laserscanning · demonstrated an early interest in get-ting into laser scanning. metco, a...

LaserScanning

TThe successful use oflaser scanning/high-defi-nition surveying forindustrial plant as-builtswas well-documentedwhen our company,

METCO Services, first began to lookinto the technology. Believing that auto-mobile assembly plants in our areamight provide fertile opportunities forscanning services, our companydemonstrated an early interest in get-ting into laser scanning. METCO, amoderate-sized civil engineering andsurveying company, first began to rentscanners in 1999 from a local instru-ment/CAD dealer, Sterling Systems, forsuitable projects.

Our hunches were correct. The autocompanies were definitely interested inlaser scanning technology for fast,accurate plant as-builts. Unfortunately,what we didn’t foresee was that thosecompanies were already tended to by acadre of AE service suppliers whoknew their factories well, making itvery difficult to compete successfullyfor this type of work.

Although the plant as-built work did not materialize as anticipated, we remained optimistic about the tech-nology. We redirected our focus ontopographic surveys and met with somesuccess. We continued to rent as neededand in September 2003 we acquired aCyrax 2500 scanner, Leica’s secondgeneration version. We found that forchallenging topographic projects thetechnology was cost-effective comparedto conventional methods, but thesetypes of projects were hard to find.

One successful example during thistime was an ALTA/ACSM Land TitleSurvey for the International Center

Building in downtown Detroit. Weused the 2500 to survey around theseven-story building (with a zero set-back), located on half of a city block.The scanner was used to locate allencroachments along vertical walls upto the top of the structure. We werealso able to accurately locate an electri-cal transformer without climbing orusing a man-lift.

Up to this point our field and officelabor costs had been keeping us fromusing scanning for “everyday” topo-graphic surveys. Although scanningrepresented added value for our clients,in terms of the richness of the data, wefound that our market wouldn’t bear asignificantly higher price for toposbased on scanning. We needed to finda way to sharply reduce our project

labor hours/costs. Fortunately, this happened fairly soon.

Scripting and Full FOVThe first part of our needed laborreduction was made possible by a LeicaHDS3000 high-accuracy, time-of-flightscanner, which we acquired in June2004. This scanner represented a bigproductivity advance over the priorgeneration Cyrax 2500, thanks to theHDS3000’s full horizontal and verticalfield-of-view (360° x 270°), compared tothe prior generation’s 40° x 40° FOV.We also learned how to take full advan-tage of “scripting,” whereby you canprogram the scanner at each set-up toautomatically survey various parts ofthe site at different densities. For exam-

Laser Scanning for Everyday Survey Work

By Martin C. Dunn, LS

Party chief Gil Mattson combines scripting with full FOV to greatly increase productivity on site.

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Displayed with permission • The American Surveyor • January/February • Copyright 2005 Cheves Media • www.TheAmericanSurveyor.com

http://www.theamericansurveyor.com

ple, drainage areas, targets, and whatwould be considered traditional “hardshots” are scanned at higher densitiesthan natural ground shots, top ofbanks, etc. Scripting is very quick, thenscanning is fully automatic. In essence,scripting over a full field-of-view turnsthe HDS3000 into an “unmanned,robotic reflectorless station,” collectinghundreds of thousands of points at different densities in minutes.

Scripting combined with theHDS3000’s full FOV enabled ourparty chief to be much more produc-tive on site. In some cases, he couldleave the scanner basically unattended,while he used another instrument topick up points, such as buried utilities,that the scanner couldn’t capture.Overall, we quickly found that formany standard site surveys we couldconsistently realize field labor savingsas large as 75% (as compared to doingthese surveys traditionally) by usingour HDS3000 scanner and “filling in”with conventional tools.

