Mobile Test

Mobile Mapping Validation

Allen Nobles, PLSNobles Consulting GroupTallahassee, Florida

2009 Spar Conference Denver, Colorado


David J. WardBusiness Development DirectorTerrapoint USA

Test Project

Evaluate the TITAN mobile scanning system against:

•Conventional survey techniques

•Static Scanning



TITAN mobile Lidar system• 360 degree coverage• 100 meter effective range• Highway speed collection• Georeferenced video• 4 meter collection height• Vehicle contained operation



Four Riegl LMS - Q120 lasers



TITAN Elevator is operated from inside the vehicle

TITAN in Production



Lidar and Linescan Fusion



Project Parameters

8500 foot suburban 4 lane highway

GPS base station adjacent to site

Collection time 1.3 hours

Two passes each direction

400 points per square meter



Project SiteTallahassee, Florida



Gaines Street, Tallahassee, Florida



Titan Lidar Processing

GPS IMU solution provides the trajectory

Linked with scan angles and ranges

Results is calibrated point cloud

Each point has X,Y,Z and Intensity

Passes are checked against one another

with Terrascan



TitanQC Process

Collected independent survey data• Kinematic profile

Terrascan• Horizontal alignment check• Vertical alignment check



Titan Survey Check

Data

Kinematic profile of project site Average DZ -0.049 FeetMinimum DZ -0.243Maximum DZ +0.112Average Magnitude 0.062Root Mean Square 0.079 (1 sigma)Std deviation 0.059



Intensity Image to Check Alignment of Striping



Vertical Check Between Drivelines

Match to 1-2 cm





We chose to test the system on a real project.

The test project was a completed and approved survey for FDOT using their standard survey practices.

A full DTM was provided to FDOT and check cross-sections were used to check the DTM data (QA/QC).



The project area was later scanned with a HDS scanner.

Gaines Street, Tallahassee, Florida



How do you test a mobile scanner?



How good was the survey control?

Is survey point data absolute?




Typical survey control results for these projects run from 1:40,000 to 1:60,000.

Survey data is also adjusted over the total site to remove errors.



Lowest Flight Altitude 360 feetNegative Scale 1”=60’Spot Elevation Accuracy +/- 0.05’

The project area was also surveyed using LAMP (Low Altitude Mapping Photography)

Control SurveyLamp Data Checks



Elevation DataPoint Survey LAMP Difference301 87.97 87.994 +0.024302 87.13 87.162 +0.032303 86.77 86.793 +0.023304 87.30 87.334 +0.034305 86.17 86.191 +0.021306 87.77 87.778 +0.008308 86.45 86.499 +0.049309 86.93 86.665 -0.010310 86.28 86.312 +0.024311 86.84 88.863 +0.023



Who is checking who now?




How good was the survey control? Survey points are not absolute. Do you check just control points? Do you test against the DTM? Surfaces are not flat in the scanner data. Adjusted survey control vs. single point RTK Local vs. network How do you check 3D data?

Project was scanned using a Leica ScanStation.

Each setup was adjusted into the existing ground control.

Two Traverses (total length 7,177 feet)Avg. Hor. error = 0.08 feet (1:40,000)Avg. Vertical error = 0.10 feet





Cross-section Points

Results from cross-data from ground survey vs. scanner data (search radius of 0.25 feet and a

max. elevation tolerance of 0.10 feet).



Used 143 points at cross-section areas. 75 points supported (68 unsupported) 53 points meet rejection tolerance 22 points were rejectedMean Deviations = 0.052 feetRMS Deviation = 0.065 feet

Results from the survey DTM vs. the HDS scanner data (search radius of 0.25 feet and a

max. elevation tolerance of 0.10 feet).



Used 368 points at cross-section areas. 159 points supported (209 unsupported) 92 points meet rejection tolerance 67 points were rejectedMean Deviations = 0.060 feetRMS Deviation = 0.070 feet

Checkpoint results using only shots within the pavement (search radius of 1.0 feet).



Used 52 points at cross-section areas. 50 points supported (2 unsupported)37 points meet rejection tolerance13 points were rejectedMean Deviations = 0.047 feetRMS Deviation = 0.060 feet

Checkpoint results using only shots within the pavement (search radius of 0.25 feet).



Used 52 points at cross-section areas. 52 points supported (0 unsupported) 35 points met rejection tolerance17 points were rejectedMean Deviations = 0.044 feetRMS Deviation = 0.055 feet



HDS Scans Titan Scans

2009 Spar Conference 2009 Spar Conference Denver, ColoradoDenver, Colorado

Mobile Mapping ValidationMobile Mapping ValidationTitan – HDS Comparison

Checkpoints for Horizontal Comparison

Titan – HDSCheckpoints for Horizontal Comparison

ΔN-0.0223

0.0379

0.0167

-0.1168

0.0029

0.0134

0.0137

0.1216

-0.0168

0.0643

0.1452

-0.0435

-0.0259

-0.1587

ΔE-0.0023

0.0508

-0.0263

0.2692

0.0849

-0.0286

0.0902

0.1068

0.2463

0.0254

-0.1189

-0.0529

-0.1837

-0.0383

PointCK1

CK2

CK2

CK3

CK4

CK5

CK6

CK7

CK8

CK9

CK10

CK11

CK12

CK13

0.084 DEV-SQ0.080 STD-DEV

North Sums East Sums

0.204 DEV-SQ0.125 STD-DEV

ΔDistance0.0224

0.0634

0.0312

0.2934

0.0849

0.0316

0.0912

0.1618

0.2469

0.0691

0.1877

0.0685

0.1855

0.1633

0.147 RMS0.0852 STD-DEV0.2934 MAX0.0224 MIN

Point to Points Distance Sums

ComparisonsTITAN to Static Scanning

Accuracies were very similar Static Scanning cleaner data than

mobile More density of points with Static Scan Both have high level of utility Mobile takes dramatically less time to

collect Mobile provides one continuous point

cloud for a corridor Mobile best suited for corridors

Questions?

Thank You.



Mobile Test

Documents

Transcript of Mobile Test