P AD-AI35 835 A METHODOLOGY FOR DIGITAL FROCESSING OF GEOGRAPHIC AND /CARTOGRAPHIC DATA(U) ARMY ENGINEER TOPOGRAPHIC LABSFORT RELVORVA R LROSENTHAL ET AL 1983ETLRO5D

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A Methodology for Digital Processing of Geo-graphic and Cartogrpahic Data

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Richaid L. Rosenthal ) all) William Opalski ) of

Douglas Caldwell ) ETL, and Carl ReedAutomel:ric.Inc.IA 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK

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I9. KEY WORoS (Continue on fevers ..e.. it ne .ces ry and Identify by block number)Automated Cartography1116wAutomated GeographyAutomated Map ProductionHardware/software Systems

Digital

Map Image

Generation

20. AOS TI AC T ( 'Co th are O re v 80lm etli " Ff necess a Id identifr by block num ber)The application of computer technology to cartography has produced numerous digi.tal techniques that are employed in a wide variety of independent automated andsemi-automated cartographic systems. These systems are used by government agenc esand private industry for compiling maps and charts. The US Army Engineer Topogra hicLaboratories (USAETL) is testing and evaluating a subset of available off-the-shelf and state-of-the-art R&D digital techniques in an Experimental Geo-Carto-graphic Laboratory System and developing a methodology for automated map and cha tproduction. The methodology, which is based upon geographic and cartographic

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principles, is defined and outlined in this paper along with early experimentalreiults derived from the integration of key hardware/software systems.

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A METHODOLOGY U DIIA PROCESSING 2Ei GEAROGRAPHIC D ATA

Mr. Ricnarc L. Rosenthal, Cartographer

Mr. William Opalski, Physical ScientistMr. Douglas Caldwell, Cartographer

United States Army Engineer Topograpic LaboratoriesFort Belvoir, Virginia 22060

(703) 664-3722

Dr. Carl ReedAutometric, Incorporated

BIOGRAPHICAL SKETCH

Richard Rosenthal is a cartographer specializing inautomated and digital techniques. He received a BA inGeography in 1976 from Boston University and a MS inCartography from the University of Wisconsin-Madison in1982. He has been employed at the US Army EngineerTopographic Laboratories since 1978. His researchinterests center on automated techniques for cartographicimage display.

ABSTRACT

The application of computer technology to cartography hasproduced numerous digital techniques that are employed in awide variety of independent automated and semi-automatedcartographic systems. These systems are used by governmentagencies and private industry for compiling maps andcharts. The U.S. Army Engineer Topographic Laboratories(USAETL) is testing and evaluating a subset of availableoff-the-shelf and state-of-the-art R&D digital techniquesin an Experimental Geo-Cartographic Laboratory System anddeveloping a methodology for automated map and chartproduction. The methodology, which is based upongeographic and cartographic principles, is defined andoutlined in this paper along with early experimentalresults derived from the integration of keyhardware/software systems.

INTRODUCTION

The methodology developed for automated map and chartproduction at USAETL is based in part on interfacingstate-of-the-art stand-alone automated cartographic systemsresident in the Labs. The experimental geo-cartographicsystem resulting from this linking of systems .3 cesigned

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to incluae input, manipulation, and output processors.Vaijc cartographic data derived in the system "flows"througn the system in an all digital mode and may be outputto a device such as the large-format laser platemaker. Thebasic assumption underlying the methodology is that thereexists a fundamental difference between geographic andcartographic data processing. Digital geographicprocessing is defined as those operations which involve themanipulation of locational data and its associatedatt'ribute identifiers. Included are the basic digitalgeographic processing operations of data capture, datamanipulation, and data retrieval. Locational data isexpressed in geographic coordinates, typically latitude andlongitude. In contrast, digital cartographic processing isdefined as those operations which involve the graphicexpression, by maps and charts, of physical features on theearth's surface. Graphic expression may be presented inboth hard-copy and soft-copy graphic (image) displays.Graphic displays use table coordinates or devicecoordinates as input.

LABORATORY ENVIRONMENT

The Experimental Geo-Cartographic Laboratory Systemmethodology has been developed by integrating existingdigital geographic and cartographic systems. Geographicdata processing is addressed by the Analytical MappingSystem (AMS) from which geographic data is passed to thecartographic systems for symbolization,editing, andplotting. The Intergraph System and the Scitex Systemprovide editing and symbolization capabilities. They maybe used to prepare edited cartographic data for imageforming systems such as the Gerber/CRT Print Head, theLarge-Format Laser Platemaker, and the Scitex Plotter. TheScitex is resident at the Defense Mapping Agency.