The second breakthrough forMETCO was making our office proce-dures more efficient for working withpoint clouds to create final 2D maps. Asmany people know, working with pointclouds in the earliest days of this tech-nology often meant many extra hoursof office processing. Today, scanningoffice efficiencies are in line with officeefficiencies for conventional site sur-veys. Together, the combination ofsignificant field labor savings plus officeefficiencies on par with traditional meth-ods has proven to be a big winner forour company and our clients.

This WSU survey took one day in thefield and less than a day in the office.

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Field WorkflowMETCO’s survey department has acomplete set of the latest tools, includ-ing Leica GPS1200 System and LeicaTPS1100 robotic total stations. Ourparty chiefs have autonomy to useequipment best suited for the job.Today, for many of our everyday sitesurveys, a combination of a laserscanner and conventional instrumentsis used.

First, the entire job is walked for opti-mum horizontal and vertical controlplacement. Primary horizontal control isestablished with static GPS sessions andvertical control with differential level

runs from the closest bench marks.While reconning the site, considerationis given to scanner position and targetplacement. Targets are needed for geo-referencing and/or tying multiple scanstogether, and we’ve found target place-ment to be a critical factor for accuratework. The HDS3000’s large field-of-view greatly simplifies the placement ofscanning targets and the location of thescanner. After control and targets areplaced, scanning commences.

Part of METCO’s scanning proce-dure uses Leica HDS3000’s internal,high-resolution digital camera to firstcapture full 360°x270° panoramicimages of the scene. These help theoperator script the scanning.

While the HDS3000 is scanning, theone-man crew uses a robotic total sta-tion or RTK GPS to measure targetsand control points, draw sketches, takenotes, and obtain invert elevations.

We also use the scanner on boundarysurveys with zero set-back, where prop-erty lines are building lines. There’s noneed for prism offsets to measure build-ing corners. We scan the fascias and inthe office create two intersecting planesfrom scan data to establish exact build-ing corners.

Office WorkflowOnce scans are registered and placedonto a solid horizontal and vertical con-trol system, the scanning database istransferred to the drafting department.Draftsmen use Cyclone software’sVirtual Surveyor module to walkthrough (virtually) a point cloud “collect-ing” data on features throughout a site.

Each point that is “collected” isassigned a line and point code thatmatches those used by field crews intheir traditional methods. This allowsfor data to be imported just as anyother file for any other topo job wouldbe. After all the data is “collected” andexported to an ASCII file, a fieldbook(.fbk) file is created utilizing theAutodesk Survey module and thenimported into Land DevelopmentDesktop for final drafting.

Putting Our Knowledge to WorkOne example of a typical topographicsurvey performed by one person withan HDS3000 is the Wayne StateUniversity (WSU) Site Survey. It took a

Point clouds of the main entrance ofFord Field, home of the NFL’s Detroit Lions, may be used for futurerenovations.continued on page 38



day in the field and less than a day inthe office. Overall, field labor for thisproject was one-fourth of what it wouldhave been if we’d done the project con-ventionally.

Although the WSU project did nottake full advantage of the HDS3000’s270° vertical FOV, METCO has takenadvantage of the full 360°x 270° onother projects. For example, we sur-veyed the interior of a high schoolauditorium in which a structural beam80' in the air was suspected of having acamber. For this, the full 360° x 270°vertical FOV was invaluable. We usedthe 360° to capture targets at tripodlevel and, without having to touch thescanner set-up, we used the HDS3000’stop window to scan the structural beamdirectly overhead.

Another project was a Site & Buildingsurvey for the main entrance of FordField, home of the NFL’s Detroit Lions,which was needed for future renova-tions and possible additions. Existingbrick pavers were to be extended, sothe client wanted to be sure that theywould be accurately located and couldbe dimensioned if necessary. METCOobtained enough data to map the areawhile collecting a series of extremelydense scans on specific areas of clientinterest in the paving patterns. A con-ventional 2D drawing was preparedshowing the location of all utilities,paving types, and existing conditions inthe area. This survey was also donewith significant labor savings.

