tors developed before the war these instrumentstogether with the necessary calculations were slowand not well suited to the urgent needs of the warThe use of automatic plotters such as the alitoste-reograph was restricted to terrestrial photographydue to the need for coplanar photography In factthis technique was used only by the Germans andFrench in eastern France where relief was suitableand by the Austro-Hungarian Army in the AlpsOskar Albrecht (1969) also refers to the use of ter-restrial photogrammetry for artillery assaults onfortresses and the use of photographs taken fromtethered balloons

The belligerent powers employed a variety ofgraphic techniques The simplest involved the pro-

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duction of a framework of existing detail on a com-pilation sheet on which new detail was added fromaerial photographs with the help of proportionaldividers Although capable of producing reason-ably accurate results this approach was labori-ous and slow (MacLeod 1919) The paper stripmethod (Thompson 1966) used for adding smallamounts of detail was equally slow and laboriousThe German Army developed a less strenuoustechnique based on the use of perspective gridsThe chief advantage of this technique was thatonce the grids had been generated detail could betransferred by eye from aerial photograph to mapThis technique was so successful that it was widelyadopted after the war for map revision Describedin most standard textbooks on photogrammetrythe perspective grid approach remained in useuntil the 1980s when simple digital techniquesrendered it obsolete

Most of the optical revision techniques reliedon the registration of a projected image of thephotograph on an existing map or on a frame-work of control Once the image was registeredthe mapmaker could either transfer the informa-tion directly to the map or produce a correctedphotographic print for use in revision TheodorScheimpflug had shown that an accurate regis-tration could be affected between the projectedimage and the control data if the projected imagewas in focus for the entire image area To satisfYthe so-called Scheimpflug condition the projectedplanes of the negative lens and easel had to meetat a common axis (Scheimpflug 1898 Blachutarid Burkhardt 1989) Even if the condition wassatisfied there were still errors of registration dueto relief displacement In the instruments usedduring World War I the Scheimpflug conditionwas hot satisfied and consequently the resultswere at best approximate (Blachut and Burkhardt1989) MacLeod (1919 1920) describes the use ofCamera Lucida and the enlarging lantern inboth of which the plane of the negative and theplane of the lens were held parallel with only thecopy board which was capable of being tilted Theeniarging lantern could maximize the depth offocus and hence the sharpness of the iinagebyreducing the aperture of the lens to the smallestdiameter possible The use of the enlarging lan-tern to produce semi-rectified prints came to bethe preferred techrnque

As already noted while most of the work onthe Western Front involved map revision innon-European theaters the need was for originalmapping (Collier 1994 Collier and Inkpen 2001)The first attempts to use aerial photography to

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construct original mapping took place during theGallipoli campaign (Dowson 1921) Not very suc-cessful these attempts demonstrated the problemsassociated with the non-stereoscopic use of aerialphotography as when troops were sent to occupypositions identified monoscopically as trenchesor ditches but which turned out to be shallowscrapes that afforded no shelter from enemy fireAttempts to create original mapping ceased whenmodern Turkish maps of the area were capturedand revised

In Egypt the Turkish threat to the Suez Canalalso resulted in experiments in mapping fromaerial photography Like the mapping in Gallipolithese were largely unsuccessful The main problemwas locating precisely where the photographs hadbeen taken over a largely featureless desert Thebulk of the mapping for the Suez Canal defenseswas therefore carried out by triangulation andplane table survey (Maule 1919)

When the Egyptian Expeditionary Force (EEF)advanced across the Sinai Peninsula to engageTurkish forces in Palestine it moved into terri-tory without up-to-date mapping of an adequatescale Western Palestine had been mapped for thePalestine Exploration Fund (PEF) in the 1870s(Conder 1878 Conder and Kitchener 1881-83) ata scale of 163360 Although based on triangula-tion the detail had been surveyed using compassand cavalry sketching board (Close 1932) and wastherefore regarded as insufficiently accurate formodern warfare British military personnel hadsurveyed Southern Palestine just before the warunder the cover of a PEF expedition (Woolleyand Lawrence 1914) But even here the scale wastoo small (1 125000) for the kind of operationsbeing undertaken The British army was thereforeconfronted with the need to map areas beyond itsfront line for which no adequate base maps wereavailable

The first successful attempts at mapping fromaerial photographs were in t~e area aroundGaza (Gavish and Biger 1983) Here control wasprovided by the intersection of prominent pointsbehind Turkish lines Based on these points acontrolled mo~aic was created from with verticalaerial photogriphs and the mosaic was then usedto crcate the line maps of the planimetry Althoughcrude by later standards the map was consideredto be a significant improvement on anything thenavailable This encouraged the surveyors led byMajor W] Maule to embark upon an ambitiousplan to create a series of topographic maps at 140000 for areas of Palestine behind Turkish lines(Maule 1919) Strips of photography were flown

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roughly parallel to the front line with additionalstrips of photography perpendicular to the frontflown at intervals to control the strips parallel tothe front Supplementary control was provided bytheodolite observations wherever possible Thesame basic arrangement pioneered in the map-ping of Gaza was followed for the series mappingHowever as the area mapped extended into thehills of Judea (the southern West Bank) it alsobecame necessary to provide some indication ofrelief Viewing the photography stereoscopicallyand form lining achieved this The nature of thetopography nearly horizontally bedded lime-stones that eroded into natural terraces madethis task relatively easySuccessfulas the mappingwas (Thomas 1919) as each new area came underBritish control mapping derived from air photoswas replaced bymapping made using conventionalground survey techniques

In a number of ways the mapping inMesopotamia can be regarded as the first exampleof true photogrammetric mapping using aerialphotography Unlike the mapping in Palestineit was produced as the end product not as aninterim solution to be replaced as soon as groundsurveys became possible And unlike the mappingon the Western Front it did not involve revision ofexisting mapping as no proper maps existed forthe area

Although developments in the use of air pho-tography had been watched with envy by thesurveyors in Mesopotamia (Survey of India 1925)until early 19I6 no airplanes had been availablefor that theater Some experience in the use ofaerial photography had been gained before thesiege of Kut-al-Amarah but it was the positionalfighting around Kut that emphasized the advan-tages of air survey Maps were required of areasbehind Turkish lines but the flat landscape meantthat surveyscould only be extended into no-mans-land This led to the first real attempt to createmaps from aerial photography As the first mapTC4 (TC are the initials of Tigris Corps theoriginal name of the force sent to Mesopotamia)has been discussed at length elsewhere (Collier1994 Pritchard 1952 Survey ofIndia 1925)

The surveyors working in Mesopotamia experi-mented with various ways of making maps fromaerial photographs drawing on the experience ofsurveyors on the Western Front and in Egypt Inthe end though they developed their own tech-nique which was well suited to local conditionsTheir technique involved creating semi-rectifiedphotographs using an enlarging lantern (Gunter1917) and then mosaicing the photographs using

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a triangulation scheme The mosaics were inkedup before the bromide prints were bleached out soas to leavejust the inked linework The importantpoint to note is that this technique was used formapping areas on both sides of the front line andwas therefore regarded as the final product Theflat floodplains of the Tigris and Euphrates Riverslent themselves to mapping using semi-controlledmosaics as there was an almost complete absenceof height to create displacement errors The map-ping of Mesopotamia from aerial photography seta precedent for post-war mapping in India

Flash Spotting and Sound RangingAs mentioned earlier the use of camouflage neces-sitated the development of techniques for targetlocation in particular the location of enemy gunpositions for counter-battery fire At the beginningof World War I guns were aimed by direct observa-tion of targets and the guns themselves were oftenpositioned in the open to improve their fields offire With the increased use of counter battery fireit became normal for guns to be dug in posi-tioned in gun pits and protected by sandbags Toprotect gun positions from enemy air observationthe gun pits were subsequently camouflaged withnetting which thwarted an accurate identificationof their positions

Flash spotting and sound ranging were devel-oped as means of tackling the problem of identify-ing and locating enemy gun positions Adopted byall the combatant nations flash spotting involvedintersecting the gun position by observing theflash as tht gun was fired Flash spotting requiredconsiderable organization as the observers had toensure that they were observing the same gun flashbut by carefully noting the times of the observa-tions it was possible to obtain accurate locationsof enemy guns Most armies established specialistunits for this purpose (Innes 1935 Chasseaud1999 Hinks 1919 Maule 1919)

Sound ranging was a more complex process inwhich the British and French enjoyed a technolog-ical lead over the Germans General Ludendorffthe German Chief of Staff who issued specialinstructions that precautions be taken to cam-ouflage the sound of guns directed the army tosecure an example of the British system (quotedin Hinks 1919) Based on a technical solutiondeveloped by Lucien Bull at the Institut Marey inParis the British system relied on an array of sixmicrophones spread over a 9-kilometer-long base-line situated about 4 km behind the front iine Themicrophones were connected to a galvanometer atthe hea~quarters As the sound of a gun reached

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each microphone in turn a signal was sent by wireto the galvanometer where it produced a distinc-tive trace on photographic film By measuring theseparation of the traces of the gun detected at eachmicrophone the distance and direction of the guncould be calculated Complex arrangements withmore than two microphones were needed becauseof uncertainty about the effect of wind speed andother factors on sound waves (see Innes 1935 andChasseaud 1999 for more technical details)

The German systemrelied on a fonvard observerand four other observers along a base of 10 to 15kilometers On hearing a gun firing the forwardobserver sent a signal by field telephone to theother observers who on receiving the signalstarted their stopwatches and noted the time inter-val before they heard the gun The times were thensent to group headquarters where the position ofthe gun was calculated An alternative and sim-pler method involved an observer noting the timeinterval between seeing a gun flash and hearingthe noise of the gun The greatest precision possi-ble with these techniques was about +200 meters

Non-military WartimeDevelopments to 1918

While the mapping efforts of the combatantnations were almost entirely directed towards thewar effort cartographers in the United States wereactively exploring civilian applications of pho-togrammetry The most important developmentwork was carried out at the US Geological Surveywhere James Bagley was developing a tri-Ienscamera and Fred Moffit was developing a trans-forming camera capable of handling the nega-tives produced by Bagleys camera (Committee onPhotographic Surveying 1921)

Developments to 1930In the period leading up to and including WorldWar I all the major powers followed broadlysimilar paths in developing photogrammetry Inmost countries attempts to develop instrumentalmethods complemented heavy reliance on graphi-cal and optical techniques for producing andrevising large-scale maps After the war a numberof countries took distinctly different paths withcontinental European countries generally puttingmost of their effort into instrumental techniqueswhile English-speaking countries focused ongraphical techniques Arguably until about 1930the approach adopted by the English-speaking

163

countries was the most fruitful as the instrumentaltechniques developed in Europe could not com-pete in cost or efficiency with British and Americanmethods

After 1930 the relative efficiencies of the twoapproaches changed markedly The Americansrecognized the changed circumstances morequickly than their British counterparts and beganadopting instrumental methods by the mid 1930sIn Britain and by extension throughout the BritishEmpire instrumental photogrammetry was still inthe experimental phase at the outbreak of WorldWar 11in 1939

The immediate post-war-one period saw a flurryof papers extolling the merits of mapping fromaerial photography At the forefront of the cam-paign to get the methods accepted in Britain wasCapt H Hamshaw Thomas (1919 1920 1924)who drew heavily on his experiences in the Sinaiand Palestine Much of the effort to promote airsurvey was conducted in non-specialist journalssuch as the GeograPhicalJournal (Newcombe 1920)and even in the popular press MacLeod who hadserved in France and had become a firm advocateof air survey methods also produced a numberof papers as well as an important official publica-tion Mapping from Air Photographs issued by theWar Office (MacLeod 1920 but see also MacLeod1922 1923a 1923b)

Britain more than in any other country held aconservative attitude towards the new techniquesand this resistance found an influential championin Harold StJ LWinterbotham A self-proclaimedexpert on air survey (see Winterbotham 19291934) Winterbotham did much to impede theadoption of air survey both in Britain and throughhis role on the Colonial Survey Committee in thecolonial territories In contrast the Dominion ter-ritories were free to determine their own policiesAlthough Canada a pioneer in photogrammetryhad been joined by India in its use of these tech-niques before the outbreak of the First World Warother Dominion territories were slower in adopt-ing air survey Australia took the lead but localfactors either delayed or advanced the adoptionof photogrammetry in Dominion territories whichwere not compelled to follow the Colonial SurveyCommittees recommendation There is a strik-ing parallel between these largely autonomousterritories and the Dutch East Indies where thesurvey department was quick to adopt photogram-metry (van Roon 1925) but made no real progressat home in The Netherlands until after World WarII

In the British context Winterbothams reser-vations concerning the cost-effectiveness of air

i64

survey methods were probably justified at leastuntil the development of Reinhard Hugershoffsaerocartograph in 1926 (Blachut and Burkhardt1989) All the air survey instruments introducedbefore the aerocartograph were essentially ter-restrial plotters adapted in some way to copewith non-coplanar photography This made theinstruments difficult and slow to set up and theyusually required two men to carry out orienta-tion and plotting operations In a well mappedcountry such as Britain cumbersome machinescould not support map revision as economically asconventional ground surveyhere Winterbothamerred even in the 1920s was in extrapolatingfrom the British experience to the colonial terri-tories where the needs were very different On thepositive side agitation by Hamshaw Thomas andothers as well as the successful application of airsurvey techniques by the Survey of India led to thesetting up of the AirSurvey Committee Part ofthe responsibility of this committee was to adviseon air survey matters but it was also responsiblefor carrying out research

In the United States the promotion of airsurvey techniques wasundertaken by Moffit (1920)and other surveyors who had not been directlyinvolved in the war effort but had carried on withtheir civilian work in government mapping agen-cies Part of this promotion was carried out in non-specialist journals but unlike in Britain there waslittle need to convince the political leadership ofthe advantages of air surveyBycontrast there waslittle attempt to promote air survey in France orGermany other than in technical or professionaljournals Almost certainly this reflects the higherstatus of engineers and technical experts in thosecountries compared with Britain The UnitedStates probably fell somewhere between Britainand the continental powers but more towards thelatter

Survey and mapping activities in Austria suf-fered a severe setback with the breakup of theHabsburg Empire at the end of World War 1The Militargeographische Institut was disbandedin 1920 (Kretschmer 1991) and its personneldispersed amongst the successor states Whilethis disintegration had clear disadvantages forAustria survey departments in Poland Hungaryand Czechoslovakiagained a cadre of trained andexperienced personnel able to form the nucleusof new national survey organizations Despite eco-nomic hardship in the wakeof the warAustria hadbegun in 1928 to supplement existing 175000topographic mapping work focused on the moun-tainous areas using terrestrial photogrammetry

CartografJhy and GeograPhic informationScience

Graphical MethodsBecause of the extensive use of graphical methodsduring WorldWar I a large body of trained person-nel was available to implement these methods forpost-war mapping But the techniques developedthus far were either non-rigorous (for example theperspective grid) or suitable only for revising smallnumbers of features (the paper strip method)What was needed was a rigorous technique thatdid not require highly skilled workers

Bagley had sowed the seeds of a rigoroustechnique during his work with the PanoramicPhotoalidade (Bagley 1917) but Martin Hotine(1927) provided the theoretical and practicalbasis for a cost-effective mapping techniqueDescribed as a Simple Method of Surveying fromAir Photographs Hotines technique becameknown as the Arundel Method (after Arundelin southern England where the technique wasfirst used experimentally) or the radial-line tech-nique Hotine subsequently developed the methodof control extension using radial-line methods(Hotine 1929) and laid the foundations for muchof the medium-scale photogrammetric mappingcarried out in the English-speaking world over thenext 40 years The American development of slot-ted templets and radial intersectors expeditedthe process of aerotriangulation (see below) butit was Hotines theoretical work that made thesedevelopments possible

None of the countries using aerial photogra-phy for topographic mapping embraced it withgreater enthusiasm than India As noted earlierthe Survey of India had acquired two examplesof Thompsons stereo-plotter Kenneth Mason(1913 1927) had used the stereo-plotter in 1913in the Pamirs with considerable success but theexperience of the Survey of India in Mesopotamiaduring World War I wasdecisive in promoting airsurvey techniques in India In 1920 a series ofexperiments conducted at Agra demonstrated theutility of air survey methods for mapping flat areasin India (Lewis and Salmond 1920) Air surveyp~oved inefficient for one-inch-to-a-milemiddot map-pmg-the cost was roughly twice as much as forground surveys-but it was economical for largerscales An experiment in urban mapping was car-ried out but its results were inconclusive

Among developed countries the United Stateswas probably the most in need of the advantagesthat air survey offered post-war mapmakers Forall its great wealth America was poorly mappedby European standards Where most Europeancountries were at least mapped at medium scale(roughly 1100000 or larger) large tracts of the

J1J129 No3

United States were not mapped even at small scaleIt was at just this small-scale range that air surveyseemed to offer the greatest advantages

The work carried out within the USCampGSand USGS prior to and during World War I hadprepared both agencies to take advantage of theemerging technology Starting in 1919 USCampGSused aerial photography for chart revision(Quillian 1919 Mattison 1919) and for wetlandsurveys (Mattison 1924 Graham 1924-25) Someproblems were encountered but the particularadvantages of air survey for mapping wetlands ledto the technique becoming the standard procedure(Landen 1952) In carrying out these surveys theUSCampGSused photography supplied by the Navyand the Army Air Corps it was the Air Corpsmulti-lens camera that established the cost-effec-tiveness of air survey (Reading 1927-28) Withinthe USGS a quadrangle in Michigan was mappedusing a conventional single-lens camera using airsurvey for the planimetry only (Thompson 1952)In 1924 a Section of Photographic Mapping wasestablished as part of the Topographic Branch atUSGS

Terrestrial photogrammetric work had beenundertaken in Russia as early as 1891 (Koch1963) but few significant additional developmentsoccurred before 1920 In 1924 the State TechnicalOffice of Aerial Photographic Survey was estab-lished Its first task was the creation of mosaics at110000 for comparison with plane table surveysThe results were considered sufficiently favorablefor mapping at 15000 based on 112000 pho-tography An ambitious program of aerial pho-tography initiated in 1925 led to the coverage ofmore than 4500000 km2 by 1940 In 1928 theCentral Scientific Research Institute for GeodesyPhotogrammetry and Cartography (ZNIlGAiK)was established to oversee development across thewhole field of mapping (Koch 1963)

Instrumental MethodsAt the end of World War I Germany and theAustro-Hungarian Empire had a clear advan-tage in the development and use of instrumen-tal photogrammetric methods While Germanycontinued to enjoy a considerable lead in thesetechniques the collapse of the Dual Monarchy andthe resultant breakup of the MilitargeographischeInstitut meant that Austria entered a period ofrelative decline Zeiss which had become theciear ieader in the design and man-ufacture ofphotogrammetric instruments not only pro-duced instruments designed by both von Ore and

165

Pulfrich but employed several leading figures inphotogrammetry including Walter BauersfeldWilli Sander and Otto von Gruber This ensuredthat Zeiss was always at or near the forefront ofdevelopments in the field

During the 1920s most efforts were directedtoward overcoming the problem inherent in theearlier generation of photogrammetric plot-ters namely the need for the photographs tobe coplanar In 1926 Hugershoff designed anaerocartograph for use with both terrestrial andaerial photography The instrument which wasmanufactured by Heyde Company in Dresdentook advantage of the theoretical developmentsin orientation theory developed by Max Gasser(1923) and von Gruber (1924) The combinationof new orientation procedures and sophisticateddesign meant that Hugershoffs aerocartographcould be used for plotting and aerotriangulation(Blachut and Burkhardt 1989) Professional rivalryled von Gruber (1932) to dispute the original-ity of Hugershoffs design as he was also to dowith Heinrich Wilds instruments and the ideas ofFourcade

Zeiss had produced their stereoplanigraph(the Cl) in 1921 based on an earlier design ofBauersfeld However it was not until the pro-duction of the C4 in 1930 that Zeiss producedan instrument that could handle both terrestrialand aerial photography Some successful mappingfrom the earlier models was reported throughthe 1920s by the Reichsamt fur Landesaufnahmewhich had a C2 (Seidel 1928) and the GeodeticInstitute in Stuttgart which had a C3 (von Gruber1932) Most of the mapping was at 15000 butscales as small as ] 20000 are reported Even inGermany systematic mapping programs usingphotogrammetry were still the exception ratherthan the rule during the 1920s

In France the Service Geographique de lArmeehad been actively experimenting with instrumen-tal photogrammetry before World War I (Bonnet1920) and had also used the technique for someterrestrial work during the war France was thuswell placed at the end of the war to keep upwith the developments elsewhere in Europe TheService had decided that terrestrial photogram-metry was best suited to 120000 mapping in highmountain areas but considered the equipment toocumbersome and imprecise for reconnaissancesurveys (Service Geographique de lArmee 1912)In 1919 a start was made on mapping in Moroccousing panoramic aerial photographs (ServiceGeographique de IArmee ]936) but the main

166

drive in France was to develop an autonomouscapability in instrumental photogrammetry

Some equipment had been developed duringthe war notably the Chambre Claire Varon andthe Appareil de photorestitution Roussilhe aninstrument for partial rectification of cadastralplans (Blachut and Burkhardt 1989 ServiceGeographique de IArmee ]936) The mostimportant development came in 1922 when thefirst Georges Poivilliers instrument was built(Poivilliers 1922 Blachut and Burkhardt 1989)Poivilliers instruments were to provide the bulkof the photogrammetric capability of the Servicewith up to four different types in use at anyonetime (Institut Geographique National 1947)Other instruments were also used largely on anexperimental basis In the mid] 920s the stereor-estituteur Boucard was in use and in the I930s aGallus Ferber instrument was used experimentally(Service Geographique de lArmee 1938) withthe latter (Blachut and Burkhardt 1989) remain-ing in service until at least the 1940s (InstitutGeographique National 1947)

Italy had been actively engaged in photogram-metry in the nineteenth century with the work ofPorro but as Blachut and Burkhardt (1989) notethe Istituto Geografico Militare showed little inter-est in the technique until many years after Porrosdeath in 1875 The resurrection of Italian photo-grammetry was largely due to two men UmbertoNistri who designed aplotter in 1919for large-scaleplotting and Ermenegildo Santoni who producedhis first instrument the autoreductor in 1921 In1926 Nistri founded the firm Ottico MeccanicaItaliana (OMI) to produce his photogrammetricinstruments Nistris early instruments all useddirect optical projection while Santonis instru-ments all used mechanical projection The IstitutoGeografico Militare was middotequipped with Santoniinstruments which it used for mapping at 125000and 110000 The Societa Anonima RilevamentiAerofotogrammetrici (SARA)on the other handused Nistri instruments largely for topographicmapptng outside Italy but also for cadastral map-ping within the country

Photogrammetry had been used in Switzerlandfor engineering surveys in the nineteenth centuryyet there had been no systematic attempt to carryout topographic mapping using the techniqueThe history of mapping in Switzerland betweenthe two world wars is largely a history of the WildHeerbrugg Company Set up in 1921 the com-pany produced its first phototheodolite in 1922and its first photogrammetric plotter the Alstereo-autograph in 1923 Its first major contribu-

Cartography and Geographic Information Science

tion to surveying came with the production of theT2 theodolite in 1924 The revolutionary design ofthis instrument-replacing engraved metal circleswith glass versions provided more accurate read-ings and better illumination-led to considerableexcitement in scientific and survey circles By thelate 1920s Wild was engaged in serial productionof the T2 and T3 theodolites the P3 phototheodo-lite and the A2 autograph which had replaced theAI In addition the Cl C2 and C3 aerial cam-eras were also in production In the space of onlyeight years Wild had become a major player in thesurvey world a position enhanced further duringthe 1930s

By the late 1920s the Landestopographie inSwitzerland had gained considerable experiencewith Wild instruments for both terrestrial andaerial surveys (Schneider 1929) Topographicmaps were produced from terrestrial photographyat 125000 while aerial photography wasused for110000 mapping (Schneider 1929 Harry 1971)

In the United States in addition to usinggraphical techniques the USGS started to inves-tigate instrumental methods In 1921 it obtaineda stereoautograph from Germany for evalua-tion but restricted the use of the instrument toplotting from terrestrial photography and notable to produce maps economically (Thompson1952) In 1927 the Geological Survey acquired theHugershoff aerocartograph the first automaticstereo-plotter used by an American governmentmapping agency (Thompson 1952) Thomas PPendleton laid down guidelines for mapping fromaerial photography within the USGS in Bulletin788-F Map Compilation from Aerial PhotograPhsissued as part of the Topographic Instructions of theUnited States Geological Survey (Pendleton 1928)Given the rapid developments in radial-line meth-ods (eg Hotine 1927) the timing of Pendletonswork was a bit unfortunate as he asserted thatradial-line techniques were really only suited foruse with multi-lens photography because therelatively short radial lines that could be drawnon single-lens photographs could not give the bestresults (Pendleton 1928 p 409)

In Britain research work carried out by the AirSurvey Committee focused on simple methods butthe Committee did not entirely ignore instrumen-tal techniques MacLeods wartime work with rec-tifiers was developed and more importantly theideas of Fourcade (l926a 1926b 1926c 1926d)on the theory and use of stereogoniometers forphotogrammetric plotters were taken up In 1926the Committee commissioned the constructionof an instrument along the lines proposed by

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Fourcade and the instrument was delivered in1928 0ar Office 1935 Hotine 1931)

In India success with non-instrumental tech-niques did not distract the Survey from instrumen-tal techniques they had helped pioneel- Mappingofficials followed developments taking place inEurope and in 1926 Mason (1927) carried outa survey in the Shaksgam using a Wild photo-theodolite and plotted the results in Switzerlandusing an autograph in the Topographical Instituteat Flums

CamerasThe tri-lens camera developed by Bagley was usedby the USGS in mapping for aeronautical chartsThis program wasjointly organized with the Corpsof Engineers and the Air Service (Committeeon Photographic Surveying 1921) and providedvaluable experience in civil applications In 1920programs with the tri-lens camera were also under-taken in Santo Domingo and Haiti

The Corps of Engineers became involved inphotogrammetric methods in 1920 when Bagleywas assigned to cooperate with the Army AirCorps in carrying out tests on aerial photographyfor topographic mapping Initially the trials usedBagleys tri-lens camera but he went on to developthe five lens T-3Acamera which was to remain thestandard mapping camera of the US Army until1940 (Landen 1952) The War Department issuedtraining regulations for mapping from aerialphotography in 1923 however the techniques dis-cussed in the regulations were largely those refinedduring World War 1

The 1930sBy the late 1920s photogrammetry had becomea cost-effective alternative to some traditionalground surveys Yet expensive photogrammetricplotting instruments and labor-intensive graphicalplotting meant that photogrammetry still lackeda decisive advantage over ground survey Duringthe 1930s a number of innovations were to swingthe balance decisivelyin favor of photogrammetricmethods

Progress was slowed if not stopped by the reces-sion that started in 1929 Some measure of theimpact can be gauged from job cutbacks at WildHeerbrugg In 1930 before the recession had amarked affect on Europe the workforce stood at260 but by 1933 the number ofjobs had droppedto 125This was the direct consequence of the deci-sions taken to retrench mapping projects as well as

167

capital programs Nearly all the annual reports forthe early 1930s mention the financial constraintsunder which organizations had to work In theUnited States some of these problems were offsetby appropriations under the Emergency Reliefand Construction Act (US Coast and GeodeticSurvey 1933) Moreover the New Deal initiated awide range of programs in which photogrammetrywas to playa major role By contrast problems inthe colonial territories were if anything worsethan in Europe and North America The declinein industrial activity in developed countries ledto a collapse in demand for raw materials fromthe colonies and as this was the main source ofgovernment revenue they could no longer pay forsurvey work Annual reports from most colonialsurvey departments make reference to a lack ofresources to meet the need for mapping Howevel~by the late 1930s as a result of rearmament inEurope governments allocated more money tosurvey organizations

Survey organizations were eager to adopt newtechniques in routine mapping programs but thepressures within governments to deal with massunemployment probably helped to promote theuse of labor-intensive methods in survey at theexpense of investment in technology Certainlyorganizations such as the Tennessee ValleyAuthority (TVA) the Agriculture AdjustmentAdministration and the Soil Conservation Servicein the United States were all heavily dependenton such labor-intensive techniques and did muchto develop them as standard mapping methodsMoreover organizations such as the USGS andthe TVA also played a role in the developmentinstrumental methods such as multiplex All ofthis was to be of vital importance to the hugephotogrammetric mapping programs that wereto emerge during World War II The scale of theseprograms would have been inconceivable withoutthe trained body of photogrammetrists developedduring the 1930s (Landen 1952)

Within the British colonial territories the conser-vative element that had inhibited the developmentof photogrammetric methods through the 1920scontinued to delay adoption of photogrammetryuntil after World War II-with some illuminatingexceptions Cyprus is the only known example ofa local survey department attempting to carry outphotogrammetric work Aerial photography wastaken in 1936 but delays in obtaining groundcontrol meant that no use was made of the pho-tography before all normal work was suspended atthe outbreak of war In all the other colonies wherephotogrammetry was attempted private survey

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companies carried out the work The earliestexample of the involvement of private air surveycompanies had been in 1927 in the mapping ofthe Anglo-Belgian boundary in the Copper Beltregion of Northern Rhodesia (Colonial SurveyCommittee 1928) Private air survey companieswere also active in Uganda Tanganyika andSouthern Rhodesia but in all cases this was surveywork for specific development projects ratherthan routine mapping (War Office 1935) Therewere discussions about the use of photogramme-try in Sierra Leone where the Aircraft OperatingCompany of South Africa proposed to revise the162500 topographic maps for pound150000 includ-ing the cost of providing ground control but thework was never carried out due to financial con-straints and the outbreak of World War II Therewere also discussions about air survey in Jamaicaand the Gold Coast but nothing came of theseprojects until after World War II It is clear fromthe literature and correspondence of the time thatthe private air survey companies were lobbyingindividual colonial governments as well as theBritish Government to adopt air survey but theColonial Survey Committee under Winterbothamwas equally forceful in its resistance to changelargely on grounds of cost (see in particularWinterbotham 1920 1921 1929 1934 1936Hemming 1933)

Increasing recognition that war with Germanywas inevitable led to a significant change in theBritish establishments attitude towards the use ofair survey In part this change reflected the retire-ment of Winterbotham in 1935 and his replace-ment as Director General of the Ordnance Surveyby MacLeod who was alwaysa warm supporter ofair survey MacLeod had followed Winterbothamfirst as Director of Military Surveys and then atthe Ordnance Surveyand in each case he playeda major role in introducing the use of photogram-metry (Clough 1952)

Advances in InstrumentationThe late 1920s had seen the design and produc-tion of the first practical plotting machines for usewith aerial photography The experience provideda foundation for the introduction during the1930s of designs that were to be the mainstaysof topographic mapping The Zeiss C4 had beenintroduced in 1930 (Burnside 1993)AsThompson(1966) notes the C4 and the superseding C5(introduced in 1935 with improved illumination)were with the Wild A5 (launched in 1937) practi-cally the only universal instruments on the marketin the 1930s Universal instruments designed to

CartograPhy and GeograPhic Information Science

handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

Vol29 No3

graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

169

Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

170

world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

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Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

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Figure 1 The state of world topographic mapping about 1900 (after Bartholomew 1890 Robinson projection)

whole Empire had been mapped by plane tablesurvey at 125000 between 1869 and 1887 anda new survey the Prazisionsaufnahme had beeninitiated in 1896 using tacheometry (Kretschmer1991)

Belgium had been mapped at 110000 and TheNetherlands was mapped at 125000 By contrastthe Spanish Instituto Geografico Estadistic hadmade relatively slow progress with the 150000Mapa Topografico Nacional which had beenstarted in 1870 Portugal had also started work on150000 mapping (in 1893) with the first sheetappearing in 1900

In Scandinavia the picture was mixed with 1100000 maps being produced in Norway (althoughcoverage was far from complete) while in Sweden1100000 was used for the southern parts of thecountry and 1200000 for northern parts InDenmark a variety of scales were published fordifferent parts of the country but in 1891 the scaleof 1100000 had been adopted as standard

North America and India were the only otherparts of the world that can be said to have hadproper mapping programs Even in NorthAmerica the volume of mapping available was rel-atively small Mapping at scales of 131680 and 124000 was available in the United States for townsand special projects while settled rural areas weremapped at a scale of 162500 For the rest of theUnited States the largest scales available were 1125000 or 1250000 In total topographic map-ping covered nearly 26 percent of the continental

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United States In Canada the only topographicmaps were at 1190080 reduced from 131680cadastral sheets The first true topographic mapswere not to be produced until 1906

One of the first tasks undertaken by the EastIndia Company when it acquired control of terri-tory in India was to carry out surveywork Much ofthe mapping was for fiscal purposes but admin-istration control and defense all required theproduction of topographic maps In consequencethe Survey of India can claim to be one of theoldest national mapping agencies By the end ofthe nineteenth century most of British India wasmapped at various topographic scales

In the newEuropean colonies ofAfricaalmost nomapping existed In the British Empire this led tothe setting up of the Colonial SurveyCommittee in1905 In the first report of the committee (ColonialSurvey Committee 1906 pp 3-4) the need formapping was set out in the introduction

The purposes for which maps are requiredin the administration of a country (especiallyan undeveloped country such as a protector-ate in Tropical Africa) are many and variedMaps are necessary to define the exact limitsof national territory to show the areas andvillages under the rule of native chiefs theyare essential for land registration and settle-ment for the allotment of mining and forestconcessions and for the organization ofinternal communications Of their necessityin war the experiences of the army in South

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Africa afford an eloquent testimony and eventhe conduct of a small war or a police expe-dition is much simplified by the existence ofreliable maps of the scene of operations

With very few exceptions the topographic map-ping available in 1900 had been produced usingground survey techniques Although the conceptof photogrammetry had been discussed since thelate 1850s (Laussedat 1860) very little had actu-ally been achieved The only extensive mappingundertaken using photographs had been that inCanada by Eduard Deville (1895) Although anumber of Europeans had in the 1890s carriedout alpine mapping using terrestrial techniquesthe equipment necessary to carry out the work costeffectivelywas not yet available in 1900

Indeed the survey techniques being used by landsurveyors in 1900 were little different from thoseused in 1800 Because accurate distance measure-ments were difficult and expensive to acquire allcontrol networks used for medium- and large-scaletopographic mapping were based on triangulationAlthough the discovery of invar (an alloy of steeland nickel with a very low coefficient of expansionwith heat) in 1896 was to make accurate distancemeasurement easier it was not until the develop-ment of electromagnetic distance measurementin the 1950s that alternatives to triangulationbecame possible Traversing for lower-order con-trol networks was used in colonial territories butonly if small-scale mapping was to be producedTraversing was also used for mapping during mili-tary operations (Close 1905)

The theodolite had undergone improvementsduring the nineteenth century These werelargely the result of improvements in the dividingengines used to graduate the horizontal and verti-cal circles Consequently it was possible to makebetter measurements on instruments with lO-inchcircles in 1900 than it had been on instrumentswith 36-inch circles in 1800 Accurate reading oftheodolite angles depended on the use of verni-ers or micrometers Vernier instruments werepreferred for expeditions and surveys in roughconditions because they were lighter and morerobust than the micrometer instruments (Reeves1933) Edward Reeves was to make a significantimprovement in theodolites with the developmentof the tangent micrometer a device which madeaccurate reading of the circles easier and perhapsmost importantly could be retrospectively fitted toexisting instruments (Close 1905 Reeves 1933)Similar devices were to be incorporated into thedesigns of theodolites from the major manufac-turers The most significant improvement in the

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design of theodolites occurred in the twentiethcentury when the lead in design passed fromBritain to Switzerland and Germany

Another development adopted by surveyors wasthe use of the telegraph for the transmission oftime signals This technique became common forthe determination of longitude until supersededby the use of radio time signals in the 1920s

Emerging TechnologyAt the beginning of the twentieth century Themost important emergent technology was with-out doubt the use of photography for surveyingAlthough attempts had been made to captureand use aerial photography the lack of a stableand reliable aerial platform meant that the useof photography was restricted to terrestrial pho-togrammetry In 1893 C B Adams had proposeda method for plotting by intersection from bal-loon photographs (US Patent 510758) Althoughthis approach never led to a practicable mappingtechnique it provided the conceptual basis for theradial-line techniques in vertical aerial photog-raphy To use terrestrial photography cost effec-tively in mapmaking it is necessary to elevate thecamera above the surface to be mapped or place itat a sufficient distance from the surface to permitcoverage of a large area In practice this meantthat terrestrial applications were best carried outwhere there were natural vantage points such asmountains and high hills

Terrestrial photogrammetry had first been dem-onstrated by Aime Laussedat in 1859 (Blachut andBurkhardt 1989) although he was at first limitedby the wet plate process Ignazio Porro in Italyand Dr A Meydenbauer in Germany improvedupon Laussedats work These early attempts allinvolved the use of graphical techniques to plotthe detail and contours from photographs Theprocess of map creation from photographs wasthus slow and laborious and it tended only to beused where difficult terrain made plane table workimpractical For the photogrammetric approach tobecome more cost effective a method of automat-ing the plotting was needed Work on developingsuch a method was being actively pursued in anumber of countries at the turn of the century

The Canadian experience had led to a system-atic use of terrestrial photography for topographicmapping along the Alaska-Canada boundary byboth Canadian and American members of thesurvey party John Flemer ofthe US Coast andGeodetic Survey (USCampGS)was assigned to makea study of European methods which led to the first

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American textbook on photogrammetry (FIemer1906) Even so this did not lead to the widespreadadoption of photogrammetry within the USCampGSas photographic techniques could still not competewith the efficiency of existing techniques (Landen1952) In 1904 the US Geological Survey (USGS)which was also interested in the use of terrestrialphotogrammetry adopted Devilles panoramiccamera approach for mapping in Alaska JamesBagley further developed the technique by rede-signing the camera and producing a panoramicphoto alidade (Bagley 1917)

Photogrammetry to 1914Until the outbreak of World War I the chief focusof photogrammetry remained terrestrial appli-cations In 1901 Henry Fourcade described amachine designed to make measurements fromstereoscopic photographs essentially a stereocom-parator (lltourcade 1901) At about the same timeCarl Pulfrich (1902) produced and described thePulfrich Zeiss stereocomparator During the 1930sthere was considerable debate over the precedencein producing a serviceable design for a stereocom-parator Otto von Gruber (1932) gives precedenceto Pulfrich by citing his 1902 paper and the 1902paper by Fourcade which appeared in Nature Butas noted above the Fourcade design was first dis-cussed in a paper published in 1901 albeit in arelatively obscure journal It is not clear whethereither designer was aware of the work of the othereven if they both produced very similar designsThis notwithstanding it is worth noting that vonGruber was also to dismiss Fourcades claim toprecedence over his own work in the design ofan instrument that employed the concept of thestereogoniometer Martin Hotine (1931) makes astrong case in support of Fourcade s precedence inboth cases Both machines could be used to makeaccurate stereoscopic measurements of pointsbut because the plan positions and heights of thepoints were computed individually maps producedfrom these measurements required interpolation

While these early machines demonstrated thepossibility of making accurate maps from stereo-scopic photographs the technique was extremelytime consuming and only suitable if no othertechnique was available Appropriate conditionsexisted in alpine mapping where ground surveywould have been hazardous or even more timeconsuming than photogrammetry Early examplesof photogrammetrically derived contours were pro-duced in the Tyrol between 1902 and 1907 by theAustrian survey using the Pulfrich stereocompara-

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tor (Kretschmer 1991) Both the Prussian GeneralStaff and later the French Service Geographiquede lArmee adopted the Pulfrich stereocompara-tor for mapping mountainous areas in Pelvoux(Service Geographique de lArmee 1912 1938)However there was general recognition that thetechnique was not cost effective(see the commentsof Major Hills followingThompson 1908)

What was needed to make the use of photogra-phy cost effectivewas the ability to produce topo-graphic details and contour lines directly from thephotographs rather than by manual interpolationIn 1908 Eduard von Orel produced his autoste-reograph (von Ore11910 1911 1912von Gruber1932 Hotine 1931 Kretschmer 1991) and in thesame year Vivian Thompson published details ofhis stereoplotter (Thompson 1908 von Gruber1932 Hotine 1931 Thompson 1974 Petrie 1977Burnside 1995) Both machines were capable ofproducing plotted detail lines and contours fromterrestrial photographs The autostereographwas quickly adopted by the Austrian survey foralpine mapping and was subsequently taken up byother national mapping departments The largestsystematic survey carried out with the autostereo-graph was some 560 km2 of the Tyrol surveyed in1911 by the Militargeographische Institut (Koner1924) Bycontrast the stereoplotter attracted littleinterest in its country of origin Great Britain butwas adopted by the Survey of India for mappingin the Karakorum Range Because these areashave not subsequently been remapped the origi-nal contours from the stereoplotter are still thoseused on the published sheets One plotter was alsoacquired for survey work in Fiji where McCawused it for mapping prior to WorldWarI (ColonialSurvey Committee 1911 1912 1913)

Both machines were suitable for mapping fromterrestrial photographs as were machines devel-oped from von Orels autostereograph (Therewere no developments from the stereoplotter)Howeverbecause both solutions required coplanarphotographs they could not be readily adaptedfor use with aerial photography which is rarely ifever coplanar This fact did not stop many abor-tive attempts to turn terrestrial photogrammetricplotters into machines capable of handling aerialphotographs

A non-technical development that was to havea significant impact on the development of pho-togrammetry was the founding of the AustrianSociety of Photogrammetry in 1907 followedby the publication in 1908 of the first volumeof the lnternationales Archiv flir PhotogrammetrieThe International Society for Photogrammetry

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was founded in Vienna in 1910 Vienna was alsothe setting for the first International Congressfor Photogrammetry in 1913 The Society wasto become one of the main vehicles for the dis-semination of information on photogrammetrywhile the congresses were the main showcases forthe latest equipment Previously the InternationalGeographical Union was the main forum for thedissemination of developments in surveying andphotogrammetry but its importance had contin-ued to decline until after World War II when italmost completely withdrew from the field

World War I (1914-1918)World War I generated an unprecedented demandfor maps at scales from 1200 for detailed trenchmaps (Chasseaud 1999) to 11000000 andsmaller for strategic planning maps (Heffernan1996)At the outbreak of war in 1914 the armies ofEurope were issued with maps at scales of 180000or smaller designed to support a war of rapidmovement in which victory would be achievedby bringing to bear an overwhelming force in adecisive battle Military leaders still believed thatoffensive operations could be successful despitethe precedent of the Russo-Japanese War of 1905which had degenerated into sieges and large bat-tles of encounter in which opposing armies foughtin the open rather than in prepared positionsNeither side could achieve a decisive blowbecauseof the superiority of defense based on rifles andmachine guns

The strength of the defenses meant that if therewas to be any hope of success in offensive opera-tions the attacking troops needed accurate mapsof the enemy defenses This included the positionsof any artillery ammunition dumps and transportinfrastructure Allof these features were difficult orimpossible to map from the front line In the caseof ammunition dumps and transport the targetscould be many miles behind the front What thearmies of both sides needed wasa wayof collectinginformation that could either be added to existingmaps or used to produce entirely new maps Mostimportantly as the artillerymen developed evermore accurate targeting they created a demandfor increasingly precise mapping to locate poten-tial targets As the war progressed the armiesexperimented with a closer integration of artilleryand infantry operations such as the rolling bar-rage (a barrage where the gunner slowlyincreasesthe range while infantry advance slowlybehind thebarrage) Again this required more precise point-ing of guns and locating of targets

Vol 29 No3

Suneyors were used to fix the position of bothguns and targets The need for secrecy-no pointin alerting the enemy that an attack was beingprepared-also changed the ways in which theguns acquired their targets Early in the war thenormal technique involved the use of rangingshots That is each gun was fired towards a poten-tial target and an observer identified the fall ofshot The obsener then told the gunner to eitherincrease or decrease the range as appropriateand to traverse left or right until the shot was fall-ing on the target The problem with this techniquewas that it revealed that a new gun had been intro-duced into a stretch of the front A large number ofranging shots revealed the introduction of a largenumber of guns and the threat of a forthcomingattack To overcome this dilemma the positions ofthe guns and targets needed to be determined pre-ciselyby surveying From this information artilleryboards were prepared to show the positions of theguns as well as the targets It was then possible todetermine the directions in which the guns neededto fire and the range to the target without reveal-ing that new guns had been positioned

The identification of targets and the accuratepositioning of guns led all the nations to adoptthe use of grids on their mapping In the latenineteenth century John Ardagh had tried toget a grid system adopted by the Survey of Indiabut without much success (Ardagh 1893) Prior toWorld War I therefore almost no maps carriedgrids The exceptions were the squared mapsused by the French artillery on maneuvers atChalons in 1911 (Chasseaud 1999) Increased useof indirect fire underscored the need for griddedmaps Unfortunately grids were adopted on an adhoc basis which led to considerable confusion Forexample the Germans used three different gridsystems with origins at Lille Rheims and Paris(Hinks 1919)The British adopted an imperial gridbased on 1000-yard grid squares even though theentire mapping on the Western Front used metricscales Despite this uncertain start it was quicklyrealized that grids had uses well beyond those ofwarfare and they became a standard feature ofmost post-war topographic mapping

Military mapping in Europe was largely focusedon map revision whereas that in Palestine Sinaiand Mesopotamia involved considerable origi-nal mapping (Collier 1994 Collier and Inkpen2001) In the initial stages of the World War I allthe belligerents used existing pre-war mappingsupplemented by photographic enlargements InFrance this involved the use of 180000 mappingsubsequently enlarged to 140000 When how-

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ever the deficiencies of the enlargements becameevident they were replaced by new mapping Onlythe German survey seems to have continued to useenlargements through to the end of the war aack1920) With the development of positional warfare140000 mapping wassoon found to be inadequateand was successively complemented by mappingat 120000 and 110000 Where necessary evenlarger scales were used (Chasseaud 1999)

Behind the lines revision and new surveys werecarried out using conventional land survey tech-niques trigonometrical control surveys and theplane table to add detail Oack 1920 Winterbotham1919a 1919b Service Geographique de lArmee1938 Albrecht 1969 Chasseaud 1999) For front-line areas and for the enemys rear areas the maindata source was aerial photography

The Development of CamerasInitially photography for intelligence and maprevision involved the acquisition of photographyfrom fairly low flying aircraft using largely impro-vised camera equipment With the development ofanti-aircraft defenses however reconnaissance air-craft were forced to fly higher and higher to avoidbeing shot down To compensate it became neces-sary to devise cameras with longer and longer focallengths if the resultant photography was to be ofuse for analysis and mapping

The earliest cameras were simple devices thatused glass plates and dark slides (devices used tochange glass negatives in a camera without expos-ing the negatives to light) Images were obtainedby observers pointing the cameras over the side ofthe aircraft The cameras were fitted with simplesighting devices to ensure that the target wasactually imaged Recognition that vertical photo-graphs were much better suited to mapping thanthe oblique pictures taken with hand-held camerasled to the cameras being fixed to the side of theaircraft Fairly quickly magazines were providedso that a series of photographs could be taken bythe observer activating a lever to change platesEven so changing the magazines still required theobserver to lean over the side of the aircraft Giventhese difficulties it seems strange that roll filmwas not used earlier especially since panoramiccameras had used it as early as the late nineteenthcentury The Germans did not introduce a filmcamera until 1916 (Albrecht 1969) and the Britishcontinued to use plate cameras until the end ofthe war

Most of the cameras used for military operationshad relatively long focal lengths the standardBritish camera in the early part of World War I had

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a focal length of 8 inches (approximately 200 mm)while the standard German camera had a focallength of 180 mm (Albrecht 1969) By the end ofthe war focal lengths of 500 mm were not uncom-mon-some German cameras had focal lengths aslarge as 1200 mm (Albrecht 1969) These lenseswere designed for reconnaissance rather thanmapping so that each photograph covered only asmall area of ground Cameras needed wide-anglelenses to minimize the amount of control neededfor mapping but none of the high-quality lensesavailable provided a wide field of viewMulti-lenscameras were developed in the nineteenth centuryto obtain broader coverage from each exposurestation but these cameras were generally largeand cumbersome and thus unsuited for militaryoperations

Control for MappingEarly attempts at using aerial photography formap revision experienced considerable difficul-ties As Malcolm MacLeod (1919 pp 382-83)noted though the photographs showed all theprincipal topographical features in great detailthere was no means of determining their exactscale or the amount of distortion due to thecamera not being truly vertical at the moment ofexposure of the plate In the absence of mechani-cal restitution instruments to overcome theseproblems two possible solutions were consideredto develop a device for mechanically determiningthe altitude and tilt of the camera at the momentof exposure or to compare the positions of pointson the photographs with their known ground coor-dinates Although both sides experimented with amechanical solution most work involved the lattertechnique This placed a heavy demand on accessto ground coordinates

The provision of control points both in andbeyond their own front line was a major problemfor all the combatant nations Placing markersover control points in frontline areas and thenfixing them by observation from the rear was notfeasible as this also enabled the enemy to fix theposition of the trenches A number of strategieswere adopted including the use of periscopictheodolites employed from within the trencheswithout exposing observers to enemy fire Thesetheodolites could be used to fix positions withinthe trenches by resection

While resection on the plane table was a com-monly used technique among topographers ithad not been widely used for instrumental obser-vations because of the relative complexity of thecalculations However the conditions of trench

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warfare left few alternatives Once adopted resec-tion remained in common use among surveyorsAn alternative adopted by the Germans was to firea flare vertically from the trenches and obsenTethe flares position from the rear using theodolitesGack 1920)

Locating control points beyond the front line waseven more difficult Where possible the position ofprominent points would be fixed by intersectionHowever in Mesopotamia there were often too fewsuitable features to intersect This led to an inno-vation by Col C P Gunter to fix control pointswithin the Turkish lines using artillery shell burstsFour observers took simultaneous observations ofindividual shell bursts while an observer in anaircraft recorded the position of the explosionson a detailed map of the trenches created from airphotographs On average out of ten shell burststhree good intersected points were observed andthe observer would have accurately marked one ofthese Points observed in this way were then usedto control and adjust the strips of photographyused for mapping (Surveyof India 1925)

Plotting DetailOnce control had been obtained it was necessaryto interpret and plot the information on photo-graphs Initially interpretation was relatively easyas there was little attempt to conceal potentialtargets from aerial observation Camouflage onlystarted to be used systematically around 1916(MacLeod 1919) thereafter photo-interpretationdeveloped into a specialist skill Use of camouflagealso led to the development of new surveyingtechniques such as flash spotting and soundranging

Extraction of detail for revision purposes wasdone by some form of graphic intersection orthrough the use of optical projection Despite someuse of more rigorous methods involving compara-tors developed before the war these instrumentstogether with the necessary calculations were slowand not well suited to the urgent needs of the warThe use of automatic plotters such as the alitoste-reograph was restricted to terrestrial photographydue to the need for coplanar photography In factthis technique was used only by the Germans andFrench in eastern France where relief was suitableand by the Austro-Hungarian Army in the AlpsOskar Albrecht (1969) also refers to the use of ter-restrial photogrammetry for artillery assaults onfortresses and the use of photographs taken fromtethered balloons