11= Analytical M S (AMS)

The Analytical Mapping System (AMS) forms the digitalgeographic processing system. AMS uses spatial datastructures in order to maintain the topological validity ofthe geographic data. Additionally, AMS incorporatesprocedures for geographic data input, data manipulation,and data retrieval. Unlike graphics systems which treatgeographic data like an engineering drawing, AMS isdesigned to treat geographic data in a rigorous manner.During geographic data capture, AMS considers the nature ofthe input sources (maps and pnotos) and removes the biasintroduced by projections and transformations. The commonproblems of paneling and edge matching are not found in AMSas all data is stored in common geographic coordinates.Hardware tools for geographic data input include adigitizing tablet and an APPS-IV analytical plotter. The

APPS-IV supports digital graphics superimpositioning.

AMS is considered state-of-the-art because it brings theadvanced concepts of topological validity and spatial datastructures into the process of digital map and chartproduction.

I=Interrah m

An Intergraph interactive graphic display and edit systemforms the cartographic processing system. The Intergraphpermits multiple siaultaneous displays of graphic data withthe ability to fully interact with the data using adigitizing tablet and menu. Cartographic data stored ingeographic coordinates in AMS is converted to tablecoordinates and transferred to the design file of theIntergraph for symbolization and cartographic expression.The system has the basic tools for creating a symbollibrary. Data is displayed as color separate sheetoverlays with a view toward editing symbol placement anddesign. A geographic names overlay is included in thecompilation. Output processors format the cartographicdata for input to raster and vector plotters such as thelarge-format laser platemaker, the CRT printhead, andseveral standard plotters and display devices.

The Intergraph system is important in the experimentalsystem because it enables the cartographer to employstate-of-the-art interactive edit technology as well aspolygon processing to output terrain analysis displays andgraphics.

Srtg Scanner/Platter

The Scitex pre-lithographic edit system is used in theproduction of nautical charts at the Defense MappingAgency. The Scitex system digitizes maps as raster data,edits them by a combination of raster and vectortechniques, and exposes the edited data on large-formatpress-ready films. Besides functioning as a comprehensivesystem for producing and updating cartographic material,the Scitex can also use digital data from other sources.Input of other digital data sets is possible using theStandard Interchange Format (SIF).

Gerbgr/CRT Printhoad

Automation of the processes of generation and placement ofmap names and symbols is available on the CRT Print HeadSystem. The system consists of a precision CRT mounted ona precision flatbed plotter, stroke and charactergenerators to control the CRT operations, and a digital

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computer to direct and control the system. In operation, alarge sheet of photographic film is mounted on the plottingtable, a data tape is read into the system, and thegeographic names and cartographic symbols are written ontothe CRT display which exposes a photographic emulsion toproduce a film image. The CRT Print Head System producestype and symbols having a wide variety of point sizes andline weights and significantly increases the speed by whichcolor separates are produced in the Defense Mapping Agencyproduction centers.

Larce-Format LaserL Pla.Lmak*.r

The Large-format Laser Printing-Plate Maker (LPM) is anexample Of a specialized scan-line raster display whichuses a constant size binary pixel. The LPM reads digitaldata from magnetic tape and employs an electro-mechanicalmeans of aiming and modulating laser-generated ultravioletlight to expose binary raster images on photosensitivemedia. The LPM was developed for use in preparing fourfoot by five foot plates of maps and charts for accurateprinting. However, the device is transparent to imagecontent and can be used in any computer-to-plate orcomputer-to-film application where large format and highaccuracy are important requirements. The active image areaon the LPM is 42 by 59 inches. An LPM image is generatedwith up to 2.6 billion binary pixels based on a 25 microndistance between pixels with a total of 42,672 pixels inthe X direction and 59,944 pixels in the Y direction.

EXPERIMENTAL GEO-CARTOGRAPHIC ISSUES

Work efforts have begun in the laboratory to translate thegeographic/cartographic data processing methodology into anoperational experimental system. The purpose is tounderstand and solve the problems that occur whenattempting to digitize and transfer data from one"independent" system to another. Problems such asvector-to-raster conversion to permit output to the laserplatemaker, and translation between symbol libraries, suchas from the Intergraph to the CRT printhead font library,are being addressed. Several interfaces and automatedcartographic functions are under development.

Routines presently being tested permit batch entry into AMSof digital geographic data currently in the DMA :nventoryand digital geographic data collected by existing DMAhardware/software systems. Batch data entry of existingdigital geographic data with associated attributes has beendemonstrated with DMA Digital Landmass Simulation DLMS)

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Digital Feature Analysis Data DFAD). Additionalcapabilities are being designed to permit batch input ofaigital data from DMA's proposed Standard Lineal FormatSLF', the Automatic Graphic Digitizing System "AGDS), andIntergraph/Scitex Standard interchange Format (SIF.