Beyond Site SurveysMETCO has fully adopted laser scan-ning for use in everyday site surveys,and we are always interested in tryingscanning on other types of projects.One such recent project was linear innature, as we wanted to compare thetime needed to complete this type of jobwith our HDS3000 to the time neededfor conventional methods.

The project consisted of topos on twoseparate sites for designing a new watermain for a residential street in Detroit.The length of the surveys was 1500 feet.Overall, we found that even for this typeof linear survey, the cost to perform withHDS versus conventional survey methodsbased on walking in a cross-sectional man-ner gave us a nice 10 percent savings.

We believe we can further reduceour costs for this type of survey by at

least another 20 percent. For example,reductions in the drafting time could berealized by only showing the gradesthat we use in conventional surveyingand not adding so much information“just because you can.” For example,on this project, our draftsman discov-ered from the scan data that the truecrown in the road surface was not inthe geometric center of the road. Eventhough the true crown location was notrequested by the client, our draftsmanhad taken the initiative to locate it,selecting an additional three points thatdefined it for each section.

Investment Payback Over time we’ve found lump-sum pric-ing to be an optimal approach forsurveys that include laser scanning.This approach avoids the need to add aseparate line item for hourly “scannerusage”, which some clients find confus-ing and may not react well to.

The lump sum approach also enablesMETCO to basically price these types ofscanning-based site surveys at the sameprice as conventional and then apply oursignificant labor savings gain on eachproject toward paying back the invest-ment in the scanner. Our client is veryhappy because for the same survey price,the client receives significant added-value. The survey is turned aroundfaster, plus the client knows that if there’sa need for additional data, then rich sur-vey data is available to him/her almostimmediately without having to re-mobi-lize a crew to revisit the site. In addition,the richness of scan data gives the clienteven further confidence that our surveyis accurate and complete.

For METCO, this type of approachallows us to pay back the scanner overa period that is just like the paybackperiod for investments in conventionalequipment, even though laser scanningsystems cost more than $100,000. Thisis a real win-win situation.

Today, we just plug our LeicaHDS3000 scanner into many of oureveryday topo, as-built and site surveys.Using scanners as “just another tool inthe tool kit,” two of our six Detroit fieldcrews are equipped with laser scanningsystems and conventional equipment.There are no “scan jobs,” only topos, as-builts, and design surveys to be completed using the appropriate tools.

In many cases the only way a clientknows that we’ve used scanning is by

the perspective scan images (instead ofphotos) that we now place on theirmaps. Otherwise, the maps are identicalto what we’ve always provided. Whenclients ask about those “interestingimages” on their new map (and theyalways ask), we explain the many value-added aspects of how we did thesurvey. Once clients understand these

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Scan images provide a unique perspective when added to traditionalmaps for METCO’s clients.



benefits, they are very appreciative andstart to ask for their next surveys to bedone with “that scanner thing.”

Using laser scanning adds a greatdeal of insurance to a survey project. Awealth of data is available that can beretrieved later if a client finds the need.Building setbacks, overhead utility lineheights, existing conditions of the vari-ous surface types and any other featurethat is within the scan can be gatheredwithout revisiting the site. We also havea permanent record of the existing con-ditions that were in place at the time of

the survey to quickly resolve any ques-tions. A surveyor can also sleep betterat night without waking up wondering,“Did I miss something?”

The ability to realize these added-value benefits for topographicsurveys on a daily basis and pay backour scanning investment in a verytimely way has made this a real suc-cess for METCO and our clients. Wehave only begun to explore the differ-ent applications that can usehigh-definition surveys for everydayoperations. As we become more

familiar with the laser scanner and itssoftware, surveys will be completedfaster and costs will continue to bereduced.

Martin Dunn is a licensed surveyorand Vice President of METCOServices in Detroit, Michigan.Founded in 1983, METCO is a moderate-sized civil engineeringand surveying company, with a primary focus on water and wastewater projects for local public and private clients.



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