The belligerent powers employed a variety ofgraphic techniques The simplest involved the pro-

Vol 29 No 3

duction of a framework of existing detail on a com-pilation sheet on which new detail was added fromaerial photographs with the help of proportionaldividers Although capable of producing reason-ably accurate results this approach was labori-ous and slow (MacLeod 1919) The paper stripmethod (Thompson 1966) used for adding smallamounts of detail was equally slow and laboriousThe German Army developed a less strenuoustechnique based on the use of perspective gridsThe chief advantage of this technique was thatonce the grids had been generated detail could betransferred by eye from aerial photograph to mapThis technique was so successful that it was widelyadopted after the war for map revision Describedin most standard textbooks on photogrammetrythe perspective grid approach remained in useuntil the 1980s when simple digital techniquesrendered it obsolete

Most of the optical revision techniques reliedon the registration of a projected image of thephotograph on an existing map or on a frame-work of control Once the image was registeredthe mapmaker could either transfer the informa-tion directly to the map or produce a correctedphotographic print for use in revision TheodorScheimpflug had shown that an accurate regis-tration could be affected between the projectedimage and the control data if the projected imagewas in focus for the entire image area To satisfYthe so-called Scheimpflug condition the projectedplanes of the negative lens and easel had to meetat a common axis (Scheimpflug 1898 Blachutarid Burkhardt 1989) Even if the condition wassatisfied there were still errors of registration dueto relief displacement In the instruments usedduring World War I the Scheimpflug conditionwas hot satisfied and consequently the resultswere at best approximate (Blachut and Burkhardt1989) MacLeod (1919 1920) describes the use ofCamera Lucida and the enlarging lantern inboth of which the plane of the negative and theplane of the lens were held parallel with only thecopy board which was capable of being tilted Theeniarging lantern could maximize the depth offocus and hence the sharpness of the iinagebyreducing the aperture of the lens to the smallestdiameter possible The use of the enlarging lan-tern to produce semi-rectified prints came to bethe preferred techrnque

As already noted while most of the work onthe Western Front involved map revision innon-European theaters the need was for originalmapping (Collier 1994 Collier and Inkpen 2001)The first attempts to use aerial photography to

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construct original mapping took place during theGallipoli campaign (Dowson 1921) Not very suc-cessful these attempts demonstrated the problemsassociated with the non-stereoscopic use of aerialphotography as when troops were sent to occupypositions identified monoscopically as trenchesor ditches but which turned out to be shallowscrapes that afforded no shelter from enemy fireAttempts to create original mapping ceased whenmodern Turkish maps of the area were capturedand revised

In Egypt the Turkish threat to the Suez Canalalso resulted in experiments in mapping fromaerial photography Like the mapping in Gallipolithese were largely unsuccessful The main problemwas locating precisely where the photographs hadbeen taken over a largely featureless desert Thebulk of the mapping for the Suez Canal defenseswas therefore carried out by triangulation andplane table survey (Maule 1919)

When the Egyptian Expeditionary Force (EEF)advanced across the Sinai Peninsula to engageTurkish forces in Palestine it moved into terri-tory without up-to-date mapping of an adequatescale Western Palestine had been mapped for thePalestine Exploration Fund (PEF) in the 1870s(Conder 1878 Conder and Kitchener 1881-83) ata scale of 163360 Although based on triangula-tion the detail had been surveyed using compassand cavalry sketching board (Close 1932) and wastherefore regarded as insufficiently accurate formodern warfare British military personnel hadsurveyed Southern Palestine just before the warunder the cover of a PEF expedition (Woolleyand Lawrence 1914) But even here the scale wastoo small (1 125000) for the kind of operationsbeing undertaken The British army was thereforeconfronted with the need to map areas beyond itsfront line for which no adequate base maps wereavailable

The first successful attempts at mapping fromaerial photographs were in t~e area aroundGaza (Gavish and Biger 1983) Here control wasprovided by the intersection of prominent pointsbehind Turkish lines Based on these points acontrolled mo~aic was created from with verticalaerial photogriphs and the mosaic was then usedto crcate the line maps of the planimetry Althoughcrude by later standards the map was consideredto be a significant improvement on anything thenavailable This encouraged the surveyors led byMajor W] Maule to embark upon an ambitiousplan to create a series of topographic maps at 140000 for areas of Palestine behind Turkish lines(Maule 1919) Strips of photography were flown

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roughly parallel to the front line with additionalstrips of photography perpendicular to the frontflown at intervals to control the strips parallel tothe front Supplementary control was provided bytheodolite observations wherever possible Thesame basic arrangement pioneered in the map-ping of Gaza was followed for the series mappingHowever as the area mapped extended into thehills of Judea (the southern West Bank) it alsobecame necessary to provide some indication ofrelief Viewing the photography stereoscopicallyand form lining achieved this The nature of thetopography nearly horizontally bedded lime-stones that eroded into natural terraces madethis task relatively easySuccessfulas the mappingwas (Thomas 1919) as each new area came underBritish control mapping derived from air photoswas replaced bymapping made using conventionalground survey techniques

In a number of ways the mapping inMesopotamia can be regarded as the first exampleof true photogrammetric mapping using aerialphotography Unlike the mapping in Palestineit was produced as the end product not as aninterim solution to be replaced as soon as groundsurveys became possible And unlike the mappingon the Western Front it did not involve revision ofexisting mapping as no proper maps existed forthe area

Although developments in the use of air pho-tography had been watched with envy by thesurveyors in Mesopotamia (Survey of India 1925)until early 19I6 no airplanes had been availablefor that theater Some experience in the use ofaerial photography had been gained before thesiege of Kut-al-Amarah but it was the positionalfighting around Kut that emphasized the advan-tages of air survey Maps were required of areasbehind Turkish lines but the flat landscape meantthat surveyscould only be extended into no-mans-land This led to the first real attempt to createmaps from aerial photography As the first mapTC4 (TC are the initials of Tigris Corps theoriginal name of the force sent to Mesopotamia)has been discussed at length elsewhere (Collier1994 Pritchard 1952 Survey ofIndia 1925)

The surveyors working in Mesopotamia experi-mented with various ways of making maps fromaerial photographs drawing on the experience ofsurveyors on the Western Front and in Egypt Inthe end though they developed their own tech-nique which was well suited to local conditionsTheir technique involved creating semi-rectifiedphotographs using an enlarging lantern (Gunter1917) and then mosaicing the photographs using

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a triangulation scheme The mosaics were inkedup before the bromide prints were bleached out soas to leavejust the inked linework The importantpoint to note is that this technique was used formapping areas on both sides of the front line andwas therefore regarded as the final product Theflat floodplains of the Tigris and Euphrates Riverslent themselves to mapping using semi-controlledmosaics as there was an almost complete absenceof height to create displacement errors The map-ping of Mesopotamia from aerial photography seta precedent for post-war mapping in India

Flash Spotting and Sound RangingAs mentioned earlier the use of camouflage neces-sitated the development of techniques for targetlocation in particular the location of enemy gunpositions for counter-battery fire At the beginningof World War I guns were aimed by direct observa-tion of targets and the guns themselves were oftenpositioned in the open to improve their fields offire With the increased use of counter battery fireit became normal for guns to be dug in posi-tioned in gun pits and protected by sandbags Toprotect gun positions from enemy air observationthe gun pits were subsequently camouflaged withnetting which thwarted an accurate identificationof their positions

Flash spotting and sound ranging were devel-oped as means of tackling the problem of identify-ing and locating enemy gun positions Adopted byall the combatant nations flash spotting involvedintersecting the gun position by observing theflash as tht gun was fired Flash spotting requiredconsiderable organization as the observers had toensure that they were observing the same gun flashbut by carefully noting the times of the observa-tions it was possible to obtain accurate locationsof enemy guns Most armies established specialistunits for this purpose (Innes 1935 Chasseaud1999 Hinks 1919 Maule 1919)

Sound ranging was a more complex process inwhich the British and French enjoyed a technolog-ical lead over the Germans General Ludendorffthe German Chief of Staff who issued specialinstructions that precautions be taken to cam-ouflage the sound of guns directed the army tosecure an example of the British system (quotedin Hinks 1919) Based on a technical solutiondeveloped by Lucien Bull at the Institut Marey inParis the British system relied on an array of sixmicrophones spread over a 9-kilometer-long base-line situated about 4 km behind the front iine Themicrophones were connected to a galvanometer atthe hea~quarters As the sound of a gun reached

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each microphone in turn a signal was sent by wireto the galvanometer where it produced a distinc-tive trace on photographic film By measuring theseparation of the traces of the gun detected at eachmicrophone the distance and direction of the guncould be calculated Complex arrangements withmore than two microphones were needed becauseof uncertainty about the effect of wind speed andother factors on sound waves (see Innes 1935 andChasseaud 1999 for more technical details)

The German systemrelied on a fonvard observerand four other observers along a base of 10 to 15kilometers On hearing a gun firing the forwardobserver sent a signal by field telephone to theother observers who on receiving the signalstarted their stopwatches and noted the time inter-val before they heard the gun The times were thensent to group headquarters where the position ofthe gun was calculated An alternative and sim-pler method involved an observer noting the timeinterval between seeing a gun flash and hearingthe noise of the gun The greatest precision possi-ble with these techniques was about +200 meters

Non-military WartimeDevelopments to 1918

While the mapping efforts of the combatantnations were almost entirely directed towards thewar effort cartographers in the United States wereactively exploring civilian applications of pho-togrammetry The most important developmentwork was carried out at the US Geological Surveywhere James Bagley was developing a tri-Ienscamera and Fred Moffit was developing a trans-forming camera capable of handling the nega-tives produced by Bagleys camera (Committee onPhotographic Surveying 1921)

Developments to 1930In the period leading up to and including WorldWar I all the major powers followed broadlysimilar paths in developing photogrammetry Inmost countries attempts to develop instrumentalmethods complemented heavy reliance on graphi-cal and optical techniques for producing andrevising large-scale maps After the war a numberof countries took distinctly different paths withcontinental European countries generally puttingmost of their effort into instrumental techniqueswhile English-speaking countries focused ongraphical techniques Arguably until about 1930the approach adopted by the English-speaking

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countries was the most fruitful as the instrumentaltechniques developed in Europe could not com-pete in cost or efficiency with British and Americanmethods

After 1930 the relative efficiencies of the twoapproaches changed markedly The Americansrecognized the changed circumstances morequickly than their British counterparts and beganadopting instrumental methods by the mid 1930sIn Britain and by extension throughout the BritishEmpire instrumental photogrammetry was still inthe experimental phase at the outbreak of WorldWar 11in 1939

The immediate post-war-one period saw a flurryof papers extolling the merits of mapping fromaerial photography At the forefront of the cam-paign to get the methods accepted in Britain wasCapt H Hamshaw Thomas (1919 1920 1924)who drew heavily on his experiences in the Sinaiand Palestine Much of the effort to promote airsurvey was conducted in non-specialist journalssuch as the GeograPhicalJournal (Newcombe 1920)and even in the popular press MacLeod who hadserved in France and had become a firm advocateof air survey methods also produced a numberof papers as well as an important official publica-tion Mapping from Air Photographs issued by theWar Office (MacLeod 1920 but see also MacLeod1922 1923a 1923b)

Britain more than in any other country held aconservative attitude towards the new techniquesand this resistance found an influential championin Harold StJ LWinterbotham A self-proclaimedexpert on air survey (see Winterbotham 19291934) Winterbotham did much to impede theadoption of air survey both in Britain and throughhis role on the Colonial Survey Committee in thecolonial territories In contrast the Dominion ter-ritories were free to determine their own policiesAlthough Canada a pioneer in photogrammetryhad been joined by India in its use of these tech-niques before the outbreak of the First World Warother Dominion territories were slower in adopt-ing air survey Australia took the lead but localfactors either delayed or advanced the adoptionof photogrammetry in Dominion territories whichwere not compelled to follow the Colonial SurveyCommittees recommendation There is a strik-ing parallel between these largely autonomousterritories and the Dutch East Indies where thesurvey department was quick to adopt photogram-metry (van Roon 1925) but made no real progressat home in The Netherlands until after World WarII

In the British context Winterbothams reser-vations concerning the cost-effectiveness of air

i64

survey methods were probably justified at leastuntil the development of Reinhard Hugershoffsaerocartograph in 1926 (Blachut and Burkhardt1989) All the air survey instruments introducedbefore the aerocartograph were essentially ter-restrial plotters adapted in some way to copewith non-coplanar photography This made theinstruments difficult and slow to set up and theyusually required two men to carry out orienta-tion and plotting operations In a well mappedcountry such as Britain cumbersome machinescould not support map revision as economically asconventional ground surveyhere Winterbothamerred even in the 1920s was in extrapolatingfrom the British experience to the colonial terri-tories where the needs were very different On thepositive side agitation by Hamshaw Thomas andothers as well as the successful application of airsurvey techniques by the Survey of India led to thesetting up of the AirSurvey Committee Part ofthe responsibility of this committee was to adviseon air survey matters but it was also responsiblefor carrying out research

In the United States the promotion of airsurvey techniques wasundertaken by Moffit (1920)and other surveyors who had not been directlyinvolved in the war effort but had carried on withtheir civilian work in government mapping agen-cies Part of this promotion was carried out in non-specialist journals but unlike in Britain there waslittle need to convince the political leadership ofthe advantages of air surveyBycontrast there waslittle attempt to promote air survey in France orGermany other than in technical or professionaljournals Almost certainly this reflects the higherstatus of engineers and technical experts in thosecountries compared with Britain The UnitedStates probably fell somewhere between Britainand the continental powers but more towards thelatter

Survey and mapping activities in Austria suf-fered a severe setback with the breakup of theHabsburg Empire at the end of World War 1The Militargeographische Institut was disbandedin 1920 (Kretschmer 1991) and its personneldispersed amongst the successor states Whilethis disintegration had clear disadvantages forAustria survey departments in Poland Hungaryand Czechoslovakiagained a cadre of trained andexperienced personnel able to form the nucleusof new national survey organizations Despite eco-nomic hardship in the wakeof the warAustria hadbegun in 1928 to supplement existing 175000topographic mapping work focused on the moun-tainous areas using terrestrial photogrammetry

CartografJhy and GeograPhic informationScience

Graphical MethodsBecause of the extensive use of graphical methodsduring WorldWar I a large body of trained person-nel was available to implement these methods forpost-war mapping But the techniques developedthus far were either non-rigorous (for example theperspective grid) or suitable only for revising smallnumbers of features (the paper strip method)What was needed was a rigorous technique thatdid not require highly skilled workers

Bagley had sowed the seeds of a rigoroustechnique during his work with the PanoramicPhotoalidade (Bagley 1917) but Martin Hotine(1927) provided the theoretical and practicalbasis for a cost-effective mapping techniqueDescribed as a Simple Method of Surveying fromAir Photographs Hotines technique becameknown as the Arundel Method (after Arundelin southern England where the technique wasfirst used experimentally) or the radial-line tech-nique Hotine subsequently developed the methodof control extension using radial-line methods(Hotine 1929) and laid the foundations for muchof the medium-scale photogrammetric mappingcarried out in the English-speaking world over thenext 40 years The American development of slot-ted templets and radial intersectors expeditedthe process of aerotriangulation (see below) butit was Hotines theoretical work that made thesedevelopments possible

None of the countries using aerial photogra-phy for topographic mapping embraced it withgreater enthusiasm than India As noted earlierthe Survey of India had acquired two examplesof Thompsons stereo-plotter Kenneth Mason(1913 1927) had used the stereo-plotter in 1913in the Pamirs with considerable success but theexperience of the Survey of India in Mesopotamiaduring World War I wasdecisive in promoting airsurvey techniques in India In 1920 a series ofexperiments conducted at Agra demonstrated theutility of air survey methods for mapping flat areasin India (Lewis and Salmond 1920) Air surveyp~oved inefficient for one-inch-to-a-milemiddot map-pmg-the cost was roughly twice as much as forground surveys-but it was economical for largerscales An experiment in urban mapping was car-ried out but its results were inconclusive

Among developed countries the United Stateswas probably the most in need of the advantagesthat air survey offered post-war mapmakers Forall its great wealth America was poorly mappedby European standards Where most Europeancountries were at least mapped at medium scale(roughly 1100000 or larger) large tracts of the

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United States were not mapped even at small scaleIt was at just this small-scale range that air surveyseemed to offer the greatest advantages

The work carried out within the USCampGSand USGS prior to and during World War I hadprepared both agencies to take advantage of theemerging technology Starting in 1919 USCampGSused aerial photography for chart revision(Quillian 1919 Mattison 1919) and for wetlandsurveys (Mattison 1924 Graham 1924-25) Someproblems were encountered but the particularadvantages of air survey for mapping wetlands ledto the technique becoming the standard procedure(Landen 1952) In carrying out these surveys theUSCampGSused photography supplied by the Navyand the Army Air Corps it was the Air Corpsmulti-lens camera that established the cost-effec-tiveness of air survey (Reading 1927-28) Withinthe USGS a quadrangle in Michigan was mappedusing a conventional single-lens camera using airsurvey for the planimetry only (Thompson 1952)In 1924 a Section of Photographic Mapping wasestablished as part of the Topographic Branch atUSGS

Terrestrial photogrammetric work had beenundertaken in Russia as early as 1891 (Koch1963) but few significant additional developmentsoccurred before 1920 In 1924 the State TechnicalOffice of Aerial Photographic Survey was estab-lished Its first task was the creation of mosaics at110000 for comparison with plane table surveysThe results were considered sufficiently favorablefor mapping at 15000 based on 112000 pho-tography An ambitious program of aerial pho-tography initiated in 1925 led to the coverage ofmore than 4500000 km2 by 1940 In 1928 theCentral Scientific Research Institute for GeodesyPhotogrammetry and Cartography (ZNIlGAiK)was established to oversee development across thewhole field of mapping (Koch 1963)

Instrumental MethodsAt the end of World War I Germany and theAustro-Hungarian Empire had a clear advan-tage in the development and use of instrumen-tal photogrammetric methods While Germanycontinued to enjoy a considerable lead in thesetechniques the collapse of the Dual Monarchy andthe resultant breakup of the MilitargeographischeInstitut meant that Austria entered a period ofrelative decline Zeiss which had become theciear ieader in the design and man-ufacture ofphotogrammetric instruments not only pro-duced instruments designed by both von Ore and

165

Pulfrich but employed several leading figures inphotogrammetry including Walter BauersfeldWilli Sander and Otto von Gruber This ensuredthat Zeiss was always at or near the forefront ofdevelopments in the field

During the 1920s most efforts were directedtoward overcoming the problem inherent in theearlier generation of photogrammetric plot-ters namely the need for the photographs tobe coplanar In 1926 Hugershoff designed anaerocartograph for use with both terrestrial andaerial photography The instrument which wasmanufactured by Heyde Company in Dresdentook advantage of the theoretical developmentsin orientation theory developed by Max Gasser(1923) and von Gruber (1924) The combinationof new orientation procedures and sophisticateddesign meant that Hugershoffs aerocartographcould be used for plotting and aerotriangulation(Blachut and Burkhardt 1989) Professional rivalryled von Gruber (1932) to dispute the original-ity of Hugershoffs design as he was also to dowith Heinrich Wilds instruments and the ideas ofFourcade

Zeiss had produced their stereoplanigraph(the Cl) in 1921 based on an earlier design ofBauersfeld However it was not until the pro-duction of the C4 in 1930 that Zeiss producedan instrument that could handle both terrestrialand aerial photography Some successful mappingfrom the earlier models was reported throughthe 1920s by the Reichsamt fur Landesaufnahmewhich had a C2 (Seidel 1928) and the GeodeticInstitute in Stuttgart which had a C3 (von Gruber1932) Most of the mapping was at 15000 butscales as small as ] 20000 are reported Even inGermany systematic mapping programs usingphotogrammetry were still the exception ratherthan the rule during the 1920s

In France the Service Geographique de lArmeehad been actively experimenting with instrumen-tal photogrammetry before World War I (Bonnet1920) and had also used the technique for someterrestrial work during the war France was thuswell placed at the end of the war to keep upwith the developments elsewhere in Europe TheService had decided that terrestrial photogram-metry was best suited to 120000 mapping in highmountain areas but considered the equipment toocumbersome and imprecise for reconnaissancesurveys (Service Geographique de lArmee 1912)In 1919 a start was made on mapping in Moroccousing panoramic aerial photographs (ServiceGeographique de IArmee ]936) but the main

166

drive in France was to develop an autonomouscapability in instrumental photogrammetry

Some equipment had been developed duringthe war notably the Chambre Claire Varon andthe Appareil de photorestitution Roussilhe aninstrument for partial rectification of cadastralplans (Blachut and Burkhardt 1989 ServiceGeographique de IArmee ]936) The mostimportant development came in 1922 when thefirst Georges Poivilliers instrument was built(Poivilliers 1922 Blachut and Burkhardt 1989)Poivilliers instruments were to provide the bulkof the photogrammetric capability of the Servicewith up to four different types in use at anyonetime (Institut Geographique National 1947)Other instruments were also used largely on anexperimental basis In the mid] 920s the stereor-estituteur Boucard was in use and in the I930s aGallus Ferber instrument was used experimentally(Service Geographique de lArmee 1938) withthe latter (Blachut and Burkhardt 1989) remain-ing in service until at least the 1940s (InstitutGeographique National 1947)

Italy had been actively engaged in photogram-metry in the nineteenth century with the work ofPorro but as Blachut and Burkhardt (1989) notethe Istituto Geografico Militare showed little inter-est in the technique until many years after Porrosdeath in 1875 The resurrection of Italian photo-grammetry was largely due to two men UmbertoNistri who designed aplotter in 1919for large-scaleplotting and Ermenegildo Santoni who producedhis first instrument the autoreductor in 1921 In1926 Nistri founded the firm Ottico MeccanicaItaliana (OMI) to produce his photogrammetricinstruments Nistris early instruments all useddirect optical projection while Santonis instru-ments all used mechanical projection The IstitutoGeografico Militare was middotequipped with Santoniinstruments which it used for mapping at 125000and 110000 The Societa Anonima RilevamentiAerofotogrammetrici (SARA)on the other handused Nistri instruments largely for topographicmapptng outside Italy but also for cadastral map-ping within the country

Photogrammetry had been used in Switzerlandfor engineering surveys in the nineteenth centuryyet there had been no systematic attempt to carryout topographic mapping using the techniqueThe history of mapping in Switzerland betweenthe two world wars is largely a history of the WildHeerbrugg Company Set up in 1921 the com-pany produced its first phototheodolite in 1922and its first photogrammetric plotter the Alstereo-autograph in 1923 Its first major contribu-

Cartography and Geographic Information Science

tion to surveying came with the production of theT2 theodolite in 1924 The revolutionary design ofthis instrument-replacing engraved metal circleswith glass versions provided more accurate read-ings and better illumination-led to considerableexcitement in scientific and survey circles By thelate 1920s Wild was engaged in serial productionof the T2 and T3 theodolites the P3 phototheodo-lite and the A2 autograph which had replaced theAI In addition the Cl C2 and C3 aerial cam-eras were also in production In the space of onlyeight years Wild had become a major player in thesurvey world a position enhanced further duringthe 1930s

By the late 1920s the Landestopographie inSwitzerland had gained considerable experiencewith Wild instruments for both terrestrial andaerial surveys (Schneider 1929) Topographicmaps were produced from terrestrial photographyat 125000 while aerial photography wasused for110000 mapping (Schneider 1929 Harry 1971)

In the United States in addition to usinggraphical techniques the USGS started to inves-tigate instrumental methods In 1921 it obtaineda stereoautograph from Germany for evalua-tion but restricted the use of the instrument toplotting from terrestrial photography and notable to produce maps economically (Thompson1952) In 1927 the Geological Survey acquired theHugershoff aerocartograph the first automaticstereo-plotter used by an American governmentmapping agency (Thompson 1952) Thomas PPendleton laid down guidelines for mapping fromaerial photography within the USGS in Bulletin788-F Map Compilation from Aerial PhotograPhsissued as part of the Topographic Instructions of theUnited States Geological Survey (Pendleton 1928)Given the rapid developments in radial-line meth-ods (eg Hotine 1927) the timing of Pendletonswork was a bit unfortunate as he asserted thatradial-line techniques were really only suited foruse with multi-lens photography because therelatively short radial lines that could be drawnon single-lens photographs could not give the bestresults (Pendleton 1928 p 409)

In Britain research work carried out by the AirSurvey Committee focused on simple methods butthe Committee did not entirely ignore instrumen-tal techniques MacLeods wartime work with rec-tifiers was developed and more importantly theideas of Fourcade (l926a 1926b 1926c 1926d)on the theory and use of stereogoniometers forphotogrammetric plotters were taken up In 1926the Committee commissioned the constructionof an instrument along the lines proposed by

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Fourcade and the instrument was delivered in1928 0ar Office 1935 Hotine 1931)

In India success with non-instrumental tech-niques did not distract the Survey from instrumen-tal techniques they had helped pioneel- Mappingofficials followed developments taking place inEurope and in 1926 Mason (1927) carried outa survey in the Shaksgam using a Wild photo-theodolite and plotted the results in Switzerlandusing an autograph in the Topographical Instituteat Flums

CamerasThe tri-lens camera developed by Bagley was usedby the USGS in mapping for aeronautical chartsThis program wasjointly organized with the Corpsof Engineers and the Air Service (Committeeon Photographic Surveying 1921) and providedvaluable experience in civil applications In 1920programs with the tri-lens camera were also under-taken in Santo Domingo and Haiti

The Corps of Engineers became involved inphotogrammetric methods in 1920 when Bagleywas assigned to cooperate with the Army AirCorps in carrying out tests on aerial photographyfor topographic mapping Initially the trials usedBagleys tri-lens camera but he went on to developthe five lens T-3Acamera which was to remain thestandard mapping camera of the US Army until1940 (Landen 1952) The War Department issuedtraining regulations for mapping from aerialphotography in 1923 however the techniques dis-cussed in the regulations were largely those refinedduring World War 1

The 1930sBy the late 1920s photogrammetry had becomea cost-effective alternative to some traditionalground surveys Yet expensive photogrammetricplotting instruments and labor-intensive graphicalplotting meant that photogrammetry still lackeda decisive advantage over ground survey Duringthe 1930s a number of innovations were to swingthe balance decisivelyin favor of photogrammetricmethods

Progress was slowed if not stopped by the reces-sion that started in 1929 Some measure of theimpact can be gauged from job cutbacks at WildHeerbrugg In 1930 before the recession had amarked affect on Europe the workforce stood at260 but by 1933 the number ofjobs had droppedto 125This was the direct consequence of the deci-sions taken to retrench mapping projects as well as

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capital programs Nearly all the annual reports forthe early 1930s mention the financial constraintsunder which organizations had to work In theUnited States some of these problems were offsetby appropriations under the Emergency Reliefand Construction Act (US Coast and GeodeticSurvey 1933) Moreover the New Deal initiated awide range of programs in which photogrammetrywas to playa major role By contrast problems inthe colonial territories were if anything worsethan in Europe and North America The declinein industrial activity in developed countries ledto a collapse in demand for raw materials fromthe colonies and as this was the main source ofgovernment revenue they could no longer pay forsurvey work Annual reports from most colonialsurvey departments make reference to a lack ofresources to meet the need for mapping Howevel~by the late 1930s as a result of rearmament inEurope governments allocated more money tosurvey organizations

Survey organizations were eager to adopt newtechniques in routine mapping programs but thepressures within governments to deal with massunemployment probably helped to promote theuse of labor-intensive methods in survey at theexpense of investment in technology Certainlyorganizations such as the Tennessee ValleyAuthority (TVA) the Agriculture AdjustmentAdministration and the Soil Conservation Servicein the United States were all heavily dependenton such labor-intensive techniques and did muchto develop them as standard mapping methodsMoreover organizations such as the USGS andthe TVA also played a role in the developmentinstrumental methods such as multiplex All ofthis was to be of vital importance to the hugephotogrammetric mapping programs that wereto emerge during World War II The scale of theseprograms would have been inconceivable withoutthe trained body of photogrammetrists developedduring the 1930s (Landen 1952)

Within the British colonial territories the conser-vative element that had inhibited the developmentof photogrammetric methods through the 1920scontinued to delay adoption of photogrammetryuntil after World War II-with some illuminatingexceptions Cyprus is the only known example ofa local survey department attempting to carry outphotogrammetric work Aerial photography wastaken in 1936 but delays in obtaining groundcontrol meant that no use was made of the pho-tography before all normal work was suspended atthe outbreak of war In all the other colonies wherephotogrammetry was attempted private survey

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companies carried out the work The earliestexample of the involvement of private air surveycompanies had been in 1927 in the mapping ofthe Anglo-Belgian boundary in the Copper Beltregion of Northern Rhodesia (Colonial SurveyCommittee 1928) Private air survey companieswere also active in Uganda Tanganyika andSouthern Rhodesia but in all cases this was surveywork for specific development projects ratherthan routine mapping (War Office 1935) Therewere discussions about the use of photogramme-try in Sierra Leone where the Aircraft OperatingCompany of South Africa proposed to revise the162500 topographic maps for pound150000 includ-ing the cost of providing ground control but thework was never carried out due to financial con-straints and the outbreak of World War II Therewere also discussions about air survey in Jamaicaand the Gold Coast but nothing came of theseprojects until after World War II It is clear fromthe literature and correspondence of the time thatthe private air survey companies were lobbyingindividual colonial governments as well as theBritish Government to adopt air survey but theColonial Survey Committee under Winterbothamwas equally forceful in its resistance to changelargely on grounds of cost (see in particularWinterbotham 1920 1921 1929 1934 1936Hemming 1933)

Increasing recognition that war with Germanywas inevitable led to a significant change in theBritish establishments attitude towards the use ofair survey In part this change reflected the retire-ment of Winterbotham in 1935 and his replace-ment as Director General of the Ordnance Surveyby MacLeod who was alwaysa warm supporter ofair survey MacLeod had followed Winterbothamfirst as Director of Military Surveys and then atthe Ordnance Surveyand in each case he playeda major role in introducing the use of photogram-metry (Clough 1952)

Advances in InstrumentationThe late 1920s had seen the design and produc-tion of the first practical plotting machines for usewith aerial photography The experience provideda foundation for the introduction during the1930s of designs that were to be the mainstaysof topographic mapping The Zeiss C4 had beenintroduced in 1930 (Burnside 1993)AsThompson(1966) notes the C4 and the superseding C5(introduced in 1935 with improved illumination)were with the Wild A5 (launched in 1937) practi-cally the only universal instruments on the marketin the 1930s Universal instruments designed to

CartograPhy and GeograPhic Information Science

handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

Vol29 No3

graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

169

Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

170

world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

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Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

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Africa afford an eloquent testimony and eventhe conduct of a small war or a police expe-dition is much simplified by the existence ofreliable maps of the scene of operations

With very few exceptions the topographic map-ping available in 1900 had been produced usingground survey techniques Although the conceptof photogrammetry had been discussed since thelate 1850s (Laussedat 1860) very little had actu-ally been achieved The only extensive mappingundertaken using photographs had been that inCanada by Eduard Deville (1895) Although anumber of Europeans had in the 1890s carriedout alpine mapping using terrestrial techniquesthe equipment necessary to carry out the work costeffectivelywas not yet available in 1900

Indeed the survey techniques being used by landsurveyors in 1900 were little different from thoseused in 1800 Because accurate distance measure-ments were difficult and expensive to acquire allcontrol networks used for medium- and large-scaletopographic mapping were based on triangulationAlthough the discovery of invar (an alloy of steeland nickel with a very low coefficient of expansionwith heat) in 1896 was to make accurate distancemeasurement easier it was not until the develop-ment of electromagnetic distance measurementin the 1950s that alternatives to triangulationbecame possible Traversing for lower-order con-trol networks was used in colonial territories butonly if small-scale mapping was to be producedTraversing was also used for mapping during mili-tary operations (Close 1905)

The theodolite had undergone improvementsduring the nineteenth century These werelargely the result of improvements in the dividingengines used to graduate the horizontal and verti-cal circles Consequently it was possible to makebetter measurements on instruments with lO-inchcircles in 1900 than it had been on instrumentswith 36-inch circles in 1800 Accurate reading oftheodolite angles depended on the use of verni-ers or micrometers Vernier instruments werepreferred for expeditions and surveys in roughconditions because they were lighter and morerobust than the micrometer instruments (Reeves1933) Edward Reeves was to make a significantimprovement in theodolites with the developmentof the tangent micrometer a device which madeaccurate reading of the circles easier and perhapsmost importantly could be retrospectively fitted toexisting instruments (Close 1905 Reeves 1933)Similar devices were to be incorporated into thedesigns of theodolites from the major manufac-turers The most significant improvement in the

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design of theodolites occurred in the twentiethcentury when the lead in design passed fromBritain to Switzerland and Germany

Another development adopted by surveyors wasthe use of the telegraph for the transmission oftime signals This technique became common forthe determination of longitude until supersededby the use of radio time signals in the 1920s

Emerging TechnologyAt the beginning of the twentieth century Themost important emergent technology was with-out doubt the use of photography for surveyingAlthough attempts had been made to captureand use aerial photography the lack of a stableand reliable aerial platform meant that the useof photography was restricted to terrestrial pho-togrammetry In 1893 C B Adams had proposeda method for plotting by intersection from bal-loon photographs (US Patent 510758) Althoughthis approach never led to a practicable mappingtechnique it provided the conceptual basis for theradial-line techniques in vertical aerial photog-raphy To use terrestrial photography cost effec-tively in mapmaking it is necessary to elevate thecamera above the surface to be mapped or place itat a sufficient distance from the surface to permitcoverage of a large area In practice this meantthat terrestrial applications were best carried outwhere there were natural vantage points such asmountains and high hills

Terrestrial photogrammetry had first been dem-onstrated by Aime Laussedat in 1859 (Blachut andBurkhardt 1989) although he was at first limitedby the wet plate process Ignazio Porro in Italyand Dr A Meydenbauer in Germany improvedupon Laussedats work These early attempts allinvolved the use of graphical techniques to plotthe detail and contours from photographs Theprocess of map creation from photographs wasthus slow and laborious and it tended only to beused where difficult terrain made plane table workimpractical For the photogrammetric approach tobecome more cost effective a method of automat-ing the plotting was needed Work on developingsuch a method was being actively pursued in anumber of countries at the turn of the century

The Canadian experience had led to a system-atic use of terrestrial photography for topographicmapping along the Alaska-Canada boundary byboth Canadian and American members of thesurvey party John Flemer ofthe US Coast andGeodetic Survey (USCampGS)was assigned to makea study of European methods which led to the first

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American textbook on photogrammetry (FIemer1906) Even so this did not lead to the widespreadadoption of photogrammetry within the USCampGSas photographic techniques could still not competewith the efficiency of existing techniques (Landen1952) In 1904 the US Geological Survey (USGS)which was also interested in the use of terrestrialphotogrammetry adopted Devilles panoramiccamera approach for mapping in Alaska JamesBagley further developed the technique by rede-signing the camera and producing a panoramicphoto alidade (Bagley 1917)

Photogrammetry to 1914Until the outbreak of World War I the chief focusof photogrammetry remained terrestrial appli-cations In 1901 Henry Fourcade described amachine designed to make measurements fromstereoscopic photographs essentially a stereocom-parator (lltourcade 1901) At about the same timeCarl Pulfrich (1902) produced and described thePulfrich Zeiss stereocomparator During the 1930sthere was considerable debate over the precedencein producing a serviceable design for a stereocom-parator Otto von Gruber (1932) gives precedenceto Pulfrich by citing his 1902 paper and the 1902paper by Fourcade which appeared in Nature Butas noted above the Fourcade design was first dis-cussed in a paper published in 1901 albeit in arelatively obscure journal It is not clear whethereither designer was aware of the work of the othereven if they both produced very similar designsThis notwithstanding it is worth noting that vonGruber was also to dismiss Fourcades claim toprecedence over his own work in the design ofan instrument that employed the concept of thestereogoniometer Martin Hotine (1931) makes astrong case in support of Fourcade s precedence inboth cases Both machines could be used to makeaccurate stereoscopic measurements of pointsbut because the plan positions and heights of thepoints were computed individually maps producedfrom these measurements required interpolation

While these early machines demonstrated thepossibility of making accurate maps from stereo-scopic photographs the technique was extremelytime consuming and only suitable if no othertechnique was available Appropriate conditionsexisted in alpine mapping where ground surveywould have been hazardous or even more timeconsuming than photogrammetry Early examplesof photogrammetrically derived contours were pro-duced in the Tyrol between 1902 and 1907 by theAustrian survey using the Pulfrich stereocompara-

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tor (Kretschmer 1991) Both the Prussian GeneralStaff and later the French Service Geographiquede lArmee adopted the Pulfrich stereocompara-tor for mapping mountainous areas in Pelvoux(Service Geographique de lArmee 1912 1938)However there was general recognition that thetechnique was not cost effective(see the commentsof Major Hills followingThompson 1908)

What was needed to make the use of photogra-phy cost effectivewas the ability to produce topo-graphic details and contour lines directly from thephotographs rather than by manual interpolationIn 1908 Eduard von Orel produced his autoste-reograph (von Ore11910 1911 1912von Gruber1932 Hotine 1931 Kretschmer 1991) and in thesame year Vivian Thompson published details ofhis stereoplotter (Thompson 1908 von Gruber1932 Hotine 1931 Thompson 1974 Petrie 1977Burnside 1995) Both machines were capable ofproducing plotted detail lines and contours fromterrestrial photographs The autostereographwas quickly adopted by the Austrian survey foralpine mapping and was subsequently taken up byother national mapping departments The largestsystematic survey carried out with the autostereo-graph was some 560 km2 of the Tyrol surveyed in1911 by the Militargeographische Institut (Koner1924) Bycontrast the stereoplotter attracted littleinterest in its country of origin Great Britain butwas adopted by the Survey of India for mappingin the Karakorum Range Because these areashave not subsequently been remapped the origi-nal contours from the stereoplotter are still thoseused on the published sheets One plotter was alsoacquired for survey work in Fiji where McCawused it for mapping prior to WorldWarI (ColonialSurvey Committee 1911 1912 1913)

Both machines were suitable for mapping fromterrestrial photographs as were machines devel-oped from von Orels autostereograph (Therewere no developments from the stereoplotter)Howeverbecause both solutions required coplanarphotographs they could not be readily adaptedfor use with aerial photography which is rarely ifever coplanar This fact did not stop many abor-tive attempts to turn terrestrial photogrammetricplotters into machines capable of handling aerialphotographs

A non-technical development that was to havea significant impact on the development of pho-togrammetry was the founding of the AustrianSociety of Photogrammetry in 1907 followedby the publication in 1908 of the first volumeof the lnternationales Archiv flir PhotogrammetrieThe International Society for Photogrammetry

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was founded in Vienna in 1910 Vienna was alsothe setting for the first International Congressfor Photogrammetry in 1913 The Society wasto become one of the main vehicles for the dis-semination of information on photogrammetrywhile the congresses were the main showcases forthe latest equipment Previously the InternationalGeographical Union was the main forum for thedissemination of developments in surveying andphotogrammetry but its importance had contin-ued to decline until after World War II when italmost completely withdrew from the field

World War I (1914-1918)World War I generated an unprecedented demandfor maps at scales from 1200 for detailed trenchmaps (Chasseaud 1999) to 11000000 andsmaller for strategic planning maps (Heffernan1996)At the outbreak of war in 1914 the armies ofEurope were issued with maps at scales of 180000or smaller designed to support a war of rapidmovement in which victory would be achievedby bringing to bear an overwhelming force in adecisive battle Military leaders still believed thatoffensive operations could be successful despitethe precedent of the Russo-Japanese War of 1905which had degenerated into sieges and large bat-tles of encounter in which opposing armies foughtin the open rather than in prepared positionsNeither side could achieve a decisive blowbecauseof the superiority of defense based on rifles andmachine guns

The strength of the defenses meant that if therewas to be any hope of success in offensive opera-tions the attacking troops needed accurate mapsof the enemy defenses This included the positionsof any artillery ammunition dumps and transportinfrastructure Allof these features were difficult orimpossible to map from the front line In the caseof ammunition dumps and transport the targetscould be many miles behind the front What thearmies of both sides needed wasa wayof collectinginformation that could either be added to existingmaps or used to produce entirely new maps Mostimportantly as the artillerymen developed evermore accurate targeting they created a demandfor increasingly precise mapping to locate poten-tial targets As the war progressed the armiesexperimented with a closer integration of artilleryand infantry operations such as the rolling bar-rage (a barrage where the gunner slowlyincreasesthe range while infantry advance slowlybehind thebarrage) Again this required more precise point-ing of guns and locating of targets

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Suneyors were used to fix the position of bothguns and targets The need for secrecy-no pointin alerting the enemy that an attack was beingprepared-also changed the ways in which theguns acquired their targets Early in the war thenormal technique involved the use of rangingshots That is each gun was fired towards a poten-tial target and an observer identified the fall ofshot The obsener then told the gunner to eitherincrease or decrease the range as appropriateand to traverse left or right until the shot was fall-ing on the target The problem with this techniquewas that it revealed that a new gun had been intro-duced into a stretch of the front A large number ofranging shots revealed the introduction of a largenumber of guns and the threat of a forthcomingattack To overcome this dilemma the positions ofthe guns and targets needed to be determined pre-ciselyby surveying From this information artilleryboards were prepared to show the positions of theguns as well as the targets It was then possible todetermine the directions in which the guns neededto fire and the range to the target without reveal-ing that new guns had been positioned

The identification of targets and the accuratepositioning of guns led all the nations to adoptthe use of grids on their mapping In the latenineteenth century John Ardagh had tried toget a grid system adopted by the Survey of Indiabut without much success (Ardagh 1893) Prior toWorld War I therefore almost no maps carriedgrids The exceptions were the squared mapsused by the French artillery on maneuvers atChalons in 1911 (Chasseaud 1999) Increased useof indirect fire underscored the need for griddedmaps Unfortunately grids were adopted on an adhoc basis which led to considerable confusion Forexample the Germans used three different gridsystems with origins at Lille Rheims and Paris(Hinks 1919)The British adopted an imperial gridbased on 1000-yard grid squares even though theentire mapping on the Western Front used metricscales Despite this uncertain start it was quicklyrealized that grids had uses well beyond those ofwarfare and they became a standard feature ofmost post-war topographic mapping

Military mapping in Europe was largely focusedon map revision whereas that in Palestine Sinaiand Mesopotamia involved considerable origi-nal mapping (Collier 1994 Collier and Inkpen2001) In the initial stages of the World War I allthe belligerents used existing pre-war mappingsupplemented by photographic enlargements InFrance this involved the use of 180000 mappingsubsequently enlarged to 140000 When how-

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ever the deficiencies of the enlargements becameevident they were replaced by new mapping Onlythe German survey seems to have continued to useenlargements through to the end of the war aack1920) With the development of positional warfare140000 mapping wassoon found to be inadequateand was successively complemented by mappingat 120000 and 110000 Where necessary evenlarger scales were used (Chasseaud 1999)

Behind the lines revision and new surveys werecarried out using conventional land survey tech-niques trigonometrical control surveys and theplane table to add detail Oack 1920 Winterbotham1919a 1919b Service Geographique de lArmee1938 Albrecht 1969 Chasseaud 1999) For front-line areas and for the enemys rear areas the maindata source was aerial photography

The Development of CamerasInitially photography for intelligence and maprevision involved the acquisition of photographyfrom fairly low flying aircraft using largely impro-vised camera equipment With the development ofanti-aircraft defenses however reconnaissance air-craft were forced to fly higher and higher to avoidbeing shot down To compensate it became neces-sary to devise cameras with longer and longer focallengths if the resultant photography was to be ofuse for analysis and mapping

The earliest cameras were simple devices thatused glass plates and dark slides (devices used tochange glass negatives in a camera without expos-ing the negatives to light) Images were obtainedby observers pointing the cameras over the side ofthe aircraft The cameras were fitted with simplesighting devices to ensure that the target wasactually imaged Recognition that vertical photo-graphs were much better suited to mapping thanthe oblique pictures taken with hand-held camerasled to the cameras being fixed to the side of theaircraft Fairly quickly magazines were providedso that a series of photographs could be taken bythe observer activating a lever to change platesEven so changing the magazines still required theobserver to lean over the side of the aircraft Giventhese difficulties it seems strange that roll filmwas not used earlier especially since panoramiccameras had used it as early as the late nineteenthcentury The Germans did not introduce a filmcamera until 1916 (Albrecht 1969) and the Britishcontinued to use plate cameras until the end ofthe war

Most of the cameras used for military operationshad relatively long focal lengths the standardBritish camera in the early part of World War I had

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a focal length of 8 inches (approximately 200 mm)while the standard German camera had a focallength of 180 mm (Albrecht 1969) By the end ofthe war focal lengths of 500 mm were not uncom-mon-some German cameras had focal lengths aslarge as 1200 mm (Albrecht 1969) These lenseswere designed for reconnaissance rather thanmapping so that each photograph covered only asmall area of ground Cameras needed wide-anglelenses to minimize the amount of control neededfor mapping but none of the high-quality lensesavailable provided a wide field of viewMulti-lenscameras were developed in the nineteenth centuryto obtain broader coverage from each exposurestation but these cameras were generally largeand cumbersome and thus unsuited for militaryoperations

Control for MappingEarly attempts at using aerial photography formap revision experienced considerable difficul-ties As Malcolm MacLeod (1919 pp 382-83)noted though the photographs showed all theprincipal topographical features in great detailthere was no means of determining their exactscale or the amount of distortion due to thecamera not being truly vertical at the moment ofexposure of the plate In the absence of mechani-cal restitution instruments to overcome theseproblems two possible solutions were consideredto develop a device for mechanically determiningthe altitude and tilt of the camera at the momentof exposure or to compare the positions of pointson the photographs with their known ground coor-dinates Although both sides experimented with amechanical solution most work involved the lattertechnique This placed a heavy demand on accessto ground coordinates

The provision of control points both in andbeyond their own front line was a major problemfor all the combatant nations Placing markersover control points in frontline areas and thenfixing them by observation from the rear was notfeasible as this also enabled the enemy to fix theposition of the trenches A number of strategieswere adopted including the use of periscopictheodolites employed from within the trencheswithout exposing observers to enemy fire Thesetheodolites could be used to fix positions withinthe trenches by resection

While resection on the plane table was a com-monly used technique among topographers ithad not been widely used for instrumental obser-vations because of the relative complexity of thecalculations However the conditions of trench

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warfare left few alternatives Once adopted resec-tion remained in common use among surveyorsAn alternative adopted by the Germans was to firea flare vertically from the trenches and obsenTethe flares position from the rear using theodolitesGack 1920)

Locating control points beyond the front line waseven more difficult Where possible the position ofprominent points would be fixed by intersectionHowever in Mesopotamia there were often too fewsuitable features to intersect This led to an inno-vation by Col C P Gunter to fix control pointswithin the Turkish lines using artillery shell burstsFour observers took simultaneous observations ofindividual shell bursts while an observer in anaircraft recorded the position of the explosionson a detailed map of the trenches created from airphotographs On average out of ten shell burststhree good intersected points were observed andthe observer would have accurately marked one ofthese Points observed in this way were then usedto control and adjust the strips of photographyused for mapping (Surveyof India 1925)

Plotting DetailOnce control had been obtained it was necessaryto interpret and plot the information on photo-graphs Initially interpretation was relatively easyas there was little attempt to conceal potentialtargets from aerial observation Camouflage onlystarted to be used systematically around 1916(MacLeod 1919) thereafter photo-interpretationdeveloped into a specialist skill Use of camouflagealso led to the development of new surveyingtechniques such as flash spotting and soundranging

Extraction of detail for revision purposes wasdone by some form of graphic intersection orthrough the use of optical projection Despite someuse of more rigorous methods involving compara-tors developed before the war these instrumentstogether with the necessary calculations were slowand not well suited to the urgent needs of the warThe use of automatic plotters such as the alitoste-reograph was restricted to terrestrial photographydue to the need for coplanar photography In factthis technique was used only by the Germans andFrench in eastern France where relief was suitableand by the Austro-Hungarian Army in the AlpsOskar Albrecht (1969) also refers to the use of ter-restrial photogrammetry for artillery assaults onfortresses and the use of photographs taken fromtethered balloons

The belligerent powers employed a variety ofgraphic techniques The simplest involved the pro-

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duction of a framework of existing detail on a com-pilation sheet on which new detail was added fromaerial photographs with the help of proportionaldividers Although capable of producing reason-ably accurate results this approach was labori-ous and slow (MacLeod 1919) The paper stripmethod (Thompson 1966) used for adding smallamounts of detail was equally slow and laboriousThe German Army developed a less strenuoustechnique based on the use of perspective gridsThe chief advantage of this technique was thatonce the grids had been generated detail could betransferred by eye from aerial photograph to mapThis technique was so successful that it was widelyadopted after the war for map revision Describedin most standard textbooks on photogrammetrythe perspective grid approach remained in useuntil the 1980s when simple digital techniquesrendered it obsolete

Most of the optical revision techniques reliedon the registration of a projected image of thephotograph on an existing map or on a frame-work of control Once the image was registeredthe mapmaker could either transfer the informa-tion directly to the map or produce a correctedphotographic print for use in revision TheodorScheimpflug had shown that an accurate regis-tration could be affected between the projectedimage and the control data if the projected imagewas in focus for the entire image area To satisfYthe so-called Scheimpflug condition the projectedplanes of the negative lens and easel had to meetat a common axis (Scheimpflug 1898 Blachutarid Burkhardt 1989) Even if the condition wassatisfied there were still errors of registration dueto relief displacement In the instruments usedduring World War I the Scheimpflug conditionwas hot satisfied and consequently the resultswere at best approximate (Blachut and Burkhardt1989) MacLeod (1919 1920) describes the use ofCamera Lucida and the enlarging lantern inboth of which the plane of the negative and theplane of the lens were held parallel with only thecopy board which was capable of being tilted Theeniarging lantern could maximize the depth offocus and hence the sharpness of the iinagebyreducing the aperture of the lens to the smallestdiameter possible The use of the enlarging lan-tern to produce semi-rectified prints came to bethe preferred techrnque

As already noted while most of the work onthe Western Front involved map revision innon-European theaters the need was for originalmapping (Collier 1994 Collier and Inkpen 2001)The first attempts to use aerial photography to

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construct original mapping took place during theGallipoli campaign (Dowson 1921) Not very suc-cessful these attempts demonstrated the problemsassociated with the non-stereoscopic use of aerialphotography as when troops were sent to occupypositions identified monoscopically as trenchesor ditches but which turned out to be shallowscrapes that afforded no shelter from enemy fireAttempts to create original mapping ceased whenmodern Turkish maps of the area were capturedand revised

In Egypt the Turkish threat to the Suez Canalalso resulted in experiments in mapping fromaerial photography Like the mapping in Gallipolithese were largely unsuccessful The main problemwas locating precisely where the photographs hadbeen taken over a largely featureless desert Thebulk of the mapping for the Suez Canal defenseswas therefore carried out by triangulation andplane table survey (Maule 1919)

