Sanborn's LiDAR Team Presentation regarding LiDAR QA/QC.
Text of LiDAR QA/QC Presentation
1. LiDAR Calibration Errors & QA/QC September 16th, 2009 GIS in The Rockies Presented By: Brandon Tilley 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 1
2. What is Calibration? Calibration varies by vendor Four different lines collected 3 perpendicular 1 parallel All used to calibrate a single mission 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 2
3. What is Calibration? This calibration is flown before and after the flight/mission Flown over a flat surface Enables user to account for the attitude of the aircraft Yaw, pitch, and roll are primarily adjusted using opposing lines Calibration settings apply to entire mission 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 3
4. What is Calibration? Roll Error Roll accounted Pitch accounted Settings applied throughout Corrected Roll mission strips Similar calibration settings for each flight Pitch Error Accurate calibration = Accurate Dataset Corrected Pitch 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 4
5. Calibration Errors Roll Pitch Can potentially be seen in Can decrease the quality of the entire project building and structure by shape Can greatly effect the Decreases accuracy of horizontal and vertical classifications, i.e. ground and accuracy of your data building classes Create sharp elevation shifts between each swath Greatly reduces the accuracy of the horizontal and vertical planes Cutting overlap usually helps with roll errors If widespread throughout project, will create inaccurate geo- referenced data 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 5
6. Relative Accuracy - Calibration Errors Roll 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 6
7. Relative Accuracy - Calibration Roll Error Corrected 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 7
8. Relative Accuracy - Calibration Roll Error- Example 2 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 8
9. Relative Accuracy - Calibration Pitch Error 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 9
10. Relative Accuracy - Calibration Pitch Error Corrected 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 10
11. Filtering Cutting over edge or overlap? No? Increases chances for less accurate data (off nadir) but provides more bare earth points per sq. m. Yes? Eliminates chances for less accurate data, less ground Removing (classifying) outliers? Ground filter: Does it classify too much? Not enough? All filter steps are necessary for an accurate BE model 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 11
12. Filtering- Under Filtering 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 12
13. Filtering- Over Filtering 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 13
14. Filtering- Ground Under Filtering Produces an inaccurate bare earth model Within the BE surface, can be vegetation, swath noise, buildings and bridges Increases manual QC TPT Over Filtering Also creates inaccurate bare earth model Cuts off mountains, hills, and other terrain features Increases manual QC TPT 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 14
15. Final QC Techniques What should your bare earth surface contain? Structures removed Artifacts/Vegetation removed Noise removed Very minimal calibration errors (if any) Common Sense Anything not man made 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 15
16. Artifact Removal Bridges/Overpasses 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 16
17. Artifact Removal Buildings/Structures 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 17
18. Artifact Removal Vegetation 2007, The Sanborn Map Company, Inc. Privileged and con
