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Comparison of Inertial Profiler Measurements with Leveling and 3D Laser Scanning

Comparison of Inertial Profiler Measurements with Leveling and 3D Laser Scanning. Abby Chin and Michael J. Olsen Oregon State University. Road Profile Users Group 28 September 2011. Outline. Research Objectives & Plan 3D Laser Scanning Field Data Observations & Future Work.

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Comparison of Inertial Profiler Measurements with Leveling and 3D Laser Scanning

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  1. Comparison of Inertial Profiler Measurements with Leveling and 3D Laser Scanning Abby Chin and Michael J. Olsen Oregon State University Road Profile Users Group 28 September 2011

  2. Outline • Research Objectives & Plan • 3D Laser Scanning • Field Data • Observations & Future Work

  3. Research Objectives • Establish certification test site • Determine repeatability and accuracy of reference profiler (inclinometer) • Develop procedures and guidelines for certification of inertial profilers

  4. Background • ODOT is implementing IRI-based incentive/disincentive program • Certification on site proved difficult • Inertial profilers were showing great repeatability, but did not meet AASHTO criteria

  5. Research Plan • Compare Methods • Inertial Profiler • Terrestrial LiDAR • Rod and Level • Inclinometer Profilers • Develop Certification Procedure Guidelines • Pavement Texture Analysis • Study Roughness and Aggregate Size

  6. What is LiDAR? LiDAR = Light Detection and Ranging Dt D • D = 0.5cDt • c = speed of light • Dt = travel time Original Slide by: Evon Silvia - Oregon State University

  7. Terrestrial LiDAR • Time of Flight System • Produces 3D Point Cloud • ~5 mm Accuracy at 50 m • Data are Geo-referenced • Targets • GPS

  8. Equipment GPS Camera Scanner Computer Power Source

  9. Data • Point Cloud • X Y Z coordinates • R G B color mapped • Intensity value (return signal strength) • 3D model

  10. Point Cloud Example

  11. Point Cloud Example

  12. Laser Scanning Advantages • Multiple Profiles • Redundant Data • Dense Point Cloud (1-5 cm Spacing) • Quick Data Acquisition • Improved Safety • Road Open to Traffic • Identify Localized Depressions • Continual Evaluation • As Built Survey Data

  13. Laser Scanning Disadvantages • Individual measurements accurate to +/- 5mm • Objects can block line of sight • Field setup time • Data processing requires training and time

  14. Mobile Laser Scan System Laser scanner GPS receiver Camera

  15. Mobile Laser Scan Example

  16. Test Site – Albany, Oregon

  17. Field Testing

  18. Field Test Setup • 528 ft Section • 6 Scan Positions • Every 50 m • GPS used to determine position • 5 Targets • Every 50 m • Total station used to determine position

  19. Point Cloud

  20. Point Cloud – Colored from Photos

  21. Field Data - Workflow • Obtain 3D point cloud • Prune data to roadway • Statistically filter data to specified spacing • Obtain profile using GIS • Input data in ProVAL

  22. Editing Point Clouds

  23. Statistical FilteringProcess http://www.lidarnews.com/content/view/8378/136/

  24. IRI Comparisons • Inclinometer Profiler • Left – 66 in/mi • Right – 84 in/mi • Laser Scanner • Left – 73 in/mi • Right – 88 in/mi

  25. ProVAL Data – Left Wheel Path Scanner Inclinometer

  26. ProVAL Data – Right Wheel Path Scanner Inclinometer

  27. Observations • Data between inclinometer profiler and laser scanner is offset • Offset gets larger • Laser scan data filtered to 1 ft intervals • Visible noise in the data • Starting points may not be exactly the same

  28. Laser Scan Data Comparison - Worst 1 ft Spacing 0.25 ft Spacing Grid Cell Dimensions2” V x 20’ H 0.5 ft Spacing

  29. Laser Scan Data Comparison - Best 1 ft Spacing 0.25 ft Spacing Grid Cell Dimensions2” V x 20’ H 0.5 ft Spacing

  30. Localized Depressions Middle Section Right End 29

  31. Questions to Investigate 30 • Laser Scanning • Can the noise be smoothed out while taking advantage of the dense data? • i.e. close point spacing • Compare the profiles in ProVAL • Are IRI values consistent? • Do the distance vs. elevation plots agree? • What are the reasons for any discrepancies?

  32. Future Work • Obtain and compare additional profiles from test site • Laser Scanning • Inertial Profiler • Rod & Level • Create procedures and guidelines for certification

  33. Questions?

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