When the Egyptian Expeditionary Force (EEF)advanced across the Sinai Peninsula to engageTurkish forces in Palestine it moved into terri-tory without up-to-date mapping of an adequatescale Western Palestine had been mapped for thePalestine Exploration Fund (PEF) in the 1870s(Conder 1878 Conder and Kitchener 1881-83) ata scale of 163360 Although based on triangula-tion the detail had been surveyed using compassand cavalry sketching board (Close 1932) and wastherefore regarded as insufficiently accurate formodern warfare British military personnel hadsurveyed Southern Palestine just before the warunder the cover of a PEF expedition (Woolleyand Lawrence 1914) But even here the scale wastoo small (1 125000) for the kind of operationsbeing undertaken The British army was thereforeconfronted with the need to map areas beyond itsfront line for which no adequate base maps wereavailable

The first successful attempts at mapping fromaerial photographs were in t~e area aroundGaza (Gavish and Biger 1983) Here control wasprovided by the intersection of prominent pointsbehind Turkish lines Based on these points acontrolled mo~aic was created from with verticalaerial photogriphs and the mosaic was then usedto crcate the line maps of the planimetry Althoughcrude by later standards the map was consideredto be a significant improvement on anything thenavailable This encouraged the surveyors led byMajor W] Maule to embark upon an ambitiousplan to create a series of topographic maps at 140000 for areas of Palestine behind Turkish lines(Maule 1919) Strips of photography were flown

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roughly parallel to the front line with additionalstrips of photography perpendicular to the frontflown at intervals to control the strips parallel tothe front Supplementary control was provided bytheodolite observations wherever possible Thesame basic arrangement pioneered in the map-ping of Gaza was followed for the series mappingHowever as the area mapped extended into thehills of Judea (the southern West Bank) it alsobecame necessary to provide some indication ofrelief Viewing the photography stereoscopicallyand form lining achieved this The nature of thetopography nearly horizontally bedded lime-stones that eroded into natural terraces madethis task relatively easySuccessfulas the mappingwas (Thomas 1919) as each new area came underBritish control mapping derived from air photoswas replaced bymapping made using conventionalground survey techniques

In a number of ways the mapping inMesopotamia can be regarded as the first exampleof true photogrammetric mapping using aerialphotography Unlike the mapping in Palestineit was produced as the end product not as aninterim solution to be replaced as soon as groundsurveys became possible And unlike the mappingon the Western Front it did not involve revision ofexisting mapping as no proper maps existed forthe area

Although developments in the use of air pho-tography had been watched with envy by thesurveyors in Mesopotamia (Survey of India 1925)until early 19I6 no airplanes had been availablefor that theater Some experience in the use ofaerial photography had been gained before thesiege of Kut-al-Amarah but it was the positionalfighting around Kut that emphasized the advan-tages of air survey Maps were required of areasbehind Turkish lines but the flat landscape meantthat surveyscould only be extended into no-mans-land This led to the first real attempt to createmaps from aerial photography As the first mapTC4 (TC are the initials of Tigris Corps theoriginal name of the force sent to Mesopotamia)has been discussed at length elsewhere (Collier1994 Pritchard 1952 Survey ofIndia 1925)

The surveyors working in Mesopotamia experi-mented with various ways of making maps fromaerial photographs drawing on the experience ofsurveyors on the Western Front and in Egypt Inthe end though they developed their own tech-nique which was well suited to local conditionsTheir technique involved creating semi-rectifiedphotographs using an enlarging lantern (Gunter1917) and then mosaicing the photographs using

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a triangulation scheme The mosaics were inkedup before the bromide prints were bleached out soas to leavejust the inked linework The importantpoint to note is that this technique was used formapping areas on both sides of the front line andwas therefore regarded as the final product Theflat floodplains of the Tigris and Euphrates Riverslent themselves to mapping using semi-controlledmosaics as there was an almost complete absenceof height to create displacement errors The map-ping of Mesopotamia from aerial photography seta precedent for post-war mapping in India

Flash Spotting and Sound RangingAs mentioned earlier the use of camouflage neces-sitated the development of techniques for targetlocation in particular the location of enemy gunpositions for counter-battery fire At the beginningof World War I guns were aimed by direct observa-tion of targets and the guns themselves were oftenpositioned in the open to improve their fields offire With the increased use of counter battery fireit became normal for guns to be dug in posi-tioned in gun pits and protected by sandbags Toprotect gun positions from enemy air observationthe gun pits were subsequently camouflaged withnetting which thwarted an accurate identificationof their positions

Flash spotting and sound ranging were devel-oped as means of tackling the problem of identify-ing and locating enemy gun positions Adopted byall the combatant nations flash spotting involvedintersecting the gun position by observing theflash as tht gun was fired Flash spotting requiredconsiderable organization as the observers had toensure that they were observing the same gun flashbut by carefully noting the times of the observa-tions it was possible to obtain accurate locationsof enemy guns Most armies established specialistunits for this purpose (Innes 1935 Chasseaud1999 Hinks 1919 Maule 1919)

Sound ranging was a more complex process inwhich the British and French enjoyed a technolog-ical lead over the Germans General Ludendorffthe German Chief of Staff who issued specialinstructions that precautions be taken to cam-ouflage the sound of guns directed the army tosecure an example of the British system (quotedin Hinks 1919) Based on a technical solutiondeveloped by Lucien Bull at the Institut Marey inParis the British system relied on an array of sixmicrophones spread over a 9-kilometer-long base-line situated about 4 km behind the front iine Themicrophones were connected to a galvanometer atthe hea~quarters As the sound of a gun reached

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each microphone in turn a signal was sent by wireto the galvanometer where it produced a distinc-tive trace on photographic film By measuring theseparation of the traces of the gun detected at eachmicrophone the distance and direction of the guncould be calculated Complex arrangements withmore than two microphones were needed becauseof uncertainty about the effect of wind speed andother factors on sound waves (see Innes 1935 andChasseaud 1999 for more technical details)

The German systemrelied on a fonvard observerand four other observers along a base of 10 to 15kilometers On hearing a gun firing the forwardobserver sent a signal by field telephone to theother observers who on receiving the signalstarted their stopwatches and noted the time inter-val before they heard the gun The times were thensent to group headquarters where the position ofthe gun was calculated An alternative and sim-pler method involved an observer noting the timeinterval between seeing a gun flash and hearingthe noise of the gun The greatest precision possi-ble with these techniques was about +200 meters

Non-military WartimeDevelopments to 1918

While the mapping efforts of the combatantnations were almost entirely directed towards thewar effort cartographers in the United States wereactively exploring civilian applications of pho-togrammetry The most important developmentwork was carried out at the US Geological Surveywhere James Bagley was developing a tri-Ienscamera and Fred Moffit was developing a trans-forming camera capable of handling the nega-tives produced by Bagleys camera (Committee onPhotographic Surveying 1921)

Developments to 1930In the period leading up to and including WorldWar I all the major powers followed broadlysimilar paths in developing photogrammetry Inmost countries attempts to develop instrumentalmethods complemented heavy reliance on graphi-cal and optical techniques for producing andrevising large-scale maps After the war a numberof countries took distinctly different paths withcontinental European countries generally puttingmost of their effort into instrumental techniqueswhile English-speaking countries focused ongraphical techniques Arguably until about 1930the approach adopted by the English-speaking

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countries was the most fruitful as the instrumentaltechniques developed in Europe could not com-pete in cost or efficiency with British and Americanmethods

After 1930 the relative efficiencies of the twoapproaches changed markedly The Americansrecognized the changed circumstances morequickly than their British counterparts and beganadopting instrumental methods by the mid 1930sIn Britain and by extension throughout the BritishEmpire instrumental photogrammetry was still inthe experimental phase at the outbreak of WorldWar 11in 1939

The immediate post-war-one period saw a flurryof papers extolling the merits of mapping fromaerial photography At the forefront of the cam-paign to get the methods accepted in Britain wasCapt H Hamshaw Thomas (1919 1920 1924)who drew heavily on his experiences in the Sinaiand Palestine Much of the effort to promote airsurvey was conducted in non-specialist journalssuch as the GeograPhicalJournal (Newcombe 1920)and even in the popular press MacLeod who hadserved in France and had become a firm advocateof air survey methods also produced a numberof papers as well as an important official publica-tion Mapping from Air Photographs issued by theWar Office (MacLeod 1920 but see also MacLeod1922 1923a 1923b)

Britain more than in any other country held aconservative attitude towards the new techniquesand this resistance found an influential championin Harold StJ LWinterbotham A self-proclaimedexpert on air survey (see Winterbotham 19291934) Winterbotham did much to impede theadoption of air survey both in Britain and throughhis role on the Colonial Survey Committee in thecolonial territories In contrast the Dominion ter-ritories were free to determine their own policiesAlthough Canada a pioneer in photogrammetryhad been joined by India in its use of these tech-niques before the outbreak of the First World Warother Dominion territories were slower in adopt-ing air survey Australia took the lead but localfactors either delayed or advanced the adoptionof photogrammetry in Dominion territories whichwere not compelled to follow the Colonial SurveyCommittees recommendation There is a strik-ing parallel between these largely autonomousterritories and the Dutch East Indies where thesurvey department was quick to adopt photogram-metry (van Roon 1925) but made no real progressat home in The Netherlands until after World WarII

In the British context Winterbothams reser-vations concerning the cost-effectiveness of air

i64

survey methods were probably justified at leastuntil the development of Reinhard Hugershoffsaerocartograph in 1926 (Blachut and Burkhardt1989) All the air survey instruments introducedbefore the aerocartograph were essentially ter-restrial plotters adapted in some way to copewith non-coplanar photography This made theinstruments difficult and slow to set up and theyusually required two men to carry out orienta-tion and plotting operations In a well mappedcountry such as Britain cumbersome machinescould not support map revision as economically asconventional ground surveyhere Winterbothamerred even in the 1920s was in extrapolatingfrom the British experience to the colonial terri-tories where the needs were very different On thepositive side agitation by Hamshaw Thomas andothers as well as the successful application of airsurvey techniques by the Survey of India led to thesetting up of the AirSurvey Committee Part ofthe responsibility of this committee was to adviseon air survey matters but it was also responsiblefor carrying out research

In the United States the promotion of airsurvey techniques wasundertaken by Moffit (1920)and other surveyors who had not been directlyinvolved in the war effort but had carried on withtheir civilian work in government mapping agen-cies Part of this promotion was carried out in non-specialist journals but unlike in Britain there waslittle need to convince the political leadership ofthe advantages of air surveyBycontrast there waslittle attempt to promote air survey in France orGermany other than in technical or professionaljournals Almost certainly this reflects the higherstatus of engineers and technical experts in thosecountries compared with Britain The UnitedStates probably fell somewhere between Britainand the continental powers but more towards thelatter

Survey and mapping activities in Austria suf-fered a severe setback with the breakup of theHabsburg Empire at the end of World War 1The Militargeographische Institut was disbandedin 1920 (Kretschmer 1991) and its personneldispersed amongst the successor states Whilethis disintegration had clear disadvantages forAustria survey departments in Poland Hungaryand Czechoslovakiagained a cadre of trained andexperienced personnel able to form the nucleusof new national survey organizations Despite eco-nomic hardship in the wakeof the warAustria hadbegun in 1928 to supplement existing 175000topographic mapping work focused on the moun-tainous areas using terrestrial photogrammetry

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Graphical MethodsBecause of the extensive use of graphical methodsduring WorldWar I a large body of trained person-nel was available to implement these methods forpost-war mapping But the techniques developedthus far were either non-rigorous (for example theperspective grid) or suitable only for revising smallnumbers of features (the paper strip method)What was needed was a rigorous technique thatdid not require highly skilled workers

Bagley had sowed the seeds of a rigoroustechnique during his work with the PanoramicPhotoalidade (Bagley 1917) but Martin Hotine(1927) provided the theoretical and practicalbasis for a cost-effective mapping techniqueDescribed as a Simple Method of Surveying fromAir Photographs Hotines technique becameknown as the Arundel Method (after Arundelin southern England where the technique wasfirst used experimentally) or the radial-line tech-nique Hotine subsequently developed the methodof control extension using radial-line methods(Hotine 1929) and laid the foundations for muchof the medium-scale photogrammetric mappingcarried out in the English-speaking world over thenext 40 years The American development of slot-ted templets and radial intersectors expeditedthe process of aerotriangulation (see below) butit was Hotines theoretical work that made thesedevelopments possible

None of the countries using aerial photogra-phy for topographic mapping embraced it withgreater enthusiasm than India As noted earlierthe Survey of India had acquired two examplesof Thompsons stereo-plotter Kenneth Mason(1913 1927) had used the stereo-plotter in 1913in the Pamirs with considerable success but theexperience of the Survey of India in Mesopotamiaduring World War I wasdecisive in promoting airsurvey techniques in India In 1920 a series ofexperiments conducted at Agra demonstrated theutility of air survey methods for mapping flat areasin India (Lewis and Salmond 1920) Air surveyp~oved inefficient for one-inch-to-a-milemiddot map-pmg-the cost was roughly twice as much as forground surveys-but it was economical for largerscales An experiment in urban mapping was car-ried out but its results were inconclusive

Among developed countries the United Stateswas probably the most in need of the advantagesthat air survey offered post-war mapmakers Forall its great wealth America was poorly mappedby European standards Where most Europeancountries were at least mapped at medium scale(roughly 1100000 or larger) large tracts of the

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United States were not mapped even at small scaleIt was at just this small-scale range that air surveyseemed to offer the greatest advantages

The work carried out within the USCampGSand USGS prior to and during World War I hadprepared both agencies to take advantage of theemerging technology Starting in 1919 USCampGSused aerial photography for chart revision(Quillian 1919 Mattison 1919) and for wetlandsurveys (Mattison 1924 Graham 1924-25) Someproblems were encountered but the particularadvantages of air survey for mapping wetlands ledto the technique becoming the standard procedure(Landen 1952) In carrying out these surveys theUSCampGSused photography supplied by the Navyand the Army Air Corps it was the Air Corpsmulti-lens camera that established the cost-effec-tiveness of air survey (Reading 1927-28) Withinthe USGS a quadrangle in Michigan was mappedusing a conventional single-lens camera using airsurvey for the planimetry only (Thompson 1952)In 1924 a Section of Photographic Mapping wasestablished as part of the Topographic Branch atUSGS

Terrestrial photogrammetric work had beenundertaken in Russia as early as 1891 (Koch1963) but few significant additional developmentsoccurred before 1920 In 1924 the State TechnicalOffice of Aerial Photographic Survey was estab-lished Its first task was the creation of mosaics at110000 for comparison with plane table surveysThe results were considered sufficiently favorablefor mapping at 15000 based on 112000 pho-tography An ambitious program of aerial pho-tography initiated in 1925 led to the coverage ofmore than 4500000 km2 by 1940 In 1928 theCentral Scientific Research Institute for GeodesyPhotogrammetry and Cartography (ZNIlGAiK)was established to oversee development across thewhole field of mapping (Koch 1963)

Instrumental MethodsAt the end of World War I Germany and theAustro-Hungarian Empire had a clear advan-tage in the development and use of instrumen-tal photogrammetric methods While Germanycontinued to enjoy a considerable lead in thesetechniques the collapse of the Dual Monarchy andthe resultant breakup of the MilitargeographischeInstitut meant that Austria entered a period ofrelative decline Zeiss which had become theciear ieader in the design and man-ufacture ofphotogrammetric instruments not only pro-duced instruments designed by both von Ore and

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Pulfrich but employed several leading figures inphotogrammetry including Walter BauersfeldWilli Sander and Otto von Gruber This ensuredthat Zeiss was always at or near the forefront ofdevelopments in the field

During the 1920s most efforts were directedtoward overcoming the problem inherent in theearlier generation of photogrammetric plot-ters namely the need for the photographs tobe coplanar In 1926 Hugershoff designed anaerocartograph for use with both terrestrial andaerial photography The instrument which wasmanufactured by Heyde Company in Dresdentook advantage of the theoretical developmentsin orientation theory developed by Max Gasser(1923) and von Gruber (1924) The combinationof new orientation procedures and sophisticateddesign meant that Hugershoffs aerocartographcould be used for plotting and aerotriangulation(Blachut and Burkhardt 1989) Professional rivalryled von Gruber (1932) to dispute the original-ity of Hugershoffs design as he was also to dowith Heinrich Wilds instruments and the ideas ofFourcade

Zeiss had produced their stereoplanigraph(the Cl) in 1921 based on an earlier design ofBauersfeld However it was not until the pro-duction of the C4 in 1930 that Zeiss producedan instrument that could handle both terrestrialand aerial photography Some successful mappingfrom the earlier models was reported throughthe 1920s by the Reichsamt fur Landesaufnahmewhich had a C2 (Seidel 1928) and the GeodeticInstitute in Stuttgart which had a C3 (von Gruber1932) Most of the mapping was at 15000 butscales as small as ] 20000 are reported Even inGermany systematic mapping programs usingphotogrammetry were still the exception ratherthan the rule during the 1920s

In France the Service Geographique de lArmeehad been actively experimenting with instrumen-tal photogrammetry before World War I (Bonnet1920) and had also used the technique for someterrestrial work during the war France was thuswell placed at the end of the war to keep upwith the developments elsewhere in Europe TheService had decided that terrestrial photogram-metry was best suited to 120000 mapping in highmountain areas but considered the equipment toocumbersome and imprecise for reconnaissancesurveys (Service Geographique de lArmee 1912)In 1919 a start was made on mapping in Moroccousing panoramic aerial photographs (ServiceGeographique de IArmee ]936) but the main

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drive in France was to develop an autonomouscapability in instrumental photogrammetry

Some equipment had been developed duringthe war notably the Chambre Claire Varon andthe Appareil de photorestitution Roussilhe aninstrument for partial rectification of cadastralplans (Blachut and Burkhardt 1989 ServiceGeographique de IArmee ]936) The mostimportant development came in 1922 when thefirst Georges Poivilliers instrument was built(Poivilliers 1922 Blachut and Burkhardt 1989)Poivilliers instruments were to provide the bulkof the photogrammetric capability of the Servicewith up to four different types in use at anyonetime (Institut Geographique National 1947)Other instruments were also used largely on anexperimental basis In the mid] 920s the stereor-estituteur Boucard was in use and in the I930s aGallus Ferber instrument was used experimentally(Service Geographique de lArmee 1938) withthe latter (Blachut and Burkhardt 1989) remain-ing in service until at least the 1940s (InstitutGeographique National 1947)

Italy had been actively engaged in photogram-metry in the nineteenth century with the work ofPorro but as Blachut and Burkhardt (1989) notethe Istituto Geografico Militare showed little inter-est in the technique until many years after Porrosdeath in 1875 The resurrection of Italian photo-grammetry was largely due to two men UmbertoNistri who designed aplotter in 1919for large-scaleplotting and Ermenegildo Santoni who producedhis first instrument the autoreductor in 1921 In1926 Nistri founded the firm Ottico MeccanicaItaliana (OMI) to produce his photogrammetricinstruments Nistris early instruments all useddirect optical projection while Santonis instru-ments all used mechanical projection The IstitutoGeografico Militare was middotequipped with Santoniinstruments which it used for mapping at 125000and 110000 The Societa Anonima RilevamentiAerofotogrammetrici (SARA)on the other handused Nistri instruments largely for topographicmapptng outside Italy but also for cadastral map-ping within the country

Photogrammetry had been used in Switzerlandfor engineering surveys in the nineteenth centuryyet there had been no systematic attempt to carryout topographic mapping using the techniqueThe history of mapping in Switzerland betweenthe two world wars is largely a history of the WildHeerbrugg Company Set up in 1921 the com-pany produced its first phototheodolite in 1922and its first photogrammetric plotter the Alstereo-autograph in 1923 Its first major contribu-

Cartography and Geographic Information Science

tion to surveying came with the production of theT2 theodolite in 1924 The revolutionary design ofthis instrument-replacing engraved metal circleswith glass versions provided more accurate read-ings and better illumination-led to considerableexcitement in scientific and survey circles By thelate 1920s Wild was engaged in serial productionof the T2 and T3 theodolites the P3 phototheodo-lite and the A2 autograph which had replaced theAI In addition the Cl C2 and C3 aerial cam-eras were also in production In the space of onlyeight years Wild had become a major player in thesurvey world a position enhanced further duringthe 1930s

By the late 1920s the Landestopographie inSwitzerland had gained considerable experiencewith Wild instruments for both terrestrial andaerial surveys (Schneider 1929) Topographicmaps were produced from terrestrial photographyat 125000 while aerial photography wasused for110000 mapping (Schneider 1929 Harry 1971)

In the United States in addition to usinggraphical techniques the USGS started to inves-tigate instrumental methods In 1921 it obtaineda stereoautograph from Germany for evalua-tion but restricted the use of the instrument toplotting from terrestrial photography and notable to produce maps economically (Thompson1952) In 1927 the Geological Survey acquired theHugershoff aerocartograph the first automaticstereo-plotter used by an American governmentmapping agency (Thompson 1952) Thomas PPendleton laid down guidelines for mapping fromaerial photography within the USGS in Bulletin788-F Map Compilation from Aerial PhotograPhsissued as part of the Topographic Instructions of theUnited States Geological Survey (Pendleton 1928)Given the rapid developments in radial-line meth-ods (eg Hotine 1927) the timing of Pendletonswork was a bit unfortunate as he asserted thatradial-line techniques were really only suited foruse with multi-lens photography because therelatively short radial lines that could be drawnon single-lens photographs could not give the bestresults (Pendleton 1928 p 409)

In Britain research work carried out by the AirSurvey Committee focused on simple methods butthe Committee did not entirely ignore instrumen-tal techniques MacLeods wartime work with rec-tifiers was developed and more importantly theideas of Fourcade (l926a 1926b 1926c 1926d)on the theory and use of stereogoniometers forphotogrammetric plotters were taken up In 1926the Committee commissioned the constructionof an instrument along the lines proposed by

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Fourcade and the instrument was delivered in1928 0ar Office 1935 Hotine 1931)

In India success with non-instrumental tech-niques did not distract the Survey from instrumen-tal techniques they had helped pioneel- Mappingofficials followed developments taking place inEurope and in 1926 Mason (1927) carried outa survey in the Shaksgam using a Wild photo-theodolite and plotted the results in Switzerlandusing an autograph in the Topographical Instituteat Flums

CamerasThe tri-lens camera developed by Bagley was usedby the USGS in mapping for aeronautical chartsThis program wasjointly organized with the Corpsof Engineers and the Air Service (Committeeon Photographic Surveying 1921) and providedvaluable experience in civil applications In 1920programs with the tri-lens camera were also under-taken in Santo Domingo and Haiti

The Corps of Engineers became involved inphotogrammetric methods in 1920 when Bagleywas assigned to cooperate with the Army AirCorps in carrying out tests on aerial photographyfor topographic mapping Initially the trials usedBagleys tri-lens camera but he went on to developthe five lens T-3Acamera which was to remain thestandard mapping camera of the US Army until1940 (Landen 1952) The War Department issuedtraining regulations for mapping from aerialphotography in 1923 however the techniques dis-cussed in the regulations were largely those refinedduring World War 1

The 1930sBy the late 1920s photogrammetry had becomea cost-effective alternative to some traditionalground surveys Yet expensive photogrammetricplotting instruments and labor-intensive graphicalplotting meant that photogrammetry still lackeda decisive advantage over ground survey Duringthe 1930s a number of innovations were to swingthe balance decisivelyin favor of photogrammetricmethods

Progress was slowed if not stopped by the reces-sion that started in 1929 Some measure of theimpact can be gauged from job cutbacks at WildHeerbrugg In 1930 before the recession had amarked affect on Europe the workforce stood at260 but by 1933 the number ofjobs had droppedto 125This was the direct consequence of the deci-sions taken to retrench mapping projects as well as

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capital programs Nearly all the annual reports forthe early 1930s mention the financial constraintsunder which organizations had to work In theUnited States some of these problems were offsetby appropriations under the Emergency Reliefand Construction Act (US Coast and GeodeticSurvey 1933) Moreover the New Deal initiated awide range of programs in which photogrammetrywas to playa major role By contrast problems inthe colonial territories were if anything worsethan in Europe and North America The declinein industrial activity in developed countries ledto a collapse in demand for raw materials fromthe colonies and as this was the main source ofgovernment revenue they could no longer pay forsurvey work Annual reports from most colonialsurvey departments make reference to a lack ofresources to meet the need for mapping Howevel~by the late 1930s as a result of rearmament inEurope governments allocated more money tosurvey organizations

Survey organizations were eager to adopt newtechniques in routine mapping programs but thepressures within governments to deal with massunemployment probably helped to promote theuse of labor-intensive methods in survey at theexpense of investment in technology Certainlyorganizations such as the Tennessee ValleyAuthority (TVA) the Agriculture AdjustmentAdministration and the Soil Conservation Servicein the United States were all heavily dependenton such labor-intensive techniques and did muchto develop them as standard mapping methodsMoreover organizations such as the USGS andthe TVA also played a role in the developmentinstrumental methods such as multiplex All ofthis was to be of vital importance to the hugephotogrammetric mapping programs that wereto emerge during World War II The scale of theseprograms would have been inconceivable withoutthe trained body of photogrammetrists developedduring the 1930s (Landen 1952)

Within the British colonial territories the conser-vative element that had inhibited the developmentof photogrammetric methods through the 1920scontinued to delay adoption of photogrammetryuntil after World War II-with some illuminatingexceptions Cyprus is the only known example ofa local survey department attempting to carry outphotogrammetric work Aerial photography wastaken in 1936 but delays in obtaining groundcontrol meant that no use was made of the pho-tography before all normal work was suspended atthe outbreak of war In all the other colonies wherephotogrammetry was attempted private survey

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companies carried out the work The earliestexample of the involvement of private air surveycompanies had been in 1927 in the mapping ofthe Anglo-Belgian boundary in the Copper Beltregion of Northern Rhodesia (Colonial SurveyCommittee 1928) Private air survey companieswere also active in Uganda Tanganyika andSouthern Rhodesia but in all cases this was surveywork for specific development projects ratherthan routine mapping (War Office 1935) Therewere discussions about the use of photogramme-try in Sierra Leone where the Aircraft OperatingCompany of South Africa proposed to revise the162500 topographic maps for pound150000 includ-ing the cost of providing ground control but thework was never carried out due to financial con-straints and the outbreak of World War II Therewere also discussions about air survey in Jamaicaand the Gold Coast but nothing came of theseprojects until after World War II It is clear fromthe literature and correspondence of the time thatthe private air survey companies were lobbyingindividual colonial governments as well as theBritish Government to adopt air survey but theColonial Survey Committee under Winterbothamwas equally forceful in its resistance to changelargely on grounds of cost (see in particularWinterbotham 1920 1921 1929 1934 1936Hemming 1933)

Increasing recognition that war with Germanywas inevitable led to a significant change in theBritish establishments attitude towards the use ofair survey In part this change reflected the retire-ment of Winterbotham in 1935 and his replace-ment as Director General of the Ordnance Surveyby MacLeod who was alwaysa warm supporter ofair survey MacLeod had followed Winterbothamfirst as Director of Military Surveys and then atthe Ordnance Surveyand in each case he playeda major role in introducing the use of photogram-metry (Clough 1952)

Advances in InstrumentationThe late 1920s had seen the design and produc-tion of the first practical plotting machines for usewith aerial photography The experience provideda foundation for the introduction during the1930s of designs that were to be the mainstaysof topographic mapping The Zeiss C4 had beenintroduced in 1930 (Burnside 1993)AsThompson(1966) notes the C4 and the superseding C5(introduced in 1935 with improved illumination)were with the Wild A5 (launched in 1937) practi-cally the only universal instruments on the marketin the 1930s Universal instruments designed to

CartograPhy and GeograPhic Information Science

handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

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graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

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Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

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world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

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Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

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American textbook on photogrammetry (FIemer1906) Even so this did not lead to the widespreadadoption of photogrammetry within the USCampGSas photographic techniques could still not competewith the efficiency of existing techniques (Landen1952) In 1904 the US Geological Survey (USGS)which was also interested in the use of terrestrialphotogrammetry adopted Devilles panoramiccamera approach for mapping in Alaska JamesBagley further developed the technique by rede-signing the camera and producing a panoramicphoto alidade (Bagley 1917)

Photogrammetry to 1914Until the outbreak of World War I the chief focusof photogrammetry remained terrestrial appli-cations In 1901 Henry Fourcade described amachine designed to make measurements fromstereoscopic photographs essentially a stereocom-parator (lltourcade 1901) At about the same timeCarl Pulfrich (1902) produced and described thePulfrich Zeiss stereocomparator During the 1930sthere was considerable debate over the precedencein producing a serviceable design for a stereocom-parator Otto von Gruber (1932) gives precedenceto Pulfrich by citing his 1902 paper and the 1902paper by Fourcade which appeared in Nature Butas noted above the Fourcade design was first dis-cussed in a paper published in 1901 albeit in arelatively obscure journal It is not clear whethereither designer was aware of the work of the othereven if they both produced very similar designsThis notwithstanding it is worth noting that vonGruber was also to dismiss Fourcades claim toprecedence over his own work in the design ofan instrument that employed the concept of thestereogoniometer Martin Hotine (1931) makes astrong case in support of Fourcade s precedence inboth cases Both machines could be used to makeaccurate stereoscopic measurements of pointsbut because the plan positions and heights of thepoints were computed individually maps producedfrom these measurements required interpolation

While these early machines demonstrated thepossibility of making accurate maps from stereo-scopic photographs the technique was extremelytime consuming and only suitable if no othertechnique was available Appropriate conditionsexisted in alpine mapping where ground surveywould have been hazardous or even more timeconsuming than photogrammetry Early examplesof photogrammetrically derived contours were pro-duced in the Tyrol between 1902 and 1907 by theAustrian survey using the Pulfrich stereocompara-

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tor (Kretschmer 1991) Both the Prussian GeneralStaff and later the French Service Geographiquede lArmee adopted the Pulfrich stereocompara-tor for mapping mountainous areas in Pelvoux(Service Geographique de lArmee 1912 1938)However there was general recognition that thetechnique was not cost effective(see the commentsof Major Hills followingThompson 1908)

What was needed to make the use of photogra-phy cost effectivewas the ability to produce topo-graphic details and contour lines directly from thephotographs rather than by manual interpolationIn 1908 Eduard von Orel produced his autoste-reograph (von Ore11910 1911 1912von Gruber1932 Hotine 1931 Kretschmer 1991) and in thesame year Vivian Thompson published details ofhis stereoplotter (Thompson 1908 von Gruber1932 Hotine 1931 Thompson 1974 Petrie 1977Burnside 1995) Both machines were capable ofproducing plotted detail lines and contours fromterrestrial photographs The autostereographwas quickly adopted by the Austrian survey foralpine mapping and was subsequently taken up byother national mapping departments The largestsystematic survey carried out with the autostereo-graph was some 560 km2 of the Tyrol surveyed in1911 by the Militargeographische Institut (Koner1924) Bycontrast the stereoplotter attracted littleinterest in its country of origin Great Britain butwas adopted by the Survey of India for mappingin the Karakorum Range Because these areashave not subsequently been remapped the origi-nal contours from the stereoplotter are still thoseused on the published sheets One plotter was alsoacquired for survey work in Fiji where McCawused it for mapping prior to WorldWarI (ColonialSurvey Committee 1911 1912 1913)

Both machines were suitable for mapping fromterrestrial photographs as were machines devel-oped from von Orels autostereograph (Therewere no developments from the stereoplotter)Howeverbecause both solutions required coplanarphotographs they could not be readily adaptedfor use with aerial photography which is rarely ifever coplanar This fact did not stop many abor-tive attempts to turn terrestrial photogrammetricplotters into machines capable of handling aerialphotographs

A non-technical development that was to havea significant impact on the development of pho-togrammetry was the founding of the AustrianSociety of Photogrammetry in 1907 followedby the publication in 1908 of the first volumeof the lnternationales Archiv flir PhotogrammetrieThe International Society for Photogrammetry

Cartography and Geographic Information Science

was founded in Vienna in 1910 Vienna was alsothe setting for the first International Congressfor Photogrammetry in 1913 The Society wasto become one of the main vehicles for the dis-semination of information on photogrammetrywhile the congresses were the main showcases forthe latest equipment Previously the InternationalGeographical Union was the main forum for thedissemination of developments in surveying andphotogrammetry but its importance had contin-ued to decline until after World War II when italmost completely withdrew from the field

World War I (1914-1918)World War I generated an unprecedented demandfor maps at scales from 1200 for detailed trenchmaps (Chasseaud 1999) to 11000000 andsmaller for strategic planning maps (Heffernan1996)At the outbreak of war in 1914 the armies ofEurope were issued with maps at scales of 180000or smaller designed to support a war of rapidmovement in which victory would be achievedby bringing to bear an overwhelming force in adecisive battle Military leaders still believed thatoffensive operations could be successful despitethe precedent of the Russo-Japanese War of 1905which had degenerated into sieges and large bat-tles of encounter in which opposing armies foughtin the open rather than in prepared positionsNeither side could achieve a decisive blowbecauseof the superiority of defense based on rifles andmachine guns

The strength of the defenses meant that if therewas to be any hope of success in offensive opera-tions the attacking troops needed accurate mapsof the enemy defenses This included the positionsof any artillery ammunition dumps and transportinfrastructure Allof these features were difficult orimpossible to map from the front line In the caseof ammunition dumps and transport the targetscould be many miles behind the front What thearmies of both sides needed wasa wayof collectinginformation that could either be added to existingmaps or used to produce entirely new maps Mostimportantly as the artillerymen developed evermore accurate targeting they created a demandfor increasingly precise mapping to locate poten-tial targets As the war progressed the armiesexperimented with a closer integration of artilleryand infantry operations such as the rolling bar-rage (a barrage where the gunner slowlyincreasesthe range while infantry advance slowlybehind thebarrage) Again this required more precise point-ing of guns and locating of targets

Vol 29 No3

Suneyors were used to fix the position of bothguns and targets The need for secrecy-no pointin alerting the enemy that an attack was beingprepared-also changed the ways in which theguns acquired their targets Early in the war thenormal technique involved the use of rangingshots That is each gun was fired towards a poten-tial target and an observer identified the fall ofshot The obsener then told the gunner to eitherincrease or decrease the range as appropriateand to traverse left or right until the shot was fall-ing on the target The problem with this techniquewas that it revealed that a new gun had been intro-duced into a stretch of the front A large number ofranging shots revealed the introduction of a largenumber of guns and the threat of a forthcomingattack To overcome this dilemma the positions ofthe guns and targets needed to be determined pre-ciselyby surveying From this information artilleryboards were prepared to show the positions of theguns as well as the targets It was then possible todetermine the directions in which the guns neededto fire and the range to the target without reveal-ing that new guns had been positioned

The identification of targets and the accuratepositioning of guns led all the nations to adoptthe use of grids on their mapping In the latenineteenth century John Ardagh had tried toget a grid system adopted by the Survey of Indiabut without much success (Ardagh 1893) Prior toWorld War I therefore almost no maps carriedgrids The exceptions were the squared mapsused by the French artillery on maneuvers atChalons in 1911 (Chasseaud 1999) Increased useof indirect fire underscored the need for griddedmaps Unfortunately grids were adopted on an adhoc basis which led to considerable confusion Forexample the Germans used three different gridsystems with origins at Lille Rheims and Paris(Hinks 1919)The British adopted an imperial gridbased on 1000-yard grid squares even though theentire mapping on the Western Front used metricscales Despite this uncertain start it was quicklyrealized that grids had uses well beyond those ofwarfare and they became a standard feature ofmost post-war topographic mapping

Military mapping in Europe was largely focusedon map revision whereas that in Palestine Sinaiand Mesopotamia involved considerable origi-nal mapping (Collier 1994 Collier and Inkpen2001) In the initial stages of the World War I allthe belligerents used existing pre-war mappingsupplemented by photographic enlargements InFrance this involved the use of 180000 mappingsubsequently enlarged to 140000 When how-

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ever the deficiencies of the enlargements becameevident they were replaced by new mapping Onlythe German survey seems to have continued to useenlargements through to the end of the war aack1920) With the development of positional warfare140000 mapping wassoon found to be inadequateand was successively complemented by mappingat 120000 and 110000 Where necessary evenlarger scales were used (Chasseaud 1999)

Behind the lines revision and new surveys werecarried out using conventional land survey tech-niques trigonometrical control surveys and theplane table to add detail Oack 1920 Winterbotham1919a 1919b Service Geographique de lArmee1938 Albrecht 1969 Chasseaud 1999) For front-line areas and for the enemys rear areas the maindata source was aerial photography

The Development of CamerasInitially photography for intelligence and maprevision involved the acquisition of photographyfrom fairly low flying aircraft using largely impro-vised camera equipment With the development ofanti-aircraft defenses however reconnaissance air-craft were forced to fly higher and higher to avoidbeing shot down To compensate it became neces-sary to devise cameras with longer and longer focallengths if the resultant photography was to be ofuse for analysis and mapping

The earliest cameras were simple devices thatused glass plates and dark slides (devices used tochange glass negatives in a camera without expos-ing the negatives to light) Images were obtainedby observers pointing the cameras over the side ofthe aircraft The cameras were fitted with simplesighting devices to ensure that the target wasactually imaged Recognition that vertical photo-graphs were much better suited to mapping thanthe oblique pictures taken with hand-held camerasled to the cameras being fixed to the side of theaircraft Fairly quickly magazines were providedso that a series of photographs could be taken bythe observer activating a lever to change platesEven so changing the magazines still required theobserver to lean over the side of the aircraft Giventhese difficulties it seems strange that roll filmwas not used earlier especially since panoramiccameras had used it as early as the late nineteenthcentury The Germans did not introduce a filmcamera until 1916 (Albrecht 1969) and the Britishcontinued to use plate cameras until the end ofthe war

Most of the cameras used for military operationshad relatively long focal lengths the standardBritish camera in the early part of World War I had

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a focal length of 8 inches (approximately 200 mm)while the standard German camera had a focallength of 180 mm (Albrecht 1969) By the end ofthe war focal lengths of 500 mm were not uncom-mon-some German cameras had focal lengths aslarge as 1200 mm (Albrecht 1969) These lenseswere designed for reconnaissance rather thanmapping so that each photograph covered only asmall area of ground Cameras needed wide-anglelenses to minimize the amount of control neededfor mapping but none of the high-quality lensesavailable provided a wide field of viewMulti-lenscameras were developed in the nineteenth centuryto obtain broader coverage from each exposurestation but these cameras were generally largeand cumbersome and thus unsuited for militaryoperations

Control for MappingEarly attempts at using aerial photography formap revision experienced considerable difficul-ties As Malcolm MacLeod (1919 pp 382-83)noted though the photographs showed all theprincipal topographical features in great detailthere was no means of determining their exactscale or the amount of distortion due to thecamera not being truly vertical at the moment ofexposure of the plate In the absence of mechani-cal restitution instruments to overcome theseproblems two possible solutions were consideredto develop a device for mechanically determiningthe altitude and tilt of the camera at the momentof exposure or to compare the positions of pointson the photographs with their known ground coor-dinates Although both sides experimented with amechanical solution most work involved the lattertechnique This placed a heavy demand on accessto ground coordinates

The provision of control points both in andbeyond their own front line was a major problemfor all the combatant nations Placing markersover control points in frontline areas and thenfixing them by observation from the rear was notfeasible as this also enabled the enemy to fix theposition of the trenches A number of strategieswere adopted including the use of periscopictheodolites employed from within the trencheswithout exposing observers to enemy fire Thesetheodolites could be used to fix positions withinthe trenches by resection

While resection on the plane table was a com-monly used technique among topographers ithad not been widely used for instrumental obser-vations because of the relative complexity of thecalculations However the conditions of trench

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warfare left few alternatives Once adopted resec-tion remained in common use among surveyorsAn alternative adopted by the Germans was to firea flare vertically from the trenches and obsenTethe flares position from the rear using theodolitesGack 1920)

Locating control points beyond the front line waseven more difficult Where possible the position ofprominent points would be fixed by intersectionHowever in Mesopotamia there were often too fewsuitable features to intersect This led to an inno-vation by Col C P Gunter to fix control pointswithin the Turkish lines using artillery shell burstsFour observers took simultaneous observations ofindividual shell bursts while an observer in anaircraft recorded the position of the explosionson a detailed map of the trenches created from airphotographs On average out of ten shell burststhree good intersected points were observed andthe observer would have accurately marked one ofthese Points observed in this way were then usedto control and adjust the strips of photographyused for mapping (Surveyof India 1925)

Plotting DetailOnce control had been obtained it was necessaryto interpret and plot the information on photo-graphs Initially interpretation was relatively easyas there was little attempt to conceal potentialtargets from aerial observation Camouflage onlystarted to be used systematically around 1916(MacLeod 1919) thereafter photo-interpretationdeveloped into a specialist skill Use of camouflagealso led to the development of new surveyingtechniques such as flash spotting and soundranging

Extraction of detail for revision purposes wasdone by some form of graphic intersection orthrough the use of optical projection Despite someuse of more rigorous methods involving compara-tors developed before the war these instrumentstogether with the necessary calculations were slowand not well suited to the urgent needs of the warThe use of automatic plotters such as the alitoste-reograph was restricted to terrestrial photographydue to the need for coplanar photography In factthis technique was used only by the Germans andFrench in eastern France where relief was suitableand by the Austro-Hungarian Army in the AlpsOskar Albrecht (1969) also refers to the use of ter-restrial photogrammetry for artillery assaults onfortresses and the use of photographs taken fromtethered balloons

The belligerent powers employed a variety ofgraphic techniques The simplest involved the pro-

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duction of a framework of existing detail on a com-pilation sheet on which new detail was added fromaerial photographs with the help of proportionaldividers Although capable of producing reason-ably accurate results this approach was labori-ous and slow (MacLeod 1919) The paper stripmethod (Thompson 1966) used for adding smallamounts of detail was equally slow and laboriousThe German Army developed a less strenuoustechnique based on the use of perspective gridsThe chief advantage of this technique was thatonce the grids had been generated detail could betransferred by eye from aerial photograph to mapThis technique was so successful that it was widelyadopted after the war for map revision Describedin most standard textbooks on photogrammetrythe perspective grid approach remained in useuntil the 1980s when simple digital techniquesrendered it obsolete

Most of the optical revision techniques reliedon the registration of a projected image of thephotograph on an existing map or on a frame-work of control Once the image was registeredthe mapmaker could either transfer the informa-tion directly to the map or produce a correctedphotographic print for use in revision TheodorScheimpflug had shown that an accurate regis-tration could be affected between the projectedimage and the control data if the projected imagewas in focus for the entire image area To satisfYthe so-called Scheimpflug condition the projectedplanes of the negative lens and easel had to meetat a common axis (Scheimpflug 1898 Blachutarid Burkhardt 1989) Even if the condition wassatisfied there were still errors of registration dueto relief displacement In the instruments usedduring World War I the Scheimpflug conditionwas hot satisfied and consequently the resultswere at best approximate (Blachut and Burkhardt1989) MacLeod (1919 1920) describes the use ofCamera Lucida and the enlarging lantern inboth of which the plane of the negative and theplane of the lens were held parallel with only thecopy board which was capable of being tilted Theeniarging lantern could maximize the depth offocus and hence the sharpness of the iinagebyreducing the aperture of the lens to the smallestdiameter possible The use of the enlarging lan-tern to produce semi-rectified prints came to bethe preferred techrnque

As already noted while most of the work onthe Western Front involved map revision innon-European theaters the need was for originalmapping (Collier 1994 Collier and Inkpen 2001)The first attempts to use aerial photography to

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construct original mapping took place during theGallipoli campaign (Dowson 1921) Not very suc-cessful these attempts demonstrated the problemsassociated with the non-stereoscopic use of aerialphotography as when troops were sent to occupypositions identified monoscopically as trenchesor ditches but which turned out to be shallowscrapes that afforded no shelter from enemy fireAttempts to create original mapping ceased whenmodern Turkish maps of the area were capturedand revised

In Egypt the Turkish threat to the Suez Canalalso resulted in experiments in mapping fromaerial photography Like the mapping in Gallipolithese were largely unsuccessful The main problemwas locating precisely where the photographs hadbeen taken over a largely featureless desert Thebulk of the mapping for the Suez Canal defenseswas therefore carried out by triangulation andplane table survey (Maule 1919)

When the Egyptian Expeditionary Force (EEF)advanced across the Sinai Peninsula to engageTurkish forces in Palestine it moved into terri-tory without up-to-date mapping of an adequatescale Western Palestine had been mapped for thePalestine Exploration Fund (PEF) in the 1870s(Conder 1878 Conder and Kitchener 1881-83) ata scale of 163360 Although based on triangula-tion the detail had been surveyed using compassand cavalry sketching board (Close 1932) and wastherefore regarded as insufficiently accurate formodern warfare British military personnel hadsurveyed Southern Palestine just before the warunder the cover of a PEF expedition (Woolleyand Lawrence 1914) But even here the scale wastoo small (1 125000) for the kind of operationsbeing undertaken The British army was thereforeconfronted with the need to map areas beyond itsfront line for which no adequate base maps wereavailable

The first successful attempts at mapping fromaerial photographs were in t~e area aroundGaza (Gavish and Biger 1983) Here control wasprovided by the intersection of prominent pointsbehind Turkish lines Based on these points acontrolled mo~aic was created from with verticalaerial photogriphs and the mosaic was then usedto crcate the line maps of the planimetry Althoughcrude by later standards the map was consideredto be a significant improvement on anything thenavailable This encouraged the surveyors led byMajor W] Maule to embark upon an ambitiousplan to create a series of topographic maps at 140000 for areas of Palestine behind Turkish lines(Maule 1919) Strips of photography were flown

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roughly parallel to the front line with additionalstrips of photography perpendicular to the frontflown at intervals to control the strips parallel tothe front Supplementary control was provided bytheodolite observations wherever possible Thesame basic arrangement pioneered in the map-ping of Gaza was followed for the series mappingHowever as the area mapped extended into thehills of Judea (the southern West Bank) it alsobecame necessary to provide some indication ofrelief Viewing the photography stereoscopicallyand form lining achieved this The nature of thetopography nearly horizontally bedded lime-stones that eroded into natural terraces madethis task relatively easySuccessfulas the mappingwas (Thomas 1919) as each new area came underBritish control mapping derived from air photoswas replaced bymapping made using conventionalground survey techniques

In a number of ways the mapping inMesopotamia can be regarded as the first exampleof true photogrammetric mapping using aerialphotography Unlike the mapping in Palestineit was produced as the end product not as aninterim solution to be replaced as soon as groundsurveys became possible And unlike the mappingon the Western Front it did not involve revision ofexisting mapping as no proper maps existed forthe area

Although developments in the use of air pho-tography had been watched with envy by thesurveyors in Mesopotamia (Survey of India 1925)until early 19I6 no airplanes had been availablefor that theater Some experience in the use ofaerial photography had been gained before thesiege of Kut-al-Amarah but it was the positionalfighting around Kut that emphasized the advan-tages of air survey Maps were required of areasbehind Turkish lines but the flat landscape meantthat surveyscould only be extended into no-mans-land This led to the first real attempt to createmaps from aerial photography As the first mapTC4 (TC are the initials of Tigris Corps theoriginal name of the force sent to Mesopotamia)has been discussed at length elsewhere (Collier1994 Pritchard 1952 Survey ofIndia 1925)

The surveyors working in Mesopotamia experi-mented with various ways of making maps fromaerial photographs drawing on the experience ofsurveyors on the Western Front and in Egypt Inthe end though they developed their own tech-nique which was well suited to local conditionsTheir technique involved creating semi-rectifiedphotographs using an enlarging lantern (Gunter1917) and then mosaicing the photographs using

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a triangulation scheme The mosaics were inkedup before the bromide prints were bleached out soas to leavejust the inked linework The importantpoint to note is that this technique was used formapping areas on both sides of the front line andwas therefore regarded as the final product Theflat floodplains of the Tigris and Euphrates Riverslent themselves to mapping using semi-controlledmosaics as there was an almost complete absenceof height to create displacement errors The map-ping of Mesopotamia from aerial photography seta precedent for post-war mapping in India

Flash Spotting and Sound RangingAs mentioned earlier the use of camouflage neces-sitated the development of techniques for targetlocation in particular the location of enemy gunpositions for counter-battery fire At the beginningof World War I guns were aimed by direct observa-tion of targets and the guns themselves were oftenpositioned in the open to improve their fields offire With the increased use of counter battery fireit became normal for guns to be dug in posi-tioned in gun pits and protected by sandbags Toprotect gun positions from enemy air observationthe gun pits were subsequently camouflaged withnetting which thwarted an accurate identificationof their positions

Flash spotting and sound ranging were devel-oped as means of tackling the problem of identify-ing and locating enemy gun positions Adopted byall the combatant nations flash spotting involvedintersecting the gun position by observing theflash as tht gun was fired Flash spotting requiredconsiderable organization as the observers had toensure that they were observing the same gun flashbut by carefully noting the times of the observa-tions it was possible to obtain accurate locationsof enemy guns Most armies established specialistunits for this purpose (Innes 1935 Chasseaud1999 Hinks 1919 Maule 1919)

Sound ranging was a more complex process inwhich the British and French enjoyed a technolog-ical lead over the Germans General Ludendorffthe German Chief of Staff who issued specialinstructions that precautions be taken to cam-ouflage the sound of guns directed the army tosecure an example of the British system (quotedin Hinks 1919) Based on a technical solutiondeveloped by Lucien Bull at the Institut Marey inParis the British system relied on an array of sixmicrophones spread over a 9-kilometer-long base-line situated about 4 km behind the front iine Themicrophones were connected to a galvanometer atthe hea~quarters As the sound of a gun reached

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each microphone in turn a signal was sent by wireto the galvanometer where it produced a distinc-tive trace on photographic film By measuring theseparation of the traces of the gun detected at eachmicrophone the distance and direction of the guncould be calculated Complex arrangements withmore than two microphones were needed becauseof uncertainty about the effect of wind speed andother factors on sound waves (see Innes 1935 andChasseaud 1999 for more technical details)

The German systemrelied on a fonvard observerand four other observers along a base of 10 to 15kilometers On hearing a gun firing the forwardobserver sent a signal by field telephone to theother observers who on receiving the signalstarted their stopwatches and noted the time inter-val before they heard the gun The times were thensent to group headquarters where the position ofthe gun was calculated An alternative and sim-pler method involved an observer noting the timeinterval between seeing a gun flash and hearingthe noise of the gun The greatest precision possi-ble with these techniques was about +200 meters

Non-military WartimeDevelopments to 1918

While the mapping efforts of the combatantnations were almost entirely directed towards thewar effort cartographers in the United States wereactively exploring civilian applications of pho-togrammetry The most important developmentwork was carried out at the US Geological Surveywhere James Bagley was developing a tri-Ienscamera and Fred Moffit was developing a trans-forming camera capable of handling the nega-tives produced by Bagleys camera (Committee onPhotographic Surveying 1921)

