LiDAR Calibration Errors & QA/QC
                                     September 16th, 2009
                               ...
What is Calibration?

•        Calibration varies by
         vendor
•        Four different lines
         collected
•   ...
What is Calibration?

•        This calibration is flown before
         and after the flight/mission

•        Flown over...
What is Calibration?

                                                                                       Roll Error
• ...
Calibration Errors

Roll                                                                              Pitch
    • Can pote...
Relative Accuracy - Calibration
Errors – Roll




© 2007, The Sanborn Map Company, Inc. Privileged and confidential inform...
Relative Accuracy - Calibration
Roll Error Corrected




© 2007, The Sanborn Map Company, Inc. Privileged and confidential...
Relative Accuracy - Calibration
Roll Error- Example 2




© 2007, The Sanborn Map Company, Inc. Privileged and confidentia...
Relative Accuracy - Calibration
Pitch Error




© 2007, The Sanborn Map Company, Inc. Privileged and confidential informat...
Relative Accuracy - Calibration
Pitch Error Corrected




© 2007, The Sanborn Map Company, Inc. Privileged and confidentia...
Filtering

•        Cutting over edge or overlap?
             •       No? Increases chances for less accurate data (off n...
Filtering- Under Filtering




© 2007, The Sanborn Map Company, Inc. Privileged and confidential information.
Distribution...
Filtering- Over Filtering




© 2007, The Sanborn Map Company, Inc. Privileged and confidential information.
Distribution ...
Filtering- Ground

• Under Filtering

             • Produces an inaccurate bare earth model
             • Within the BE ...
Final QC Techniques

• What should your bare earth
  surface contain?
             • Structures removed
             • Art...
Artifact Removal – Bridges/Overpasses




  © 2007, The Sanborn Map Company, Inc. Privileged and confidential information....
Artifact Removal – Buildings/Structures




  © 2007, The Sanborn Map Company, Inc. Privileged and confidential informatio...
Artifact Removal – Vegetation




© 2007, The Sanborn Map Company, Inc. Privileged and confidential information.
Distribut...
Clients’ Specifications
         Standard LIDAR 1.4m
•        Automated process yields 89% of Artifacts removed
•        A...
Efficiency

                                                                                 •   Tiled datasets
          ...
Thank You!




Graphics provided by Leica

        © 2007, The Sanborn Map Company, Inc. Privileged and confidential infor...
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LiDAR QA/QC Presentation

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Sanborn's LiDAR Team Presentation regarding LiDAR QA/QC.

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LiDAR QA/QC Presentation

  1. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 12. Filtering- Under Filtering © 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 12
  13. 13. Filtering- Over Filtering © 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 13
  14. 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. 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. 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. 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. 18. Artifact Removal – Vegetation © 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 18
  19. 19. Clients’ Specifications Standard LIDAR 1.4m • Automated process yields 89% of Artifacts removed • Automated process yields 90% of all outliers removed • Automated process yields 90% of all vegetation removed • Automated process yields 93% of all Building removed FEMA Compliant LIDAR • Automated process yields 90% of Artifacts or as required by FEMA lead • Outliers removed per the FEMA lead provisions for a limited percentage of outliers • Automated process yields 95% of all vegetation removed and as per FEMA lead provisions • Automated process yields 98% of all Building removed and as per FEMA lead provisions High Density LIDAR 0.7m • Automated and manual processes yields 95% of Artifacts removed • Automated process yields 98% of all outliers removed • Automated process yields 97% of all vegetation removed • Automated process yields 99% of all Building removed © 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 19
  20. 20. Efficiency • Tiled datasets • Fast read/write • Multitasking • Data tracking • Easy to use tools for classifying points © 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing. 20
  21. 21. Thank You! Graphics provided by Leica © 2007, The Sanborn Map Company, Inc. Privileged and confidential information. Distribution or copying prohibited unless approved in writing.

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