A= L Intergraph Interface

The Analytical Mapping System generates basic point, line,and area data with associated attributes using one of manyavailable map transformations. The resultant digitalcartographic data is output to magnetic tape which isprocessed on the Intergraph system by the AMS/Intergraphinterface software. The interface software consists of asingle module that reformats point, line, and areacoordinates that are in AMS Export format into an internalIntergraph format. The Intergraph Interactive GraphicsDisplay System (IGDS) offers software callable subroutinesthat allow an application program to convert data to theIGDS proprietary internal data structures and build ahierarchical data base containing associated featureattributes.

Automated. Car tographi c BU rmA" Sybo Formation

The Intergraph interactive display and edit system is beingused as a test bed to evaluate the feasibility ofimplementing a digital symbol library based on the DefenseMapping Agency (DMA) Product Specificatons for 1:50,000Scale Topographic Maps of Foreign Areas. The process ofusing Intergraphs basic edit and symbol generation routinesis under study. Complex symbols such as dual case roadintersections and variable shaped bridges will requiredevelopment of a sophisticated set of edit instructionswhich can be initiated with a single command. In somecases a series of menu commands will be designed so that acartographer can construct variable dimensioned symbolswhile performing map edit/compilation on the Intergraph.

Full symbolization is currently possible using automatedsymbolization routines which convert rudimentary digitalrepresentations of point, line, and area features into afinished cartographic form. Examples include theconversion of centerline road data to dual-cased graphicform; the conversion of point locations and identifiers toappropriate point symbols; and the application of fillpatterns to tagged areal features. The automatedsymbolization normally performed at this point is limitedto graphic conversions which generate vectorrepresentations of cartographic symbols. Digital vectorrepresentations can be applied to all cartographic symbolsexcept continuous tone and constant tone area tints.

- . . . . . . . . , : - . . .

Symbolization of continuous tone and constant tone areatints has been demonstrated using the map image modifyingprocess known as digital halftoning. In manual andcomputer-assisted map production methodologies, halftoneand tint screens are applied to a map image forming mediumusing open-window negatives and mechanical registrationsystems to control image position. In the automatedprocessing methodology, area fill algorithms apply digitalhalftones and tint screens using the digitalrepresentations of area features to control image position.Registration of digital graphic images, including rasterrepresentations of points, lines, areas, and halftonescreens, is provided by the computer and is maintainedwithin the resolution and accuracy of the output plotter.

The process of symbolization is applied to standardtopngraphic charts and terrain analysis overlays (thematicmaps) which are compiled using Intergraph's polygonprocessor. This processor is a basic capability of theIntergraph.

AutoatedMU magg QutnuM,

The Scitex and Laser Platemaker arn two high-resolutionraster plotters which are available for output of fullysymbolized cartographic images. The Scitex is accessedusing the Standard Interchange Format (SIF) forphotoplotter emulation. The Scitex converts SIF data intoraster format for plotting. Raster data for output on theLaser Platemaker is derived from vector data generatedusing Calcomp compatible graphics routines. Imagesgenerated for output on the Scitex an( the Laser Platemakercontain raster representations of point, line, and areasymbols including halftone screens.

The Gerber/CRT Print Head is also available for output ofsymbolized cartographic images. The requirement for a CRTPrint Head symbol library and a translation table tointerface the Intergraph symbol library is underinvestigation. The CRT Print Head can currently printIntergraph symbols using Calcomp compatible routines.

Ling Generalization =n Featulre Dilacement

While full symbolization has been demonstrated and iscurrently possible, modification of the symbolized data :snecessary to produce quality map products. Tasks whichhave traditionally fallen under the realm of "cartographiclicense n are required. These include such generalizationtasks as selection, simplification, and displacement. 5TLis investigating the manual generalization process at DMAand reviewing state-of-the-art digital techniques. Basedon this study, research and development software can be

3evelopea to evaluate the promising algorithms needed for:ully automated cartographic processing.

CONCLUSION

The Experimental Geo-Cartographic Laboratory Systemprovides a test-bed for developing a unified geographic and

cartographic methodology. Existing systems for geographicdata collection and manipulation, cartographicsymbolization and editing, and automated map image output

have been identified and initially integrated. Theintegration of these systems has raised a number pressingissues concerning a digital flow: issues of data

reformatting, cartographic symbolization, and the digital

definition of "cartographic license". ETL researchers are

addressing these issues to bring an all digital geographic

and multi-product cartographic production system closer toreality.