Developments to 1930In the period leading up to and including WorldWar I all the major powers followed broadlysimilar paths in developing photogrammetry Inmost countries attempts to develop instrumentalmethods complemented heavy reliance on graphi-cal and optical techniques for producing andrevising large-scale maps After the war a numberof countries took distinctly different paths withcontinental European countries generally puttingmost of their effort into instrumental techniqueswhile English-speaking countries focused ongraphical techniques Arguably until about 1930the approach adopted by the English-speaking

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countries was the most fruitful as the instrumentaltechniques developed in Europe could not com-pete in cost or efficiency with British and Americanmethods

After 1930 the relative efficiencies of the twoapproaches changed markedly The Americansrecognized the changed circumstances morequickly than their British counterparts and beganadopting instrumental methods by the mid 1930sIn Britain and by extension throughout the BritishEmpire instrumental photogrammetry was still inthe experimental phase at the outbreak of WorldWar 11in 1939

The immediate post-war-one period saw a flurryof papers extolling the merits of mapping fromaerial photography At the forefront of the cam-paign to get the methods accepted in Britain wasCapt H Hamshaw Thomas (1919 1920 1924)who drew heavily on his experiences in the Sinaiand Palestine Much of the effort to promote airsurvey was conducted in non-specialist journalssuch as the GeograPhicalJournal (Newcombe 1920)and even in the popular press MacLeod who hadserved in France and had become a firm advocateof air survey methods also produced a numberof papers as well as an important official publica-tion Mapping from Air Photographs issued by theWar Office (MacLeod 1920 but see also MacLeod1922 1923a 1923b)

Britain more than in any other country held aconservative attitude towards the new techniquesand this resistance found an influential championin Harold StJ LWinterbotham A self-proclaimedexpert on air survey (see Winterbotham 19291934) Winterbotham did much to impede theadoption of air survey both in Britain and throughhis role on the Colonial Survey Committee in thecolonial territories In contrast the Dominion ter-ritories were free to determine their own policiesAlthough Canada a pioneer in photogrammetryhad been joined by India in its use of these tech-niques before the outbreak of the First World Warother Dominion territories were slower in adopt-ing air survey Australia took the lead but localfactors either delayed or advanced the adoptionof photogrammetry in Dominion territories whichwere not compelled to follow the Colonial SurveyCommittees recommendation There is a strik-ing parallel between these largely autonomousterritories and the Dutch East Indies where thesurvey department was quick to adopt photogram-metry (van Roon 1925) but made no real progressat home in The Netherlands until after World WarII

In the British context Winterbothams reser-vations concerning the cost-effectiveness of air

i64

survey methods were probably justified at leastuntil the development of Reinhard Hugershoffsaerocartograph in 1926 (Blachut and Burkhardt1989) All the air survey instruments introducedbefore the aerocartograph were essentially ter-restrial plotters adapted in some way to copewith non-coplanar photography This made theinstruments difficult and slow to set up and theyusually required two men to carry out orienta-tion and plotting operations In a well mappedcountry such as Britain cumbersome machinescould not support map revision as economically asconventional ground surveyhere Winterbothamerred even in the 1920s was in extrapolatingfrom the British experience to the colonial terri-tories where the needs were very different On thepositive side agitation by Hamshaw Thomas andothers as well as the successful application of airsurvey techniques by the Survey of India led to thesetting up of the AirSurvey Committee Part ofthe responsibility of this committee was to adviseon air survey matters but it was also responsiblefor carrying out research

In the United States the promotion of airsurvey techniques wasundertaken by Moffit (1920)and other surveyors who had not been directlyinvolved in the war effort but had carried on withtheir civilian work in government mapping agen-cies Part of this promotion was carried out in non-specialist journals but unlike in Britain there waslittle need to convince the political leadership ofthe advantages of air surveyBycontrast there waslittle attempt to promote air survey in France orGermany other than in technical or professionaljournals Almost certainly this reflects the higherstatus of engineers and technical experts in thosecountries compared with Britain The UnitedStates probably fell somewhere between Britainand the continental powers but more towards thelatter

Survey and mapping activities in Austria suf-fered a severe setback with the breakup of theHabsburg Empire at the end of World War 1The Militargeographische Institut was disbandedin 1920 (Kretschmer 1991) and its personneldispersed amongst the successor states Whilethis disintegration had clear disadvantages forAustria survey departments in Poland Hungaryand Czechoslovakiagained a cadre of trained andexperienced personnel able to form the nucleusof new national survey organizations Despite eco-nomic hardship in the wakeof the warAustria hadbegun in 1928 to supplement existing 175000topographic mapping work focused on the moun-tainous areas using terrestrial photogrammetry

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Graphical MethodsBecause of the extensive use of graphical methodsduring WorldWar I a large body of trained person-nel was available to implement these methods forpost-war mapping But the techniques developedthus far were either non-rigorous (for example theperspective grid) or suitable only for revising smallnumbers of features (the paper strip method)What was needed was a rigorous technique thatdid not require highly skilled workers

Bagley had sowed the seeds of a rigoroustechnique during his work with the PanoramicPhotoalidade (Bagley 1917) but Martin Hotine(1927) provided the theoretical and practicalbasis for a cost-effective mapping techniqueDescribed as a Simple Method of Surveying fromAir Photographs Hotines technique becameknown as the Arundel Method (after Arundelin southern England where the technique wasfirst used experimentally) or the radial-line tech-nique Hotine subsequently developed the methodof control extension using radial-line methods(Hotine 1929) and laid the foundations for muchof the medium-scale photogrammetric mappingcarried out in the English-speaking world over thenext 40 years The American development of slot-ted templets and radial intersectors expeditedthe process of aerotriangulation (see below) butit was Hotines theoretical work that made thesedevelopments possible

None of the countries using aerial photogra-phy for topographic mapping embraced it withgreater enthusiasm than India As noted earlierthe Survey of India had acquired two examplesof Thompsons stereo-plotter Kenneth Mason(1913 1927) had used the stereo-plotter in 1913in the Pamirs with considerable success but theexperience of the Survey of India in Mesopotamiaduring World War I wasdecisive in promoting airsurvey techniques in India In 1920 a series ofexperiments conducted at Agra demonstrated theutility of air survey methods for mapping flat areasin India (Lewis and Salmond 1920) Air surveyp~oved inefficient for one-inch-to-a-milemiddot map-pmg-the cost was roughly twice as much as forground surveys-but it was economical for largerscales An experiment in urban mapping was car-ried out but its results were inconclusive

Among developed countries the United Stateswas probably the most in need of the advantagesthat air survey offered post-war mapmakers Forall its great wealth America was poorly mappedby European standards Where most Europeancountries were at least mapped at medium scale(roughly 1100000 or larger) large tracts of the

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United States were not mapped even at small scaleIt was at just this small-scale range that air surveyseemed to offer the greatest advantages

The work carried out within the USCampGSand USGS prior to and during World War I hadprepared both agencies to take advantage of theemerging technology Starting in 1919 USCampGSused aerial photography for chart revision(Quillian 1919 Mattison 1919) and for wetlandsurveys (Mattison 1924 Graham 1924-25) Someproblems were encountered but the particularadvantages of air survey for mapping wetlands ledto the technique becoming the standard procedure(Landen 1952) In carrying out these surveys theUSCampGSused photography supplied by the Navyand the Army Air Corps it was the Air Corpsmulti-lens camera that established the cost-effec-tiveness of air survey (Reading 1927-28) Withinthe USGS a quadrangle in Michigan was mappedusing a conventional single-lens camera using airsurvey for the planimetry only (Thompson 1952)In 1924 a Section of Photographic Mapping wasestablished as part of the Topographic Branch atUSGS

Terrestrial photogrammetric work had beenundertaken in Russia as early as 1891 (Koch1963) but few significant additional developmentsoccurred before 1920 In 1924 the State TechnicalOffice of Aerial Photographic Survey was estab-lished Its first task was the creation of mosaics at110000 for comparison with plane table surveysThe results were considered sufficiently favorablefor mapping at 15000 based on 112000 pho-tography An ambitious program of aerial pho-tography initiated in 1925 led to the coverage ofmore than 4500000 km2 by 1940 In 1928 theCentral Scientific Research Institute for GeodesyPhotogrammetry and Cartography (ZNIlGAiK)was established to oversee development across thewhole field of mapping (Koch 1963)

Instrumental MethodsAt the end of World War I Germany and theAustro-Hungarian Empire had a clear advan-tage in the development and use of instrumen-tal photogrammetric methods While Germanycontinued to enjoy a considerable lead in thesetechniques the collapse of the Dual Monarchy andthe resultant breakup of the MilitargeographischeInstitut meant that Austria entered a period ofrelative decline Zeiss which had become theciear ieader in the design and man-ufacture ofphotogrammetric instruments not only pro-duced instruments designed by both von Ore and

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Pulfrich but employed several leading figures inphotogrammetry including Walter BauersfeldWilli Sander and Otto von Gruber This ensuredthat Zeiss was always at or near the forefront ofdevelopments in the field

During the 1920s most efforts were directedtoward overcoming the problem inherent in theearlier generation of photogrammetric plot-ters namely the need for the photographs tobe coplanar In 1926 Hugershoff designed anaerocartograph for use with both terrestrial andaerial photography The instrument which wasmanufactured by Heyde Company in Dresdentook advantage of the theoretical developmentsin orientation theory developed by Max Gasser(1923) and von Gruber (1924) The combinationof new orientation procedures and sophisticateddesign meant that Hugershoffs aerocartographcould be used for plotting and aerotriangulation(Blachut and Burkhardt 1989) Professional rivalryled von Gruber (1932) to dispute the original-ity of Hugershoffs design as he was also to dowith Heinrich Wilds instruments and the ideas ofFourcade

Zeiss had produced their stereoplanigraph(the Cl) in 1921 based on an earlier design ofBauersfeld However it was not until the pro-duction of the C4 in 1930 that Zeiss producedan instrument that could handle both terrestrialand aerial photography Some successful mappingfrom the earlier models was reported throughthe 1920s by the Reichsamt fur Landesaufnahmewhich had a C2 (Seidel 1928) and the GeodeticInstitute in Stuttgart which had a C3 (von Gruber1932) Most of the mapping was at 15000 butscales as small as ] 20000 are reported Even inGermany systematic mapping programs usingphotogrammetry were still the exception ratherthan the rule during the 1920s

In France the Service Geographique de lArmeehad been actively experimenting with instrumen-tal photogrammetry before World War I (Bonnet1920) and had also used the technique for someterrestrial work during the war France was thuswell placed at the end of the war to keep upwith the developments elsewhere in Europe TheService had decided that terrestrial photogram-metry was best suited to 120000 mapping in highmountain areas but considered the equipment toocumbersome and imprecise for reconnaissancesurveys (Service Geographique de lArmee 1912)In 1919 a start was made on mapping in Moroccousing panoramic aerial photographs (ServiceGeographique de IArmee ]936) but the main

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drive in France was to develop an autonomouscapability in instrumental photogrammetry

Some equipment had been developed duringthe war notably the Chambre Claire Varon andthe Appareil de photorestitution Roussilhe aninstrument for partial rectification of cadastralplans (Blachut and Burkhardt 1989 ServiceGeographique de IArmee ]936) The mostimportant development came in 1922 when thefirst Georges Poivilliers instrument was built(Poivilliers 1922 Blachut and Burkhardt 1989)Poivilliers instruments were to provide the bulkof the photogrammetric capability of the Servicewith up to four different types in use at anyonetime (Institut Geographique National 1947)Other instruments were also used largely on anexperimental basis In the mid] 920s the stereor-estituteur Boucard was in use and in the I930s aGallus Ferber instrument was used experimentally(Service Geographique de lArmee 1938) withthe latter (Blachut and Burkhardt 1989) remain-ing in service until at least the 1940s (InstitutGeographique National 1947)

Italy had been actively engaged in photogram-metry in the nineteenth century with the work ofPorro but as Blachut and Burkhardt (1989) notethe Istituto Geografico Militare showed little inter-est in the technique until many years after Porrosdeath in 1875 The resurrection of Italian photo-grammetry was largely due to two men UmbertoNistri who designed aplotter in 1919for large-scaleplotting and Ermenegildo Santoni who producedhis first instrument the autoreductor in 1921 In1926 Nistri founded the firm Ottico MeccanicaItaliana (OMI) to produce his photogrammetricinstruments Nistris early instruments all useddirect optical projection while Santonis instru-ments all used mechanical projection The IstitutoGeografico Militare was middotequipped with Santoniinstruments which it used for mapping at 125000and 110000 The Societa Anonima RilevamentiAerofotogrammetrici (SARA)on the other handused Nistri instruments largely for topographicmapptng outside Italy but also for cadastral map-ping within the country

Photogrammetry had been used in Switzerlandfor engineering surveys in the nineteenth centuryyet there had been no systematic attempt to carryout topographic mapping using the techniqueThe history of mapping in Switzerland betweenthe two world wars is largely a history of the WildHeerbrugg Company Set up in 1921 the com-pany produced its first phototheodolite in 1922and its first photogrammetric plotter the Alstereo-autograph in 1923 Its first major contribu-

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tion to surveying came with the production of theT2 theodolite in 1924 The revolutionary design ofthis instrument-replacing engraved metal circleswith glass versions provided more accurate read-ings and better illumination-led to considerableexcitement in scientific and survey circles By thelate 1920s Wild was engaged in serial productionof the T2 and T3 theodolites the P3 phototheodo-lite and the A2 autograph which had replaced theAI In addition the Cl C2 and C3 aerial cam-eras were also in production In the space of onlyeight years Wild had become a major player in thesurvey world a position enhanced further duringthe 1930s

By the late 1920s the Landestopographie inSwitzerland had gained considerable experiencewith Wild instruments for both terrestrial andaerial surveys (Schneider 1929) Topographicmaps were produced from terrestrial photographyat 125000 while aerial photography wasused for110000 mapping (Schneider 1929 Harry 1971)

In the United States in addition to usinggraphical techniques the USGS started to inves-tigate instrumental methods In 1921 it obtaineda stereoautograph from Germany for evalua-tion but restricted the use of the instrument toplotting from terrestrial photography and notable to produce maps economically (Thompson1952) In 1927 the Geological Survey acquired theHugershoff aerocartograph the first automaticstereo-plotter used by an American governmentmapping agency (Thompson 1952) Thomas PPendleton laid down guidelines for mapping fromaerial photography within the USGS in Bulletin788-F Map Compilation from Aerial PhotograPhsissued as part of the Topographic Instructions of theUnited States Geological Survey (Pendleton 1928)Given the rapid developments in radial-line meth-ods (eg Hotine 1927) the timing of Pendletonswork was a bit unfortunate as he asserted thatradial-line techniques were really only suited foruse with multi-lens photography because therelatively short radial lines that could be drawnon single-lens photographs could not give the bestresults (Pendleton 1928 p 409)

In Britain research work carried out by the AirSurvey Committee focused on simple methods butthe Committee did not entirely ignore instrumen-tal techniques MacLeods wartime work with rec-tifiers was developed and more importantly theideas of Fourcade (l926a 1926b 1926c 1926d)on the theory and use of stereogoniometers forphotogrammetric plotters were taken up In 1926the Committee commissioned the constructionof an instrument along the lines proposed by

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Fourcade and the instrument was delivered in1928 0ar Office 1935 Hotine 1931)

In India success with non-instrumental tech-niques did not distract the Survey from instrumen-tal techniques they had helped pioneel- Mappingofficials followed developments taking place inEurope and in 1926 Mason (1927) carried outa survey in the Shaksgam using a Wild photo-theodolite and plotted the results in Switzerlandusing an autograph in the Topographical Instituteat Flums

CamerasThe tri-lens camera developed by Bagley was usedby the USGS in mapping for aeronautical chartsThis program wasjointly organized with the Corpsof Engineers and the Air Service (Committeeon Photographic Surveying 1921) and providedvaluable experience in civil applications In 1920programs with the tri-lens camera were also under-taken in Santo Domingo and Haiti

The Corps of Engineers became involved inphotogrammetric methods in 1920 when Bagleywas assigned to cooperate with the Army AirCorps in carrying out tests on aerial photographyfor topographic mapping Initially the trials usedBagleys tri-lens camera but he went on to developthe five lens T-3Acamera which was to remain thestandard mapping camera of the US Army until1940 (Landen 1952) The War Department issuedtraining regulations for mapping from aerialphotography in 1923 however the techniques dis-cussed in the regulations were largely those refinedduring World War 1

The 1930sBy the late 1920s photogrammetry had becomea cost-effective alternative to some traditionalground surveys Yet expensive photogrammetricplotting instruments and labor-intensive graphicalplotting meant that photogrammetry still lackeda decisive advantage over ground survey Duringthe 1930s a number of innovations were to swingthe balance decisivelyin favor of photogrammetricmethods

Progress was slowed if not stopped by the reces-sion that started in 1929 Some measure of theimpact can be gauged from job cutbacks at WildHeerbrugg In 1930 before the recession had amarked affect on Europe the workforce stood at260 but by 1933 the number ofjobs had droppedto 125This was the direct consequence of the deci-sions taken to retrench mapping projects as well as

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capital programs Nearly all the annual reports forthe early 1930s mention the financial constraintsunder which organizations had to work In theUnited States some of these problems were offsetby appropriations under the Emergency Reliefand Construction Act (US Coast and GeodeticSurvey 1933) Moreover the New Deal initiated awide range of programs in which photogrammetrywas to playa major role By contrast problems inthe colonial territories were if anything worsethan in Europe and North America The declinein industrial activity in developed countries ledto a collapse in demand for raw materials fromthe colonies and as this was the main source ofgovernment revenue they could no longer pay forsurvey work Annual reports from most colonialsurvey departments make reference to a lack ofresources to meet the need for mapping Howevel~by the late 1930s as a result of rearmament inEurope governments allocated more money tosurvey organizations

Survey organizations were eager to adopt newtechniques in routine mapping programs but thepressures within governments to deal with massunemployment probably helped to promote theuse of labor-intensive methods in survey at theexpense of investment in technology Certainlyorganizations such as the Tennessee ValleyAuthority (TVA) the Agriculture AdjustmentAdministration and the Soil Conservation Servicein the United States were all heavily dependenton such labor-intensive techniques and did muchto develop them as standard mapping methodsMoreover organizations such as the USGS andthe TVA also played a role in the developmentinstrumental methods such as multiplex All ofthis was to be of vital importance to the hugephotogrammetric mapping programs that wereto emerge during World War II The scale of theseprograms would have been inconceivable withoutthe trained body of photogrammetrists developedduring the 1930s (Landen 1952)

Within the British colonial territories the conser-vative element that had inhibited the developmentof photogrammetric methods through the 1920scontinued to delay adoption of photogrammetryuntil after World War II-with some illuminatingexceptions Cyprus is the only known example ofa local survey department attempting to carry outphotogrammetric work Aerial photography wastaken in 1936 but delays in obtaining groundcontrol meant that no use was made of the pho-tography before all normal work was suspended atthe outbreak of war In all the other colonies wherephotogrammetry was attempted private survey

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companies carried out the work The earliestexample of the involvement of private air surveycompanies had been in 1927 in the mapping ofthe Anglo-Belgian boundary in the Copper Beltregion of Northern Rhodesia (Colonial SurveyCommittee 1928) Private air survey companieswere also active in Uganda Tanganyika andSouthern Rhodesia but in all cases this was surveywork for specific development projects ratherthan routine mapping (War Office 1935) Therewere discussions about the use of photogramme-try in Sierra Leone where the Aircraft OperatingCompany of South Africa proposed to revise the162500 topographic maps for pound150000 includ-ing the cost of providing ground control but thework was never carried out due to financial con-straints and the outbreak of World War II Therewere also discussions about air survey in Jamaicaand the Gold Coast but nothing came of theseprojects until after World War II It is clear fromthe literature and correspondence of the time thatthe private air survey companies were lobbyingindividual colonial governments as well as theBritish Government to adopt air survey but theColonial Survey Committee under Winterbothamwas equally forceful in its resistance to changelargely on grounds of cost (see in particularWinterbotham 1920 1921 1929 1934 1936Hemming 1933)

Increasing recognition that war with Germanywas inevitable led to a significant change in theBritish establishments attitude towards the use ofair survey In part this change reflected the retire-ment of Winterbotham in 1935 and his replace-ment as Director General of the Ordnance Surveyby MacLeod who was alwaysa warm supporter ofair survey MacLeod had followed Winterbothamfirst as Director of Military Surveys and then atthe Ordnance Surveyand in each case he playeda major role in introducing the use of photogram-metry (Clough 1952)

Advances in InstrumentationThe late 1920s had seen the design and produc-tion of the first practical plotting machines for usewith aerial photography The experience provideda foundation for the introduction during the1930s of designs that were to be the mainstaysof topographic mapping The Zeiss C4 had beenintroduced in 1930 (Burnside 1993)AsThompson(1966) notes the C4 and the superseding C5(introduced in 1935 with improved illumination)were with the Wild A5 (launched in 1937) practi-cally the only universal instruments on the marketin the 1930s Universal instruments designed to

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handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

Vol29 No3

graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

169

Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

170

world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

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Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

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Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

171

was founded in Vienna in 1910 Vienna was alsothe setting for the first International Congressfor Photogrammetry in 1913 The Society wasto become one of the main vehicles for the dis-semination of information on photogrammetrywhile the congresses were the main showcases forthe latest equipment Previously the InternationalGeographical Union was the main forum for thedissemination of developments in surveying andphotogrammetry but its importance had contin-ued to decline until after World War II when italmost completely withdrew from the field

World War I (1914-1918)World War I generated an unprecedented demandfor maps at scales from 1200 for detailed trenchmaps (Chasseaud 1999) to 11000000 andsmaller for strategic planning maps (Heffernan1996)At the outbreak of war in 1914 the armies ofEurope were issued with maps at scales of 180000or smaller designed to support a war of rapidmovement in which victory would be achievedby bringing to bear an overwhelming force in adecisive battle Military leaders still believed thatoffensive operations could be successful despitethe precedent of the Russo-Japanese War of 1905which had degenerated into sieges and large bat-tles of encounter in which opposing armies foughtin the open rather than in prepared positionsNeither side could achieve a decisive blowbecauseof the superiority of defense based on rifles andmachine guns

The strength of the defenses meant that if therewas to be any hope of success in offensive opera-tions the attacking troops needed accurate mapsof the enemy defenses This included the positionsof any artillery ammunition dumps and transportinfrastructure Allof these features were difficult orimpossible to map from the front line In the caseof ammunition dumps and transport the targetscould be many miles behind the front What thearmies of both sides needed wasa wayof collectinginformation that could either be added to existingmaps or used to produce entirely new maps Mostimportantly as the artillerymen developed evermore accurate targeting they created a demandfor increasingly precise mapping to locate poten-tial targets As the war progressed the armiesexperimented with a closer integration of artilleryand infantry operations such as the rolling bar-rage (a barrage where the gunner slowlyincreasesthe range while infantry advance slowlybehind thebarrage) Again this required more precise point-ing of guns and locating of targets

Vol 29 No3

Suneyors were used to fix the position of bothguns and targets The need for secrecy-no pointin alerting the enemy that an attack was beingprepared-also changed the ways in which theguns acquired their targets Early in the war thenormal technique involved the use of rangingshots That is each gun was fired towards a poten-tial target and an observer identified the fall ofshot The obsener then told the gunner to eitherincrease or decrease the range as appropriateand to traverse left or right until the shot was fall-ing on the target The problem with this techniquewas that it revealed that a new gun had been intro-duced into a stretch of the front A large number ofranging shots revealed the introduction of a largenumber of guns and the threat of a forthcomingattack To overcome this dilemma the positions ofthe guns and targets needed to be determined pre-ciselyby surveying From this information artilleryboards were prepared to show the positions of theguns as well as the targets It was then possible todetermine the directions in which the guns neededto fire and the range to the target without reveal-ing that new guns had been positioned

The identification of targets and the accuratepositioning of guns led all the nations to adoptthe use of grids on their mapping In the latenineteenth century John Ardagh had tried toget a grid system adopted by the Survey of Indiabut without much success (Ardagh 1893) Prior toWorld War I therefore almost no maps carriedgrids The exceptions were the squared mapsused by the French artillery on maneuvers atChalons in 1911 (Chasseaud 1999) Increased useof indirect fire underscored the need for griddedmaps Unfortunately grids were adopted on an adhoc basis which led to considerable confusion Forexample the Germans used three different gridsystems with origins at Lille Rheims and Paris(Hinks 1919)The British adopted an imperial gridbased on 1000-yard grid squares even though theentire mapping on the Western Front used metricscales Despite this uncertain start it was quicklyrealized that grids had uses well beyond those ofwarfare and they became a standard feature ofmost post-war topographic mapping

Military mapping in Europe was largely focusedon map revision whereas that in Palestine Sinaiand Mesopotamia involved considerable origi-nal mapping (Collier 1994 Collier and Inkpen2001) In the initial stages of the World War I allthe belligerents used existing pre-war mappingsupplemented by photographic enlargements InFrance this involved the use of 180000 mappingsubsequently enlarged to 140000 When how-

159

ever the deficiencies of the enlargements becameevident they were replaced by new mapping Onlythe German survey seems to have continued to useenlargements through to the end of the war aack1920) With the development of positional warfare140000 mapping wassoon found to be inadequateand was successively complemented by mappingat 120000 and 110000 Where necessary evenlarger scales were used (Chasseaud 1999)

Behind the lines revision and new surveys werecarried out using conventional land survey tech-niques trigonometrical control surveys and theplane table to add detail Oack 1920 Winterbotham1919a 1919b Service Geographique de lArmee1938 Albrecht 1969 Chasseaud 1999) For front-line areas and for the enemys rear areas the maindata source was aerial photography

The Development of CamerasInitially photography for intelligence and maprevision involved the acquisition of photographyfrom fairly low flying aircraft using largely impro-vised camera equipment With the development ofanti-aircraft defenses however reconnaissance air-craft were forced to fly higher and higher to avoidbeing shot down To compensate it became neces-sary to devise cameras with longer and longer focallengths if the resultant photography was to be ofuse for analysis and mapping

The earliest cameras were simple devices thatused glass plates and dark slides (devices used tochange glass negatives in a camera without expos-ing the negatives to light) Images were obtainedby observers pointing the cameras over the side ofthe aircraft The cameras were fitted with simplesighting devices to ensure that the target wasactually imaged Recognition that vertical photo-graphs were much better suited to mapping thanthe oblique pictures taken with hand-held camerasled to the cameras being fixed to the side of theaircraft Fairly quickly magazines were providedso that a series of photographs could be taken bythe observer activating a lever to change platesEven so changing the magazines still required theobserver to lean over the side of the aircraft Giventhese difficulties it seems strange that roll filmwas not used earlier especially since panoramiccameras had used it as early as the late nineteenthcentury The Germans did not introduce a filmcamera until 1916 (Albrecht 1969) and the Britishcontinued to use plate cameras until the end ofthe war

Most of the cameras used for military operationshad relatively long focal lengths the standardBritish camera in the early part of World War I had

160

a focal length of 8 inches (approximately 200 mm)while the standard German camera had a focallength of 180 mm (Albrecht 1969) By the end ofthe war focal lengths of 500 mm were not uncom-mon-some German cameras had focal lengths aslarge as 1200 mm (Albrecht 1969) These lenseswere designed for reconnaissance rather thanmapping so that each photograph covered only asmall area of ground Cameras needed wide-anglelenses to minimize the amount of control neededfor mapping but none of the high-quality lensesavailable provided a wide field of viewMulti-lenscameras were developed in the nineteenth centuryto obtain broader coverage from each exposurestation but these cameras were generally largeand cumbersome and thus unsuited for militaryoperations

Control for MappingEarly attempts at using aerial photography formap revision experienced considerable difficul-ties As Malcolm MacLeod (1919 pp 382-83)noted though the photographs showed all theprincipal topographical features in great detailthere was no means of determining their exactscale or the amount of distortion due to thecamera not being truly vertical at the moment ofexposure of the plate In the absence of mechani-cal restitution instruments to overcome theseproblems two possible solutions were consideredto develop a device for mechanically determiningthe altitude and tilt of the camera at the momentof exposure or to compare the positions of pointson the photographs with their known ground coor-dinates Although both sides experimented with amechanical solution most work involved the lattertechnique This placed a heavy demand on accessto ground coordinates

The provision of control points both in andbeyond their own front line was a major problemfor all the combatant nations Placing markersover control points in frontline areas and thenfixing them by observation from the rear was notfeasible as this also enabled the enemy to fix theposition of the trenches A number of strategieswere adopted including the use of periscopictheodolites employed from within the trencheswithout exposing observers to enemy fire Thesetheodolites could be used to fix positions withinthe trenches by resection

While resection on the plane table was a com-monly used technique among topographers ithad not been widely used for instrumental obser-vations because of the relative complexity of thecalculations However the conditions of trench

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warfare left few alternatives Once adopted resec-tion remained in common use among surveyorsAn alternative adopted by the Germans was to firea flare vertically from the trenches and obsenTethe flares position from the rear using theodolitesGack 1920)

Locating control points beyond the front line waseven more difficult Where possible the position ofprominent points would be fixed by intersectionHowever in Mesopotamia there were often too fewsuitable features to intersect This led to an inno-vation by Col C P Gunter to fix control pointswithin the Turkish lines using artillery shell burstsFour observers took simultaneous observations ofindividual shell bursts while an observer in anaircraft recorded the position of the explosionson a detailed map of the trenches created from airphotographs On average out of ten shell burststhree good intersected points were observed andthe observer would have accurately marked one ofthese Points observed in this way were then usedto control and adjust the strips of photographyused for mapping (Surveyof India 1925)

Plotting DetailOnce control had been obtained it was necessaryto interpret and plot the information on photo-graphs Initially interpretation was relatively easyas there was little attempt to conceal potentialtargets from aerial observation Camouflage onlystarted to be used systematically around 1916(MacLeod 1919) thereafter photo-interpretationdeveloped into a specialist skill Use of camouflagealso led to the development of new surveyingtechniques such as flash spotting and soundranging

Extraction of detail for revision purposes wasdone by some form of graphic intersection orthrough the use of optical projection Despite someuse of more rigorous methods involving compara-tors developed before the war these instrumentstogether with the necessary calculations were slowand not well suited to the urgent needs of the warThe use of automatic plotters such as the alitoste-reograph was restricted to terrestrial photographydue to the need for coplanar photography In factthis technique was used only by the Germans andFrench in eastern France where relief was suitableand by the Austro-Hungarian Army in the AlpsOskar Albrecht (1969) also refers to the use of ter-restrial photogrammetry for artillery assaults onfortresses and the use of photographs taken fromtethered balloons

The belligerent powers employed a variety ofgraphic techniques The simplest involved the pro-

Vol 29 No 3

duction of a framework of existing detail on a com-pilation sheet on which new detail was added fromaerial photographs with the help of proportionaldividers Although capable of producing reason-ably accurate results this approach was labori-ous and slow (MacLeod 1919) The paper stripmethod (Thompson 1966) used for adding smallamounts of detail was equally slow and laboriousThe German Army developed a less strenuoustechnique based on the use of perspective gridsThe chief advantage of this technique was thatonce the grids had been generated detail could betransferred by eye from aerial photograph to mapThis technique was so successful that it was widelyadopted after the war for map revision Describedin most standard textbooks on photogrammetrythe perspective grid approach remained in useuntil the 1980s when simple digital techniquesrendered it obsolete

Most of the optical revision techniques reliedon the registration of a projected image of thephotograph on an existing map or on a frame-work of control Once the image was registeredthe mapmaker could either transfer the informa-tion directly to the map or produce a correctedphotographic print for use in revision TheodorScheimpflug had shown that an accurate regis-tration could be affected between the projectedimage and the control data if the projected imagewas in focus for the entire image area To satisfYthe so-called Scheimpflug condition the projectedplanes of the negative lens and easel had to meetat a common axis (Scheimpflug 1898 Blachutarid Burkhardt 1989) Even if the condition wassatisfied there were still errors of registration dueto relief displacement In the instruments usedduring World War I the Scheimpflug conditionwas hot satisfied and consequently the resultswere at best approximate (Blachut and Burkhardt1989) MacLeod (1919 1920) describes the use ofCamera Lucida and the enlarging lantern inboth of which the plane of the negative and theplane of the lens were held parallel with only thecopy board which was capable of being tilted Theeniarging lantern could maximize the depth offocus and hence the sharpness of the iinagebyreducing the aperture of the lens to the smallestdiameter possible The use of the enlarging lan-tern to produce semi-rectified prints came to bethe preferred techrnque

As already noted while most of the work onthe Western Front involved map revision innon-European theaters the need was for originalmapping (Collier 1994 Collier and Inkpen 2001)The first attempts to use aerial photography to

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construct original mapping took place during theGallipoli campaign (Dowson 1921) Not very suc-cessful these attempts demonstrated the problemsassociated with the non-stereoscopic use of aerialphotography as when troops were sent to occupypositions identified monoscopically as trenchesor ditches but which turned out to be shallowscrapes that afforded no shelter from enemy fireAttempts to create original mapping ceased whenmodern Turkish maps of the area were capturedand revised

In Egypt the Turkish threat to the Suez Canalalso resulted in experiments in mapping fromaerial photography Like the mapping in Gallipolithese were largely unsuccessful The main problemwas locating precisely where the photographs hadbeen taken over a largely featureless desert Thebulk of the mapping for the Suez Canal defenseswas therefore carried out by triangulation andplane table survey (Maule 1919)

When the Egyptian Expeditionary Force (EEF)advanced across the Sinai Peninsula to engageTurkish forces in Palestine it moved into terri-tory without up-to-date mapping of an adequatescale Western Palestine had been mapped for thePalestine Exploration Fund (PEF) in the 1870s(Conder 1878 Conder and Kitchener 1881-83) ata scale of 163360 Although based on triangula-tion the detail had been surveyed using compassand cavalry sketching board (Close 1932) and wastherefore regarded as insufficiently accurate formodern warfare British military personnel hadsurveyed Southern Palestine just before the warunder the cover of a PEF expedition (Woolleyand Lawrence 1914) But even here the scale wastoo small (1 125000) for the kind of operationsbeing undertaken The British army was thereforeconfronted with the need to map areas beyond itsfront line for which no adequate base maps wereavailable

The first successful attempts at mapping fromaerial photographs were in t~e area aroundGaza (Gavish and Biger 1983) Here control wasprovided by the intersection of prominent pointsbehind Turkish lines Based on these points acontrolled mo~aic was created from with verticalaerial photogriphs and the mosaic was then usedto crcate the line maps of the planimetry Althoughcrude by later standards the map was consideredto be a significant improvement on anything thenavailable This encouraged the surveyors led byMajor W] Maule to embark upon an ambitiousplan to create a series of topographic maps at 140000 for areas of Palestine behind Turkish lines(Maule 1919) Strips of photography were flown

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roughly parallel to the front line with additionalstrips of photography perpendicular to the frontflown at intervals to control the strips parallel tothe front Supplementary control was provided bytheodolite observations wherever possible Thesame basic arrangement pioneered in the map-ping of Gaza was followed for the series mappingHowever as the area mapped extended into thehills of Judea (the southern West Bank) it alsobecame necessary to provide some indication ofrelief Viewing the photography stereoscopicallyand form lining achieved this The nature of thetopography nearly horizontally bedded lime-stones that eroded into natural terraces madethis task relatively easySuccessfulas the mappingwas (Thomas 1919) as each new area came underBritish control mapping derived from air photoswas replaced bymapping made using conventionalground survey techniques

In a number of ways the mapping inMesopotamia can be regarded as the first exampleof true photogrammetric mapping using aerialphotography Unlike the mapping in Palestineit was produced as the end product not as aninterim solution to be replaced as soon as groundsurveys became possible And unlike the mappingon the Western Front it did not involve revision ofexisting mapping as no proper maps existed forthe area

Although developments in the use of air pho-tography had been watched with envy by thesurveyors in Mesopotamia (Survey of India 1925)until early 19I6 no airplanes had been availablefor that theater Some experience in the use ofaerial photography had been gained before thesiege of Kut-al-Amarah but it was the positionalfighting around Kut that emphasized the advan-tages of air survey Maps were required of areasbehind Turkish lines but the flat landscape meantthat surveyscould only be extended into no-mans-land This led to the first real attempt to createmaps from aerial photography As the first mapTC4 (TC are the initials of Tigris Corps theoriginal name of the force sent to Mesopotamia)has been discussed at length elsewhere (Collier1994 Pritchard 1952 Survey ofIndia 1925)

The surveyors working in Mesopotamia experi-mented with various ways of making maps fromaerial photographs drawing on the experience ofsurveyors on the Western Front and in Egypt Inthe end though they developed their own tech-nique which was well suited to local conditionsTheir technique involved creating semi-rectifiedphotographs using an enlarging lantern (Gunter1917) and then mosaicing the photographs using

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a triangulation scheme The mosaics were inkedup before the bromide prints were bleached out soas to leavejust the inked linework The importantpoint to note is that this technique was used formapping areas on both sides of the front line andwas therefore regarded as the final product Theflat floodplains of the Tigris and Euphrates Riverslent themselves to mapping using semi-controlledmosaics as there was an almost complete absenceof height to create displacement errors The map-ping of Mesopotamia from aerial photography seta precedent for post-war mapping in India

Flash Spotting and Sound RangingAs mentioned earlier the use of camouflage neces-sitated the development of techniques for targetlocation in particular the location of enemy gunpositions for counter-battery fire At the beginningof World War I guns were aimed by direct observa-tion of targets and the guns themselves were oftenpositioned in the open to improve their fields offire With the increased use of counter battery fireit became normal for guns to be dug in posi-tioned in gun pits and protected by sandbags Toprotect gun positions from enemy air observationthe gun pits were subsequently camouflaged withnetting which thwarted an accurate identificationof their positions

Flash spotting and sound ranging were devel-oped as means of tackling the problem of identify-ing and locating enemy gun positions Adopted byall the combatant nations flash spotting involvedintersecting the gun position by observing theflash as tht gun was fired Flash spotting requiredconsiderable organization as the observers had toensure that they were observing the same gun flashbut by carefully noting the times of the observa-tions it was possible to obtain accurate locationsof enemy guns Most armies established specialistunits for this purpose (Innes 1935 Chasseaud1999 Hinks 1919 Maule 1919)

Sound ranging was a more complex process inwhich the British and French enjoyed a technolog-ical lead over the Germans General Ludendorffthe German Chief of Staff who issued specialinstructions that precautions be taken to cam-ouflage the sound of guns directed the army tosecure an example of the British system (quotedin Hinks 1919) Based on a technical solutiondeveloped by Lucien Bull at the Institut Marey inParis the British system relied on an array of sixmicrophones spread over a 9-kilometer-long base-line situated about 4 km behind the front iine Themicrophones were connected to a galvanometer atthe hea~quarters As the sound of a gun reached

l1Jl 29 No3

each microphone in turn a signal was sent by wireto the galvanometer where it produced a distinc-tive trace on photographic film By measuring theseparation of the traces of the gun detected at eachmicrophone the distance and direction of the guncould be calculated Complex arrangements withmore than two microphones were needed becauseof uncertainty about the effect of wind speed andother factors on sound waves (see Innes 1935 andChasseaud 1999 for more technical details)

The German systemrelied on a fonvard observerand four other observers along a base of 10 to 15kilometers On hearing a gun firing the forwardobserver sent a signal by field telephone to theother observers who on receiving the signalstarted their stopwatches and noted the time inter-val before they heard the gun The times were thensent to group headquarters where the position ofthe gun was calculated An alternative and sim-pler method involved an observer noting the timeinterval between seeing a gun flash and hearingthe noise of the gun The greatest precision possi-ble with these techniques was about +200 meters

Non-military WartimeDevelopments to 1918

While the mapping efforts of the combatantnations were almost entirely directed towards thewar effort cartographers in the United States wereactively exploring civilian applications of pho-togrammetry The most important developmentwork was carried out at the US Geological Surveywhere James Bagley was developing a tri-Ienscamera and Fred Moffit was developing a trans-forming camera capable of handling the nega-tives produced by Bagleys camera (Committee onPhotographic Surveying 1921)

Developments to 1930In the period leading up to and including WorldWar I all the major powers followed broadlysimilar paths in developing photogrammetry Inmost countries attempts to develop instrumentalmethods complemented heavy reliance on graphi-cal and optical techniques for producing andrevising large-scale maps After the war a numberof countries took distinctly different paths withcontinental European countries generally puttingmost of their effort into instrumental techniqueswhile English-speaking countries focused ongraphical techniques Arguably until about 1930the approach adopted by the English-speaking

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countries was the most fruitful as the instrumentaltechniques developed in Europe could not com-pete in cost or efficiency with British and Americanmethods

After 1930 the relative efficiencies of the twoapproaches changed markedly The Americansrecognized the changed circumstances morequickly than their British counterparts and beganadopting instrumental methods by the mid 1930sIn Britain and by extension throughout the BritishEmpire instrumental photogrammetry was still inthe experimental phase at the outbreak of WorldWar 11in 1939

The immediate post-war-one period saw a flurryof papers extolling the merits of mapping fromaerial photography At the forefront of the cam-paign to get the methods accepted in Britain wasCapt H Hamshaw Thomas (1919 1920 1924)who drew heavily on his experiences in the Sinaiand Palestine Much of the effort to promote airsurvey was conducted in non-specialist journalssuch as the GeograPhicalJournal (Newcombe 1920)and even in the popular press MacLeod who hadserved in France and had become a firm advocateof air survey methods also produced a numberof papers as well as an important official publica-tion Mapping from Air Photographs issued by theWar Office (MacLeod 1920 but see also MacLeod1922 1923a 1923b)

Britain more than in any other country held aconservative attitude towards the new techniquesand this resistance found an influential championin Harold StJ LWinterbotham A self-proclaimedexpert on air survey (see Winterbotham 19291934) Winterbotham did much to impede theadoption of air survey both in Britain and throughhis role on the Colonial Survey Committee in thecolonial territories In contrast the Dominion ter-ritories were free to determine their own policiesAlthough Canada a pioneer in photogrammetryhad been joined by India in its use of these tech-niques before the outbreak of the First World Warother Dominion territories were slower in adopt-ing air survey Australia took the lead but localfactors either delayed or advanced the adoptionof photogrammetry in Dominion territories whichwere not compelled to follow the Colonial SurveyCommittees recommendation There is a strik-ing parallel between these largely autonomousterritories and the Dutch East Indies where thesurvey department was quick to adopt photogram-metry (van Roon 1925) but made no real progressat home in The Netherlands until after World WarII

In the British context Winterbothams reser-vations concerning the cost-effectiveness of air

i64

survey methods were probably justified at leastuntil the development of Reinhard Hugershoffsaerocartograph in 1926 (Blachut and Burkhardt1989) All the air survey instruments introducedbefore the aerocartograph were essentially ter-restrial plotters adapted in some way to copewith non-coplanar photography This made theinstruments difficult and slow to set up and theyusually required two men to carry out orienta-tion and plotting operations In a well mappedcountry such as Britain cumbersome machinescould not support map revision as economically asconventional ground surveyhere Winterbothamerred even in the 1920s was in extrapolatingfrom the British experience to the colonial terri-tories where the needs were very different On thepositive side agitation by Hamshaw Thomas andothers as well as the successful application of airsurvey techniques by the Survey of India led to thesetting up of the AirSurvey Committee Part ofthe responsibility of this committee was to adviseon air survey matters but it was also responsiblefor carrying out research

In the United States the promotion of airsurvey techniques wasundertaken by Moffit (1920)and other surveyors who had not been directlyinvolved in the war effort but had carried on withtheir civilian work in government mapping agen-cies Part of this promotion was carried out in non-specialist journals but unlike in Britain there waslittle need to convince the political leadership ofthe advantages of air surveyBycontrast there waslittle attempt to promote air survey in France orGermany other than in technical or professionaljournals Almost certainly this reflects the higherstatus of engineers and technical experts in thosecountries compared with Britain The UnitedStates probably fell somewhere between Britainand the continental powers but more towards thelatter

Survey and mapping activities in Austria suf-fered a severe setback with the breakup of theHabsburg Empire at the end of World War 1The Militargeographische Institut was disbandedin 1920 (Kretschmer 1991) and its personneldispersed amongst the successor states Whilethis disintegration had clear disadvantages forAustria survey departments in Poland Hungaryand Czechoslovakiagained a cadre of trained andexperienced personnel able to form the nucleusof new national survey organizations Despite eco-nomic hardship in the wakeof the warAustria hadbegun in 1928 to supplement existing 175000topographic mapping work focused on the moun-tainous areas using terrestrial photogrammetry

CartografJhy and GeograPhic informationScience

Graphical MethodsBecause of the extensive use of graphical methodsduring WorldWar I a large body of trained person-nel was available to implement these methods forpost-war mapping But the techniques developedthus far were either non-rigorous (for example theperspective grid) or suitable only for revising smallnumbers of features (the paper strip method)What was needed was a rigorous technique thatdid not require highly skilled workers

Bagley had sowed the seeds of a rigoroustechnique during his work with the PanoramicPhotoalidade (Bagley 1917) but Martin Hotine(1927) provided the theoretical and practicalbasis for a cost-effective mapping techniqueDescribed as a Simple Method of Surveying fromAir Photographs Hotines technique becameknown as the Arundel Method (after Arundelin southern England where the technique wasfirst used experimentally) or the radial-line tech-nique Hotine subsequently developed the methodof control extension using radial-line methods(Hotine 1929) and laid the foundations for muchof the medium-scale photogrammetric mappingcarried out in the English-speaking world over thenext 40 years The American development of slot-ted templets and radial intersectors expeditedthe process of aerotriangulation (see below) butit was Hotines theoretical work that made thesedevelopments possible

None of the countries using aerial photogra-phy for topographic mapping embraced it withgreater enthusiasm than India As noted earlierthe Survey of India had acquired two examplesof Thompsons stereo-plotter Kenneth Mason(1913 1927) had used the stereo-plotter in 1913in the Pamirs with considerable success but theexperience of the Survey of India in Mesopotamiaduring World War I wasdecisive in promoting airsurvey techniques in India In 1920 a series ofexperiments conducted at Agra demonstrated theutility of air survey methods for mapping flat areasin India (Lewis and Salmond 1920) Air surveyp~oved inefficient for one-inch-to-a-milemiddot map-pmg-the cost was roughly twice as much as forground surveys-but it was economical for largerscales An experiment in urban mapping was car-ried out but its results were inconclusive

Among developed countries the United Stateswas probably the most in need of the advantagesthat air survey offered post-war mapmakers Forall its great wealth America was poorly mappedby European standards Where most Europeancountries were at least mapped at medium scale(roughly 1100000 or larger) large tracts of the

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United States were not mapped even at small scaleIt was at just this small-scale range that air surveyseemed to offer the greatest advantages

The work carried out within the USCampGSand USGS prior to and during World War I hadprepared both agencies to take advantage of theemerging technology Starting in 1919 USCampGSused aerial photography for chart revision(Quillian 1919 Mattison 1919) and for wetlandsurveys (Mattison 1924 Graham 1924-25) Someproblems were encountered but the particularadvantages of air survey for mapping wetlands ledto the technique becoming the standard procedure(Landen 1952) In carrying out these surveys theUSCampGSused photography supplied by the Navyand the Army Air Corps it was the Air Corpsmulti-lens camera that established the cost-effec-tiveness of air survey (Reading 1927-28) Withinthe USGS a quadrangle in Michigan was mappedusing a conventional single-lens camera using airsurvey for the planimetry only (Thompson 1952)In 1924 a Section of Photographic Mapping wasestablished as part of the Topographic Branch atUSGS

Terrestrial photogrammetric work had beenundertaken in Russia as early as 1891 (Koch1963) but few significant additional developmentsoccurred before 1920 In 1924 the State TechnicalOffice of Aerial Photographic Survey was estab-lished Its first task was the creation of mosaics at110000 for comparison with plane table surveysThe results were considered sufficiently favorablefor mapping at 15000 based on 112000 pho-tography An ambitious program of aerial pho-tography initiated in 1925 led to the coverage ofmore than 4500000 km2 by 1940 In 1928 theCentral Scientific Research Institute for GeodesyPhotogrammetry and Cartography (ZNIlGAiK)was established to oversee development across thewhole field of mapping (Koch 1963)

Instrumental MethodsAt the end of World War I Germany and theAustro-Hungarian Empire had a clear advan-tage in the development and use of instrumen-tal photogrammetric methods While Germanycontinued to enjoy a considerable lead in thesetechniques the collapse of the Dual Monarchy andthe resultant breakup of the MilitargeographischeInstitut meant that Austria entered a period ofrelative decline Zeiss which had become theciear ieader in the design and man-ufacture ofphotogrammetric instruments not only pro-duced instruments designed by both von Ore and

165

Pulfrich but employed several leading figures inphotogrammetry including Walter BauersfeldWilli Sander and Otto von Gruber This ensuredthat Zeiss was always at or near the forefront ofdevelopments in the field

During the 1920s most efforts were directedtoward overcoming the problem inherent in theearlier generation of photogrammetric plot-ters namely the need for the photographs tobe coplanar In 1926 Hugershoff designed anaerocartograph for use with both terrestrial andaerial photography The instrument which wasmanufactured by Heyde Company in Dresdentook advantage of the theoretical developmentsin orientation theory developed by Max Gasser(1923) and von Gruber (1924) The combinationof new orientation procedures and sophisticateddesign meant that Hugershoffs aerocartographcould be used for plotting and aerotriangulation(Blachut and Burkhardt 1989) Professional rivalryled von Gruber (1932) to dispute the original-ity of Hugershoffs design as he was also to dowith Heinrich Wilds instruments and the ideas ofFourcade

Zeiss had produced their stereoplanigraph(the Cl) in 1921 based on an earlier design ofBauersfeld However it was not until the pro-duction of the C4 in 1930 that Zeiss producedan instrument that could handle both terrestrialand aerial photography Some successful mappingfrom the earlier models was reported throughthe 1920s by the Reichsamt fur Landesaufnahmewhich had a C2 (Seidel 1928) and the GeodeticInstitute in Stuttgart which had a C3 (von Gruber1932) Most of the mapping was at 15000 butscales as small as ] 20000 are reported Even inGermany systematic mapping programs usingphotogrammetry were still the exception ratherthan the rule during the 1920s

In France the Service Geographique de lArmeehad been actively experimenting with instrumen-tal photogrammetry before World War I (Bonnet1920) and had also used the technique for someterrestrial work during the war France was thuswell placed at the end of the war to keep upwith the developments elsewhere in Europe TheService had decided that terrestrial photogram-metry was best suited to 120000 mapping in highmountain areas but considered the equipment toocumbersome and imprecise for reconnaissancesurveys (Service Geographique de lArmee 1912)In 1919 a start was made on mapping in Moroccousing panoramic aerial photographs (ServiceGeographique de IArmee ]936) but the main

166

drive in France was to develop an autonomouscapability in instrumental photogrammetry

