1 / 17

LIDAR Accuracy on Asphalt Road

LIDAR Accuracy on Asphalt Road Arttu Soininen Terrasolid Ltd Case story Task: produce an accurate asphalt road surface model Purpose: asphalt is going to be resurfaced machinery is going to be automatically guided by total station positioning Note:

Gideon
Download Presentation

LIDAR Accuracy on Asphalt Road

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. LIDAR Accuracy on Asphalt Road Arttu Soininen Terrasolid Ltd

  2. Case story • Task: • produce an accurate asphalt road surface model • Purpose: • asphalt is going to be resurfaced • machinery is going to be automatically guided by total station positioning • Note: • we assume that total station network is perfect • 481 total station points on asphalt for control • surrounding terrain is not important

  3. Coordinate setup • TerraScan uses integer coordinate system • Sentimeter steps OK for general terrain mapping • Use millimeter or 1/10 of a millimeter for best accuracy work

  4. Laser scanning • 15 km of road • TopEye measured in October 2003 with a scanner measuring about 7000 points per second • Digital camera images with 2 cm resolution • Flown in two directions at 100 m altitude

  5. Initial laser data accuracy • IMU / scanner misalignment angles carefully calibrated from data set • TerraMatch gives no real HRP improvement • Average difference between surfaces from different flightlines 3.689 cm • Average difference on asphalt 3.440 cm

  6. Dz correction for whole flightlines • TerraMatch gave dz corrections for whole flightlines: • -1.7 cm line 1 • +0.7 cm line 2 • +0.8 cm line 3 • +0.4 cm line 4 • -0.2 cm line 5 • Average difference between surfaces from different flightlines after correction 3.299 cm, on asphalt 2.997 cm

  7. Fluctuating elevation correction • Corrects for inaccuracy of trajectory elevations • TerraMatch computed elevation difference of each flightline to others at 1 second intervals • Each 1 second interval was corrected with the average of 3 consecutive seconds • Correction limited to max 2 cm • Average difference between surfaces from different flightlines 3.070 cm

  8. Find Fluctuations • Correction will modify laser points of each interval with a unique dz correction • User can select: • how correction curve is averaged from consecutive intervals • what is the maximum correction to apply

  9. Find Fluctuations - Before

  10. Find Fluctuations - After

  11. Cutting edges of scan lines • TerraScan cut edges of scan lines where accuracy is not as good as at the center of scan lines

  12. Geoid correction • Transform from GRS80 ellipsoid to orthometric height • Average elevation difference between LIDAR surface and total station points was computed for each 1 km interval

  13. Smoothing of laser surface • Classify points within 10 cm from ground to ground • Smoothen laser surface • Std dev asphalt against total station points 2.32 cm

  14. Smoothing 10 cm spread • Improves accuracy on hard surfaces • Requires interactive work -- draw polygons • Raises laser data on hard surfaces: • systematic biases on different surfaces closer • Example before: • laser data 5 cm too high on asphalt • laser data 9 cm too high in terrain • Example after: • laser data 7 cm too high on asphalt • laser data 9 cm too high in terrain

  15. Breaklines on asphalt • 2D breaklines drawn on orthophoto were draped to laser point surface • smoothenes variations in longitudinal direction • Std dev of resulting TIN model: • fix points 2.02 cm, min -5.60, max +5.30

  16. Summary of steps • Match laser strips internally: • HRP misalignment  3.440 cm • Dz per flightline  2.997 cm • Elevation fluctuations  2.705 cm • Cut overlap • Classify ground • Geoid correction based on local points  2.48 cm • Classify 10 cm spread and smoothen  2.32 cm • Drape breaklines on laser surface • Model breaklines + surrounding terrain  2.02 cm

More Related