Some equipment had been developed duringthe war notably the Chambre Claire Varon andthe Appareil de photorestitution Roussilhe aninstrument for partial rectification of cadastralplans (Blachut and Burkhardt 1989 ServiceGeographique de IArmee ]936) The mostimportant development came in 1922 when thefirst Georges Poivilliers instrument was built(Poivilliers 1922 Blachut and Burkhardt 1989)Poivilliers instruments were to provide the bulkof the photogrammetric capability of the Servicewith up to four different types in use at anyonetime (Institut Geographique National 1947)Other instruments were also used largely on anexperimental basis In the mid] 920s the stereor-estituteur Boucard was in use and in the I930s aGallus Ferber instrument was used experimentally(Service Geographique de lArmee 1938) withthe latter (Blachut and Burkhardt 1989) remain-ing in service until at least the 1940s (InstitutGeographique National 1947)

Italy had been actively engaged in photogram-metry in the nineteenth century with the work ofPorro but as Blachut and Burkhardt (1989) notethe Istituto Geografico Militare showed little inter-est in the technique until many years after Porrosdeath in 1875 The resurrection of Italian photo-grammetry was largely due to two men UmbertoNistri who designed aplotter in 1919for large-scaleplotting and Ermenegildo Santoni who producedhis first instrument the autoreductor in 1921 In1926 Nistri founded the firm Ottico MeccanicaItaliana (OMI) to produce his photogrammetricinstruments Nistris early instruments all useddirect optical projection while Santonis instru-ments all used mechanical projection The IstitutoGeografico Militare was middotequipped with Santoniinstruments which it used for mapping at 125000and 110000 The Societa Anonima RilevamentiAerofotogrammetrici (SARA)on the other handused Nistri instruments largely for topographicmapptng outside Italy but also for cadastral map-ping within the country

Photogrammetry had been used in Switzerlandfor engineering surveys in the nineteenth centuryyet there had been no systematic attempt to carryout topographic mapping using the techniqueThe history of mapping in Switzerland betweenthe two world wars is largely a history of the WildHeerbrugg Company Set up in 1921 the com-pany produced its first phototheodolite in 1922and its first photogrammetric plotter the Alstereo-autograph in 1923 Its first major contribu-

Cartography and Geographic Information Science

tion to surveying came with the production of theT2 theodolite in 1924 The revolutionary design ofthis instrument-replacing engraved metal circleswith glass versions provided more accurate read-ings and better illumination-led to considerableexcitement in scientific and survey circles By thelate 1920s Wild was engaged in serial productionof the T2 and T3 theodolites the P3 phototheodo-lite and the A2 autograph which had replaced theAI In addition the Cl C2 and C3 aerial cam-eras were also in production In the space of onlyeight years Wild had become a major player in thesurvey world a position enhanced further duringthe 1930s

By the late 1920s the Landestopographie inSwitzerland had gained considerable experiencewith Wild instruments for both terrestrial andaerial surveys (Schneider 1929) Topographicmaps were produced from terrestrial photographyat 125000 while aerial photography wasused for110000 mapping (Schneider 1929 Harry 1971)

In the United States in addition to usinggraphical techniques the USGS started to inves-tigate instrumental methods In 1921 it obtaineda stereoautograph from Germany for evalua-tion but restricted the use of the instrument toplotting from terrestrial photography and notable to produce maps economically (Thompson1952) In 1927 the Geological Survey acquired theHugershoff aerocartograph the first automaticstereo-plotter used by an American governmentmapping agency (Thompson 1952) Thomas PPendleton laid down guidelines for mapping fromaerial photography within the USGS in Bulletin788-F Map Compilation from Aerial PhotograPhsissued as part of the Topographic Instructions of theUnited States Geological Survey (Pendleton 1928)Given the rapid developments in radial-line meth-ods (eg Hotine 1927) the timing of Pendletonswork was a bit unfortunate as he asserted thatradial-line techniques were really only suited foruse with multi-lens photography because therelatively short radial lines that could be drawnon single-lens photographs could not give the bestresults (Pendleton 1928 p 409)

In Britain research work carried out by the AirSurvey Committee focused on simple methods butthe Committee did not entirely ignore instrumen-tal techniques MacLeods wartime work with rec-tifiers was developed and more importantly theideas of Fourcade (l926a 1926b 1926c 1926d)on the theory and use of stereogoniometers forphotogrammetric plotters were taken up In 1926the Committee commissioned the constructionof an instrument along the lines proposed by

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Fourcade and the instrument was delivered in1928 0ar Office 1935 Hotine 1931)

In India success with non-instrumental tech-niques did not distract the Survey from instrumen-tal techniques they had helped pioneel- Mappingofficials followed developments taking place inEurope and in 1926 Mason (1927) carried outa survey in the Shaksgam using a Wild photo-theodolite and plotted the results in Switzerlandusing an autograph in the Topographical Instituteat Flums

CamerasThe tri-lens camera developed by Bagley was usedby the USGS in mapping for aeronautical chartsThis program wasjointly organized with the Corpsof Engineers and the Air Service (Committeeon Photographic Surveying 1921) and providedvaluable experience in civil applications In 1920programs with the tri-lens camera were also under-taken in Santo Domingo and Haiti

The Corps of Engineers became involved inphotogrammetric methods in 1920 when Bagleywas assigned to cooperate with the Army AirCorps in carrying out tests on aerial photographyfor topographic mapping Initially the trials usedBagleys tri-lens camera but he went on to developthe five lens T-3Acamera which was to remain thestandard mapping camera of the US Army until1940 (Landen 1952) The War Department issuedtraining regulations for mapping from aerialphotography in 1923 however the techniques dis-cussed in the regulations were largely those refinedduring World War 1

The 1930sBy the late 1920s photogrammetry had becomea cost-effective alternative to some traditionalground surveys Yet expensive photogrammetricplotting instruments and labor-intensive graphicalplotting meant that photogrammetry still lackeda decisive advantage over ground survey Duringthe 1930s a number of innovations were to swingthe balance decisivelyin favor of photogrammetricmethods

Progress was slowed if not stopped by the reces-sion that started in 1929 Some measure of theimpact can be gauged from job cutbacks at WildHeerbrugg In 1930 before the recession had amarked affect on Europe the workforce stood at260 but by 1933 the number ofjobs had droppedto 125This was the direct consequence of the deci-sions taken to retrench mapping projects as well as

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capital programs Nearly all the annual reports forthe early 1930s mention the financial constraintsunder which organizations had to work In theUnited States some of these problems were offsetby appropriations under the Emergency Reliefand Construction Act (US Coast and GeodeticSurvey 1933) Moreover the New Deal initiated awide range of programs in which photogrammetrywas to playa major role By contrast problems inthe colonial territories were if anything worsethan in Europe and North America The declinein industrial activity in developed countries ledto a collapse in demand for raw materials fromthe colonies and as this was the main source ofgovernment revenue they could no longer pay forsurvey work Annual reports from most colonialsurvey departments make reference to a lack ofresources to meet the need for mapping Howevel~by the late 1930s as a result of rearmament inEurope governments allocated more money tosurvey organizations

Survey organizations were eager to adopt newtechniques in routine mapping programs but thepressures within governments to deal with massunemployment probably helped to promote theuse of labor-intensive methods in survey at theexpense of investment in technology Certainlyorganizations such as the Tennessee ValleyAuthority (TVA) the Agriculture AdjustmentAdministration and the Soil Conservation Servicein the United States were all heavily dependenton such labor-intensive techniques and did muchto develop them as standard mapping methodsMoreover organizations such as the USGS andthe TVA also played a role in the developmentinstrumental methods such as multiplex All ofthis was to be of vital importance to the hugephotogrammetric mapping programs that wereto emerge during World War II The scale of theseprograms would have been inconceivable withoutthe trained body of photogrammetrists developedduring the 1930s (Landen 1952)

Within the British colonial territories the conser-vative element that had inhibited the developmentof photogrammetric methods through the 1920scontinued to delay adoption of photogrammetryuntil after World War II-with some illuminatingexceptions Cyprus is the only known example ofa local survey department attempting to carry outphotogrammetric work Aerial photography wastaken in 1936 but delays in obtaining groundcontrol meant that no use was made of the pho-tography before all normal work was suspended atthe outbreak of war In all the other colonies wherephotogrammetry was attempted private survey

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companies carried out the work The earliestexample of the involvement of private air surveycompanies had been in 1927 in the mapping ofthe Anglo-Belgian boundary in the Copper Beltregion of Northern Rhodesia (Colonial SurveyCommittee 1928) Private air survey companieswere also active in Uganda Tanganyika andSouthern Rhodesia but in all cases this was surveywork for specific development projects ratherthan routine mapping (War Office 1935) Therewere discussions about the use of photogramme-try in Sierra Leone where the Aircraft OperatingCompany of South Africa proposed to revise the162500 topographic maps for pound150000 includ-ing the cost of providing ground control but thework was never carried out due to financial con-straints and the outbreak of World War II Therewere also discussions about air survey in Jamaicaand the Gold Coast but nothing came of theseprojects until after World War II It is clear fromthe literature and correspondence of the time thatthe private air survey companies were lobbyingindividual colonial governments as well as theBritish Government to adopt air survey but theColonial Survey Committee under Winterbothamwas equally forceful in its resistance to changelargely on grounds of cost (see in particularWinterbotham 1920 1921 1929 1934 1936Hemming 1933)

Increasing recognition that war with Germanywas inevitable led to a significant change in theBritish establishments attitude towards the use ofair survey In part this change reflected the retire-ment of Winterbotham in 1935 and his replace-ment as Director General of the Ordnance Surveyby MacLeod who was alwaysa warm supporter ofair survey MacLeod had followed Winterbothamfirst as Director of Military Surveys and then atthe Ordnance Surveyand in each case he playeda major role in introducing the use of photogram-metry (Clough 1952)

Advances in InstrumentationThe late 1920s had seen the design and produc-tion of the first practical plotting machines for usewith aerial photography The experience provideda foundation for the introduction during the1930s of designs that were to be the mainstaysof topographic mapping The Zeiss C4 had beenintroduced in 1930 (Burnside 1993)AsThompson(1966) notes the C4 and the superseding C5(introduced in 1935 with improved illumination)were with the Wild A5 (launched in 1937) practi-cally the only universal instruments on the marketin the 1930s Universal instruments designed to

CartograPhy and GeograPhic Information Science

handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

Vol29 No3

graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

169

Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

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world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

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Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

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ever the deficiencies of the enlargements becameevident they were replaced by new mapping Onlythe German survey seems to have continued to useenlargements through to the end of the war aack1920) With the development of positional warfare140000 mapping wassoon found to be inadequateand was successively complemented by mappingat 120000 and 110000 Where necessary evenlarger scales were used (Chasseaud 1999)

Behind the lines revision and new surveys werecarried out using conventional land survey tech-niques trigonometrical control surveys and theplane table to add detail Oack 1920 Winterbotham1919a 1919b Service Geographique de lArmee1938 Albrecht 1969 Chasseaud 1999) For front-line areas and for the enemys rear areas the maindata source was aerial photography

The Development of CamerasInitially photography for intelligence and maprevision involved the acquisition of photographyfrom fairly low flying aircraft using largely impro-vised camera equipment With the development ofanti-aircraft defenses however reconnaissance air-craft were forced to fly higher and higher to avoidbeing shot down To compensate it became neces-sary to devise cameras with longer and longer focallengths if the resultant photography was to be ofuse for analysis and mapping

The earliest cameras were simple devices thatused glass plates and dark slides (devices used tochange glass negatives in a camera without expos-ing the negatives to light) Images were obtainedby observers pointing the cameras over the side ofthe aircraft The cameras were fitted with simplesighting devices to ensure that the target wasactually imaged Recognition that vertical photo-graphs were much better suited to mapping thanthe oblique pictures taken with hand-held camerasled to the cameras being fixed to the side of theaircraft Fairly quickly magazines were providedso that a series of photographs could be taken bythe observer activating a lever to change platesEven so changing the magazines still required theobserver to lean over the side of the aircraft Giventhese difficulties it seems strange that roll filmwas not used earlier especially since panoramiccameras had used it as early as the late nineteenthcentury The Germans did not introduce a filmcamera until 1916 (Albrecht 1969) and the Britishcontinued to use plate cameras until the end ofthe war

Most of the cameras used for military operationshad relatively long focal lengths the standardBritish camera in the early part of World War I had

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a focal length of 8 inches (approximately 200 mm)while the standard German camera had a focallength of 180 mm (Albrecht 1969) By the end ofthe war focal lengths of 500 mm were not uncom-mon-some German cameras had focal lengths aslarge as 1200 mm (Albrecht 1969) These lenseswere designed for reconnaissance rather thanmapping so that each photograph covered only asmall area of ground Cameras needed wide-anglelenses to minimize the amount of control neededfor mapping but none of the high-quality lensesavailable provided a wide field of viewMulti-lenscameras were developed in the nineteenth centuryto obtain broader coverage from each exposurestation but these cameras were generally largeand cumbersome and thus unsuited for militaryoperations

Control for MappingEarly attempts at using aerial photography formap revision experienced considerable difficul-ties As Malcolm MacLeod (1919 pp 382-83)noted though the photographs showed all theprincipal topographical features in great detailthere was no means of determining their exactscale or the amount of distortion due to thecamera not being truly vertical at the moment ofexposure of the plate In the absence of mechani-cal restitution instruments to overcome theseproblems two possible solutions were consideredto develop a device for mechanically determiningthe altitude and tilt of the camera at the momentof exposure or to compare the positions of pointson the photographs with their known ground coor-dinates Although both sides experimented with amechanical solution most work involved the lattertechnique This placed a heavy demand on accessto ground coordinates

The provision of control points both in andbeyond their own front line was a major problemfor all the combatant nations Placing markersover control points in frontline areas and thenfixing them by observation from the rear was notfeasible as this also enabled the enemy to fix theposition of the trenches A number of strategieswere adopted including the use of periscopictheodolites employed from within the trencheswithout exposing observers to enemy fire Thesetheodolites could be used to fix positions withinthe trenches by resection

While resection on the plane table was a com-monly used technique among topographers ithad not been widely used for instrumental obser-vations because of the relative complexity of thecalculations However the conditions of trench

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warfare left few alternatives Once adopted resec-tion remained in common use among surveyorsAn alternative adopted by the Germans was to firea flare vertically from the trenches and obsenTethe flares position from the rear using theodolitesGack 1920)

Locating control points beyond the front line waseven more difficult Where possible the position ofprominent points would be fixed by intersectionHowever in Mesopotamia there were often too fewsuitable features to intersect This led to an inno-vation by Col C P Gunter to fix control pointswithin the Turkish lines using artillery shell burstsFour observers took simultaneous observations ofindividual shell bursts while an observer in anaircraft recorded the position of the explosionson a detailed map of the trenches created from airphotographs On average out of ten shell burststhree good intersected points were observed andthe observer would have accurately marked one ofthese Points observed in this way were then usedto control and adjust the strips of photographyused for mapping (Surveyof India 1925)

Plotting DetailOnce control had been obtained it was necessaryto interpret and plot the information on photo-graphs Initially interpretation was relatively easyas there was little attempt to conceal potentialtargets from aerial observation Camouflage onlystarted to be used systematically around 1916(MacLeod 1919) thereafter photo-interpretationdeveloped into a specialist skill Use of camouflagealso led to the development of new surveyingtechniques such as flash spotting and soundranging

Extraction of detail for revision purposes wasdone by some form of graphic intersection orthrough the use of optical projection Despite someuse of more rigorous methods involving compara-tors developed before the war these instrumentstogether with the necessary calculations were slowand not well suited to the urgent needs of the warThe use of automatic plotters such as the alitoste-reograph was restricted to terrestrial photographydue to the need for coplanar photography In factthis technique was used only by the Germans andFrench in eastern France where relief was suitableand by the Austro-Hungarian Army in the AlpsOskar Albrecht (1969) also refers to the use of ter-restrial photogrammetry for artillery assaults onfortresses and the use of photographs taken fromtethered balloons

The belligerent powers employed a variety ofgraphic techniques The simplest involved the pro-

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duction of a framework of existing detail on a com-pilation sheet on which new detail was added fromaerial photographs with the help of proportionaldividers Although capable of producing reason-ably accurate results this approach was labori-ous and slow (MacLeod 1919) The paper stripmethod (Thompson 1966) used for adding smallamounts of detail was equally slow and laboriousThe German Army developed a less strenuoustechnique based on the use of perspective gridsThe chief advantage of this technique was thatonce the grids had been generated detail could betransferred by eye from aerial photograph to mapThis technique was so successful that it was widelyadopted after the war for map revision Describedin most standard textbooks on photogrammetrythe perspective grid approach remained in useuntil the 1980s when simple digital techniquesrendered it obsolete

Most of the optical revision techniques reliedon the registration of a projected image of thephotograph on an existing map or on a frame-work of control Once the image was registeredthe mapmaker could either transfer the informa-tion directly to the map or produce a correctedphotographic print for use in revision TheodorScheimpflug had shown that an accurate regis-tration could be affected between the projectedimage and the control data if the projected imagewas in focus for the entire image area To satisfYthe so-called Scheimpflug condition the projectedplanes of the negative lens and easel had to meetat a common axis (Scheimpflug 1898 Blachutarid Burkhardt 1989) Even if the condition wassatisfied there were still errors of registration dueto relief displacement In the instruments usedduring World War I the Scheimpflug conditionwas hot satisfied and consequently the resultswere at best approximate (Blachut and Burkhardt1989) MacLeod (1919 1920) describes the use ofCamera Lucida and the enlarging lantern inboth of which the plane of the negative and theplane of the lens were held parallel with only thecopy board which was capable of being tilted Theeniarging lantern could maximize the depth offocus and hence the sharpness of the iinagebyreducing the aperture of the lens to the smallestdiameter possible The use of the enlarging lan-tern to produce semi-rectified prints came to bethe preferred techrnque

As already noted while most of the work onthe Western Front involved map revision innon-European theaters the need was for originalmapping (Collier 1994 Collier and Inkpen 2001)The first attempts to use aerial photography to

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construct original mapping took place during theGallipoli campaign (Dowson 1921) Not very suc-cessful these attempts demonstrated the problemsassociated with the non-stereoscopic use of aerialphotography as when troops were sent to occupypositions identified monoscopically as trenchesor ditches but which turned out to be shallowscrapes that afforded no shelter from enemy fireAttempts to create original mapping ceased whenmodern Turkish maps of the area were capturedand revised

In Egypt the Turkish threat to the Suez Canalalso resulted in experiments in mapping fromaerial photography Like the mapping in Gallipolithese were largely unsuccessful The main problemwas locating precisely where the photographs hadbeen taken over a largely featureless desert Thebulk of the mapping for the Suez Canal defenseswas therefore carried out by triangulation andplane table survey (Maule 1919)

When the Egyptian Expeditionary Force (EEF)advanced across the Sinai Peninsula to engageTurkish forces in Palestine it moved into terri-tory without up-to-date mapping of an adequatescale Western Palestine had been mapped for thePalestine Exploration Fund (PEF) in the 1870s(Conder 1878 Conder and Kitchener 1881-83) ata scale of 163360 Although based on triangula-tion the detail had been surveyed using compassand cavalry sketching board (Close 1932) and wastherefore regarded as insufficiently accurate formodern warfare British military personnel hadsurveyed Southern Palestine just before the warunder the cover of a PEF expedition (Woolleyand Lawrence 1914) But even here the scale wastoo small (1 125000) for the kind of operationsbeing undertaken The British army was thereforeconfronted with the need to map areas beyond itsfront line for which no adequate base maps wereavailable

The first successful attempts at mapping fromaerial photographs were in t~e area aroundGaza (Gavish and Biger 1983) Here control wasprovided by the intersection of prominent pointsbehind Turkish lines Based on these points acontrolled mo~aic was created from with verticalaerial photogriphs and the mosaic was then usedto crcate the line maps of the planimetry Althoughcrude by later standards the map was consideredto be a significant improvement on anything thenavailable This encouraged the surveyors led byMajor W] Maule to embark upon an ambitiousplan to create a series of topographic maps at 140000 for areas of Palestine behind Turkish lines(Maule 1919) Strips of photography were flown

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roughly parallel to the front line with additionalstrips of photography perpendicular to the frontflown at intervals to control the strips parallel tothe front Supplementary control was provided bytheodolite observations wherever possible Thesame basic arrangement pioneered in the map-ping of Gaza was followed for the series mappingHowever as the area mapped extended into thehills of Judea (the southern West Bank) it alsobecame necessary to provide some indication ofrelief Viewing the photography stereoscopicallyand form lining achieved this The nature of thetopography nearly horizontally bedded lime-stones that eroded into natural terraces madethis task relatively easySuccessfulas the mappingwas (Thomas 1919) as each new area came underBritish control mapping derived from air photoswas replaced bymapping made using conventionalground survey techniques

In a number of ways the mapping inMesopotamia can be regarded as the first exampleof true photogrammetric mapping using aerialphotography Unlike the mapping in Palestineit was produced as the end product not as aninterim solution to be replaced as soon as groundsurveys became possible And unlike the mappingon the Western Front it did not involve revision ofexisting mapping as no proper maps existed forthe area

Although developments in the use of air pho-tography had been watched with envy by thesurveyors in Mesopotamia (Survey of India 1925)until early 19I6 no airplanes had been availablefor that theater Some experience in the use ofaerial photography had been gained before thesiege of Kut-al-Amarah but it was the positionalfighting around Kut that emphasized the advan-tages of air survey Maps were required of areasbehind Turkish lines but the flat landscape meantthat surveyscould only be extended into no-mans-land This led to the first real attempt to createmaps from aerial photography As the first mapTC4 (TC are the initials of Tigris Corps theoriginal name of the force sent to Mesopotamia)has been discussed at length elsewhere (Collier1994 Pritchard 1952 Survey ofIndia 1925)

The surveyors working in Mesopotamia experi-mented with various ways of making maps fromaerial photographs drawing on the experience ofsurveyors on the Western Front and in Egypt Inthe end though they developed their own tech-nique which was well suited to local conditionsTheir technique involved creating semi-rectifiedphotographs using an enlarging lantern (Gunter1917) and then mosaicing the photographs using

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a triangulation scheme The mosaics were inkedup before the bromide prints were bleached out soas to leavejust the inked linework The importantpoint to note is that this technique was used formapping areas on both sides of the front line andwas therefore regarded as the final product Theflat floodplains of the Tigris and Euphrates Riverslent themselves to mapping using semi-controlledmosaics as there was an almost complete absenceof height to create displacement errors The map-ping of Mesopotamia from aerial photography seta precedent for post-war mapping in India

Flash Spotting and Sound RangingAs mentioned earlier the use of camouflage neces-sitated the development of techniques for targetlocation in particular the location of enemy gunpositions for counter-battery fire At the beginningof World War I guns were aimed by direct observa-tion of targets and the guns themselves were oftenpositioned in the open to improve their fields offire With the increased use of counter battery fireit became normal for guns to be dug in posi-tioned in gun pits and protected by sandbags Toprotect gun positions from enemy air observationthe gun pits were subsequently camouflaged withnetting which thwarted an accurate identificationof their positions

Flash spotting and sound ranging were devel-oped as means of tackling the problem of identify-ing and locating enemy gun positions Adopted byall the combatant nations flash spotting involvedintersecting the gun position by observing theflash as tht gun was fired Flash spotting requiredconsiderable organization as the observers had toensure that they were observing the same gun flashbut by carefully noting the times of the observa-tions it was possible to obtain accurate locationsof enemy guns Most armies established specialistunits for this purpose (Innes 1935 Chasseaud1999 Hinks 1919 Maule 1919)

Sound ranging was a more complex process inwhich the British and French enjoyed a technolog-ical lead over the Germans General Ludendorffthe German Chief of Staff who issued specialinstructions that precautions be taken to cam-ouflage the sound of guns directed the army tosecure an example of the British system (quotedin Hinks 1919) Based on a technical solutiondeveloped by Lucien Bull at the Institut Marey inParis the British system relied on an array of sixmicrophones spread over a 9-kilometer-long base-line situated about 4 km behind the front iine Themicrophones were connected to a galvanometer atthe hea~quarters As the sound of a gun reached

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each microphone in turn a signal was sent by wireto the galvanometer where it produced a distinc-tive trace on photographic film By measuring theseparation of the traces of the gun detected at eachmicrophone the distance and direction of the guncould be calculated Complex arrangements withmore than two microphones were needed becauseof uncertainty about the effect of wind speed andother factors on sound waves (see Innes 1935 andChasseaud 1999 for more technical details)

The German systemrelied on a fonvard observerand four other observers along a base of 10 to 15kilometers On hearing a gun firing the forwardobserver sent a signal by field telephone to theother observers who on receiving the signalstarted their stopwatches and noted the time inter-val before they heard the gun The times were thensent to group headquarters where the position ofthe gun was calculated An alternative and sim-pler method involved an observer noting the timeinterval between seeing a gun flash and hearingthe noise of the gun The greatest precision possi-ble with these techniques was about +200 meters

Non-military WartimeDevelopments to 1918

While the mapping efforts of the combatantnations were almost entirely directed towards thewar effort cartographers in the United States wereactively exploring civilian applications of pho-togrammetry The most important developmentwork was carried out at the US Geological Surveywhere James Bagley was developing a tri-Ienscamera and Fred Moffit was developing a trans-forming camera capable of handling the nega-tives produced by Bagleys camera (Committee onPhotographic Surveying 1921)

Developments to 1930In the period leading up to and including WorldWar I all the major powers followed broadlysimilar paths in developing photogrammetry Inmost countries attempts to develop instrumentalmethods complemented heavy reliance on graphi-cal and optical techniques for producing andrevising large-scale maps After the war a numberof countries took distinctly different paths withcontinental European countries generally puttingmost of their effort into instrumental techniqueswhile English-speaking countries focused ongraphical techniques Arguably until about 1930the approach adopted by the English-speaking

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countries was the most fruitful as the instrumentaltechniques developed in Europe could not com-pete in cost or efficiency with British and Americanmethods

After 1930 the relative efficiencies of the twoapproaches changed markedly The Americansrecognized the changed circumstances morequickly than their British counterparts and beganadopting instrumental methods by the mid 1930sIn Britain and by extension throughout the BritishEmpire instrumental photogrammetry was still inthe experimental phase at the outbreak of WorldWar 11in 1939

The immediate post-war-one period saw a flurryof papers extolling the merits of mapping fromaerial photography At the forefront of the cam-paign to get the methods accepted in Britain wasCapt H Hamshaw Thomas (1919 1920 1924)who drew heavily on his experiences in the Sinaiand Palestine Much of the effort to promote airsurvey was conducted in non-specialist journalssuch as the GeograPhicalJournal (Newcombe 1920)and even in the popular press MacLeod who hadserved in France and had become a firm advocateof air survey methods also produced a numberof papers as well as an important official publica-tion Mapping from Air Photographs issued by theWar Office (MacLeod 1920 but see also MacLeod1922 1923a 1923b)

Britain more than in any other country held aconservative attitude towards the new techniquesand this resistance found an influential championin Harold StJ LWinterbotham A self-proclaimedexpert on air survey (see Winterbotham 19291934) Winterbotham did much to impede theadoption of air survey both in Britain and throughhis role on the Colonial Survey Committee in thecolonial territories In contrast the Dominion ter-ritories were free to determine their own policiesAlthough Canada a pioneer in photogrammetryhad been joined by India in its use of these tech-niques before the outbreak of the First World Warother Dominion territories were slower in adopt-ing air survey Australia took the lead but localfactors either delayed or advanced the adoptionof photogrammetry in Dominion territories whichwere not compelled to follow the Colonial SurveyCommittees recommendation There is a strik-ing parallel between these largely autonomousterritories and the Dutch East Indies where thesurvey department was quick to adopt photogram-metry (van Roon 1925) but made no real progressat home in The Netherlands until after World WarII

In the British context Winterbothams reser-vations concerning the cost-effectiveness of air

i64

survey methods were probably justified at leastuntil the development of Reinhard Hugershoffsaerocartograph in 1926 (Blachut and Burkhardt1989) All the air survey instruments introducedbefore the aerocartograph were essentially ter-restrial plotters adapted in some way to copewith non-coplanar photography This made theinstruments difficult and slow to set up and theyusually required two men to carry out orienta-tion and plotting operations In a well mappedcountry such as Britain cumbersome machinescould not support map revision as economically asconventional ground surveyhere Winterbothamerred even in the 1920s was in extrapolatingfrom the British experience to the colonial terri-tories where the needs were very different On thepositive side agitation by Hamshaw Thomas andothers as well as the successful application of airsurvey techniques by the Survey of India led to thesetting up of the AirSurvey Committee Part ofthe responsibility of this committee was to adviseon air survey matters but it was also responsiblefor carrying out research

In the United States the promotion of airsurvey techniques wasundertaken by Moffit (1920)and other surveyors who had not been directlyinvolved in the war effort but had carried on withtheir civilian work in government mapping agen-cies Part of this promotion was carried out in non-specialist journals but unlike in Britain there waslittle need to convince the political leadership ofthe advantages of air surveyBycontrast there waslittle attempt to promote air survey in France orGermany other than in technical or professionaljournals Almost certainly this reflects the higherstatus of engineers and technical experts in thosecountries compared with Britain The UnitedStates probably fell somewhere between Britainand the continental powers but more towards thelatter

Survey and mapping activities in Austria suf-fered a severe setback with the breakup of theHabsburg Empire at the end of World War 1The Militargeographische Institut was disbandedin 1920 (Kretschmer 1991) and its personneldispersed amongst the successor states Whilethis disintegration had clear disadvantages forAustria survey departments in Poland Hungaryand Czechoslovakiagained a cadre of trained andexperienced personnel able to form the nucleusof new national survey organizations Despite eco-nomic hardship in the wakeof the warAustria hadbegun in 1928 to supplement existing 175000topographic mapping work focused on the moun-tainous areas using terrestrial photogrammetry

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Graphical MethodsBecause of the extensive use of graphical methodsduring WorldWar I a large body of trained person-nel was available to implement these methods forpost-war mapping But the techniques developedthus far were either non-rigorous (for example theperspective grid) or suitable only for revising smallnumbers of features (the paper strip method)What was needed was a rigorous technique thatdid not require highly skilled workers

Bagley had sowed the seeds of a rigoroustechnique during his work with the PanoramicPhotoalidade (Bagley 1917) but Martin Hotine(1927) provided the theoretical and practicalbasis for a cost-effective mapping techniqueDescribed as a Simple Method of Surveying fromAir Photographs Hotines technique becameknown as the Arundel Method (after Arundelin southern England where the technique wasfirst used experimentally) or the radial-line tech-nique Hotine subsequently developed the methodof control extension using radial-line methods(Hotine 1929) and laid the foundations for muchof the medium-scale photogrammetric mappingcarried out in the English-speaking world over thenext 40 years The American development of slot-ted templets and radial intersectors expeditedthe process of aerotriangulation (see below) butit was Hotines theoretical work that made thesedevelopments possible

None of the countries using aerial photogra-phy for topographic mapping embraced it withgreater enthusiasm than India As noted earlierthe Survey of India had acquired two examplesof Thompsons stereo-plotter Kenneth Mason(1913 1927) had used the stereo-plotter in 1913in the Pamirs with considerable success but theexperience of the Survey of India in Mesopotamiaduring World War I wasdecisive in promoting airsurvey techniques in India In 1920 a series ofexperiments conducted at Agra demonstrated theutility of air survey methods for mapping flat areasin India (Lewis and Salmond 1920) Air surveyp~oved inefficient for one-inch-to-a-milemiddot map-pmg-the cost was roughly twice as much as forground surveys-but it was economical for largerscales An experiment in urban mapping was car-ried out but its results were inconclusive

Among developed countries the United Stateswas probably the most in need of the advantagesthat air survey offered post-war mapmakers Forall its great wealth America was poorly mappedby European standards Where most Europeancountries were at least mapped at medium scale(roughly 1100000 or larger) large tracts of the

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United States were not mapped even at small scaleIt was at just this small-scale range that air surveyseemed to offer the greatest advantages

The work carried out within the USCampGSand USGS prior to and during World War I hadprepared both agencies to take advantage of theemerging technology Starting in 1919 USCampGSused aerial photography for chart revision(Quillian 1919 Mattison 1919) and for wetlandsurveys (Mattison 1924 Graham 1924-25) Someproblems were encountered but the particularadvantages of air survey for mapping wetlands ledto the technique becoming the standard procedure(Landen 1952) In carrying out these surveys theUSCampGSused photography supplied by the Navyand the Army Air Corps it was the Air Corpsmulti-lens camera that established the cost-effec-tiveness of air survey (Reading 1927-28) Withinthe USGS a quadrangle in Michigan was mappedusing a conventional single-lens camera using airsurvey for the planimetry only (Thompson 1952)In 1924 a Section of Photographic Mapping wasestablished as part of the Topographic Branch atUSGS

Terrestrial photogrammetric work had beenundertaken in Russia as early as 1891 (Koch1963) but few significant additional developmentsoccurred before 1920 In 1924 the State TechnicalOffice of Aerial Photographic Survey was estab-lished Its first task was the creation of mosaics at110000 for comparison with plane table surveysThe results were considered sufficiently favorablefor mapping at 15000 based on 112000 pho-tography An ambitious program of aerial pho-tography initiated in 1925 led to the coverage ofmore than 4500000 km2 by 1940 In 1928 theCentral Scientific Research Institute for GeodesyPhotogrammetry and Cartography (ZNIlGAiK)was established to oversee development across thewhole field of mapping (Koch 1963)

Instrumental MethodsAt the end of World War I Germany and theAustro-Hungarian Empire had a clear advan-tage in the development and use of instrumen-tal photogrammetric methods While Germanycontinued to enjoy a considerable lead in thesetechniques the collapse of the Dual Monarchy andthe resultant breakup of the MilitargeographischeInstitut meant that Austria entered a period ofrelative decline Zeiss which had become theciear ieader in the design and man-ufacture ofphotogrammetric instruments not only pro-duced instruments designed by both von Ore and

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Pulfrich but employed several leading figures inphotogrammetry including Walter BauersfeldWilli Sander and Otto von Gruber This ensuredthat Zeiss was always at or near the forefront ofdevelopments in the field

During the 1920s most efforts were directedtoward overcoming the problem inherent in theearlier generation of photogrammetric plot-ters namely the need for the photographs tobe coplanar In 1926 Hugershoff designed anaerocartograph for use with both terrestrial andaerial photography The instrument which wasmanufactured by Heyde Company in Dresdentook advantage of the theoretical developmentsin orientation theory developed by Max Gasser(1923) and von Gruber (1924) The combinationof new orientation procedures and sophisticateddesign meant that Hugershoffs aerocartographcould be used for plotting and aerotriangulation(Blachut and Burkhardt 1989) Professional rivalryled von Gruber (1932) to dispute the original-ity of Hugershoffs design as he was also to dowith Heinrich Wilds instruments and the ideas ofFourcade

Zeiss had produced their stereoplanigraph(the Cl) in 1921 based on an earlier design ofBauersfeld However it was not until the pro-duction of the C4 in 1930 that Zeiss producedan instrument that could handle both terrestrialand aerial photography Some successful mappingfrom the earlier models was reported throughthe 1920s by the Reichsamt fur Landesaufnahmewhich had a C2 (Seidel 1928) and the GeodeticInstitute in Stuttgart which had a C3 (von Gruber1932) Most of the mapping was at 15000 butscales as small as ] 20000 are reported Even inGermany systematic mapping programs usingphotogrammetry were still the exception ratherthan the rule during the 1920s

In France the Service Geographique de lArmeehad been actively experimenting with instrumen-tal photogrammetry before World War I (Bonnet1920) and had also used the technique for someterrestrial work during the war France was thuswell placed at the end of the war to keep upwith the developments elsewhere in Europe TheService had decided that terrestrial photogram-metry was best suited to 120000 mapping in highmountain areas but considered the equipment toocumbersome and imprecise for reconnaissancesurveys (Service Geographique de lArmee 1912)In 1919 a start was made on mapping in Moroccousing panoramic aerial photographs (ServiceGeographique de IArmee ]936) but the main

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drive in France was to develop an autonomouscapability in instrumental photogrammetry

Some equipment had been developed duringthe war notably the Chambre Claire Varon andthe Appareil de photorestitution Roussilhe aninstrument for partial rectification of cadastralplans (Blachut and Burkhardt 1989 ServiceGeographique de IArmee ]936) The mostimportant development came in 1922 when thefirst Georges Poivilliers instrument was built(Poivilliers 1922 Blachut and Burkhardt 1989)Poivilliers instruments were to provide the bulkof the photogrammetric capability of the Servicewith up to four different types in use at anyonetime (Institut Geographique National 1947)Other instruments were also used largely on anexperimental basis In the mid] 920s the stereor-estituteur Boucard was in use and in the I930s aGallus Ferber instrument was used experimentally(Service Geographique de lArmee 1938) withthe latter (Blachut and Burkhardt 1989) remain-ing in service until at least the 1940s (InstitutGeographique National 1947)

Italy had been actively engaged in photogram-metry in the nineteenth century with the work ofPorro but as Blachut and Burkhardt (1989) notethe Istituto Geografico Militare showed little inter-est in the technique until many years after Porrosdeath in 1875 The resurrection of Italian photo-grammetry was largely due to two men UmbertoNistri who designed aplotter in 1919for large-scaleplotting and Ermenegildo Santoni who producedhis first instrument the autoreductor in 1921 In1926 Nistri founded the firm Ottico MeccanicaItaliana (OMI) to produce his photogrammetricinstruments Nistris early instruments all useddirect optical projection while Santonis instru-ments all used mechanical projection The IstitutoGeografico Militare was middotequipped with Santoniinstruments which it used for mapping at 125000and 110000 The Societa Anonima RilevamentiAerofotogrammetrici (SARA)on the other handused Nistri instruments largely for topographicmapptng outside Italy but also for cadastral map-ping within the country

Photogrammetry had been used in Switzerlandfor engineering surveys in the nineteenth centuryyet there had been no systematic attempt to carryout topographic mapping using the techniqueThe history of mapping in Switzerland betweenthe two world wars is largely a history of the WildHeerbrugg Company Set up in 1921 the com-pany produced its first phototheodolite in 1922and its first photogrammetric plotter the Alstereo-autograph in 1923 Its first major contribu-

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tion to surveying came with the production of theT2 theodolite in 1924 The revolutionary design ofthis instrument-replacing engraved metal circleswith glass versions provided more accurate read-ings and better illumination-led to considerableexcitement in scientific and survey circles By thelate 1920s Wild was engaged in serial productionof the T2 and T3 theodolites the P3 phototheodo-lite and the A2 autograph which had replaced theAI In addition the Cl C2 and C3 aerial cam-eras were also in production In the space of onlyeight years Wild had become a major player in thesurvey world a position enhanced further duringthe 1930s

By the late 1920s the Landestopographie inSwitzerland had gained considerable experiencewith Wild instruments for both terrestrial andaerial surveys (Schneider 1929) Topographicmaps were produced from terrestrial photographyat 125000 while aerial photography wasused for110000 mapping (Schneider 1929 Harry 1971)

In the United States in addition to usinggraphical techniques the USGS started to inves-tigate instrumental methods In 1921 it obtaineda stereoautograph from Germany for evalua-tion but restricted the use of the instrument toplotting from terrestrial photography and notable to produce maps economically (Thompson1952) In 1927 the Geological Survey acquired theHugershoff aerocartograph the first automaticstereo-plotter used by an American governmentmapping agency (Thompson 1952) Thomas PPendleton laid down guidelines for mapping fromaerial photography within the USGS in Bulletin788-F Map Compilation from Aerial PhotograPhsissued as part of the Topographic Instructions of theUnited States Geological Survey (Pendleton 1928)Given the rapid developments in radial-line meth-ods (eg Hotine 1927) the timing of Pendletonswork was a bit unfortunate as he asserted thatradial-line techniques were really only suited foruse with multi-lens photography because therelatively short radial lines that could be drawnon single-lens photographs could not give the bestresults (Pendleton 1928 p 409)

In Britain research work carried out by the AirSurvey Committee focused on simple methods butthe Committee did not entirely ignore instrumen-tal techniques MacLeods wartime work with rec-tifiers was developed and more importantly theideas of Fourcade (l926a 1926b 1926c 1926d)on the theory and use of stereogoniometers forphotogrammetric plotters were taken up In 1926the Committee commissioned the constructionof an instrument along the lines proposed by

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Fourcade and the instrument was delivered in1928 0ar Office 1935 Hotine 1931)

In India success with non-instrumental tech-niques did not distract the Survey from instrumen-tal techniques they had helped pioneel- Mappingofficials followed developments taking place inEurope and in 1926 Mason (1927) carried outa survey in the Shaksgam using a Wild photo-theodolite and plotted the results in Switzerlandusing an autograph in the Topographical Instituteat Flums

CamerasThe tri-lens camera developed by Bagley was usedby the USGS in mapping for aeronautical chartsThis program wasjointly organized with the Corpsof Engineers and the Air Service (Committeeon Photographic Surveying 1921) and providedvaluable experience in civil applications In 1920programs with the tri-lens camera were also under-taken in Santo Domingo and Haiti

The Corps of Engineers became involved inphotogrammetric methods in 1920 when Bagleywas assigned to cooperate with the Army AirCorps in carrying out tests on aerial photographyfor topographic mapping Initially the trials usedBagleys tri-lens camera but he went on to developthe five lens T-3Acamera which was to remain thestandard mapping camera of the US Army until1940 (Landen 1952) The War Department issuedtraining regulations for mapping from aerialphotography in 1923 however the techniques dis-cussed in the regulations were largely those refinedduring World War 1

The 1930sBy the late 1920s photogrammetry had becomea cost-effective alternative to some traditionalground surveys Yet expensive photogrammetricplotting instruments and labor-intensive graphicalplotting meant that photogrammetry still lackeda decisive advantage over ground survey Duringthe 1930s a number of innovations were to swingthe balance decisivelyin favor of photogrammetricmethods

Progress was slowed if not stopped by the reces-sion that started in 1929 Some measure of theimpact can be gauged from job cutbacks at WildHeerbrugg In 1930 before the recession had amarked affect on Europe the workforce stood at260 but by 1933 the number ofjobs had droppedto 125This was the direct consequence of the deci-sions taken to retrench mapping projects as well as

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capital programs Nearly all the annual reports forthe early 1930s mention the financial constraintsunder which organizations had to work In theUnited States some of these problems were offsetby appropriations under the Emergency Reliefand Construction Act (US Coast and GeodeticSurvey 1933) Moreover the New Deal initiated awide range of programs in which photogrammetrywas to playa major role By contrast problems inthe colonial territories were if anything worsethan in Europe and North America The declinein industrial activity in developed countries ledto a collapse in demand for raw materials fromthe colonies and as this was the main source ofgovernment revenue they could no longer pay forsurvey work Annual reports from most colonialsurvey departments make reference to a lack ofresources to meet the need for mapping Howevel~by the late 1930s as a result of rearmament inEurope governments allocated more money tosurvey organizations

Survey organizations were eager to adopt newtechniques in routine mapping programs but thepressures within governments to deal with massunemployment probably helped to promote theuse of labor-intensive methods in survey at theexpense of investment in technology Certainlyorganizations such as the Tennessee ValleyAuthority (TVA) the Agriculture AdjustmentAdministration and the Soil Conservation Servicein the United States were all heavily dependenton such labor-intensive techniques and did muchto develop them as standard mapping methodsMoreover organizations such as the USGS andthe TVA also played a role in the developmentinstrumental methods such as multiplex All ofthis was to be of vital importance to the hugephotogrammetric mapping programs that wereto emerge during World War II The scale of theseprograms would have been inconceivable withoutthe trained body of photogrammetrists developedduring the 1930s (Landen 1952)

Within the British colonial territories the conser-vative element that had inhibited the developmentof photogrammetric methods through the 1920scontinued to delay adoption of photogrammetryuntil after World War II-with some illuminatingexceptions Cyprus is the only known example ofa local survey department attempting to carry outphotogrammetric work Aerial photography wastaken in 1936 but delays in obtaining groundcontrol meant that no use was made of the pho-tography before all normal work was suspended atthe outbreak of war In all the other colonies wherephotogrammetry was attempted private survey

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companies carried out the work The earliestexample of the involvement of private air surveycompanies had been in 1927 in the mapping ofthe Anglo-Belgian boundary in the Copper Beltregion of Northern Rhodesia (Colonial SurveyCommittee 1928) Private air survey companieswere also active in Uganda Tanganyika andSouthern Rhodesia but in all cases this was surveywork for specific development projects ratherthan routine mapping (War Office 1935) Therewere discussions about the use of photogramme-try in Sierra Leone where the Aircraft OperatingCompany of South Africa proposed to revise the162500 topographic maps for pound150000 includ-ing the cost of providing ground control but thework was never carried out due to financial con-straints and the outbreak of World War II Therewere also discussions about air survey in Jamaicaand the Gold Coast but nothing came of theseprojects until after World War II It is clear fromthe literature and correspondence of the time thatthe private air survey companies were lobbyingindividual colonial governments as well as theBritish Government to adopt air survey but theColonial Survey Committee under Winterbothamwas equally forceful in its resistance to changelargely on grounds of cost (see in particularWinterbotham 1920 1921 1929 1934 1936Hemming 1933)

Increasing recognition that war with Germanywas inevitable led to a significant change in theBritish establishments attitude towards the use ofair survey In part this change reflected the retire-ment of Winterbotham in 1935 and his replace-ment as Director General of the Ordnance Surveyby MacLeod who was alwaysa warm supporter ofair survey MacLeod had followed Winterbothamfirst as Director of Military Surveys and then atthe Ordnance Surveyand in each case he playeda major role in introducing the use of photogram-metry (Clough 1952)

Advances in InstrumentationThe late 1920s had seen the design and produc-tion of the first practical plotting machines for usewith aerial photography The experience provideda foundation for the introduction during the1930s of designs that were to be the mainstaysof topographic mapping The Zeiss C4 had beenintroduced in 1930 (Burnside 1993)AsThompson(1966) notes the C4 and the superseding C5(introduced in 1935 with improved illumination)were with the Wild A5 (launched in 1937) practi-cally the only universal instruments on the marketin the 1930s Universal instruments designed to

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handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

Vol29 No3

graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

169

Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

170

world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

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Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

171

warfare left few alternatives Once adopted resec-tion remained in common use among surveyorsAn alternative adopted by the Germans was to firea flare vertically from the trenches and obsenTethe flares position from the rear using theodolitesGack 1920)

Locating control points beyond the front line waseven more difficult Where possible the position ofprominent points would be fixed by intersectionHowever in Mesopotamia there were often too fewsuitable features to intersect This led to an inno-vation by Col C P Gunter to fix control pointswithin the Turkish lines using artillery shell burstsFour observers took simultaneous observations ofindividual shell bursts while an observer in anaircraft recorded the position of the explosionson a detailed map of the trenches created from airphotographs On average out of ten shell burststhree good intersected points were observed andthe observer would have accurately marked one ofthese Points observed in this way were then usedto control and adjust the strips of photographyused for mapping (Surveyof India 1925)

Plotting DetailOnce control had been obtained it was necessaryto interpret and plot the information on photo-graphs Initially interpretation was relatively easyas there was little attempt to conceal potentialtargets from aerial observation Camouflage onlystarted to be used systematically around 1916(MacLeod 1919) thereafter photo-interpretationdeveloped into a specialist skill Use of camouflagealso led to the development of new surveyingtechniques such as flash spotting and soundranging

Extraction of detail for revision purposes wasdone by some form of graphic intersection orthrough the use of optical projection Despite someuse of more rigorous methods involving compara-tors developed before the war these instrumentstogether with the necessary calculations were slowand not well suited to the urgent needs of the warThe use of automatic plotters such as the alitoste-reograph was restricted to terrestrial photographydue to the need for coplanar photography In factthis technique was used only by the Germans andFrench in eastern France where relief was suitableand by the Austro-Hungarian Army in the AlpsOskar Albrecht (1969) also refers to the use of ter-restrial photogrammetry for artillery assaults onfortresses and the use of photographs taken fromtethered balloons

The belligerent powers employed a variety ofgraphic techniques The simplest involved the pro-

Vol 29 No 3

duction of a framework of existing detail on a com-pilation sheet on which new detail was added fromaerial photographs with the help of proportionaldividers Although capable of producing reason-ably accurate results this approach was labori-ous and slow (MacLeod 1919) The paper stripmethod (Thompson 1966) used for adding smallamounts of detail was equally slow and laboriousThe German Army developed a less strenuoustechnique based on the use of perspective gridsThe chief advantage of this technique was thatonce the grids had been generated detail could betransferred by eye from aerial photograph to mapThis technique was so successful that it was widelyadopted after the war for map revision Describedin most standard textbooks on photogrammetrythe perspective grid approach remained in useuntil the 1980s when simple digital techniquesrendered it obsolete

Most of the optical revision techniques reliedon the registration of a projected image of thephotograph on an existing map or on a frame-work of control Once the image was registeredthe mapmaker could either transfer the informa-tion directly to the map or produce a correctedphotographic print for use in revision TheodorScheimpflug had shown that an accurate regis-tration could be affected between the projectedimage and the control data if the projected imagewas in focus for the entire image area To satisfYthe so-called Scheimpflug condition the projectedplanes of the negative lens and easel had to meetat a common axis (Scheimpflug 1898 Blachutarid Burkhardt 1989) Even if the condition wassatisfied there were still errors of registration dueto relief displacement In the instruments usedduring World War I the Scheimpflug conditionwas hot satisfied and consequently the resultswere at best approximate (Blachut and Burkhardt1989) MacLeod (1919 1920) describes the use ofCamera Lucida and the enlarging lantern inboth of which the plane of the negative and theplane of the lens were held parallel with only thecopy board which was capable of being tilted Theeniarging lantern could maximize the depth offocus and hence the sharpness of the iinagebyreducing the aperture of the lens to the smallestdiameter possible The use of the enlarging lan-tern to produce semi-rectified prints came to bethe preferred techrnque

As already noted while most of the work onthe Western Front involved map revision innon-European theaters the need was for originalmapping (Collier 1994 Collier and Inkpen 2001)The first attempts to use aerial photography to

161

construct original mapping took place during theGallipoli campaign (Dowson 1921) Not very suc-cessful these attempts demonstrated the problemsassociated with the non-stereoscopic use of aerialphotography as when troops were sent to occupypositions identified monoscopically as trenchesor ditches but which turned out to be shallowscrapes that afforded no shelter from enemy fireAttempts to create original mapping ceased whenmodern Turkish maps of the area were capturedand revised

In Egypt the Turkish threat to the Suez Canalalso resulted in experiments in mapping fromaerial photography Like the mapping in Gallipolithese were largely unsuccessful The main problemwas locating precisely where the photographs hadbeen taken over a largely featureless desert Thebulk of the mapping for the Suez Canal defenseswas therefore carried out by triangulation andplane table survey (Maule 1919)

When the Egyptian Expeditionary Force (EEF)advanced across the Sinai Peninsula to engageTurkish forces in Palestine it moved into terri-tory without up-to-date mapping of an adequatescale Western Palestine had been mapped for thePalestine Exploration Fund (PEF) in the 1870s(Conder 1878 Conder and Kitchener 1881-83) ata scale of 163360 Although based on triangula-tion the detail had been surveyed using compassand cavalry sketching board (Close 1932) and wastherefore regarded as insufficiently accurate formodern warfare British military personnel hadsurveyed Southern Palestine just before the warunder the cover of a PEF expedition (Woolleyand Lawrence 1914) But even here the scale wastoo small (1 125000) for the kind of operationsbeing undertaken The British army was thereforeconfronted with the need to map areas beyond itsfront line for which no adequate base maps wereavailable

The first successful attempts at mapping fromaerial photographs were in t~e area aroundGaza (Gavish and Biger 1983) Here control wasprovided by the intersection of prominent pointsbehind Turkish lines Based on these points acontrolled mo~aic was created from with verticalaerial photogriphs and the mosaic was then usedto crcate the line maps of the planimetry Althoughcrude by later standards the map was consideredto be a significant improvement on anything thenavailable This encouraged the surveyors led byMajor W] Maule to embark upon an ambitiousplan to create a series of topographic maps at 140000 for areas of Palestine behind Turkish lines(Maule 1919) Strips of photography were flown

162

roughly parallel to the front line with additionalstrips of photography perpendicular to the frontflown at intervals to control the strips parallel tothe front Supplementary control was provided bytheodolite observations wherever possible Thesame basic arrangement pioneered in the map-ping of Gaza was followed for the series mappingHowever as the area mapped extended into thehills of Judea (the southern West Bank) it alsobecame necessary to provide some indication ofrelief Viewing the photography stereoscopicallyand form lining achieved this The nature of thetopography nearly horizontally bedded lime-stones that eroded into natural terraces madethis task relatively easySuccessfulas the mappingwas (Thomas 1919) as each new area came underBritish control mapping derived from air photoswas replaced bymapping made using conventionalground survey techniques

In a number of ways the mapping inMesopotamia can be regarded as the first exampleof true photogrammetric mapping using aerialphotography Unlike the mapping in Palestineit was produced as the end product not as aninterim solution to be replaced as soon as groundsurveys became possible And unlike the mappingon the Western Front it did not involve revision ofexisting mapping as no proper maps existed forthe area

Although developments in the use of air pho-tography had been watched with envy by thesurveyors in Mesopotamia (Survey of India 1925)until early 19I6 no airplanes had been availablefor that theater Some experience in the use ofaerial photography had been gained before thesiege of Kut-al-Amarah but it was the positionalfighting around Kut that emphasized the advan-tages of air survey Maps were required of areasbehind Turkish lines but the flat landscape meantthat surveyscould only be extended into no-mans-land This led to the first real attempt to createmaps from aerial photography As the first mapTC4 (TC are the initials of Tigris Corps theoriginal name of the force sent to Mesopotamia)has been discussed at length elsewhere (Collier1994 Pritchard 1952 Survey ofIndia 1925)

The surveyors working in Mesopotamia experi-mented with various ways of making maps fromaerial photographs drawing on the experience ofsurveyors on the Western Front and in Egypt Inthe end though they developed their own tech-nique which was well suited to local conditionsTheir technique involved creating semi-rectifiedphotographs using an enlarging lantern (Gunter1917) and then mosaicing the photographs using

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a triangulation scheme The mosaics were inkedup before the bromide prints were bleached out soas to leavejust the inked linework The importantpoint to note is that this technique was used formapping areas on both sides of the front line andwas therefore regarded as the final product Theflat floodplains of the Tigris and Euphrates Riverslent themselves to mapping using semi-controlledmosaics as there was an almost complete absenceof height to create displacement errors The map-ping of Mesopotamia from aerial photography seta precedent for post-war mapping in India

Flash Spotting and Sound RangingAs mentioned earlier the use of camouflage neces-sitated the development of techniques for targetlocation in particular the location of enemy gunpositions for counter-battery fire At the beginningof World War I guns were aimed by direct observa-tion of targets and the guns themselves were oftenpositioned in the open to improve their fields offire With the increased use of counter battery fireit became normal for guns to be dug in posi-tioned in gun pits and protected by sandbags Toprotect gun positions from enemy air observationthe gun pits were subsequently camouflaged withnetting which thwarted an accurate identificationof their positions

Flash spotting and sound ranging were devel-oped as means of tackling the problem of identify-ing and locating enemy gun positions Adopted byall the combatant nations flash spotting involvedintersecting the gun position by observing theflash as tht gun was fired Flash spotting requiredconsiderable organization as the observers had toensure that they were observing the same gun flashbut by carefully noting the times of the observa-tions it was possible to obtain accurate locationsof enemy guns Most armies established specialistunits for this purpose (Innes 1935 Chasseaud1999 Hinks 1919 Maule 1919)

Sound ranging was a more complex process inwhich the British and French enjoyed a technolog-ical lead over the Germans General Ludendorffthe German Chief of Staff who issued specialinstructions that precautions be taken to cam-ouflage the sound of guns directed the army tosecure an example of the British system (quotedin Hinks 1919) Based on a technical solutiondeveloped by Lucien Bull at the Institut Marey inParis the British system relied on an array of sixmicrophones spread over a 9-kilometer-long base-line situated about 4 km behind the front iine Themicrophones were connected to a galvanometer atthe hea~quarters As the sound of a gun reached

l1Jl 29 No3

each microphone in turn a signal was sent by wireto the galvanometer where it produced a distinc-tive trace on photographic film By measuring theseparation of the traces of the gun detected at eachmicrophone the distance and direction of the guncould be calculated Complex arrangements withmore than two microphones were needed becauseof uncertainty about the effect of wind speed andother factors on sound waves (see Innes 1935 andChasseaud 1999 for more technical details)

The German systemrelied on a fonvard observerand four other observers along a base of 10 to 15kilometers On hearing a gun firing the forwardobserver sent a signal by field telephone to theother observers who on receiving the signalstarted their stopwatches and noted the time inter-val before they heard the gun The times were thensent to group headquarters where the position ofthe gun was calculated An alternative and sim-pler method involved an observer noting the timeinterval between seeing a gun flash and hearingthe noise of the gun The greatest precision possi-ble with these techniques was about +200 meters

Non-military WartimeDevelopments to 1918

While the mapping efforts of the combatantnations were almost entirely directed towards thewar effort cartographers in the United States wereactively exploring civilian applications of pho-togrammetry The most important developmentwork was carried out at the US Geological Surveywhere James Bagley was developing a tri-Ienscamera and Fred Moffit was developing a trans-forming camera capable of handling the nega-tives produced by Bagleys camera (Committee onPhotographic Surveying 1921)

Developments to 1930In the period leading up to and including WorldWar I all the major powers followed broadlysimilar paths in developing photogrammetry Inmost countries attempts to develop instrumentalmethods complemented heavy reliance on graphi-cal and optical techniques for producing andrevising large-scale maps After the war a numberof countries took distinctly different paths withcontinental European countries generally puttingmost of their effort into instrumental techniqueswhile English-speaking countries focused ongraphical techniques Arguably until about 1930the approach adopted by the English-speaking

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countries was the most fruitful as the instrumentaltechniques developed in Europe could not com-pete in cost or efficiency with British and Americanmethods

After 1930 the relative efficiencies of the twoapproaches changed markedly The Americansrecognized the changed circumstances morequickly than their British counterparts and beganadopting instrumental methods by the mid 1930sIn Britain and by extension throughout the BritishEmpire instrumental photogrammetry was still inthe experimental phase at the outbreak of WorldWar 11in 1939

The immediate post-war-one period saw a flurryof papers extolling the merits of mapping fromaerial photography At the forefront of the cam-paign to get the methods accepted in Britain wasCapt H Hamshaw Thomas (1919 1920 1924)who drew heavily on his experiences in the Sinaiand Palestine Much of the effort to promote airsurvey was conducted in non-specialist journalssuch as the GeograPhicalJournal (Newcombe 1920)and even in the popular press MacLeod who hadserved in France and had become a firm advocateof air survey methods also produced a numberof papers as well as an important official publica-tion Mapping from Air Photographs issued by theWar Office (MacLeod 1920 but see also MacLeod1922 1923a 1923b)

Britain more than in any other country held aconservative attitude towards the new techniquesand this resistance found an influential championin Harold StJ LWinterbotham A self-proclaimedexpert on air survey (see Winterbotham 19291934) Winterbotham did much to impede theadoption of air survey both in Britain and throughhis role on the Colonial Survey Committee in thecolonial territories In contrast the Dominion ter-ritories were free to determine their own policiesAlthough Canada a pioneer in photogrammetryhad been joined by India in its use of these tech-niques before the outbreak of the First World Warother Dominion territories were slower in adopt-ing air survey Australia took the lead but localfactors either delayed or advanced the adoptionof photogrammetry in Dominion territories whichwere not compelled to follow the Colonial SurveyCommittees recommendation There is a strik-ing parallel between these largely autonomousterritories and the Dutch East Indies where thesurvey department was quick to adopt photogram-metry (van Roon 1925) but made no real progressat home in The Netherlands until after World WarII

In the British context Winterbothams reser-vations concerning the cost-effectiveness of air

i64

survey methods were probably justified at leastuntil the development of Reinhard Hugershoffsaerocartograph in 1926 (Blachut and Burkhardt1989) All the air survey instruments introducedbefore the aerocartograph were essentially ter-restrial plotters adapted in some way to copewith non-coplanar photography This made theinstruments difficult and slow to set up and theyusually required two men to carry out orienta-tion and plotting operations In a well mappedcountry such as Britain cumbersome machinescould not support map revision as economically asconventional ground surveyhere Winterbothamerred even in the 1920s was in extrapolatingfrom the British experience to the colonial terri-tories where the needs were very different On thepositive side agitation by Hamshaw Thomas andothers as well as the successful application of airsurvey techniques by the Survey of India led to thesetting up of the AirSurvey Committee Part ofthe responsibility of this committee was to adviseon air survey matters but it was also responsiblefor carrying out research

In the United States the promotion of airsurvey techniques wasundertaken by Moffit (1920)and other surveyors who had not been directlyinvolved in the war effort but had carried on withtheir civilian work in government mapping agen-cies Part of this promotion was carried out in non-specialist journals but unlike in Britain there waslittle need to convince the political leadership ofthe advantages of air surveyBycontrast there waslittle attempt to promote air survey in France orGermany other than in technical or professionaljournals Almost certainly this reflects the higherstatus of engineers and technical experts in thosecountries compared with Britain The UnitedStates probably fell somewhere between Britainand the continental powers but more towards thelatter

Survey and mapping activities in Austria suf-fered a severe setback with the breakup of theHabsburg Empire at the end of World War 1The Militargeographische Institut was disbandedin 1920 (Kretschmer 1991) and its personneldispersed amongst the successor states Whilethis disintegration had clear disadvantages forAustria survey departments in Poland Hungaryand Czechoslovakiagained a cadre of trained andexperienced personnel able to form the nucleusof new national survey organizations Despite eco-nomic hardship in the wakeof the warAustria hadbegun in 1928 to supplement existing 175000topographic mapping work focused on the moun-tainous areas using terrestrial photogrammetry

CartografJhy and GeograPhic informationScience

Graphical MethodsBecause of the extensive use of graphical methodsduring WorldWar I a large body of trained person-nel was available to implement these methods forpost-war mapping But the techniques developedthus far were either non-rigorous (for example theperspective grid) or suitable only for revising smallnumbers of features (the paper strip method)What was needed was a rigorous technique thatdid not require highly skilled workers

Bagley had sowed the seeds of a rigoroustechnique during his work with the PanoramicPhotoalidade (Bagley 1917) but Martin Hotine(1927) provided the theoretical and practicalbasis for a cost-effective mapping techniqueDescribed as a Simple Method of Surveying fromAir Photographs Hotines technique becameknown as the Arundel Method (after Arundelin southern England where the technique wasfirst used experimentally) or the radial-line tech-nique Hotine subsequently developed the methodof control extension using radial-line methods(Hotine 1929) and laid the foundations for muchof the medium-scale photogrammetric mappingcarried out in the English-speaking world over thenext 40 years The American development of slot-ted templets and radial intersectors expeditedthe process of aerotriangulation (see below) butit was Hotines theoretical work that made thesedevelopments possible

None of the countries using aerial photogra-phy for topographic mapping embraced it withgreater enthusiasm than India As noted earlierthe Survey of India had acquired two examplesof Thompsons stereo-plotter Kenneth Mason(1913 1927) had used the stereo-plotter in 1913in the Pamirs with considerable success but theexperience of the Survey of India in Mesopotamiaduring World War I wasdecisive in promoting airsurvey techniques in India In 1920 a series ofexperiments conducted at Agra demonstrated theutility of air survey methods for mapping flat areasin India (Lewis and Salmond 1920) Air surveyp~oved inefficient for one-inch-to-a-milemiddot map-pmg-the cost was roughly twice as much as forground surveys-but it was economical for largerscales An experiment in urban mapping was car-ried out but its results were inconclusive

Among developed countries the United Stateswas probably the most in need of the advantagesthat air survey offered post-war mapmakers Forall its great wealth America was poorly mappedby European standards Where most Europeancountries were at least mapped at medium scale(roughly 1100000 or larger) large tracts of the

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United States were not mapped even at small scaleIt was at just this small-scale range that air surveyseemed to offer the greatest advantages

The work carried out within the USCampGSand USGS prior to and during World War I hadprepared both agencies to take advantage of theemerging technology Starting in 1919 USCampGSused aerial photography for chart revision(Quillian 1919 Mattison 1919) and for wetlandsurveys (Mattison 1924 Graham 1924-25) Someproblems were encountered but the particularadvantages of air survey for mapping wetlands ledto the technique becoming the standard procedure(Landen 1952) In carrying out these surveys theUSCampGSused photography supplied by the Navyand the Army Air Corps it was the Air Corpsmulti-lens camera that established the cost-effec-tiveness of air survey (Reading 1927-28) Withinthe USGS a quadrangle in Michigan was mappedusing a conventional single-lens camera using airsurvey for the planimetry only (Thompson 1952)In 1924 a Section of Photographic Mapping wasestablished as part of the Topographic Branch atUSGS

Terrestrial photogrammetric work had beenundertaken in Russia as early as 1891 (Koch1963) but few significant additional developmentsoccurred before 1920 In 1924 the State TechnicalOffice of Aerial Photographic Survey was estab-lished Its first task was the creation of mosaics at110000 for comparison with plane table surveysThe results were considered sufficiently favorablefor mapping at 15000 based on 112000 pho-tography An ambitious program of aerial pho-tography initiated in 1925 led to the coverage ofmore than 4500000 km2 by 1940 In 1928 theCentral Scientific Research Institute for GeodesyPhotogrammetry and Cartography (ZNIlGAiK)was established to oversee development across thewhole field of mapping (Koch 1963)

Instrumental MethodsAt the end of World War I Germany and theAustro-Hungarian Empire had a clear advan-tage in the development and use of instrumen-tal photogrammetric methods While Germanycontinued to enjoy a considerable lead in thesetechniques the collapse of the Dual Monarchy andthe resultant breakup of the MilitargeographischeInstitut meant that Austria entered a period ofrelative decline Zeiss which had become theciear ieader in the design and man-ufacture ofphotogrammetric instruments not only pro-duced instruments designed by both von Ore and

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Pulfrich but employed several leading figures inphotogrammetry including Walter BauersfeldWilli Sander and Otto von Gruber This ensuredthat Zeiss was always at or near the forefront ofdevelopments in the field

During the 1920s most efforts were directedtoward overcoming the problem inherent in theearlier generation of photogrammetric plot-ters namely the need for the photographs tobe coplanar In 1926 Hugershoff designed anaerocartograph for use with both terrestrial andaerial photography The instrument which wasmanufactured by Heyde Company in Dresdentook advantage of the theoretical developmentsin orientation theory developed by Max Gasser(1923) and von Gruber (1924) The combinationof new orientation procedures and sophisticateddesign meant that Hugershoffs aerocartographcould be used for plotting and aerotriangulation(Blachut and Burkhardt 1989) Professional rivalryled von Gruber (1932) to dispute the original-ity of Hugershoffs design as he was also to dowith Heinrich Wilds instruments and the ideas ofFourcade

Zeiss had produced their stereoplanigraph(the Cl) in 1921 based on an earlier design ofBauersfeld However it was not until the pro-duction of the C4 in 1930 that Zeiss producedan instrument that could handle both terrestrialand aerial photography Some successful mappingfrom the earlier models was reported throughthe 1920s by the Reichsamt fur Landesaufnahmewhich had a C2 (Seidel 1928) and the GeodeticInstitute in Stuttgart which had a C3 (von Gruber1932) Most of the mapping was at 15000 butscales as small as ] 20000 are reported Even inGermany systematic mapping programs usingphotogrammetry were still the exception ratherthan the rule during the 1920s

In France the Service Geographique de lArmeehad been actively experimenting with instrumen-tal photogrammetry before World War I (Bonnet1920) and had also used the technique for someterrestrial work during the war France was thuswell placed at the end of the war to keep upwith the developments elsewhere in Europe TheService had decided that terrestrial photogram-metry was best suited to 120000 mapping in highmountain areas but considered the equipment toocumbersome and imprecise for reconnaissancesurveys (Service Geographique de lArmee 1912)In 1919 a start was made on mapping in Moroccousing panoramic aerial photographs (ServiceGeographique de IArmee ]936) but the main

166

drive in France was to develop an autonomouscapability in instrumental photogrammetry

Some equipment had been developed duringthe war notably the Chambre Claire Varon andthe Appareil de photorestitution Roussilhe aninstrument for partial rectification of cadastralplans (Blachut and Burkhardt 1989 ServiceGeographique de IArmee ]936) The mostimportant development came in 1922 when thefirst Georges Poivilliers instrument was built(Poivilliers 1922 Blachut and Burkhardt 1989)Poivilliers instruments were to provide the bulkof the photogrammetric capability of the Servicewith up to four different types in use at anyonetime (Institut Geographique National 1947)Other instruments were also used largely on anexperimental basis In the mid] 920s the stereor-estituteur Boucard was in use and in the I930s aGallus Ferber instrument was used experimentally(Service Geographique de lArmee 1938) withthe latter (Blachut and Burkhardt 1989) remain-ing in service until at least the 1940s (InstitutGeographique National 1947)

Italy had been actively engaged in photogram-metry in the nineteenth century with the work ofPorro but as Blachut and Burkhardt (1989) notethe Istituto Geografico Militare showed little inter-est in the technique until many years after Porrosdeath in 1875 The resurrection of Italian photo-grammetry was largely due to two men UmbertoNistri who designed aplotter in 1919for large-scaleplotting and Ermenegildo Santoni who producedhis first instrument the autoreductor in 1921 In1926 Nistri founded the firm Ottico MeccanicaItaliana (OMI) to produce his photogrammetricinstruments Nistris early instruments all useddirect optical projection while Santonis instru-ments all used mechanical projection The IstitutoGeografico Militare was middotequipped with Santoniinstruments which it used for mapping at 125000and 110000 The Societa Anonima RilevamentiAerofotogrammetrici (SARA)on the other handused Nistri instruments largely for topographicmapptng outside Italy but also for cadastral map-ping within the country

Photogrammetry had been used in Switzerlandfor engineering surveys in the nineteenth centuryyet there had been no systematic attempt to carryout topographic mapping using the techniqueThe history of mapping in Switzerland betweenthe two world wars is largely a history of the WildHeerbrugg Company Set up in 1921 the com-pany produced its first phototheodolite in 1922and its first photogrammetric plotter the Alstereo-autograph in 1923 Its first major contribu-

Cartography and Geographic Information Science

tion to surveying came with the production of theT2 theodolite in 1924 The revolutionary design ofthis instrument-replacing engraved metal circleswith glass versions provided more accurate read-ings and better illumination-led to considerableexcitement in scientific and survey circles By thelate 1920s Wild was engaged in serial productionof the T2 and T3 theodolites the P3 phototheodo-lite and the A2 autograph which had replaced theAI In addition the Cl C2 and C3 aerial cam-eras were also in production In the space of onlyeight years Wild had become a major player in thesurvey world a position enhanced further duringthe 1930s

By the late 1920s the Landestopographie inSwitzerland had gained considerable experiencewith Wild instruments for both terrestrial andaerial surveys (Schneider 1929) Topographicmaps were produced from terrestrial photographyat 125000 while aerial photography wasused for110000 mapping (Schneider 1929 Harry 1971)

In the United States in addition to usinggraphical techniques the USGS started to inves-tigate instrumental methods In 1921 it obtaineda stereoautograph from Germany for evalua-tion but restricted the use of the instrument toplotting from terrestrial photography and notable to produce maps economically (Thompson1952) In 1927 the Geological Survey acquired theHugershoff aerocartograph the first automaticstereo-plotter used by an American governmentmapping agency (Thompson 1952) Thomas PPendleton laid down guidelines for mapping fromaerial photography within the USGS in Bulletin788-F Map Compilation from Aerial PhotograPhsissued as part of the Topographic Instructions of theUnited States Geological Survey (Pendleton 1928)Given the rapid developments in radial-line meth-ods (eg Hotine 1927) the timing of Pendletonswork was a bit unfortunate as he asserted thatradial-line techniques were really only suited foruse with multi-lens photography because therelatively short radial lines that could be drawnon single-lens photographs could not give the bestresults (Pendleton 1928 p 409)

In Britain research work carried out by the AirSurvey Committee focused on simple methods butthe Committee did not entirely ignore instrumen-tal techniques MacLeods wartime work with rec-tifiers was developed and more importantly theideas of Fourcade (l926a 1926b 1926c 1926d)on the theory and use of stereogoniometers forphotogrammetric plotters were taken up In 1926the Committee commissioned the constructionof an instrument along the lines proposed by

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Fourcade and the instrument was delivered in1928 0ar Office 1935 Hotine 1931)

In India success with non-instrumental tech-niques did not distract the Survey from instrumen-tal techniques they had helped pioneel- Mappingofficials followed developments taking place inEurope and in 1926 Mason (1927) carried outa survey in the Shaksgam using a Wild photo-theodolite and plotted the results in Switzerlandusing an autograph in the Topographical Instituteat Flums

CamerasThe tri-lens camera developed by Bagley was usedby the USGS in mapping for aeronautical chartsThis program wasjointly organized with the Corpsof Engineers and the Air Service (Committeeon Photographic Surveying 1921) and providedvaluable experience in civil applications In 1920programs with the tri-lens camera were also under-taken in Santo Domingo and Haiti

The Corps of Engineers became involved inphotogrammetric methods in 1920 when Bagleywas assigned to cooperate with the Army AirCorps in carrying out tests on aerial photographyfor topographic mapping Initially the trials usedBagleys tri-lens camera but he went on to developthe five lens T-3Acamera which was to remain thestandard mapping camera of the US Army until1940 (Landen 1952) The War Department issuedtraining regulations for mapping from aerialphotography in 1923 however the techniques dis-cussed in the regulations were largely those refinedduring World War 1

The 1930sBy the late 1920s photogrammetry had becomea cost-effective alternative to some traditionalground surveys Yet expensive photogrammetricplotting instruments and labor-intensive graphicalplotting meant that photogrammetry still lackeda decisive advantage over ground survey Duringthe 1930s a number of innovations were to swingthe balance decisivelyin favor of photogrammetricmethods

Progress was slowed if not stopped by the reces-sion that started in 1929 Some measure of theimpact can be gauged from job cutbacks at WildHeerbrugg In 1930 before the recession had amarked affect on Europe the workforce stood at260 but by 1933 the number ofjobs had droppedto 125This was the direct consequence of the deci-sions taken to retrench mapping projects as well as

167

capital programs Nearly all the annual reports forthe early 1930s mention the financial constraintsunder which organizations had to work In theUnited States some of these problems were offsetby appropriations under the Emergency Reliefand Construction Act (US Coast and GeodeticSurvey 1933) Moreover the New Deal initiated awide range of programs in which photogrammetrywas to playa major role By contrast problems inthe colonial territories were if anything worsethan in Europe and North America The declinein industrial activity in developed countries ledto a collapse in demand for raw materials fromthe colonies and as this was the main source ofgovernment revenue they could no longer pay forsurvey work Annual reports from most colonialsurvey departments make reference to a lack ofresources to meet the need for mapping Howevel~by the late 1930s as a result of rearmament inEurope governments allocated more money tosurvey organizations

Survey organizations were eager to adopt newtechniques in routine mapping programs but thepressures within governments to deal with massunemployment probably helped to promote theuse of labor-intensive methods in survey at theexpense of investment in technology Certainlyorganizations such as the Tennessee ValleyAuthority (TVA) the Agriculture AdjustmentAdministration and the Soil Conservation Servicein the United States were all heavily dependenton such labor-intensive techniques and did muchto develop them as standard mapping methodsMoreover organizations such as the USGS andthe TVA also played a role in the developmentinstrumental methods such as multiplex All ofthis was to be of vital importance to the hugephotogrammetric mapping programs that wereto emerge during World War II The scale of theseprograms would have been inconceivable withoutthe trained body of photogrammetrists developedduring the 1930s (Landen 1952)

Within the British colonial territories the conser-vative element that had inhibited the developmentof photogrammetric methods through the 1920scontinued to delay adoption of photogrammetryuntil after World War II-with some illuminatingexceptions Cyprus is the only known example ofa local survey department attempting to carry outphotogrammetric work Aerial photography wastaken in 1936 but delays in obtaining groundcontrol meant that no use was made of the pho-tography before all normal work was suspended atthe outbreak of war In all the other colonies wherephotogrammetry was attempted private survey

168

companies carried out the work The earliestexample of the involvement of private air surveycompanies had been in 1927 in the mapping ofthe Anglo-Belgian boundary in the Copper Beltregion of Northern Rhodesia (Colonial SurveyCommittee 1928) Private air survey companieswere also active in Uganda Tanganyika andSouthern Rhodesia but in all cases this was surveywork for specific development projects ratherthan routine mapping (War Office 1935) Therewere discussions about the use of photogramme-try in Sierra Leone where the Aircraft OperatingCompany of South Africa proposed to revise the162500 topographic maps for pound150000 includ-ing the cost of providing ground control but thework was never carried out due to financial con-straints and the outbreak of World War II Therewere also discussions about air survey in Jamaicaand the Gold Coast but nothing came of theseprojects until after World War II It is clear fromthe literature and correspondence of the time thatthe private air survey companies were lobbyingindividual colonial governments as well as theBritish Government to adopt air survey but theColonial Survey Committee under Winterbothamwas equally forceful in its resistance to changelargely on grounds of cost (see in particularWinterbotham 1920 1921 1929 1934 1936Hemming 1933)

Increasing recognition that war with Germanywas inevitable led to a significant change in theBritish establishments attitude towards the use ofair survey In part this change reflected the retire-ment of Winterbotham in 1935 and his replace-ment as Director General of the Ordnance Surveyby MacLeod who was alwaysa warm supporter ofair survey MacLeod had followed Winterbothamfirst as Director of Military Surveys and then atthe Ordnance Surveyand in each case he playeda major role in introducing the use of photogram-metry (Clough 1952)

Advances in InstrumentationThe late 1920s had seen the design and produc-tion of the first practical plotting machines for usewith aerial photography The experience provideda foundation for the introduction during the1930s of designs that were to be the mainstaysof topographic mapping The Zeiss C4 had beenintroduced in 1930 (Burnside 1993)AsThompson(1966) notes the C4 and the superseding C5(introduced in 1935 with improved illumination)were with the Wild A5 (launched in 1937) practi-cally the only universal instruments on the marketin the 1930s Universal instruments designed to

CartograPhy and GeograPhic Information Science

handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

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graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

169

Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

170

world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

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Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

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construct original mapping took place during theGallipoli campaign (Dowson 1921) Not very suc-cessful these attempts demonstrated the problemsassociated with the non-stereoscopic use of aerialphotography as when troops were sent to occupypositions identified monoscopically as trenchesor ditches but which turned out to be shallowscrapes that afforded no shelter from enemy fireAttempts to create original mapping ceased whenmodern Turkish maps of the area were capturedand revised

In Egypt the Turkish threat to the Suez Canalalso resulted in experiments in mapping fromaerial photography Like the mapping in Gallipolithese were largely unsuccessful The main problemwas locating precisely where the photographs hadbeen taken over a largely featureless desert Thebulk of the mapping for the Suez Canal defenseswas therefore carried out by triangulation andplane table survey (Maule 1919)

When the Egyptian Expeditionary Force (EEF)advanced across the Sinai Peninsula to engageTurkish forces in Palestine it moved into terri-tory without up-to-date mapping of an adequatescale Western Palestine had been mapped for thePalestine Exploration Fund (PEF) in the 1870s(Conder 1878 Conder and Kitchener 1881-83) ata scale of 163360 Although based on triangula-tion the detail had been surveyed using compassand cavalry sketching board (Close 1932) and wastherefore regarded as insufficiently accurate formodern warfare British military personnel hadsurveyed Southern Palestine just before the warunder the cover of a PEF expedition (Woolleyand Lawrence 1914) But even here the scale wastoo small (1 125000) for the kind of operationsbeing undertaken The British army was thereforeconfronted with the need to map areas beyond itsfront line for which no adequate base maps wereavailable

The first successful attempts at mapping fromaerial photographs were in t~e area aroundGaza (Gavish and Biger 1983) Here control wasprovided by the intersection of prominent pointsbehind Turkish lines Based on these points acontrolled mo~aic was created from with verticalaerial photogriphs and the mosaic was then usedto crcate the line maps of the planimetry Althoughcrude by later standards the map was consideredto be a significant improvement on anything thenavailable This encouraged the surveyors led byMajor W] Maule to embark upon an ambitiousplan to create a series of topographic maps at 140000 for areas of Palestine behind Turkish lines(Maule 1919) Strips of photography were flown

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roughly parallel to the front line with additionalstrips of photography perpendicular to the frontflown at intervals to control the strips parallel tothe front Supplementary control was provided bytheodolite observations wherever possible Thesame basic arrangement pioneered in the map-ping of Gaza was followed for the series mappingHowever as the area mapped extended into thehills of Judea (the southern West Bank) it alsobecame necessary to provide some indication ofrelief Viewing the photography stereoscopicallyand form lining achieved this The nature of thetopography nearly horizontally bedded lime-stones that eroded into natural terraces madethis task relatively easySuccessfulas the mappingwas (Thomas 1919) as each new area came underBritish control mapping derived from air photoswas replaced bymapping made using conventionalground survey techniques

In a number of ways the mapping inMesopotamia can be regarded as the first exampleof true photogrammetric mapping using aerialphotography Unlike the mapping in Palestineit was produced as the end product not as aninterim solution to be replaced as soon as groundsurveys became possible And unlike the mappingon the Western Front it did not involve revision ofexisting mapping as no proper maps existed forthe area

Although developments in the use of air pho-tography had been watched with envy by thesurveyors in Mesopotamia (Survey of India 1925)until early 19I6 no airplanes had been availablefor that theater Some experience in the use ofaerial photography had been gained before thesiege of Kut-al-Amarah but it was the positionalfighting around Kut that emphasized the advan-tages of air survey Maps were required of areasbehind Turkish lines but the flat landscape meantthat surveyscould only be extended into no-mans-land This led to the first real attempt to createmaps from aerial photography As the first mapTC4 (TC are the initials of Tigris Corps theoriginal name of the force sent to Mesopotamia)has been discussed at length elsewhere (Collier1994 Pritchard 1952 Survey ofIndia 1925)

The surveyors working in Mesopotamia experi-mented with various ways of making maps fromaerial photographs drawing on the experience ofsurveyors on the Western Front and in Egypt Inthe end though they developed their own tech-nique which was well suited to local conditionsTheir technique involved creating semi-rectifiedphotographs using an enlarging lantern (Gunter1917) and then mosaicing the photographs using

Cartography and Geographic Information Science

a triangulation scheme The mosaics were inkedup before the bromide prints were bleached out soas to leavejust the inked linework The importantpoint to note is that this technique was used formapping areas on both sides of the front line andwas therefore regarded as the final product Theflat floodplains of the Tigris and Euphrates Riverslent themselves to mapping using semi-controlledmosaics as there was an almost complete absenceof height to create displacement errors The map-ping of Mesopotamia from aerial photography seta precedent for post-war mapping in India

Flash Spotting and Sound RangingAs mentioned earlier the use of camouflage neces-sitated the development of techniques for targetlocation in particular the location of enemy gunpositions for counter-battery fire At the beginningof World War I guns were aimed by direct observa-tion of targets and the guns themselves were oftenpositioned in the open to improve their fields offire With the increased use of counter battery fireit became normal for guns to be dug in posi-tioned in gun pits and protected by sandbags Toprotect gun positions from enemy air observationthe gun pits were subsequently camouflaged withnetting which thwarted an accurate identificationof their positions

Flash spotting and sound ranging were devel-oped as means of tackling the problem of identify-ing and locating enemy gun positions Adopted byall the combatant nations flash spotting involvedintersecting the gun position by observing theflash as tht gun was fired Flash spotting requiredconsiderable organization as the observers had toensure that they were observing the same gun flashbut by carefully noting the times of the observa-tions it was possible to obtain accurate locationsof enemy guns Most armies established specialistunits for this purpose (Innes 1935 Chasseaud1999 Hinks 1919 Maule 1919)

Sound ranging was a more complex process inwhich the British and French enjoyed a technolog-ical lead over the Germans General Ludendorffthe German Chief of Staff who issued specialinstructions that precautions be taken to cam-ouflage the sound of guns directed the army tosecure an example of the British system (quotedin Hinks 1919) Based on a technical solutiondeveloped by Lucien Bull at the Institut Marey inParis the British system relied on an array of sixmicrophones spread over a 9-kilometer-long base-line situated about 4 km behind the front iine Themicrophones were connected to a galvanometer atthe hea~quarters As the sound of a gun reached

l1Jl 29 No3

each microphone in turn a signal was sent by wireto the galvanometer where it produced a distinc-tive trace on photographic film By measuring theseparation of the traces of the gun detected at eachmicrophone the distance and direction of the guncould be calculated Complex arrangements withmore than two microphones were needed becauseof uncertainty about the effect of wind speed andother factors on sound waves (see Innes 1935 andChasseaud 1999 for more technical details)

The German systemrelied on a fonvard observerand four other observers along a base of 10 to 15kilometers On hearing a gun firing the forwardobserver sent a signal by field telephone to theother observers who on receiving the signalstarted their stopwatches and noted the time inter-val before they heard the gun The times were thensent to group headquarters where the position ofthe gun was calculated An alternative and sim-pler method involved an observer noting the timeinterval between seeing a gun flash and hearingthe noise of the gun The greatest precision possi-ble with these techniques was about +200 meters

Non-military WartimeDevelopments to 1918

While the mapping efforts of the combatantnations were almost entirely directed towards thewar effort cartographers in the United States wereactively exploring civilian applications of pho-togrammetry The most important developmentwork was carried out at the US Geological Surveywhere James Bagley was developing a tri-Ienscamera and Fred Moffit was developing a trans-forming camera capable of handling the nega-tives produced by Bagleys camera (Committee onPhotographic Surveying 1921)

Developments to 1930In the period leading up to and including WorldWar I all the major powers followed broadlysimilar paths in developing photogrammetry Inmost countries attempts to develop instrumentalmethods complemented heavy reliance on graphi-cal and optical techniques for producing andrevising large-scale maps After the war a numberof countries took distinctly different paths withcontinental European countries generally puttingmost of their effort into instrumental techniqueswhile English-speaking countries focused ongraphical techniques Arguably until about 1930the approach adopted by the English-speaking

163

countries was the most fruitful as the instrumentaltechniques developed in Europe could not com-pete in cost or efficiency with British and Americanmethods

After 1930 the relative efficiencies of the twoapproaches changed markedly The Americansrecognized the changed circumstances morequickly than their British counterparts and beganadopting instrumental methods by the mid 1930sIn Britain and by extension throughout the BritishEmpire instrumental photogrammetry was still inthe experimental phase at the outbreak of WorldWar 11in 1939

The immediate post-war-one period saw a flurryof papers extolling the merits of mapping fromaerial photography At the forefront of the cam-paign to get the methods accepted in Britain wasCapt H Hamshaw Thomas (1919 1920 1924)who drew heavily on his experiences in the Sinaiand Palestine Much of the effort to promote airsurvey was conducted in non-specialist journalssuch as the GeograPhicalJournal (Newcombe 1920)and even in the popular press MacLeod who hadserved in France and had become a firm advocateof air survey methods also produced a numberof papers as well as an important official publica-tion Mapping from Air Photographs issued by theWar Office (MacLeod 1920 but see also MacLeod1922 1923a 1923b)

Britain more than in any other country held aconservative attitude towards the new techniquesand this resistance found an influential championin Harold StJ LWinterbotham A self-proclaimedexpert on air survey (see Winterbotham 19291934) Winterbotham did much to impede theadoption of air survey both in Britain and throughhis role on the Colonial Survey Committee in thecolonial territories In contrast the Dominion ter-ritories were free to determine their own policiesAlthough Canada a pioneer in photogrammetryhad been joined by India in its use of these tech-niques before the outbreak of the First World Warother Dominion territories were slower in adopt-ing air survey Australia took the lead but localfactors either delayed or advanced the adoptionof photogrammetry in Dominion territories whichwere not compelled to follow the Colonial SurveyCommittees recommendation There is a strik-ing parallel between these largely autonomousterritories and the Dutch East Indies where thesurvey department was quick to adopt photogram-metry (van Roon 1925) but made no real progressat home in The Netherlands until after World WarII

In the British context Winterbothams reser-vations concerning the cost-effectiveness of air

i64

survey methods were probably justified at leastuntil the development of Reinhard Hugershoffsaerocartograph in 1926 (Blachut and Burkhardt1989) All the air survey instruments introducedbefore the aerocartograph were essentially ter-restrial plotters adapted in some way to copewith non-coplanar photography This made theinstruments difficult and slow to set up and theyusually required two men to carry out orienta-tion and plotting operations In a well mappedcountry such as Britain cumbersome machinescould not support map revision as economically asconventional ground surveyhere Winterbothamerred even in the 1920s was in extrapolatingfrom the British experience to the colonial terri-tories where the needs were very different On thepositive side agitation by Hamshaw Thomas andothers as well as the successful application of airsurvey techniques by the Survey of India led to thesetting up of the AirSurvey Committee Part ofthe responsibility of this committee was to adviseon air survey matters but it was also responsiblefor carrying out research

In the United States the promotion of airsurvey techniques wasundertaken by Moffit (1920)and other surveyors who had not been directlyinvolved in the war effort but had carried on withtheir civilian work in government mapping agen-cies Part of this promotion was carried out in non-specialist journals but unlike in Britain there waslittle need to convince the political leadership ofthe advantages of air surveyBycontrast there waslittle attempt to promote air survey in France orGermany other than in technical or professionaljournals Almost certainly this reflects the higherstatus of engineers and technical experts in thosecountries compared with Britain The UnitedStates probably fell somewhere between Britainand the continental powers but more towards thelatter

Survey and mapping activities in Austria suf-fered a severe setback with the breakup of theHabsburg Empire at the end of World War 1The Militargeographische Institut was disbandedin 1920 (Kretschmer 1991) and its personneldispersed amongst the successor states Whilethis disintegration had clear disadvantages forAustria survey departments in Poland Hungaryand Czechoslovakiagained a cadre of trained andexperienced personnel able to form the nucleusof new national survey organizations Despite eco-nomic hardship in the wakeof the warAustria hadbegun in 1928 to supplement existing 175000topographic mapping work focused on the moun-tainous areas using terrestrial photogrammetry

CartografJhy and GeograPhic informationScience

Graphical MethodsBecause of the extensive use of graphical methodsduring WorldWar I a large body of trained person-nel was available to implement these methods forpost-war mapping But the techniques developedthus far were either non-rigorous (for example theperspective grid) or suitable only for revising smallnumbers of features (the paper strip method)What was needed was a rigorous technique thatdid not require highly skilled workers

Bagley had sowed the seeds of a rigoroustechnique during his work with the PanoramicPhotoalidade (Bagley 1917) but Martin Hotine(1927) provided the theoretical and practicalbasis for a cost-effective mapping techniqueDescribed as a Simple Method of Surveying fromAir Photographs Hotines technique becameknown as the Arundel Method (after Arundelin southern England where the technique wasfirst used experimentally) or the radial-line tech-nique Hotine subsequently developed the methodof control extension using radial-line methods(Hotine 1929) and laid the foundations for muchof the medium-scale photogrammetric mappingcarried out in the English-speaking world over thenext 40 years The American development of slot-ted templets and radial intersectors expeditedthe process of aerotriangulation (see below) butit was Hotines theoretical work that made thesedevelopments possible

None of the countries using aerial photogra-phy for topographic mapping embraced it withgreater enthusiasm than India As noted earlierthe Survey of India had acquired two examplesof Thompsons stereo-plotter Kenneth Mason(1913 1927) had used the stereo-plotter in 1913in the Pamirs with considerable success but theexperience of the Survey of India in Mesopotamiaduring World War I wasdecisive in promoting airsurvey techniques in India In 1920 a series ofexperiments conducted at Agra demonstrated theutility of air survey methods for mapping flat areasin India (Lewis and Salmond 1920) Air surveyp~oved inefficient for one-inch-to-a-milemiddot map-pmg-the cost was roughly twice as much as forground surveys-but it was economical for largerscales An experiment in urban mapping was car-ried out but its results were inconclusive

Among developed countries the United Stateswas probably the most in need of the advantagesthat air survey offered post-war mapmakers Forall its great wealth America was poorly mappedby European standards Where most Europeancountries were at least mapped at medium scale(roughly 1100000 or larger) large tracts of the

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United States were not mapped even at small scaleIt was at just this small-scale range that air surveyseemed to offer the greatest advantages

The work carried out within the USCampGSand USGS prior to and during World War I hadprepared both agencies to take advantage of theemerging technology Starting in 1919 USCampGSused aerial photography for chart revision(Quillian 1919 Mattison 1919) and for wetlandsurveys (Mattison 1924 Graham 1924-25) Someproblems were encountered but the particularadvantages of air survey for mapping wetlands ledto the technique becoming the standard procedure(Landen 1952) In carrying out these surveys theUSCampGSused photography supplied by the Navyand the Army Air Corps it was the Air Corpsmulti-lens camera that established the cost-effec-tiveness of air survey (Reading 1927-28) Withinthe USGS a quadrangle in Michigan was mappedusing a conventional single-lens camera using airsurvey for the planimetry only (Thompson 1952)In 1924 a Section of Photographic Mapping wasestablished as part of the Topographic Branch atUSGS

Terrestrial photogrammetric work had beenundertaken in Russia as early as 1891 (Koch1963) but few significant additional developmentsoccurred before 1920 In 1924 the State TechnicalOffice of Aerial Photographic Survey was estab-lished Its first task was the creation of mosaics at110000 for comparison with plane table surveysThe results were considered sufficiently favorablefor mapping at 15000 based on 112000 pho-tography An ambitious program of aerial pho-tography initiated in 1925 led to the coverage ofmore than 4500000 km2 by 1940 In 1928 theCentral Scientific Research Institute for GeodesyPhotogrammetry and Cartography (ZNIlGAiK)was established to oversee development across thewhole field of mapping (Koch 1963)

Instrumental MethodsAt the end of World War I Germany and theAustro-Hungarian Empire had a clear advan-tage in the development and use of instrumen-tal photogrammetric methods While Germanycontinued to enjoy a considerable lead in thesetechniques the collapse of the Dual Monarchy andthe resultant breakup of the MilitargeographischeInstitut meant that Austria entered a period ofrelative decline Zeiss which had become theciear ieader in the design and man-ufacture ofphotogrammetric instruments not only pro-duced instruments designed by both von Ore and

165

Pulfrich but employed several leading figures inphotogrammetry including Walter BauersfeldWilli Sander and Otto von Gruber This ensuredthat Zeiss was always at or near the forefront ofdevelopments in the field

During the 1920s most efforts were directedtoward overcoming the problem inherent in theearlier generation of photogrammetric plot-ters namely the need for the photographs tobe coplanar In 1926 Hugershoff designed anaerocartograph for use with both terrestrial andaerial photography The instrument which wasmanufactured by Heyde Company in Dresdentook advantage of the theoretical developmentsin orientation theory developed by Max Gasser(1923) and von Gruber (1924) The combinationof new orientation procedures and sophisticateddesign meant that Hugershoffs aerocartographcould be used for plotting and aerotriangulation(Blachut and Burkhardt 1989) Professional rivalryled von Gruber (1932) to dispute the original-ity of Hugershoffs design as he was also to dowith Heinrich Wilds instruments and the ideas ofFourcade

Zeiss had produced their stereoplanigraph(the Cl) in 1921 based on an earlier design ofBauersfeld However it was not until the pro-duction of the C4 in 1930 that Zeiss producedan instrument that could handle both terrestrialand aerial photography Some successful mappingfrom the earlier models was reported throughthe 1920s by the Reichsamt fur Landesaufnahmewhich had a C2 (Seidel 1928) and the GeodeticInstitute in Stuttgart which had a C3 (von Gruber1932) Most of the mapping was at 15000 butscales as small as ] 20000 are reported Even inGermany systematic mapping programs usingphotogrammetry were still the exception ratherthan the rule during the 1920s

In France the Service Geographique de lArmeehad been actively experimenting with instrumen-tal photogrammetry before World War I (Bonnet1920) and had also used the technique for someterrestrial work during the war France was thuswell placed at the end of the war to keep upwith the developments elsewhere in Europe TheService had decided that terrestrial photogram-metry was best suited to 120000 mapping in highmountain areas but considered the equipment toocumbersome and imprecise for reconnaissancesurveys (Service Geographique de lArmee 1912)In 1919 a start was made on mapping in Moroccousing panoramic aerial photographs (ServiceGeographique de IArmee ]936) but the main

166

drive in France was to develop an autonomouscapability in instrumental photogrammetry

Some equipment had been developed duringthe war notably the Chambre Claire Varon andthe Appareil de photorestitution Roussilhe aninstrument for partial rectification of cadastralplans (Blachut and Burkhardt 1989 ServiceGeographique de IArmee ]936) The mostimportant development came in 1922 when thefirst Georges Poivilliers instrument was built(Poivilliers 1922 Blachut and Burkhardt 1989)Poivilliers instruments were to provide the bulkof the photogrammetric capability of the Servicewith up to four different types in use at anyonetime (Institut Geographique National 1947)Other instruments were also used largely on anexperimental basis In the mid] 920s the stereor-estituteur Boucard was in use and in the I930s aGallus Ferber instrument was used experimentally(Service Geographique de lArmee 1938) withthe latter (Blachut and Burkhardt 1989) remain-ing in service until at least the 1940s (InstitutGeographique National 1947)

Italy had been actively engaged in photogram-metry in the nineteenth century with the work ofPorro but as Blachut and Burkhardt (1989) notethe Istituto Geografico Militare showed little inter-est in the technique until many years after Porrosdeath in 1875 The resurrection of Italian photo-grammetry was largely due to two men UmbertoNistri who designed aplotter in 1919for large-scaleplotting and Ermenegildo Santoni who producedhis first instrument the autoreductor in 1921 In1926 Nistri founded the firm Ottico MeccanicaItaliana (OMI) to produce his photogrammetricinstruments Nistris early instruments all useddirect optical projection while Santonis instru-ments all used mechanical projection The IstitutoGeografico Militare was middotequipped with Santoniinstruments which it used for mapping at 125000and 110000 The Societa Anonima RilevamentiAerofotogrammetrici (SARA)on the other handused Nistri instruments largely for topographicmapptng outside Italy but also for cadastral map-ping within the country

Photogrammetry had been used in Switzerlandfor engineering surveys in the nineteenth centuryyet there had been no systematic attempt to carryout topographic mapping using the techniqueThe history of mapping in Switzerland betweenthe two world wars is largely a history of the WildHeerbrugg Company Set up in 1921 the com-pany produced its first phototheodolite in 1922and its first photogrammetric plotter the Alstereo-autograph in 1923 Its first major contribu-

Cartography and Geographic Information Science

tion to surveying came with the production of theT2 theodolite in 1924 The revolutionary design ofthis instrument-replacing engraved metal circleswith glass versions provided more accurate read-ings and better illumination-led to considerableexcitement in scientific and survey circles By thelate 1920s Wild was engaged in serial productionof the T2 and T3 theodolites the P3 phototheodo-lite and the A2 autograph which had replaced theAI In addition the Cl C2 and C3 aerial cam-eras were also in production In the space of onlyeight years Wild had become a major player in thesurvey world a position enhanced further duringthe 1930s

By the late 1920s the Landestopographie inSwitzerland had gained considerable experiencewith Wild instruments for both terrestrial andaerial surveys (Schneider 1929) Topographicmaps were produced from terrestrial photographyat 125000 while aerial photography wasused for110000 mapping (Schneider 1929 Harry 1971)

In the United States in addition to usinggraphical techniques the USGS started to inves-tigate instrumental methods In 1921 it obtaineda stereoautograph from Germany for evalua-tion but restricted the use of the instrument toplotting from terrestrial photography and notable to produce maps economically (Thompson1952) In 1927 the Geological Survey acquired theHugershoff aerocartograph the first automaticstereo-plotter used by an American governmentmapping agency (Thompson 1952) Thomas PPendleton laid down guidelines for mapping fromaerial photography within the USGS in Bulletin788-F Map Compilation from Aerial PhotograPhsissued as part of the Topographic Instructions of theUnited States Geological Survey (Pendleton 1928)Given the rapid developments in radial-line meth-ods (eg Hotine 1927) the timing of Pendletonswork was a bit unfortunate as he asserted thatradial-line techniques were really only suited foruse with multi-lens photography because therelatively short radial lines that could be drawnon single-lens photographs could not give the bestresults (Pendleton 1928 p 409)

In Britain research work carried out by the AirSurvey Committee focused on simple methods butthe Committee did not entirely ignore instrumen-tal techniques MacLeods wartime work with rec-tifiers was developed and more importantly theideas of Fourcade (l926a 1926b 1926c 1926d)on the theory and use of stereogoniometers forphotogrammetric plotters were taken up In 1926the Committee commissioned the constructionof an instrument along the lines proposed by

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Fourcade and the instrument was delivered in1928 0ar Office 1935 Hotine 1931)

In India success with non-instrumental tech-niques did not distract the Survey from instrumen-tal techniques they had helped pioneel- Mappingofficials followed developments taking place inEurope and in 1926 Mason (1927) carried outa survey in the Shaksgam using a Wild photo-theodolite and plotted the results in Switzerlandusing an autograph in the Topographical Instituteat Flums

CamerasThe tri-lens camera developed by Bagley was usedby the USGS in mapping for aeronautical chartsThis program wasjointly organized with the Corpsof Engineers and the Air Service (Committeeon Photographic Surveying 1921) and providedvaluable experience in civil applications In 1920programs with the tri-lens camera were also under-taken in Santo Domingo and Haiti

The Corps of Engineers became involved inphotogrammetric methods in 1920 when Bagleywas assigned to cooperate with the Army AirCorps in carrying out tests on aerial photographyfor topographic mapping Initially the trials usedBagleys tri-lens camera but he went on to developthe five lens T-3Acamera which was to remain thestandard mapping camera of the US Army until1940 (Landen 1952) The War Department issuedtraining regulations for mapping from aerialphotography in 1923 however the techniques dis-cussed in the regulations were largely those refinedduring World War 1

The 1930sBy the late 1920s photogrammetry had becomea cost-effective alternative to some traditionalground surveys Yet expensive photogrammetricplotting instruments and labor-intensive graphicalplotting meant that photogrammetry still lackeda decisive advantage over ground survey Duringthe 1930s a number of innovations were to swingthe balance decisivelyin favor of photogrammetricmethods

Progress was slowed if not stopped by the reces-sion that started in 1929 Some measure of theimpact can be gauged from job cutbacks at WildHeerbrugg In 1930 before the recession had amarked affect on Europe the workforce stood at260 but by 1933 the number ofjobs had droppedto 125This was the direct consequence of the deci-sions taken to retrench mapping projects as well as

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capital programs Nearly all the annual reports forthe early 1930s mention the financial constraintsunder which organizations had to work In theUnited States some of these problems were offsetby appropriations under the Emergency Reliefand Construction Act (US Coast and GeodeticSurvey 1933) Moreover the New Deal initiated awide range of programs in which photogrammetrywas to playa major role By contrast problems inthe colonial territories were if anything worsethan in Europe and North America The declinein industrial activity in developed countries ledto a collapse in demand for raw materials fromthe colonies and as this was the main source ofgovernment revenue they could no longer pay forsurvey work Annual reports from most colonialsurvey departments make reference to a lack ofresources to meet the need for mapping Howevel~by the late 1930s as a result of rearmament inEurope governments allocated more money tosurvey organizations

Survey organizations were eager to adopt newtechniques in routine mapping programs but thepressures within governments to deal with massunemployment probably helped to promote theuse of labor-intensive methods in survey at theexpense of investment in technology Certainlyorganizations such as the Tennessee ValleyAuthority (TVA) the Agriculture AdjustmentAdministration and the Soil Conservation Servicein the United States were all heavily dependenton such labor-intensive techniques and did muchto develop them as standard mapping methodsMoreover organizations such as the USGS andthe TVA also played a role in the developmentinstrumental methods such as multiplex All ofthis was to be of vital importance to the hugephotogrammetric mapping programs that wereto emerge during World War II The scale of theseprograms would have been inconceivable withoutthe trained body of photogrammetrists developedduring the 1930s (Landen 1952)

Within the British colonial territories the conser-vative element that had inhibited the developmentof photogrammetric methods through the 1920scontinued to delay adoption of photogrammetryuntil after World War II-with some illuminatingexceptions Cyprus is the only known example ofa local survey department attempting to carry outphotogrammetric work Aerial photography wastaken in 1936 but delays in obtaining groundcontrol meant that no use was made of the pho-tography before all normal work was suspended atthe outbreak of war In all the other colonies wherephotogrammetry was attempted private survey

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companies carried out the work The earliestexample of the involvement of private air surveycompanies had been in 1927 in the mapping ofthe Anglo-Belgian boundary in the Copper Beltregion of Northern Rhodesia (Colonial SurveyCommittee 1928) Private air survey companieswere also active in Uganda Tanganyika andSouthern Rhodesia but in all cases this was surveywork for specific development projects ratherthan routine mapping (War Office 1935) Therewere discussions about the use of photogramme-try in Sierra Leone where the Aircraft OperatingCompany of South Africa proposed to revise the162500 topographic maps for pound150000 includ-ing the cost of providing ground control but thework was never carried out due to financial con-straints and the outbreak of World War II Therewere also discussions about air survey in Jamaicaand the Gold Coast but nothing came of theseprojects until after World War II It is clear fromthe literature and correspondence of the time thatthe private air survey companies were lobbyingindividual colonial governments as well as theBritish Government to adopt air survey but theColonial Survey Committee under Winterbothamwas equally forceful in its resistance to changelargely on grounds of cost (see in particularWinterbotham 1920 1921 1929 1934 1936Hemming 1933)

Increasing recognition that war with Germanywas inevitable led to a significant change in theBritish establishments attitude towards the use ofair survey In part this change reflected the retire-ment of Winterbotham in 1935 and his replace-ment as Director General of the Ordnance Surveyby MacLeod who was alwaysa warm supporter ofair survey MacLeod had followed Winterbothamfirst as Director of Military Surveys and then atthe Ordnance Surveyand in each case he playeda major role in introducing the use of photogram-metry (Clough 1952)

Advances in InstrumentationThe late 1920s had seen the design and produc-tion of the first practical plotting machines for usewith aerial photography The experience provideda foundation for the introduction during the1930s of designs that were to be the mainstaysof topographic mapping The Zeiss C4 had beenintroduced in 1930 (Burnside 1993)AsThompson(1966) notes the C4 and the superseding C5(introduced in 1935 with improved illumination)were with the Wild A5 (launched in 1937) practi-cally the only universal instruments on the marketin the 1930s Universal instruments designed to

CartograPhy and GeograPhic Information Science

handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

Vol29 No3

graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

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Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

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world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

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Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

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a triangulation scheme The mosaics were inkedup before the bromide prints were bleached out soas to leavejust the inked linework The importantpoint to note is that this technique was used formapping areas on both sides of the front line andwas therefore regarded as the final product Theflat floodplains of the Tigris and Euphrates Riverslent themselves to mapping using semi-controlledmosaics as there was an almost complete absenceof height to create displacement errors The map-ping of Mesopotamia from aerial photography seta precedent for post-war mapping in India

Flash Spotting and Sound RangingAs mentioned earlier the use of camouflage neces-sitated the development of techniques for targetlocation in particular the location of enemy gunpositions for counter-battery fire At the beginningof World War I guns were aimed by direct observa-tion of targets and the guns themselves were oftenpositioned in the open to improve their fields offire With the increased use of counter battery fireit became normal for guns to be dug in posi-tioned in gun pits and protected by sandbags Toprotect gun positions from enemy air observationthe gun pits were subsequently camouflaged withnetting which thwarted an accurate identificationof their positions

Flash spotting and sound ranging were devel-oped as means of tackling the problem of identify-ing and locating enemy gun positions Adopted byall the combatant nations flash spotting involvedintersecting the gun position by observing theflash as tht gun was fired Flash spotting requiredconsiderable organization as the observers had toensure that they were observing the same gun flashbut by carefully noting the times of the observa-tions it was possible to obtain accurate locationsof enemy guns Most armies established specialistunits for this purpose (Innes 1935 Chasseaud1999 Hinks 1919 Maule 1919)

Sound ranging was a more complex process inwhich the British and French enjoyed a technolog-ical lead over the Germans General Ludendorffthe German Chief of Staff who issued specialinstructions that precautions be taken to cam-ouflage the sound of guns directed the army tosecure an example of the British system (quotedin Hinks 1919) Based on a technical solutiondeveloped by Lucien Bull at the Institut Marey inParis the British system relied on an array of sixmicrophones spread over a 9-kilometer-long base-line situated about 4 km behind the front iine Themicrophones were connected to a galvanometer atthe hea~quarters As the sound of a gun reached

l1Jl 29 No3

each microphone in turn a signal was sent by wireto the galvanometer where it produced a distinc-tive trace on photographic film By measuring theseparation of the traces of the gun detected at eachmicrophone the distance and direction of the guncould be calculated Complex arrangements withmore than two microphones were needed becauseof uncertainty about the effect of wind speed andother factors on sound waves (see Innes 1935 andChasseaud 1999 for more technical details)

The German systemrelied on a fonvard observerand four other observers along a base of 10 to 15kilometers On hearing a gun firing the forwardobserver sent a signal by field telephone to theother observers who on receiving the signalstarted their stopwatches and noted the time inter-val before they heard the gun The times were thensent to group headquarters where the position ofthe gun was calculated An alternative and sim-pler method involved an observer noting the timeinterval between seeing a gun flash and hearingthe noise of the gun The greatest precision possi-ble with these techniques was about +200 meters

Non-military WartimeDevelopments to 1918

While the mapping efforts of the combatantnations were almost entirely directed towards thewar effort cartographers in the United States wereactively exploring civilian applications of pho-togrammetry The most important developmentwork was carried out at the US Geological Surveywhere James Bagley was developing a tri-Ienscamera and Fred Moffit was developing a trans-forming camera capable of handling the nega-tives produced by Bagleys camera (Committee onPhotographic Surveying 1921)

Developments to 1930In the period leading up to and including WorldWar I all the major powers followed broadlysimilar paths in developing photogrammetry Inmost countries attempts to develop instrumentalmethods complemented heavy reliance on graphi-cal and optical techniques for producing andrevising large-scale maps After the war a numberof countries took distinctly different paths withcontinental European countries generally puttingmost of their effort into instrumental techniqueswhile English-speaking countries focused ongraphical techniques Arguably until about 1930the approach adopted by the English-speaking

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countries was the most fruitful as the instrumentaltechniques developed in Europe could not com-pete in cost or efficiency with British and Americanmethods

After 1930 the relative efficiencies of the twoapproaches changed markedly The Americansrecognized the changed circumstances morequickly than their British counterparts and beganadopting instrumental methods by the mid 1930sIn Britain and by extension throughout the BritishEmpire instrumental photogrammetry was still inthe experimental phase at the outbreak of WorldWar 11in 1939

The immediate post-war-one period saw a flurryof papers extolling the merits of mapping fromaerial photography At the forefront of the cam-paign to get the methods accepted in Britain wasCapt H Hamshaw Thomas (1919 1920 1924)who drew heavily on his experiences in the Sinaiand Palestine Much of the effort to promote airsurvey was conducted in non-specialist journalssuch as the GeograPhicalJournal (Newcombe 1920)and even in the popular press MacLeod who hadserved in France and had become a firm advocateof air survey methods also produced a numberof papers as well as an important official publica-tion Mapping from Air Photographs issued by theWar Office (MacLeod 1920 but see also MacLeod1922 1923a 1923b)

Britain more than in any other country held aconservative attitude towards the new techniquesand this resistance found an influential championin Harold StJ LWinterbotham A self-proclaimedexpert on air survey (see Winterbotham 19291934) Winterbotham did much to impede theadoption of air survey both in Britain and throughhis role on the Colonial Survey Committee in thecolonial territories In contrast the Dominion ter-ritories were free to determine their own policiesAlthough Canada a pioneer in photogrammetryhad been joined by India in its use of these tech-niques before the outbreak of the First World Warother Dominion territories were slower in adopt-ing air survey Australia took the lead but localfactors either delayed or advanced the adoptionof photogrammetry in Dominion territories whichwere not compelled to follow the Colonial SurveyCommittees recommendation There is a strik-ing parallel between these largely autonomousterritories and the Dutch East Indies where thesurvey department was quick to adopt photogram-metry (van Roon 1925) but made no real progressat home in The Netherlands until after World WarII

In the British context Winterbothams reser-vations concerning the cost-effectiveness of air

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survey methods were probably justified at leastuntil the development of Reinhard Hugershoffsaerocartograph in 1926 (Blachut and Burkhardt1989) All the air survey instruments introducedbefore the aerocartograph were essentially ter-restrial plotters adapted in some way to copewith non-coplanar photography This made theinstruments difficult and slow to set up and theyusually required two men to carry out orienta-tion and plotting operations In a well mappedcountry such as Britain cumbersome machinescould not support map revision as economically asconventional ground surveyhere Winterbothamerred even in the 1920s was in extrapolatingfrom the British experience to the colonial terri-tories where the needs were very different On thepositive side agitation by Hamshaw Thomas andothers as well as the successful application of airsurvey techniques by the Survey of India led to thesetting up of the AirSurvey Committee Part ofthe responsibility of this committee was to adviseon air survey matters but it was also responsiblefor carrying out research

In the United States the promotion of airsurvey techniques wasundertaken by Moffit (1920)and other surveyors who had not been directlyinvolved in the war effort but had carried on withtheir civilian work in government mapping agen-cies Part of this promotion was carried out in non-specialist journals but unlike in Britain there waslittle need to convince the political leadership ofthe advantages of air surveyBycontrast there waslittle attempt to promote air survey in France orGermany other than in technical or professionaljournals Almost certainly this reflects the higherstatus of engineers and technical experts in thosecountries compared with Britain The UnitedStates probably fell somewhere between Britainand the continental powers but more towards thelatter

Survey and mapping activities in Austria suf-fered a severe setback with the breakup of theHabsburg Empire at the end of World War 1The Militargeographische Institut was disbandedin 1920 (Kretschmer 1991) and its personneldispersed amongst the successor states Whilethis disintegration had clear disadvantages forAustria survey departments in Poland Hungaryand Czechoslovakiagained a cadre of trained andexperienced personnel able to form the nucleusof new national survey organizations Despite eco-nomic hardship in the wakeof the warAustria hadbegun in 1928 to supplement existing 175000topographic mapping work focused on the moun-tainous areas using terrestrial photogrammetry

CartografJhy and GeograPhic informationScience

Graphical MethodsBecause of the extensive use of graphical methodsduring WorldWar I a large body of trained person-nel was available to implement these methods forpost-war mapping But the techniques developedthus far were either non-rigorous (for example theperspective grid) or suitable only for revising smallnumbers of features (the paper strip method)What was needed was a rigorous technique thatdid not require highly skilled workers

Bagley had sowed the seeds of a rigoroustechnique during his work with the PanoramicPhotoalidade (Bagley 1917) but Martin Hotine(1927) provided the theoretical and practicalbasis for a cost-effective mapping techniqueDescribed as a Simple Method of Surveying fromAir Photographs Hotines technique becameknown as the Arundel Method (after Arundelin southern England where the technique wasfirst used experimentally) or the radial-line tech-nique Hotine subsequently developed the methodof control extension using radial-line methods(Hotine 1929) and laid the foundations for muchof the medium-scale photogrammetric mappingcarried out in the English-speaking world over thenext 40 years The American development of slot-ted templets and radial intersectors expeditedthe process of aerotriangulation (see below) butit was Hotines theoretical work that made thesedevelopments possible

None of the countries using aerial photogra-phy for topographic mapping embraced it withgreater enthusiasm than India As noted earlierthe Survey of India had acquired two examplesof Thompsons stereo-plotter Kenneth Mason(1913 1927) had used the stereo-plotter in 1913in the Pamirs with considerable success but theexperience of the Survey of India in Mesopotamiaduring World War I wasdecisive in promoting airsurvey techniques in India In 1920 a series ofexperiments conducted at Agra demonstrated theutility of air survey methods for mapping flat areasin India (Lewis and Salmond 1920) Air surveyp~oved inefficient for one-inch-to-a-milemiddot map-pmg-the cost was roughly twice as much as forground surveys-but it was economical for largerscales An experiment in urban mapping was car-ried out but its results were inconclusive

Among developed countries the United Stateswas probably the most in need of the advantagesthat air survey offered post-war mapmakers Forall its great wealth America was poorly mappedby European standards Where most Europeancountries were at least mapped at medium scale(roughly 1100000 or larger) large tracts of the

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United States were not mapped even at small scaleIt was at just this small-scale range that air surveyseemed to offer the greatest advantages

The work carried out within the USCampGSand USGS prior to and during World War I hadprepared both agencies to take advantage of theemerging technology Starting in 1919 USCampGSused aerial photography for chart revision(Quillian 1919 Mattison 1919) and for wetlandsurveys (Mattison 1924 Graham 1924-25) Someproblems were encountered but the particularadvantages of air survey for mapping wetlands ledto the technique becoming the standard procedure(Landen 1952) In carrying out these surveys theUSCampGSused photography supplied by the Navyand the Army Air Corps it was the Air Corpsmulti-lens camera that established the cost-effec-tiveness of air survey (Reading 1927-28) Withinthe USGS a quadrangle in Michigan was mappedusing a conventional single-lens camera using airsurvey for the planimetry only (Thompson 1952)In 1924 a Section of Photographic Mapping wasestablished as part of the Topographic Branch atUSGS

Terrestrial photogrammetric work had beenundertaken in Russia as early as 1891 (Koch1963) but few significant additional developmentsoccurred before 1920 In 1924 the State TechnicalOffice of Aerial Photographic Survey was estab-lished Its first task was the creation of mosaics at110000 for comparison with plane table surveysThe results were considered sufficiently favorablefor mapping at 15000 based on 112000 pho-tography An ambitious program of aerial pho-tography initiated in 1925 led to the coverage ofmore than 4500000 km2 by 1940 In 1928 theCentral Scientific Research Institute for GeodesyPhotogrammetry and Cartography (ZNIlGAiK)was established to oversee development across thewhole field of mapping (Koch 1963)

Instrumental MethodsAt the end of World War I Germany and theAustro-Hungarian Empire had a clear advan-tage in the development and use of instrumen-tal photogrammetric methods While Germanycontinued to enjoy a considerable lead in thesetechniques the collapse of the Dual Monarchy andthe resultant breakup of the MilitargeographischeInstitut meant that Austria entered a period ofrelative decline Zeiss which had become theciear ieader in the design and man-ufacture ofphotogrammetric instruments not only pro-duced instruments designed by both von Ore and

165

Pulfrich but employed several leading figures inphotogrammetry including Walter BauersfeldWilli Sander and Otto von Gruber This ensuredthat Zeiss was always at or near the forefront ofdevelopments in the field

During the 1920s most efforts were directedtoward overcoming the problem inherent in theearlier generation of photogrammetric plot-ters namely the need for the photographs tobe coplanar In 1926 Hugershoff designed anaerocartograph for use with both terrestrial andaerial photography The instrument which wasmanufactured by Heyde Company in Dresdentook advantage of the theoretical developmentsin orientation theory developed by Max Gasser(1923) and von Gruber (1924) The combinationof new orientation procedures and sophisticateddesign meant that Hugershoffs aerocartographcould be used for plotting and aerotriangulation(Blachut and Burkhardt 1989) Professional rivalryled von Gruber (1932) to dispute the original-ity of Hugershoffs design as he was also to dowith Heinrich Wilds instruments and the ideas ofFourcade

Zeiss had produced their stereoplanigraph(the Cl) in 1921 based on an earlier design ofBauersfeld However it was not until the pro-duction of the C4 in 1930 that Zeiss producedan instrument that could handle both terrestrialand aerial photography Some successful mappingfrom the earlier models was reported throughthe 1920s by the Reichsamt fur Landesaufnahmewhich had a C2 (Seidel 1928) and the GeodeticInstitute in Stuttgart which had a C3 (von Gruber1932) Most of the mapping was at 15000 butscales as small as ] 20000 are reported Even inGermany systematic mapping programs usingphotogrammetry were still the exception ratherthan the rule during the 1920s

In France the Service Geographique de lArmeehad been actively experimenting with instrumen-tal photogrammetry before World War I (Bonnet1920) and had also used the technique for someterrestrial work during the war France was thuswell placed at the end of the war to keep upwith the developments elsewhere in Europe TheService had decided that terrestrial photogram-metry was best suited to 120000 mapping in highmountain areas but considered the equipment toocumbersome and imprecise for reconnaissancesurveys (Service Geographique de lArmee 1912)In 1919 a start was made on mapping in Moroccousing panoramic aerial photographs (ServiceGeographique de IArmee ]936) but the main

166

drive in France was to develop an autonomouscapability in instrumental photogrammetry

Some equipment had been developed duringthe war notably the Chambre Claire Varon andthe Appareil de photorestitution Roussilhe aninstrument for partial rectification of cadastralplans (Blachut and Burkhardt 1989 ServiceGeographique de IArmee ]936) The mostimportant development came in 1922 when thefirst Georges Poivilliers instrument was built(Poivilliers 1922 Blachut and Burkhardt 1989)Poivilliers instruments were to provide the bulkof the photogrammetric capability of the Servicewith up to four different types in use at anyonetime (Institut Geographique National 1947)Other instruments were also used largely on anexperimental basis In the mid] 920s the stereor-estituteur Boucard was in use and in the I930s aGallus Ferber instrument was used experimentally(Service Geographique de lArmee 1938) withthe latter (Blachut and Burkhardt 1989) remain-ing in service until at least the 1940s (InstitutGeographique National 1947)

Italy had been actively engaged in photogram-metry in the nineteenth century with the work ofPorro but as Blachut and Burkhardt (1989) notethe Istituto Geografico Militare showed little inter-est in the technique until many years after Porrosdeath in 1875 The resurrection of Italian photo-grammetry was largely due to two men UmbertoNistri who designed aplotter in 1919for large-scaleplotting and Ermenegildo Santoni who producedhis first instrument the autoreductor in 1921 In1926 Nistri founded the firm Ottico MeccanicaItaliana (OMI) to produce his photogrammetricinstruments Nistris early instruments all useddirect optical projection while Santonis instru-ments all used mechanical projection The IstitutoGeografico Militare was middotequipped with Santoniinstruments which it used for mapping at 125000and 110000 The Societa Anonima RilevamentiAerofotogrammetrici (SARA)on the other handused Nistri instruments largely for topographicmapptng outside Italy but also for cadastral map-ping within the country

Photogrammetry had been used in Switzerlandfor engineering surveys in the nineteenth centuryyet there had been no systematic attempt to carryout topographic mapping using the techniqueThe history of mapping in Switzerland betweenthe two world wars is largely a history of the WildHeerbrugg Company Set up in 1921 the com-pany produced its first phototheodolite in 1922and its first photogrammetric plotter the Alstereo-autograph in 1923 Its first major contribu-

Cartography and Geographic Information Science

tion to surveying came with the production of theT2 theodolite in 1924 The revolutionary design ofthis instrument-replacing engraved metal circleswith glass versions provided more accurate read-ings and better illumination-led to considerableexcitement in scientific and survey circles By thelate 1920s Wild was engaged in serial productionof the T2 and T3 theodolites the P3 phototheodo-lite and the A2 autograph which had replaced theAI In addition the Cl C2 and C3 aerial cam-eras were also in production In the space of onlyeight years Wild had become a major player in thesurvey world a position enhanced further duringthe 1930s

By the late 1920s the Landestopographie inSwitzerland had gained considerable experiencewith Wild instruments for both terrestrial andaerial surveys (Schneider 1929) Topographicmaps were produced from terrestrial photographyat 125000 while aerial photography wasused for110000 mapping (Schneider 1929 Harry 1971)

In the United States in addition to usinggraphical techniques the USGS started to inves-tigate instrumental methods In 1921 it obtaineda stereoautograph from Germany for evalua-tion but restricted the use of the instrument toplotting from terrestrial photography and notable to produce maps economically (Thompson1952) In 1927 the Geological Survey acquired theHugershoff aerocartograph the first automaticstereo-plotter used by an American governmentmapping agency (Thompson 1952) Thomas PPendleton laid down guidelines for mapping fromaerial photography within the USGS in Bulletin788-F Map Compilation from Aerial PhotograPhsissued as part of the Topographic Instructions of theUnited States Geological Survey (Pendleton 1928)Given the rapid developments in radial-line meth-ods (eg Hotine 1927) the timing of Pendletonswork was a bit unfortunate as he asserted thatradial-line techniques were really only suited foruse with multi-lens photography because therelatively short radial lines that could be drawnon single-lens photographs could not give the bestresults (Pendleton 1928 p 409)

In Britain research work carried out by the AirSurvey Committee focused on simple methods butthe Committee did not entirely ignore instrumen-tal techniques MacLeods wartime work with rec-tifiers was developed and more importantly theideas of Fourcade (l926a 1926b 1926c 1926d)on the theory and use of stereogoniometers forphotogrammetric plotters were taken up In 1926the Committee commissioned the constructionof an instrument along the lines proposed by

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Fourcade and the instrument was delivered in1928 0ar Office 1935 Hotine 1931)

In India success with non-instrumental tech-niques did not distract the Survey from instrumen-tal techniques they had helped pioneel- Mappingofficials followed developments taking place inEurope and in 1926 Mason (1927) carried outa survey in the Shaksgam using a Wild photo-theodolite and plotted the results in Switzerlandusing an autograph in the Topographical Instituteat Flums

CamerasThe tri-lens camera developed by Bagley was usedby the USGS in mapping for aeronautical chartsThis program wasjointly organized with the Corpsof Engineers and the Air Service (Committeeon Photographic Surveying 1921) and providedvaluable experience in civil applications In 1920programs with the tri-lens camera were also under-taken in Santo Domingo and Haiti

The Corps of Engineers became involved inphotogrammetric methods in 1920 when Bagleywas assigned to cooperate with the Army AirCorps in carrying out tests on aerial photographyfor topographic mapping Initially the trials usedBagleys tri-lens camera but he went on to developthe five lens T-3Acamera which was to remain thestandard mapping camera of the US Army until1940 (Landen 1952) The War Department issuedtraining regulations for mapping from aerialphotography in 1923 however the techniques dis-cussed in the regulations were largely those refinedduring World War 1

The 1930sBy the late 1920s photogrammetry had becomea cost-effective alternative to some traditionalground surveys Yet expensive photogrammetricplotting instruments and labor-intensive graphicalplotting meant that photogrammetry still lackeda decisive advantage over ground survey Duringthe 1930s a number of innovations were to swingthe balance decisivelyin favor of photogrammetricmethods

Progress was slowed if not stopped by the reces-sion that started in 1929 Some measure of theimpact can be gauged from job cutbacks at WildHeerbrugg In 1930 before the recession had amarked affect on Europe the workforce stood at260 but by 1933 the number ofjobs had droppedto 125This was the direct consequence of the deci-sions taken to retrench mapping projects as well as

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capital programs Nearly all the annual reports forthe early 1930s mention the financial constraintsunder which organizations had to work In theUnited States some of these problems were offsetby appropriations under the Emergency Reliefand Construction Act (US Coast and GeodeticSurvey 1933) Moreover the New Deal initiated awide range of programs in which photogrammetrywas to playa major role By contrast problems inthe colonial territories were if anything worsethan in Europe and North America The declinein industrial activity in developed countries ledto a collapse in demand for raw materials fromthe colonies and as this was the main source ofgovernment revenue they could no longer pay forsurvey work Annual reports from most colonialsurvey departments make reference to a lack ofresources to meet the need for mapping Howevel~by the late 1930s as a result of rearmament inEurope governments allocated more money tosurvey organizations

Survey organizations were eager to adopt newtechniques in routine mapping programs but thepressures within governments to deal with massunemployment probably helped to promote theuse of labor-intensive methods in survey at theexpense of investment in technology Certainlyorganizations such as the Tennessee ValleyAuthority (TVA) the Agriculture AdjustmentAdministration and the Soil Conservation Servicein the United States were all heavily dependenton such labor-intensive techniques and did muchto develop them as standard mapping methodsMoreover organizations such as the USGS andthe TVA also played a role in the developmentinstrumental methods such as multiplex All ofthis was to be of vital importance to the hugephotogrammetric mapping programs that wereto emerge during World War II The scale of theseprograms would have been inconceivable withoutthe trained body of photogrammetrists developedduring the 1930s (Landen 1952)

Within the British colonial territories the conser-vative element that had inhibited the developmentof photogrammetric methods through the 1920scontinued to delay adoption of photogrammetryuntil after World War II-with some illuminatingexceptions Cyprus is the only known example ofa local survey department attempting to carry outphotogrammetric work Aerial photography wastaken in 1936 but delays in obtaining groundcontrol meant that no use was made of the pho-tography before all normal work was suspended atthe outbreak of war In all the other colonies wherephotogrammetry was attempted private survey

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companies carried out the work The earliestexample of the involvement of private air surveycompanies had been in 1927 in the mapping ofthe Anglo-Belgian boundary in the Copper Beltregion of Northern Rhodesia (Colonial SurveyCommittee 1928) Private air survey companieswere also active in Uganda Tanganyika andSouthern Rhodesia but in all cases this was surveywork for specific development projects ratherthan routine mapping (War Office 1935) Therewere discussions about the use of photogramme-try in Sierra Leone where the Aircraft OperatingCompany of South Africa proposed to revise the162500 topographic maps for pound150000 includ-ing the cost of providing ground control but thework was never carried out due to financial con-straints and the outbreak of World War II Therewere also discussions about air survey in Jamaicaand the Gold Coast but nothing came of theseprojects until after World War II It is clear fromthe literature and correspondence of the time thatthe private air survey companies were lobbyingindividual colonial governments as well as theBritish Government to adopt air survey but theColonial Survey Committee under Winterbothamwas equally forceful in its resistance to changelargely on grounds of cost (see in particularWinterbotham 1920 1921 1929 1934 1936Hemming 1933)

Increasing recognition that war with Germanywas inevitable led to a significant change in theBritish establishments attitude towards the use ofair survey In part this change reflected the retire-ment of Winterbotham in 1935 and his replace-ment as Director General of the Ordnance Surveyby MacLeod who was alwaysa warm supporter ofair survey MacLeod had followed Winterbothamfirst as Director of Military Surveys and then atthe Ordnance Surveyand in each case he playeda major role in introducing the use of photogram-metry (Clough 1952)

Advances in InstrumentationThe late 1920s had seen the design and produc-tion of the first practical plotting machines for usewith aerial photography The experience provideda foundation for the introduction during the1930s of designs that were to be the mainstaysof topographic mapping The Zeiss C4 had beenintroduced in 1930 (Burnside 1993)AsThompson(1966) notes the C4 and the superseding C5(introduced in 1935 with improved illumination)were with the Wild A5 (launched in 1937) practi-cally the only universal instruments on the marketin the 1930s Universal instruments designed to

CartograPhy and GeograPhic Information Science

handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

Vol29 No3

graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

169

Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

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world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

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Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

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countries was the most fruitful as the instrumentaltechniques developed in Europe could not com-pete in cost or efficiency with British and Americanmethods

After 1930 the relative efficiencies of the twoapproaches changed markedly The Americansrecognized the changed circumstances morequickly than their British counterparts and beganadopting instrumental methods by the mid 1930sIn Britain and by extension throughout the BritishEmpire instrumental photogrammetry was still inthe experimental phase at the outbreak of WorldWar 11in 1939

The immediate post-war-one period saw a flurryof papers extolling the merits of mapping fromaerial photography At the forefront of the cam-paign to get the methods accepted in Britain wasCapt H Hamshaw Thomas (1919 1920 1924)who drew heavily on his experiences in the Sinaiand Palestine Much of the effort to promote airsurvey was conducted in non-specialist journalssuch as the GeograPhicalJournal (Newcombe 1920)and even in the popular press MacLeod who hadserved in France and had become a firm advocateof air survey methods also produced a numberof papers as well as an important official publica-tion Mapping from Air Photographs issued by theWar Office (MacLeod 1920 but see also MacLeod1922 1923a 1923b)

Britain more than in any other country held aconservative attitude towards the new techniquesand this resistance found an influential championin Harold StJ LWinterbotham A self-proclaimedexpert on air survey (see Winterbotham 19291934) Winterbotham did much to impede theadoption of air survey both in Britain and throughhis role on the Colonial Survey Committee in thecolonial territories In contrast the Dominion ter-ritories were free to determine their own policiesAlthough Canada a pioneer in photogrammetryhad been joined by India in its use of these tech-niques before the outbreak of the First World Warother Dominion territories were slower in adopt-ing air survey Australia took the lead but localfactors either delayed or advanced the adoptionof photogrammetry in Dominion territories whichwere not compelled to follow the Colonial SurveyCommittees recommendation There is a strik-ing parallel between these largely autonomousterritories and the Dutch East Indies where thesurvey department was quick to adopt photogram-metry (van Roon 1925) but made no real progressat home in The Netherlands until after World WarII

In the British context Winterbothams reser-vations concerning the cost-effectiveness of air

i64

survey methods were probably justified at leastuntil the development of Reinhard Hugershoffsaerocartograph in 1926 (Blachut and Burkhardt1989) All the air survey instruments introducedbefore the aerocartograph were essentially ter-restrial plotters adapted in some way to copewith non-coplanar photography This made theinstruments difficult and slow to set up and theyusually required two men to carry out orienta-tion and plotting operations In a well mappedcountry such as Britain cumbersome machinescould not support map revision as economically asconventional ground surveyhere Winterbothamerred even in the 1920s was in extrapolatingfrom the British experience to the colonial terri-tories where the needs were very different On thepositive side agitation by Hamshaw Thomas andothers as well as the successful application of airsurvey techniques by the Survey of India led to thesetting up of the AirSurvey Committee Part ofthe responsibility of this committee was to adviseon air survey matters but it was also responsiblefor carrying out research

In the United States the promotion of airsurvey techniques wasundertaken by Moffit (1920)and other surveyors who had not been directlyinvolved in the war effort but had carried on withtheir civilian work in government mapping agen-cies Part of this promotion was carried out in non-specialist journals but unlike in Britain there waslittle need to convince the political leadership ofthe advantages of air surveyBycontrast there waslittle attempt to promote air survey in France orGermany other than in technical or professionaljournals Almost certainly this reflects the higherstatus of engineers and technical experts in thosecountries compared with Britain The UnitedStates probably fell somewhere between Britainand the continental powers but more towards thelatter

Survey and mapping activities in Austria suf-fered a severe setback with the breakup of theHabsburg Empire at the end of World War 1The Militargeographische Institut was disbandedin 1920 (Kretschmer 1991) and its personneldispersed amongst the successor states Whilethis disintegration had clear disadvantages forAustria survey departments in Poland Hungaryand Czechoslovakiagained a cadre of trained andexperienced personnel able to form the nucleusof new national survey organizations Despite eco-nomic hardship in the wakeof the warAustria hadbegun in 1928 to supplement existing 175000topographic mapping work focused on the moun-tainous areas using terrestrial photogrammetry

CartografJhy and GeograPhic informationScience

Graphical MethodsBecause of the extensive use of graphical methodsduring WorldWar I a large body of trained person-nel was available to implement these methods forpost-war mapping But the techniques developedthus far were either non-rigorous (for example theperspective grid) or suitable only for revising smallnumbers of features (the paper strip method)What was needed was a rigorous technique thatdid not require highly skilled workers

Bagley had sowed the seeds of a rigoroustechnique during his work with the PanoramicPhotoalidade (Bagley 1917) but Martin Hotine(1927) provided the theoretical and practicalbasis for a cost-effective mapping techniqueDescribed as a Simple Method of Surveying fromAir Photographs Hotines technique becameknown as the Arundel Method (after Arundelin southern England where the technique wasfirst used experimentally) or the radial-line tech-nique Hotine subsequently developed the methodof control extension using radial-line methods(Hotine 1929) and laid the foundations for muchof the medium-scale photogrammetric mappingcarried out in the English-speaking world over thenext 40 years The American development of slot-ted templets and radial intersectors expeditedthe process of aerotriangulation (see below) butit was Hotines theoretical work that made thesedevelopments possible

None of the countries using aerial photogra-phy for topographic mapping embraced it withgreater enthusiasm than India As noted earlierthe Survey of India had acquired two examplesof Thompsons stereo-plotter Kenneth Mason(1913 1927) had used the stereo-plotter in 1913in the Pamirs with considerable success but theexperience of the Survey of India in Mesopotamiaduring World War I wasdecisive in promoting airsurvey techniques in India In 1920 a series ofexperiments conducted at Agra demonstrated theutility of air survey methods for mapping flat areasin India (Lewis and Salmond 1920) Air surveyp~oved inefficient for one-inch-to-a-milemiddot map-pmg-the cost was roughly twice as much as forground surveys-but it was economical for largerscales An experiment in urban mapping was car-ried out but its results were inconclusive

Among developed countries the United Stateswas probably the most in need of the advantagesthat air survey offered post-war mapmakers Forall its great wealth America was poorly mappedby European standards Where most Europeancountries were at least mapped at medium scale(roughly 1100000 or larger) large tracts of the

J1J129 No3

United States were not mapped even at small scaleIt was at just this small-scale range that air surveyseemed to offer the greatest advantages

The work carried out within the USCampGSand USGS prior to and during World War I hadprepared both agencies to take advantage of theemerging technology Starting in 1919 USCampGSused aerial photography for chart revision(Quillian 1919 Mattison 1919) and for wetlandsurveys (Mattison 1924 Graham 1924-25) Someproblems were encountered but the particularadvantages of air survey for mapping wetlands ledto the technique becoming the standard procedure(Landen 1952) In carrying out these surveys theUSCampGSused photography supplied by the Navyand the Army Air Corps it was the Air Corpsmulti-lens camera that established the cost-effec-tiveness of air survey (Reading 1927-28) Withinthe USGS a quadrangle in Michigan was mappedusing a conventional single-lens camera using airsurvey for the planimetry only (Thompson 1952)In 1924 a Section of Photographic Mapping wasestablished as part of the Topographic Branch atUSGS

Terrestrial photogrammetric work had beenundertaken in Russia as early as 1891 (Koch1963) but few significant additional developmentsoccurred before 1920 In 1924 the State TechnicalOffice of Aerial Photographic Survey was estab-lished Its first task was the creation of mosaics at110000 for comparison with plane table surveysThe results were considered sufficiently favorablefor mapping at 15000 based on 112000 pho-tography An ambitious program of aerial pho-tography initiated in 1925 led to the coverage ofmore than 4500000 km2 by 1940 In 1928 theCentral Scientific Research Institute for GeodesyPhotogrammetry and Cartography (ZNIlGAiK)was established to oversee development across thewhole field of mapping (Koch 1963)

Instrumental MethodsAt the end of World War I Germany and theAustro-Hungarian Empire had a clear advan-tage in the development and use of instrumen-tal photogrammetric methods While Germanycontinued to enjoy a considerable lead in thesetechniques the collapse of the Dual Monarchy andthe resultant breakup of the MilitargeographischeInstitut meant that Austria entered a period ofrelative decline Zeiss which had become theciear ieader in the design and man-ufacture ofphotogrammetric instruments not only pro-duced instruments designed by both von Ore and

165

Pulfrich but employed several leading figures inphotogrammetry including Walter BauersfeldWilli Sander and Otto von Gruber This ensuredthat Zeiss was always at or near the forefront ofdevelopments in the field

During the 1920s most efforts were directedtoward overcoming the problem inherent in theearlier generation of photogrammetric plot-ters namely the need for the photographs tobe coplanar In 1926 Hugershoff designed anaerocartograph for use with both terrestrial andaerial photography The instrument which wasmanufactured by Heyde Company in Dresdentook advantage of the theoretical developmentsin orientation theory developed by Max Gasser(1923) and von Gruber (1924) The combinationof new orientation procedures and sophisticateddesign meant that Hugershoffs aerocartographcould be used for plotting and aerotriangulation(Blachut and Burkhardt 1989) Professional rivalryled von Gruber (1932) to dispute the original-ity of Hugershoffs design as he was also to dowith Heinrich Wilds instruments and the ideas ofFourcade

Zeiss had produced their stereoplanigraph(the Cl) in 1921 based on an earlier design ofBauersfeld However it was not until the pro-duction of the C4 in 1930 that Zeiss producedan instrument that could handle both terrestrialand aerial photography Some successful mappingfrom the earlier models was reported throughthe 1920s by the Reichsamt fur Landesaufnahmewhich had a C2 (Seidel 1928) and the GeodeticInstitute in Stuttgart which had a C3 (von Gruber1932) Most of the mapping was at 15000 butscales as small as ] 20000 are reported Even inGermany systematic mapping programs usingphotogrammetry were still the exception ratherthan the rule during the 1920s

In France the Service Geographique de lArmeehad been actively experimenting with instrumen-tal photogrammetry before World War I (Bonnet1920) and had also used the technique for someterrestrial work during the war France was thuswell placed at the end of the war to keep upwith the developments elsewhere in Europe TheService had decided that terrestrial photogram-metry was best suited to 120000 mapping in highmountain areas but considered the equipment toocumbersome and imprecise for reconnaissancesurveys (Service Geographique de lArmee 1912)In 1919 a start was made on mapping in Moroccousing panoramic aerial photographs (ServiceGeographique de IArmee ]936) but the main

166

drive in France was to develop an autonomouscapability in instrumental photogrammetry

Some equipment had been developed duringthe war notably the Chambre Claire Varon andthe Appareil de photorestitution Roussilhe aninstrument for partial rectification of cadastralplans (Blachut and Burkhardt 1989 ServiceGeographique de IArmee ]936) The mostimportant development came in 1922 when thefirst Georges Poivilliers instrument was built(Poivilliers 1922 Blachut and Burkhardt 1989)Poivilliers instruments were to provide the bulkof the photogrammetric capability of the Servicewith up to four different types in use at anyonetime (Institut Geographique National 1947)Other instruments were also used largely on anexperimental basis In the mid] 920s the stereor-estituteur Boucard was in use and in the I930s aGallus Ferber instrument was used experimentally(Service Geographique de lArmee 1938) withthe latter (Blachut and Burkhardt 1989) remain-ing in service until at least the 1940s (InstitutGeographique National 1947)

Italy had been actively engaged in photogram-metry in the nineteenth century with the work ofPorro but as Blachut and Burkhardt (1989) notethe Istituto Geografico Militare showed little inter-est in the technique until many years after Porrosdeath in 1875 The resurrection of Italian photo-grammetry was largely due to two men UmbertoNistri who designed aplotter in 1919for large-scaleplotting and Ermenegildo Santoni who producedhis first instrument the autoreductor in 1921 In1926 Nistri founded the firm Ottico MeccanicaItaliana (OMI) to produce his photogrammetricinstruments Nistris early instruments all useddirect optical projection while Santonis instru-ments all used mechanical projection The IstitutoGeografico Militare was middotequipped with Santoniinstruments which it used for mapping at 125000and 110000 The Societa Anonima RilevamentiAerofotogrammetrici (SARA)on the other handused Nistri instruments largely for topographicmapptng outside Italy but also for cadastral map-ping within the country

Photogrammetry had been used in Switzerlandfor engineering surveys in the nineteenth centuryyet there had been no systematic attempt to carryout topographic mapping using the techniqueThe history of mapping in Switzerland betweenthe two world wars is largely a history of the WildHeerbrugg Company Set up in 1921 the com-pany produced its first phototheodolite in 1922and its first photogrammetric plotter the Alstereo-autograph in 1923 Its first major contribu-

Cartography and Geographic Information Science

tion to surveying came with the production of theT2 theodolite in 1924 The revolutionary design ofthis instrument-replacing engraved metal circleswith glass versions provided more accurate read-ings and better illumination-led to considerableexcitement in scientific and survey circles By thelate 1920s Wild was engaged in serial productionof the T2 and T3 theodolites the P3 phototheodo-lite and the A2 autograph which had replaced theAI In addition the Cl C2 and C3 aerial cam-eras were also in production In the space of onlyeight years Wild had become a major player in thesurvey world a position enhanced further duringthe 1930s

By the late 1920s the Landestopographie inSwitzerland had gained considerable experiencewith Wild instruments for both terrestrial andaerial surveys (Schneider 1929) Topographicmaps were produced from terrestrial photographyat 125000 while aerial photography wasused for110000 mapping (Schneider 1929 Harry 1971)

In the United States in addition to usinggraphical techniques the USGS started to inves-tigate instrumental methods In 1921 it obtaineda stereoautograph from Germany for evalua-tion but restricted the use of the instrument toplotting from terrestrial photography and notable to produce maps economically (Thompson1952) In 1927 the Geological Survey acquired theHugershoff aerocartograph the first automaticstereo-plotter used by an American governmentmapping agency (Thompson 1952) Thomas PPendleton laid down guidelines for mapping fromaerial photography within the USGS in Bulletin788-F Map Compilation from Aerial PhotograPhsissued as part of the Topographic Instructions of theUnited States Geological Survey (Pendleton 1928)Given the rapid developments in radial-line meth-ods (eg Hotine 1927) the timing of Pendletonswork was a bit unfortunate as he asserted thatradial-line techniques were really only suited foruse with multi-lens photography because therelatively short radial lines that could be drawnon single-lens photographs could not give the bestresults (Pendleton 1928 p 409)

In Britain research work carried out by the AirSurvey Committee focused on simple methods butthe Committee did not entirely ignore instrumen-tal techniques MacLeods wartime work with rec-tifiers was developed and more importantly theideas of Fourcade (l926a 1926b 1926c 1926d)on the theory and use of stereogoniometers forphotogrammetric plotters were taken up In 1926the Committee commissioned the constructionof an instrument along the lines proposed by

Vol 29 No3

Fourcade and the instrument was delivered in1928 0ar Office 1935 Hotine 1931)

In India success with non-instrumental tech-niques did not distract the Survey from instrumen-tal techniques they had helped pioneel- Mappingofficials followed developments taking place inEurope and in 1926 Mason (1927) carried outa survey in the Shaksgam using a Wild photo-theodolite and plotted the results in Switzerlandusing an autograph in the Topographical Instituteat Flums

CamerasThe tri-lens camera developed by Bagley was usedby the USGS in mapping for aeronautical chartsThis program wasjointly organized with the Corpsof Engineers and the Air Service (Committeeon Photographic Surveying 1921) and providedvaluable experience in civil applications In 1920programs with the tri-lens camera were also under-taken in Santo Domingo and Haiti

The Corps of Engineers became involved inphotogrammetric methods in 1920 when Bagleywas assigned to cooperate with the Army AirCorps in carrying out tests on aerial photographyfor topographic mapping Initially the trials usedBagleys tri-lens camera but he went on to developthe five lens T-3Acamera which was to remain thestandard mapping camera of the US Army until1940 (Landen 1952) The War Department issuedtraining regulations for mapping from aerialphotography in 1923 however the techniques dis-cussed in the regulations were largely those refinedduring World War 1

The 1930sBy the late 1920s photogrammetry had becomea cost-effective alternative to some traditionalground surveys Yet expensive photogrammetricplotting instruments and labor-intensive graphicalplotting meant that photogrammetry still lackeda decisive advantage over ground survey Duringthe 1930s a number of innovations were to swingthe balance decisivelyin favor of photogrammetricmethods

Progress was slowed if not stopped by the reces-sion that started in 1929 Some measure of theimpact can be gauged from job cutbacks at WildHeerbrugg In 1930 before the recession had amarked affect on Europe the workforce stood at260 but by 1933 the number ofjobs had droppedto 125This was the direct consequence of the deci-sions taken to retrench mapping projects as well as

167

capital programs Nearly all the annual reports forthe early 1930s mention the financial constraintsunder which organizations had to work In theUnited States some of these problems were offsetby appropriations under the Emergency Reliefand Construction Act (US Coast and GeodeticSurvey 1933) Moreover the New Deal initiated awide range of programs in which photogrammetrywas to playa major role By contrast problems inthe colonial territories were if anything worsethan in Europe and North America The declinein industrial activity in developed countries ledto a collapse in demand for raw materials fromthe colonies and as this was the main source ofgovernment revenue they could no longer pay forsurvey work Annual reports from most colonialsurvey departments make reference to a lack ofresources to meet the need for mapping Howevel~by the late 1930s as a result of rearmament inEurope governments allocated more money tosurvey organizations

Survey organizations were eager to adopt newtechniques in routine mapping programs but thepressures within governments to deal with massunemployment probably helped to promote theuse of labor-intensive methods in survey at theexpense of investment in technology Certainlyorganizations such as the Tennessee ValleyAuthority (TVA) the Agriculture AdjustmentAdministration and the Soil Conservation Servicein the United States were all heavily dependenton such labor-intensive techniques and did muchto develop them as standard mapping methodsMoreover organizations such as the USGS andthe TVA also played a role in the developmentinstrumental methods such as multiplex All ofthis was to be of vital importance to the hugephotogrammetric mapping programs that wereto emerge during World War II The scale of theseprograms would have been inconceivable withoutthe trained body of photogrammetrists developedduring the 1930s (Landen 1952)

Within the British colonial territories the conser-vative element that had inhibited the developmentof photogrammetric methods through the 1920scontinued to delay adoption of photogrammetryuntil after World War II-with some illuminatingexceptions Cyprus is the only known example ofa local survey department attempting to carry outphotogrammetric work Aerial photography wastaken in 1936 but delays in obtaining groundcontrol meant that no use was made of the pho-tography before all normal work was suspended atthe outbreak of war In all the other colonies wherephotogrammetry was attempted private survey

168

companies carried out the work The earliestexample of the involvement of private air surveycompanies had been in 1927 in the mapping ofthe Anglo-Belgian boundary in the Copper Beltregion of Northern Rhodesia (Colonial SurveyCommittee 1928) Private air survey companieswere also active in Uganda Tanganyika andSouthern Rhodesia but in all cases this was surveywork for specific development projects ratherthan routine mapping (War Office 1935) Therewere discussions about the use of photogramme-try in Sierra Leone where the Aircraft OperatingCompany of South Africa proposed to revise the162500 topographic maps for pound150000 includ-ing the cost of providing ground control but thework was never carried out due to financial con-straints and the outbreak of World War II Therewere also discussions about air survey in Jamaicaand the Gold Coast but nothing came of theseprojects until after World War II It is clear fromthe literature and correspondence of the time thatthe private air survey companies were lobbyingindividual colonial governments as well as theBritish Government to adopt air survey but theColonial Survey Committee under Winterbothamwas equally forceful in its resistance to changelargely on grounds of cost (see in particularWinterbotham 1920 1921 1929 1934 1936Hemming 1933)

Increasing recognition that war with Germanywas inevitable led to a significant change in theBritish establishments attitude towards the use ofair survey In part this change reflected the retire-ment of Winterbotham in 1935 and his replace-ment as Director General of the Ordnance Surveyby MacLeod who was alwaysa warm supporter ofair survey MacLeod had followed Winterbothamfirst as Director of Military Surveys and then atthe Ordnance Surveyand in each case he playeda major role in introducing the use of photogram-metry (Clough 1952)

Advances in InstrumentationThe late 1920s had seen the design and produc-tion of the first practical plotting machines for usewith aerial photography The experience provideda foundation for the introduction during the1930s of designs that were to be the mainstaysof topographic mapping The Zeiss C4 had beenintroduced in 1930 (Burnside 1993)AsThompson(1966) notes the C4 and the superseding C5(introduced in 1935 with improved illumination)were with the Wild A5 (launched in 1937) practi-cally the only universal instruments on the marketin the 1930s Universal instruments designed to

CartograPhy and GeograPhic Information Science

handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

Vol29 No3

graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

169

Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

170

world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

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Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

171

Graphical MethodsBecause of the extensive use of graphical methodsduring WorldWar I a large body of trained person-nel was available to implement these methods forpost-war mapping But the techniques developedthus far were either non-rigorous (for example theperspective grid) or suitable only for revising smallnumbers of features (the paper strip method)What was needed was a rigorous technique thatdid not require highly skilled workers

Bagley had sowed the seeds of a rigoroustechnique during his work with the PanoramicPhotoalidade (Bagley 1917) but Martin Hotine(1927) provided the theoretical and practicalbasis for a cost-effective mapping techniqueDescribed as a Simple Method of Surveying fromAir Photographs Hotines technique becameknown as the Arundel Method (after Arundelin southern England where the technique wasfirst used experimentally) or the radial-line tech-nique Hotine subsequently developed the methodof control extension using radial-line methods(Hotine 1929) and laid the foundations for muchof the medium-scale photogrammetric mappingcarried out in the English-speaking world over thenext 40 years The American development of slot-ted templets and radial intersectors expeditedthe process of aerotriangulation (see below) butit was Hotines theoretical work that made thesedevelopments possible

None of the countries using aerial photogra-phy for topographic mapping embraced it withgreater enthusiasm than India As noted earlierthe Survey of India had acquired two examplesof Thompsons stereo-plotter Kenneth Mason(1913 1927) had used the stereo-plotter in 1913in the Pamirs with considerable success but theexperience of the Survey of India in Mesopotamiaduring World War I wasdecisive in promoting airsurvey techniques in India In 1920 a series ofexperiments conducted at Agra demonstrated theutility of air survey methods for mapping flat areasin India (Lewis and Salmond 1920) Air surveyp~oved inefficient for one-inch-to-a-milemiddot map-pmg-the cost was roughly twice as much as forground surveys-but it was economical for largerscales An experiment in urban mapping was car-ried out but its results were inconclusive

Among developed countries the United Stateswas probably the most in need of the advantagesthat air survey offered post-war mapmakers Forall its great wealth America was poorly mappedby European standards Where most Europeancountries were at least mapped at medium scale(roughly 1100000 or larger) large tracts of the

J1J129 No3

United States were not mapped even at small scaleIt was at just this small-scale range that air surveyseemed to offer the greatest advantages

The work carried out within the USCampGSand USGS prior to and during World War I hadprepared both agencies to take advantage of theemerging technology Starting in 1919 USCampGSused aerial photography for chart revision(Quillian 1919 Mattison 1919) and for wetlandsurveys (Mattison 1924 Graham 1924-25) Someproblems were encountered but the particularadvantages of air survey for mapping wetlands ledto the technique becoming the standard procedure(Landen 1952) In carrying out these surveys theUSCampGSused photography supplied by the Navyand the Army Air Corps it was the Air Corpsmulti-lens camera that established the cost-effec-tiveness of air survey (Reading 1927-28) Withinthe USGS a quadrangle in Michigan was mappedusing a conventional single-lens camera using airsurvey for the planimetry only (Thompson 1952)In 1924 a Section of Photographic Mapping wasestablished as part of the Topographic Branch atUSGS

Terrestrial photogrammetric work had beenundertaken in Russia as early as 1891 (Koch1963) but few significant additional developmentsoccurred before 1920 In 1924 the State TechnicalOffice of Aerial Photographic Survey was estab-lished Its first task was the creation of mosaics at110000 for comparison with plane table surveysThe results were considered sufficiently favorablefor mapping at 15000 based on 112000 pho-tography An ambitious program of aerial pho-tography initiated in 1925 led to the coverage ofmore than 4500000 km2 by 1940 In 1928 theCentral Scientific Research Institute for GeodesyPhotogrammetry and Cartography (ZNIlGAiK)was established to oversee development across thewhole field of mapping (Koch 1963)

Instrumental MethodsAt the end of World War I Germany and theAustro-Hungarian Empire had a clear advan-tage in the development and use of instrumen-tal photogrammetric methods While Germanycontinued to enjoy a considerable lead in thesetechniques the collapse of the Dual Monarchy andthe resultant breakup of the MilitargeographischeInstitut meant that Austria entered a period ofrelative decline Zeiss which had become theciear ieader in the design and man-ufacture ofphotogrammetric instruments not only pro-duced instruments designed by both von Ore and

165

Pulfrich but employed several leading figures inphotogrammetry including Walter BauersfeldWilli Sander and Otto von Gruber This ensuredthat Zeiss was always at or near the forefront ofdevelopments in the field

During the 1920s most efforts were directedtoward overcoming the problem inherent in theearlier generation of photogrammetric plot-ters namely the need for the photographs tobe coplanar In 1926 Hugershoff designed anaerocartograph for use with both terrestrial andaerial photography The instrument which wasmanufactured by Heyde Company in Dresdentook advantage of the theoretical developmentsin orientation theory developed by Max Gasser(1923) and von Gruber (1924) The combinationof new orientation procedures and sophisticateddesign meant that Hugershoffs aerocartographcould be used for plotting and aerotriangulation(Blachut and Burkhardt 1989) Professional rivalryled von Gruber (1932) to dispute the original-ity of Hugershoffs design as he was also to dowith Heinrich Wilds instruments and the ideas ofFourcade

Zeiss had produced their stereoplanigraph(the Cl) in 1921 based on an earlier design ofBauersfeld However it was not until the pro-duction of the C4 in 1930 that Zeiss producedan instrument that could handle both terrestrialand aerial photography Some successful mappingfrom the earlier models was reported throughthe 1920s by the Reichsamt fur Landesaufnahmewhich had a C2 (Seidel 1928) and the GeodeticInstitute in Stuttgart which had a C3 (von Gruber1932) Most of the mapping was at 15000 butscales as small as ] 20000 are reported Even inGermany systematic mapping programs usingphotogrammetry were still the exception ratherthan the rule during the 1920s

In France the Service Geographique de lArmeehad been actively experimenting with instrumen-tal photogrammetry before World War I (Bonnet1920) and had also used the technique for someterrestrial work during the war France was thuswell placed at the end of the war to keep upwith the developments elsewhere in Europe TheService had decided that terrestrial photogram-metry was best suited to 120000 mapping in highmountain areas but considered the equipment toocumbersome and imprecise for reconnaissancesurveys (Service Geographique de lArmee 1912)In 1919 a start was made on mapping in Moroccousing panoramic aerial photographs (ServiceGeographique de IArmee ]936) but the main

166

drive in France was to develop an autonomouscapability in instrumental photogrammetry

Some equipment had been developed duringthe war notably the Chambre Claire Varon andthe Appareil de photorestitution Roussilhe aninstrument for partial rectification of cadastralplans (Blachut and Burkhardt 1989 ServiceGeographique de IArmee ]936) The mostimportant development came in 1922 when thefirst Georges Poivilliers instrument was built(Poivilliers 1922 Blachut and Burkhardt 1989)Poivilliers instruments were to provide the bulkof the photogrammetric capability of the Servicewith up to four different types in use at anyonetime (Institut Geographique National 1947)Other instruments were also used largely on anexperimental basis In the mid] 920s the stereor-estituteur Boucard was in use and in the I930s aGallus Ferber instrument was used experimentally(Service Geographique de lArmee 1938) withthe latter (Blachut and Burkhardt 1989) remain-ing in service until at least the 1940s (InstitutGeographique National 1947)

Italy had been actively engaged in photogram-metry in the nineteenth century with the work ofPorro but as Blachut and Burkhardt (1989) notethe Istituto Geografico Militare showed little inter-est in the technique until many years after Porrosdeath in 1875 The resurrection of Italian photo-grammetry was largely due to two men UmbertoNistri who designed aplotter in 1919for large-scaleplotting and Ermenegildo Santoni who producedhis first instrument the autoreductor in 1921 In1926 Nistri founded the firm Ottico MeccanicaItaliana (OMI) to produce his photogrammetricinstruments Nistris early instruments all useddirect optical projection while Santonis instru-ments all used mechanical projection The IstitutoGeografico Militare was middotequipped with Santoniinstruments which it used for mapping at 125000and 110000 The Societa Anonima RilevamentiAerofotogrammetrici (SARA)on the other handused Nistri instruments largely for topographicmapptng outside Italy but also for cadastral map-ping within the country

Photogrammetry had been used in Switzerlandfor engineering surveys in the nineteenth centuryyet there had been no systematic attempt to carryout topographic mapping using the techniqueThe history of mapping in Switzerland betweenthe two world wars is largely a history of the WildHeerbrugg Company Set up in 1921 the com-pany produced its first phototheodolite in 1922and its first photogrammetric plotter the Alstereo-autograph in 1923 Its first major contribu-

Cartography and Geographic Information Science

tion to surveying came with the production of theT2 theodolite in 1924 The revolutionary design ofthis instrument-replacing engraved metal circleswith glass versions provided more accurate read-ings and better illumination-led to considerableexcitement in scientific and survey circles By thelate 1920s Wild was engaged in serial productionof the T2 and T3 theodolites the P3 phototheodo-lite and the A2 autograph which had replaced theAI In addition the Cl C2 and C3 aerial cam-eras were also in production In the space of onlyeight years Wild had become a major player in thesurvey world a position enhanced further duringthe 1930s

By the late 1920s the Landestopographie inSwitzerland had gained considerable experiencewith Wild instruments for both terrestrial andaerial surveys (Schneider 1929) Topographicmaps were produced from terrestrial photographyat 125000 while aerial photography wasused for110000 mapping (Schneider 1929 Harry 1971)

In the United States in addition to usinggraphical techniques the USGS started to inves-tigate instrumental methods In 1921 it obtaineda stereoautograph from Germany for evalua-tion but restricted the use of the instrument toplotting from terrestrial photography and notable to produce maps economically (Thompson1952) In 1927 the Geological Survey acquired theHugershoff aerocartograph the first automaticstereo-plotter used by an American governmentmapping agency (Thompson 1952) Thomas PPendleton laid down guidelines for mapping fromaerial photography within the USGS in Bulletin788-F Map Compilation from Aerial PhotograPhsissued as part of the Topographic Instructions of theUnited States Geological Survey (Pendleton 1928)Given the rapid developments in radial-line meth-ods (eg Hotine 1927) the timing of Pendletonswork was a bit unfortunate as he asserted thatradial-line techniques were really only suited foruse with multi-lens photography because therelatively short radial lines that could be drawnon single-lens photographs could not give the bestresults (Pendleton 1928 p 409)

In Britain research work carried out by the AirSurvey Committee focused on simple methods butthe Committee did not entirely ignore instrumen-tal techniques MacLeods wartime work with rec-tifiers was developed and more importantly theideas of Fourcade (l926a 1926b 1926c 1926d)on the theory and use of stereogoniometers forphotogrammetric plotters were taken up In 1926the Committee commissioned the constructionof an instrument along the lines proposed by

Vol 29 No3

Fourcade and the instrument was delivered in1928 0ar Office 1935 Hotine 1931)

In India success with non-instrumental tech-niques did not distract the Survey from instrumen-tal techniques they had helped pioneel- Mappingofficials followed developments taking place inEurope and in 1926 Mason (1927) carried outa survey in the Shaksgam using a Wild photo-theodolite and plotted the results in Switzerlandusing an autograph in the Topographical Instituteat Flums

CamerasThe tri-lens camera developed by Bagley was usedby the USGS in mapping for aeronautical chartsThis program wasjointly organized with the Corpsof Engineers and the Air Service (Committeeon Photographic Surveying 1921) and providedvaluable experience in civil applications In 1920programs with the tri-lens camera were also under-taken in Santo Domingo and Haiti

The Corps of Engineers became involved inphotogrammetric methods in 1920 when Bagleywas assigned to cooperate with the Army AirCorps in carrying out tests on aerial photographyfor topographic mapping Initially the trials usedBagleys tri-lens camera but he went on to developthe five lens T-3Acamera which was to remain thestandard mapping camera of the US Army until1940 (Landen 1952) The War Department issuedtraining regulations for mapping from aerialphotography in 1923 however the techniques dis-cussed in the regulations were largely those refinedduring World War 1

The 1930sBy the late 1920s photogrammetry had becomea cost-effective alternative to some traditionalground surveys Yet expensive photogrammetricplotting instruments and labor-intensive graphicalplotting meant that photogrammetry still lackeda decisive advantage over ground survey Duringthe 1930s a number of innovations were to swingthe balance decisivelyin favor of photogrammetricmethods

Progress was slowed if not stopped by the reces-sion that started in 1929 Some measure of theimpact can be gauged from job cutbacks at WildHeerbrugg In 1930 before the recession had amarked affect on Europe the workforce stood at260 but by 1933 the number ofjobs had droppedto 125This was the direct consequence of the deci-sions taken to retrench mapping projects as well as

167

capital programs Nearly all the annual reports forthe early 1930s mention the financial constraintsunder which organizations had to work In theUnited States some of these problems were offsetby appropriations under the Emergency Reliefand Construction Act (US Coast and GeodeticSurvey 1933) Moreover the New Deal initiated awide range of programs in which photogrammetrywas to playa major role By contrast problems inthe colonial territories were if anything worsethan in Europe and North America The declinein industrial activity in developed countries ledto a collapse in demand for raw materials fromthe colonies and as this was the main source ofgovernment revenue they could no longer pay forsurvey work Annual reports from most colonialsurvey departments make reference to a lack ofresources to meet the need for mapping Howevel~by the late 1930s as a result of rearmament inEurope governments allocated more money tosurvey organizations

Survey organizations were eager to adopt newtechniques in routine mapping programs but thepressures within governments to deal with massunemployment probably helped to promote theuse of labor-intensive methods in survey at theexpense of investment in technology Certainlyorganizations such as the Tennessee ValleyAuthority (TVA) the Agriculture AdjustmentAdministration and the Soil Conservation Servicein the United States were all heavily dependenton such labor-intensive techniques and did muchto develop them as standard mapping methodsMoreover organizations such as the USGS andthe TVA also played a role in the developmentinstrumental methods such as multiplex All ofthis was to be of vital importance to the hugephotogrammetric mapping programs that wereto emerge during World War II The scale of theseprograms would have been inconceivable withoutthe trained body of photogrammetrists developedduring the 1930s (Landen 1952)

Within the British colonial territories the conser-vative element that had inhibited the developmentof photogrammetric methods through the 1920scontinued to delay adoption of photogrammetryuntil after World War II-with some illuminatingexceptions Cyprus is the only known example ofa local survey department attempting to carry outphotogrammetric work Aerial photography wastaken in 1936 but delays in obtaining groundcontrol meant that no use was made of the pho-tography before all normal work was suspended atthe outbreak of war In all the other colonies wherephotogrammetry was attempted private survey

168

companies carried out the work The earliestexample of the involvement of private air surveycompanies had been in 1927 in the mapping ofthe Anglo-Belgian boundary in the Copper Beltregion of Northern Rhodesia (Colonial SurveyCommittee 1928) Private air survey companieswere also active in Uganda Tanganyika andSouthern Rhodesia but in all cases this was surveywork for specific development projects ratherthan routine mapping (War Office 1935) Therewere discussions about the use of photogramme-try in Sierra Leone where the Aircraft OperatingCompany of South Africa proposed to revise the162500 topographic maps for pound150000 includ-ing the cost of providing ground control but thework was never carried out due to financial con-straints and the outbreak of World War II Therewere also discussions about air survey in Jamaicaand the Gold Coast but nothing came of theseprojects until after World War II It is clear fromthe literature and correspondence of the time thatthe private air survey companies were lobbyingindividual colonial governments as well as theBritish Government to adopt air survey but theColonial Survey Committee under Winterbothamwas equally forceful in its resistance to changelargely on grounds of cost (see in particularWinterbotham 1920 1921 1929 1934 1936Hemming 1933)

Increasing recognition that war with Germanywas inevitable led to a significant change in theBritish establishments attitude towards the use ofair survey In part this change reflected the retire-ment of Winterbotham in 1935 and his replace-ment as Director General of the Ordnance Surveyby MacLeod who was alwaysa warm supporter ofair survey MacLeod had followed Winterbothamfirst as Director of Military Surveys and then atthe Ordnance Surveyand in each case he playeda major role in introducing the use of photogram-metry (Clough 1952)

Advances in InstrumentationThe late 1920s had seen the design and produc-tion of the first practical plotting machines for usewith aerial photography The experience provideda foundation for the introduction during the1930s of designs that were to be the mainstaysof topographic mapping The Zeiss C4 had beenintroduced in 1930 (Burnside 1993)AsThompson(1966) notes the C4 and the superseding C5(introduced in 1935 with improved illumination)were with the Wild A5 (launched in 1937) practi-cally the only universal instruments on the marketin the 1930s Universal instruments designed to

CartograPhy and GeograPhic Information Science

handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

Vol29 No3

graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

169

Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

170

world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

1J129 No3

Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

171

Pulfrich but employed several leading figures inphotogrammetry including Walter BauersfeldWilli Sander and Otto von Gruber This ensuredthat Zeiss was always at or near the forefront ofdevelopments in the field

During the 1920s most efforts were directedtoward overcoming the problem inherent in theearlier generation of photogrammetric plot-ters namely the need for the photographs tobe coplanar In 1926 Hugershoff designed anaerocartograph for use with both terrestrial andaerial photography The instrument which wasmanufactured by Heyde Company in Dresdentook advantage of the theoretical developmentsin orientation theory developed by Max Gasser(1923) and von Gruber (1924) The combinationof new orientation procedures and sophisticateddesign meant that Hugershoffs aerocartographcould be used for plotting and aerotriangulation(Blachut and Burkhardt 1989) Professional rivalryled von Gruber (1932) to dispute the original-ity of Hugershoffs design as he was also to dowith Heinrich Wilds instruments and the ideas ofFourcade

Zeiss had produced their stereoplanigraph(the Cl) in 1921 based on an earlier design ofBauersfeld However it was not until the pro-duction of the C4 in 1930 that Zeiss producedan instrument that could handle both terrestrialand aerial photography Some successful mappingfrom the earlier models was reported throughthe 1920s by the Reichsamt fur Landesaufnahmewhich had a C2 (Seidel 1928) and the GeodeticInstitute in Stuttgart which had a C3 (von Gruber1932) Most of the mapping was at 15000 butscales as small as ] 20000 are reported Even inGermany systematic mapping programs usingphotogrammetry were still the exception ratherthan the rule during the 1920s

In France the Service Geographique de lArmeehad been actively experimenting with instrumen-tal photogrammetry before World War I (Bonnet1920) and had also used the technique for someterrestrial work during the war France was thuswell placed at the end of the war to keep upwith the developments elsewhere in Europe TheService had decided that terrestrial photogram-metry was best suited to 120000 mapping in highmountain areas but considered the equipment toocumbersome and imprecise for reconnaissancesurveys (Service Geographique de lArmee 1912)In 1919 a start was made on mapping in Moroccousing panoramic aerial photographs (ServiceGeographique de IArmee ]936) but the main

166

drive in France was to develop an autonomouscapability in instrumental photogrammetry

Some equipment had been developed duringthe war notably the Chambre Claire Varon andthe Appareil de photorestitution Roussilhe aninstrument for partial rectification of cadastralplans (Blachut and Burkhardt 1989 ServiceGeographique de IArmee ]936) The mostimportant development came in 1922 when thefirst Georges Poivilliers instrument was built(Poivilliers 1922 Blachut and Burkhardt 1989)Poivilliers instruments were to provide the bulkof the photogrammetric capability of the Servicewith up to four different types in use at anyonetime (Institut Geographique National 1947)Other instruments were also used largely on anexperimental basis In the mid] 920s the stereor-estituteur Boucard was in use and in the I930s aGallus Ferber instrument was used experimentally(Service Geographique de lArmee 1938) withthe latter (Blachut and Burkhardt 1989) remain-ing in service until at least the 1940s (InstitutGeographique National 1947)

Italy had been actively engaged in photogram-metry in the nineteenth century with the work ofPorro but as Blachut and Burkhardt (1989) notethe Istituto Geografico Militare showed little inter-est in the technique until many years after Porrosdeath in 1875 The resurrection of Italian photo-grammetry was largely due to two men UmbertoNistri who designed aplotter in 1919for large-scaleplotting and Ermenegildo Santoni who producedhis first instrument the autoreductor in 1921 In1926 Nistri founded the firm Ottico MeccanicaItaliana (OMI) to produce his photogrammetricinstruments Nistris early instruments all useddirect optical projection while Santonis instru-ments all used mechanical projection The IstitutoGeografico Militare was middotequipped with Santoniinstruments which it used for mapping at 125000and 110000 The Societa Anonima RilevamentiAerofotogrammetrici (SARA)on the other handused Nistri instruments largely for topographicmapptng outside Italy but also for cadastral map-ping within the country

Photogrammetry had been used in Switzerlandfor engineering surveys in the nineteenth centuryyet there had been no systematic attempt to carryout topographic mapping using the techniqueThe history of mapping in Switzerland betweenthe two world wars is largely a history of the WildHeerbrugg Company Set up in 1921 the com-pany produced its first phototheodolite in 1922and its first photogrammetric plotter the Alstereo-autograph in 1923 Its first major contribu-

Cartography and Geographic Information Science

tion to surveying came with the production of theT2 theodolite in 1924 The revolutionary design ofthis instrument-replacing engraved metal circleswith glass versions provided more accurate read-ings and better illumination-led to considerableexcitement in scientific and survey circles By thelate 1920s Wild was engaged in serial productionof the T2 and T3 theodolites the P3 phototheodo-lite and the A2 autograph which had replaced theAI In addition the Cl C2 and C3 aerial cam-eras were also in production In the space of onlyeight years Wild had become a major player in thesurvey world a position enhanced further duringthe 1930s

By the late 1920s the Landestopographie inSwitzerland had gained considerable experiencewith Wild instruments for both terrestrial andaerial surveys (Schneider 1929) Topographicmaps were produced from terrestrial photographyat 125000 while aerial photography wasused for110000 mapping (Schneider 1929 Harry 1971)

In the United States in addition to usinggraphical techniques the USGS started to inves-tigate instrumental methods In 1921 it obtaineda stereoautograph from Germany for evalua-tion but restricted the use of the instrument toplotting from terrestrial photography and notable to produce maps economically (Thompson1952) In 1927 the Geological Survey acquired theHugershoff aerocartograph the first automaticstereo-plotter used by an American governmentmapping agency (Thompson 1952) Thomas PPendleton laid down guidelines for mapping fromaerial photography within the USGS in Bulletin788-F Map Compilation from Aerial PhotograPhsissued as part of the Topographic Instructions of theUnited States Geological Survey (Pendleton 1928)Given the rapid developments in radial-line meth-ods (eg Hotine 1927) the timing of Pendletonswork was a bit unfortunate as he asserted thatradial-line techniques were really only suited foruse with multi-lens photography because therelatively short radial lines that could be drawnon single-lens photographs could not give the bestresults (Pendleton 1928 p 409)

In Britain research work carried out by the AirSurvey Committee focused on simple methods butthe Committee did not entirely ignore instrumen-tal techniques MacLeods wartime work with rec-tifiers was developed and more importantly theideas of Fourcade (l926a 1926b 1926c 1926d)on the theory and use of stereogoniometers forphotogrammetric plotters were taken up In 1926the Committee commissioned the constructionof an instrument along the lines proposed by

Vol 29 No3

Fourcade and the instrument was delivered in1928 0ar Office 1935 Hotine 1931)

In India success with non-instrumental tech-niques did not distract the Survey from instrumen-tal techniques they had helped pioneel- Mappingofficials followed developments taking place inEurope and in 1926 Mason (1927) carried outa survey in the Shaksgam using a Wild photo-theodolite and plotted the results in Switzerlandusing an autograph in the Topographical Instituteat Flums

CamerasThe tri-lens camera developed by Bagley was usedby the USGS in mapping for aeronautical chartsThis program wasjointly organized with the Corpsof Engineers and the Air Service (Committeeon Photographic Surveying 1921) and providedvaluable experience in civil applications In 1920programs with the tri-lens camera were also under-taken in Santo Domingo and Haiti

The Corps of Engineers became involved inphotogrammetric methods in 1920 when Bagleywas assigned to cooperate with the Army AirCorps in carrying out tests on aerial photographyfor topographic mapping Initially the trials usedBagleys tri-lens camera but he went on to developthe five lens T-3Acamera which was to remain thestandard mapping camera of the US Army until1940 (Landen 1952) The War Department issuedtraining regulations for mapping from aerialphotography in 1923 however the techniques dis-cussed in the regulations were largely those refinedduring World War 1

The 1930sBy the late 1920s photogrammetry had becomea cost-effective alternative to some traditionalground surveys Yet expensive photogrammetricplotting instruments and labor-intensive graphicalplotting meant that photogrammetry still lackeda decisive advantage over ground survey Duringthe 1930s a number of innovations were to swingthe balance decisivelyin favor of photogrammetricmethods

Progress was slowed if not stopped by the reces-sion that started in 1929 Some measure of theimpact can be gauged from job cutbacks at WildHeerbrugg In 1930 before the recession had amarked affect on Europe the workforce stood at260 but by 1933 the number ofjobs had droppedto 125This was the direct consequence of the deci-sions taken to retrench mapping projects as well as

167

capital programs Nearly all the annual reports forthe early 1930s mention the financial constraintsunder which organizations had to work In theUnited States some of these problems were offsetby appropriations under the Emergency Reliefand Construction Act (US Coast and GeodeticSurvey 1933) Moreover the New Deal initiated awide range of programs in which photogrammetrywas to playa major role By contrast problems inthe colonial territories were if anything worsethan in Europe and North America The declinein industrial activity in developed countries ledto a collapse in demand for raw materials fromthe colonies and as this was the main source ofgovernment revenue they could no longer pay forsurvey work Annual reports from most colonialsurvey departments make reference to a lack ofresources to meet the need for mapping Howevel~by the late 1930s as a result of rearmament inEurope governments allocated more money tosurvey organizations

Survey organizations were eager to adopt newtechniques in routine mapping programs but thepressures within governments to deal with massunemployment probably helped to promote theuse of labor-intensive methods in survey at theexpense of investment in technology Certainlyorganizations such as the Tennessee ValleyAuthority (TVA) the Agriculture AdjustmentAdministration and the Soil Conservation Servicein the United States were all heavily dependenton such labor-intensive techniques and did muchto develop them as standard mapping methodsMoreover organizations such as the USGS andthe TVA also played a role in the developmentinstrumental methods such as multiplex All ofthis was to be of vital importance to the hugephotogrammetric mapping programs that wereto emerge during World War II The scale of theseprograms would have been inconceivable withoutthe trained body of photogrammetrists developedduring the 1930s (Landen 1952)

Within the British colonial territories the conser-vative element that had inhibited the developmentof photogrammetric methods through the 1920scontinued to delay adoption of photogrammetryuntil after World War II-with some illuminatingexceptions Cyprus is the only known example ofa local survey department attempting to carry outphotogrammetric work Aerial photography wastaken in 1936 but delays in obtaining groundcontrol meant that no use was made of the pho-tography before all normal work was suspended atthe outbreak of war In all the other colonies wherephotogrammetry was attempted private survey

168

companies carried out the work The earliestexample of the involvement of private air surveycompanies had been in 1927 in the mapping ofthe Anglo-Belgian boundary in the Copper Beltregion of Northern Rhodesia (Colonial SurveyCommittee 1928) Private air survey companieswere also active in Uganda Tanganyika andSouthern Rhodesia but in all cases this was surveywork for specific development projects ratherthan routine mapping (War Office 1935) Therewere discussions about the use of photogramme-try in Sierra Leone where the Aircraft OperatingCompany of South Africa proposed to revise the162500 topographic maps for pound150000 includ-ing the cost of providing ground control but thework was never carried out due to financial con-straints and the outbreak of World War II Therewere also discussions about air survey in Jamaicaand the Gold Coast but nothing came of theseprojects until after World War II It is clear fromthe literature and correspondence of the time thatthe private air survey companies were lobbyingindividual colonial governments as well as theBritish Government to adopt air survey but theColonial Survey Committee under Winterbothamwas equally forceful in its resistance to changelargely on grounds of cost (see in particularWinterbotham 1920 1921 1929 1934 1936Hemming 1933)

Increasing recognition that war with Germanywas inevitable led to a significant change in theBritish establishments attitude towards the use ofair survey In part this change reflected the retire-ment of Winterbotham in 1935 and his replace-ment as Director General of the Ordnance Surveyby MacLeod who was alwaysa warm supporter ofair survey MacLeod had followed Winterbothamfirst as Director of Military Surveys and then atthe Ordnance Surveyand in each case he playeda major role in introducing the use of photogram-metry (Clough 1952)

Advances in InstrumentationThe late 1920s had seen the design and produc-tion of the first practical plotting machines for usewith aerial photography The experience provideda foundation for the introduction during the1930s of designs that were to be the mainstaysof topographic mapping The Zeiss C4 had beenintroduced in 1930 (Burnside 1993)AsThompson(1966) notes the C4 and the superseding C5(introduced in 1935 with improved illumination)were with the Wild A5 (launched in 1937) practi-cally the only universal instruments on the marketin the 1930s Universal instruments designed to

CartograPhy and GeograPhic Information Science

handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

Vol29 No3

graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

169

Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

170

world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

1J129 No3

Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

171

tion to surveying came with the production of theT2 theodolite in 1924 The revolutionary design ofthis instrument-replacing engraved metal circleswith glass versions provided more accurate read-ings and better illumination-led to considerableexcitement in scientific and survey circles By thelate 1920s Wild was engaged in serial productionof the T2 and T3 theodolites the P3 phototheodo-lite and the A2 autograph which had replaced theAI In addition the Cl C2 and C3 aerial cam-eras were also in production In the space of onlyeight years Wild had become a major player in thesurvey world a position enhanced further duringthe 1930s

By the late 1920s the Landestopographie inSwitzerland had gained considerable experiencewith Wild instruments for both terrestrial andaerial surveys (Schneider 1929) Topographicmaps were produced from terrestrial photographyat 125000 while aerial photography wasused for110000 mapping (Schneider 1929 Harry 1971)

In the United States in addition to usinggraphical techniques the USGS started to inves-tigate instrumental methods In 1921 it obtaineda stereoautograph from Germany for evalua-tion but restricted the use of the instrument toplotting from terrestrial photography and notable to produce maps economically (Thompson1952) In 1927 the Geological Survey acquired theHugershoff aerocartograph the first automaticstereo-plotter used by an American governmentmapping agency (Thompson 1952) Thomas PPendleton laid down guidelines for mapping fromaerial photography within the USGS in Bulletin788-F Map Compilation from Aerial PhotograPhsissued as part of the Topographic Instructions of theUnited States Geological Survey (Pendleton 1928)Given the rapid developments in radial-line meth-ods (eg Hotine 1927) the timing of Pendletonswork was a bit unfortunate as he asserted thatradial-line techniques were really only suited foruse with multi-lens photography because therelatively short radial lines that could be drawnon single-lens photographs could not give the bestresults (Pendleton 1928 p 409)

In Britain research work carried out by the AirSurvey Committee focused on simple methods butthe Committee did not entirely ignore instrumen-tal techniques MacLeods wartime work with rec-tifiers was developed and more importantly theideas of Fourcade (l926a 1926b 1926c 1926d)on the theory and use of stereogoniometers forphotogrammetric plotters were taken up In 1926the Committee commissioned the constructionof an instrument along the lines proposed by

Vol 29 No3

Fourcade and the instrument was delivered in1928 0ar Office 1935 Hotine 1931)

In India success with non-instrumental tech-niques did not distract the Survey from instrumen-tal techniques they had helped pioneel- Mappingofficials followed developments taking place inEurope and in 1926 Mason (1927) carried outa survey in the Shaksgam using a Wild photo-theodolite and plotted the results in Switzerlandusing an autograph in the Topographical Instituteat Flums

CamerasThe tri-lens camera developed by Bagley was usedby the USGS in mapping for aeronautical chartsThis program wasjointly organized with the Corpsof Engineers and the Air Service (Committeeon Photographic Surveying 1921) and providedvaluable experience in civil applications In 1920programs with the tri-lens camera were also under-taken in Santo Domingo and Haiti

The Corps of Engineers became involved inphotogrammetric methods in 1920 when Bagleywas assigned to cooperate with the Army AirCorps in carrying out tests on aerial photographyfor topographic mapping Initially the trials usedBagleys tri-lens camera but he went on to developthe five lens T-3Acamera which was to remain thestandard mapping camera of the US Army until1940 (Landen 1952) The War Department issuedtraining regulations for mapping from aerialphotography in 1923 however the techniques dis-cussed in the regulations were largely those refinedduring World War 1

The 1930sBy the late 1920s photogrammetry had becomea cost-effective alternative to some traditionalground surveys Yet expensive photogrammetricplotting instruments and labor-intensive graphicalplotting meant that photogrammetry still lackeda decisive advantage over ground survey Duringthe 1930s a number of innovations were to swingthe balance decisivelyin favor of photogrammetricmethods

Progress was slowed if not stopped by the reces-sion that started in 1929 Some measure of theimpact can be gauged from job cutbacks at WildHeerbrugg In 1930 before the recession had amarked affect on Europe the workforce stood at260 but by 1933 the number ofjobs had droppedto 125This was the direct consequence of the deci-sions taken to retrench mapping projects as well as

167

capital programs Nearly all the annual reports forthe early 1930s mention the financial constraintsunder which organizations had to work In theUnited States some of these problems were offsetby appropriations under the Emergency Reliefand Construction Act (US Coast and GeodeticSurvey 1933) Moreover the New Deal initiated awide range of programs in which photogrammetrywas to playa major role By contrast problems inthe colonial territories were if anything worsethan in Europe and North America The declinein industrial activity in developed countries ledto a collapse in demand for raw materials fromthe colonies and as this was the main source ofgovernment revenue they could no longer pay forsurvey work Annual reports from most colonialsurvey departments make reference to a lack ofresources to meet the need for mapping Howevel~by the late 1930s as a result of rearmament inEurope governments allocated more money tosurvey organizations

Survey organizations were eager to adopt newtechniques in routine mapping programs but thepressures within governments to deal with massunemployment probably helped to promote theuse of labor-intensive methods in survey at theexpense of investment in technology Certainlyorganizations such as the Tennessee ValleyAuthority (TVA) the Agriculture AdjustmentAdministration and the Soil Conservation Servicein the United States were all heavily dependenton such labor-intensive techniques and did muchto develop them as standard mapping methodsMoreover organizations such as the USGS andthe TVA also played a role in the developmentinstrumental methods such as multiplex All ofthis was to be of vital importance to the hugephotogrammetric mapping programs that wereto emerge during World War II The scale of theseprograms would have been inconceivable withoutthe trained body of photogrammetrists developedduring the 1930s (Landen 1952)

Within the British colonial territories the conser-vative element that had inhibited the developmentof photogrammetric methods through the 1920scontinued to delay adoption of photogrammetryuntil after World War II-with some illuminatingexceptions Cyprus is the only known example ofa local survey department attempting to carry outphotogrammetric work Aerial photography wastaken in 1936 but delays in obtaining groundcontrol meant that no use was made of the pho-tography before all normal work was suspended atthe outbreak of war In all the other colonies wherephotogrammetry was attempted private survey

168

companies carried out the work The earliestexample of the involvement of private air surveycompanies had been in 1927 in the mapping ofthe Anglo-Belgian boundary in the Copper Beltregion of Northern Rhodesia (Colonial SurveyCommittee 1928) Private air survey companieswere also active in Uganda Tanganyika andSouthern Rhodesia but in all cases this was surveywork for specific development projects ratherthan routine mapping (War Office 1935) Therewere discussions about the use of photogramme-try in Sierra Leone where the Aircraft OperatingCompany of South Africa proposed to revise the162500 topographic maps for pound150000 includ-ing the cost of providing ground control but thework was never carried out due to financial con-straints and the outbreak of World War II Therewere also discussions about air survey in Jamaicaand the Gold Coast but nothing came of theseprojects until after World War II It is clear fromthe literature and correspondence of the time thatthe private air survey companies were lobbyingindividual colonial governments as well as theBritish Government to adopt air survey but theColonial Survey Committee under Winterbothamwas equally forceful in its resistance to changelargely on grounds of cost (see in particularWinterbotham 1920 1921 1929 1934 1936Hemming 1933)

Increasing recognition that war with Germanywas inevitable led to a significant change in theBritish establishments attitude towards the use ofair survey In part this change reflected the retire-ment of Winterbotham in 1935 and his replace-ment as Director General of the Ordnance Surveyby MacLeod who was alwaysa warm supporter ofair survey MacLeod had followed Winterbothamfirst as Director of Military Surveys and then atthe Ordnance Surveyand in each case he playeda major role in introducing the use of photogram-metry (Clough 1952)

Advances in InstrumentationThe late 1920s had seen the design and produc-tion of the first practical plotting machines for usewith aerial photography The experience provideda foundation for the introduction during the1930s of designs that were to be the mainstaysof topographic mapping The Zeiss C4 had beenintroduced in 1930 (Burnside 1993)AsThompson(1966) notes the C4 and the superseding C5(introduced in 1935 with improved illumination)were with the Wild A5 (launched in 1937) practi-cally the only universal instruments on the marketin the 1930s Universal instruments designed to

CartograPhy and GeograPhic Information Science

handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

Vol29 No3

graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

169

Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

170

world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

1J129 No3

Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

171

capital programs Nearly all the annual reports forthe early 1930s mention the financial constraintsunder which organizations had to work In theUnited States some of these problems were offsetby appropriations under the Emergency Reliefand Construction Act (US Coast and GeodeticSurvey 1933) Moreover the New Deal initiated awide range of programs in which photogrammetrywas to playa major role By contrast problems inthe colonial territories were if anything worsethan in Europe and North America The declinein industrial activity in developed countries ledto a collapse in demand for raw materials fromthe colonies and as this was the main source ofgovernment revenue they could no longer pay forsurvey work Annual reports from most colonialsurvey departments make reference to a lack ofresources to meet the need for mapping Howevel~by the late 1930s as a result of rearmament inEurope governments allocated more money tosurvey organizations

Survey organizations were eager to adopt newtechniques in routine mapping programs but thepressures within governments to deal with massunemployment probably helped to promote theuse of labor-intensive methods in survey at theexpense of investment in technology Certainlyorganizations such as the Tennessee ValleyAuthority (TVA) the Agriculture AdjustmentAdministration and the Soil Conservation Servicein the United States were all heavily dependenton such labor-intensive techniques and did muchto develop them as standard mapping methodsMoreover organizations such as the USGS andthe TVA also played a role in the developmentinstrumental methods such as multiplex All ofthis was to be of vital importance to the hugephotogrammetric mapping programs that wereto emerge during World War II The scale of theseprograms would have been inconceivable withoutthe trained body of photogrammetrists developedduring the 1930s (Landen 1952)

Within the British colonial territories the conser-vative element that had inhibited the developmentof photogrammetric methods through the 1920scontinued to delay adoption of photogrammetryuntil after World War II-with some illuminatingexceptions Cyprus is the only known example ofa local survey department attempting to carry outphotogrammetric work Aerial photography wastaken in 1936 but delays in obtaining groundcontrol meant that no use was made of the pho-tography before all normal work was suspended atthe outbreak of war In all the other colonies wherephotogrammetry was attempted private survey

168

companies carried out the work The earliestexample of the involvement of private air surveycompanies had been in 1927 in the mapping ofthe Anglo-Belgian boundary in the Copper Beltregion of Northern Rhodesia (Colonial SurveyCommittee 1928) Private air survey companieswere also active in Uganda Tanganyika andSouthern Rhodesia but in all cases this was surveywork for specific development projects ratherthan routine mapping (War Office 1935) Therewere discussions about the use of photogramme-try in Sierra Leone where the Aircraft OperatingCompany of South Africa proposed to revise the162500 topographic maps for pound150000 includ-ing the cost of providing ground control but thework was never carried out due to financial con-straints and the outbreak of World War II Therewere also discussions about air survey in Jamaicaand the Gold Coast but nothing came of theseprojects until after World War II It is clear fromthe literature and correspondence of the time thatthe private air survey companies were lobbyingindividual colonial governments as well as theBritish Government to adopt air survey but theColonial Survey Committee under Winterbothamwas equally forceful in its resistance to changelargely on grounds of cost (see in particularWinterbotham 1920 1921 1929 1934 1936Hemming 1933)

Increasing recognition that war with Germanywas inevitable led to a significant change in theBritish establishments attitude towards the use ofair survey In part this change reflected the retire-ment of Winterbotham in 1935 and his replace-ment as Director General of the Ordnance Surveyby MacLeod who was alwaysa warm supporter ofair survey MacLeod had followed Winterbothamfirst as Director of Military Surveys and then atthe Ordnance Surveyand in each case he playeda major role in introducing the use of photogram-metry (Clough 1952)

Advances in InstrumentationThe late 1920s had seen the design and produc-tion of the first practical plotting machines for usewith aerial photography The experience provideda foundation for the introduction during the1930s of designs that were to be the mainstaysof topographic mapping The Zeiss C4 had beenintroduced in 1930 (Burnside 1993)AsThompson(1966) notes the C4 and the superseding C5(introduced in 1935 with improved illumination)were with the Wild A5 (launched in 1937) practi-cally the only universal instruments on the marketin the 1930s Universal instruments designed to

CartograPhy and GeograPhic Information Science

handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

Vol29 No3

graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

169

Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

170

world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

1J129 No3

Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

171

handle all kinds of photography could also beused in aerial triangulation The Wild A5 (Figure2) was to be one of the most successful first orderplotters used for large-scale mapping until it wasreplaced by another Wild design the A8 in 1950In France improved versions of the Poivillierswere introduced culminating in the Type C Aseach new instrument was designed it was takenup by the Service Geographique de IArmee Bythe early 1940s the Service had eleven Type B two

Type B perfectione two Type A and six Type CInstruments in routine production with additionalinstruments available (Institut GeographiqueNational 1947) Similarly there were considerableadvances in the design of Italian instruments byboth Nistri and Santoni In 1934 the first of thestereosimplex range was introduced for militaryuse (Burnside 1996 Istituto Geografico Militare1942) but it was never used commercially As Thompsn (1966) points out highly complexInstruments lIke the C series from Zeisswhile veryaccurate were not suitable for large-scale produc-tion of topographic mapping Needed were rela-tively simple low-cost instruments that could beus~d in mass production of topographic mapping~t IS therefore arguable that the most importantInnovation in instrumentation was the multiplex(FIgure 3) Introduced by Zeiss and OMI-Nistri~n1933 the concept was quickly adopted by otherl~strument manufacturers including Bausch andLomb and Williamson (Blachut and Burkhardt1989) The relative simplicity and low cost of mul-tiplex instruments made them very attractive formedium-scale topographic mapping They wereto open up the era of mass production of topo-

Vol29 No3

graphic maps using photogrammetricmethods

As previously noted the TennesseeValley Authority and USGS wereinvolved in the development of multi-plex instruments in the United StatesThe US Army Air Force at WrightField acquired a few early models forevaluation and the proven usefulnessof the equipment led in turn to theUSGS acquiring a model in 1935 andevaluating it during 1936 In 1938USGS and TVAset up an office of mul-tiplex machines built under license byBausch and Lomb (Pendleton 1938)The basic design was much improvedby Bausch and Lomb in cooperationwith USGS and TVA The Corps ofEngineers was also an early user ofthe equipment and Bausch and Lombdeveloped an oblique version for the

Corps use The USCampGS also made some useof the multiplex but remained largely wedded totheir multi-lens cameras because of the reducedneed for ground control in coastal mapping

In B~itain despite the resistance to air surveyfrom Wmterbotham and other conservatives therehad been a number of attempts to use instrumen-tal techniques even in the 1920s (WarOffice 1935Seymour 1980) In general these had not beena great success largely because of cost The AirSurvey Committee which continued to sponsorresearch in photogrammetry commissioned theconstruction of photogrammetric plotters basedon the ideas of lltourcade(Hotine 1931 Burnside1997) By the time World War II began a numberof prototypes had been constructed but the out-break of war brought these developments to a haltThe Ordnance Survey had also purchased the newWild A5 for evaluation Bombing of OrdnanceSurvey facilities in 1940 destroyed the prototypemachines and also damaged the A5 The A5 wassubsequently rebuilt and joined another A5 beingused to map potential bomber targets (Seymour1980)

Advances in Graphical MethodsBy the early 1930s radial-line techniques hadbecome widely accepted for providing planimetricmapping from aerial photography Although itwas also possible to plot contour lines using thisapproach the need for large amounts of groundcontrol limited its usefulness The radial-linetechnique as developed by Hotine (1927 1929)sut1ered from a number of drawbacks Firstly it

169

Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

170

world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

1J129 No3

Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

171

Figure 3 The Zeiss multiplex

involved a two-stage process to create a minor con-trol plot at a known scale before any plotting couldbe carried out Secondly it could only be used forthe production of strips of control This meant thatground control points were needed for each stripIf a block formation and adjustment process couldbe developed it would speed up the process andreduce the need for ground control points Thebreakthrough came in 1936 when CWCollier ofthe US Soil Conservation Service developed theslotted-templet method (Kelsh 1940) As DavidLanden notes this was one of the most importantinventions in photogrammetry which made pos-sible the mass production of photogrammetricmaps at low cost and great speed (l952 p 884)By the early 1950s slotted-temp let methods werein use in nearly every country involved in mapmaking (Figure 4) Thus by the end of the 1930swith the development of the multiplex and theslotted-templet method all the tools were in placeto permit the exponential growth in topographicmapping that was to start during World War II

ConclusionsAt the start of the twentieth century good-qualitytopographic mapping existed with few exceptionsonly in parts of Europe North America and IndiaAlthough adequate mapping for the rest of the

170

world was recognized as a prerequisite for devel-opment (penck 1893) the mapping technology ofthe day could not meet the need Photogrammetryoffered the possibility of providing detailed sur-veys for large areas in a cost-effectiveway if suit-able methods and equipment could be developedDuring the first three decades a range of tech-niques and types of equipment were developedbut they could still not meet the growing needs formapping Nonetheless in the United States andRussia large areas were mapped at medium scalesusing the new techniques The important break-throughs that were to permit intensive cost-effec-tive use ofphotogrammetry in the rest of the worldoccurred in the early 1930swith the developmentof a cheap and efficient plotter the multiplex andan efficient radial-line technique based on slottedtemplets Although World War II delayed theirimpact on civilian mapping both developmentswere to revolutionize large- and medium-scaletopographic cartography

ReferencesAlbrecht O 1969 Das Kriegsvennessungswesen wiihrend

des Weltkrieges 1914-18 Deutsche GeodatischeKommission Munich Germany

Ardagh J 1893 Printed letter to Royal GeographicalSociety from Government House RoyalGeographicalSociety Archives Calcutta India

CartograPhy and GeograPhic Information Science

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

1J129 No3

Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

171

Figure 4 Slotted templets being laid at the Soil Conservation Service US Department of Agriculture

Bagley JW 1917 The use of the panoramic camera intopographic surveying US Geological Survey USGSBulletin no 657 Washington DC GovernmentPrinting Office

Bartholomew J G 1890 The mapping of the WorldScottish Geographical Magazine 6 293-305

Blachut TJ and R Burkhardt 1989 Historical devel-opment of photogrammetric methods and instrumentsThe International Society for Photogrammetryand Remote Sensing and the American Society ofPhotogrammetry FallsChurch Virginia

Bonnet C 1920 Photogrammetrie In ServiceGeographique de lArmee Conference surles Methodes et les Procedes de Geodesie deTopographie et de Cartographie en usage auService Geographique de IArmee 1912-13 ParisImprimerie du Service Geographique de (Armee (2eTirage Edition de 1920) pp 1-23

Burnside CD 1993 The Photogrammetric Societyanalogue instrument project Photogrammetric Record14 565-82

Burnside CD 1995 The Photogrammetric Societyanalogue instrument project A fourth extractPhotogrammetric Record 15 85-90

Burnside CD 1996 The Photogrammetric Societyanalogue instrument project A seventh extractPhotogrammetric Record 15 527-44

Burnside CD 1997 The Photogrammetric Societyanalogue instrument project An eighth extractPhotogrammetric Record 15 791-802

1J129 No3

Chasseaud P 1999 Artillerys astrologers A history ofBritish survey and mapping on the Western FrontLewes Sussex Mapbooks

Close CF 1905 Textbook of topographical and geograPhi-cal surveying London UK His Majestys StationeryOffice

Close CF 1932 A fifty-year retrospective Empire SurveyReview 1 146-50

CloughAB 1952Maps and survey WrrOfficeLondonUKCollier P 1994 Innovative military mapping using

aerial photography in the First World War SinaiPalestine and Mesopotamia 1914-1919 CartograPhicjournal 3] 100-104

Collier P and R Inkpen 2001 Mapping Palestine andMesopotamia in the First World War CartograPhicjournal 38 ]43-54

Colonial Survey Committee 1906 The surveys and explo-rations of British Africa Colonial Reports-Annual no500 London UK His Majestys Stationery Office

Colonial Survey Committee 1911 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports Annual no 685 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1912 The surveys of BritishAfrica Ceylon Cyprus Fiji jamaica Trinidad BritishHonduras Colonial Reports-Annual no 730 LondonUK His Majestys Stationery Office

Colonial Survey Committee 1913 The surveys ofBritish Mrica British Honduras Ceylon CyprusFUiHong Kong Jamaica Malay States and Trinidad

171

Colonial Reports-Annual no 775 London UK HisMajestys Stationery Office

Colonial Survey Committee 1928 Report of the ColonialSurvey Committee 1927 Colonial Reports Annual no1383 London UK His Majestys Stationery Office

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Deville E 1895 Photographic surveying including theelements of descriptive geometry and perspectiveOttawa Canada Government Printing Bureau

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Fourcade HG 1926b The optical transformation ofprojections and its application to mapping from airphotographs Transactions of the Royal Society of SouthAfrica 14 51-78

Fourcade HG 1926c On some conditions for the cor-rect vision of stereoscopic pictures Transactions of theRoyal Society of South Africa 14 79-91

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Gasser M 1923 Verfahren wm mechanischen Einstellenlehrerer Projektions-Apparate die zum Ausmessenvon sich uberdeckenden Luftaufnahmen dienenPatentschrift Nr 520782

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Gunter CP 1917 Compilation of the Baghdad cityplan from air photographs by the Map CompilationSection GHQ Mesopotamian Expeditionary ForcePRO WO 302551

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Hinks AR 1919 German war maps and surveyGeographicaljournal 53 30-44

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War Office 1935 Report of the Air Survey CommitteeNo 2 London UK His MajesLysStationery Office

Winterbotham H StJL 1919a British survey on theWestern Front Geographicaljournal 53 253-76

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Winterbotham H St]L 1919b Geographical workwith the army in France Geographical journal 5412-28

Winterbotham H StJL 1920 The economic limits ofaeroplane photography for mapping and its applica-bility to cadastral plans Geographical journal 55 481

Winterbotham H StJL 1921 The development andpresent possibilities of air photography for mappingBritish journal of PhotograPhy 68 16-20

Winterbotham H St]L 1929 The use of air photo-graphs for mapping (marked Confidential and for

the eyes of the Air Survey Committee only) Boundwith draft reports to the Colonial Survey CommitteeOrdnance Survey Library Southampton UK

Winterbotham H StJL 1934 Sidelights Confidentialbriefing papers to incoming Director General ofthe Ordnance Survey Ordnance Survey LibrarySouthampton UK

Winterbotham H StJL 1936 Mapping of the colonialempire The Scottish Geowaphical Magazine 52 289-99

WoolleycL and Lawrence T E 1914 The Wildernessof Zin Palestine Exploration Fund Annual 1914-1915

Staff contributing to theExploratory Essays Initiative

Syracuse UniversityRebecca Carlson

Karen CulcasiKate Krezel

Ahmed SaadMolly Schmelzle

University of Wisconsin-MadisonBeth Freundlich

Jude LeimerTeresita ReedPaul Tierney

174 Carlography and GeograPhic Information Science