The Technology Aerial LiDAR Mobile LiDAR Aerial photography

Transcription

1 The Evolution of Mobile Mapping Presented by: Allen Ibaugh, AICP, GISP

2 Where it all began

3 Where we are Today

4 The Technology Aerial LiDAR Mobile LiDAR Aerial photography

5 Right-of-Way Imagery Mobile Data Collection

6 Mobile Data Collection Pavement Imagery

7 Mobile Data Collection Mobile LiDAR Terrain Modeling

8 Contour Generation Mobile LiDAR

9 Data Collection Process Collection Processing Software Platform Workflow Tools Data Delivery Tools

10 Mobile Asset Collection Vehicle Collection Platform

11 Processing Workflow Acquisition Post-Processing Calibration Classification

12 Drive Planning Project Area Point Density Single Platform Imagery LiDAR Inertial Measurements GPS Distance Measuring Instrument Data Acquisition

13 Post-Processing Base Stations 2 Trimble RTK-Capable Rovers Maintain short baselines for better accuracies GLONASS-capable receivers Inertial Solution Integrated with LiDAR Ground Control Typically used for accuracy assessment l 20 f 9 % At least 20 points to satisfy 95% confidence level

14 Data Calibration Uncalibrated Data ft discrepancy between di drive lines

15 Data Calibration Calibrated Data < ft discrepancy between drive di lines

16 Unclassified Data All points are positionally correct, but they don t know What they are Need to be assigned to a Class of data Typical Classes are listed to the right Classification allows for modeling and analysis of the point cloud. Data Classification

17 Classified Data Data Classification Brown is Ground class Green is filtered noise such as vehicles, elevated features or any non-ground point

18 Case Study SR417 Mobile LiDAR Data Collection Project

19 Intent Project Presentation Investigate the effectiveness of Mobile Data Collection vs. Low-Altitude Mapping and Photography (LAMP) and Traditional Surveying Improve Safety for Field Crews and Limit Traffic Interruptions Requirements Mobile Scan of Entire Paved Surface, including on and off- ramps 0.05-foot relative accuracy (15mm) Assessment of Absolute Accuracy Digital Terrain Model (DTM) and 3D Breaklines Certification by Independent Survey and Mapping Company

20 Site Orlando, Florida Project Presentation 4 Centerline Mile Toll Highway (including interchanges) 2-3 Lanes on Main thoroughfare 2-5 lanes on Toll plaza and On / Exit Ramps Highway Segment is being re-aligned and rehabilitated

21 Alternatives Project Presentation Low-Altitude Mapping and Photogrammetry (LAMP) Traditional Surveying Benefits of Mobile Platform Efficiency Safety LiDAR Cost-Effective Short Turnaround

22 Control Points Field Procedure Painted, Reflective Xs along the route Inside Shoulder, Outside Shoulder and in Gores, where appropriate Calibration Bore-Sight Alignment to align Scanner with IMU Control Sections driven and then calibrated using EarthView Software Survey All Lanes Driven in Both Directions ~ 25 lane miles of data Drive Speed (~60 mph)

23

24 Control Points Control Validation Used to validate horizontal and vertical accuracy (they are apparent in the point cloud) Used for tie-in in adjustments (if necessary, depending on business requirements)

25 Target Stencil Size important in order to be observed on raw LiDAR point Cloud Size dependent on LiDAR sensor type and collection speed of vehicle Center of Target Surveyed by traditional methods Surveyed Corners / Ends of Target beneficial but not a must

26

27 Data Collection Raw LiDAR points clouds created automatically ti Accuracy relates directly to GPS post processing of vehicle trace at 100 Hz No significant processing required to generate raw point clouds. Automation is the key!

28 DTM Creation Creation of DTM is an automated t process Grid spacing (longitudinal and transverse) is user-definable

29 DTM Creation Each grid point can be a single shot or average of a set of points with a certain range around the location

30 DTM Creation Each grid point can be a single shot or average of a set of points with a certain range around the location Single DTM point Single DTM point created by ~ 20 raw LiDAR shots

31 3D Breakline Creation Breaklines are a common requirement in DTM / TIN modeling Usually represent pavement markings / edge of pavement Breaklines digitized using point cloud intensity

32 Results (units in feet)

33 Results Efficiency / Return on Investment Mobile Survey took 1 day (2 day including vehicle calibration) as compared to greater than 3 months for convention methods Processing Time took 10 days comparable to conventional methods Valued Added Features Digital Images provide desktop capabilities to review project site (perform manual measurements as required) REDUCED FIELD VISITS!

34 Lessons Learned Point Cloud Coverage is Key! Drive in Shoulders / Medians Drive Through Gores Drive Every Lane (eliminates noise caused by passing vehicles) Drive Every Lane twice (redundancy little impact on cost) GPS Base Station is critical to achieve best possible accuracies.

35 Sign Detection Automated Sign Detection using LiDAR Sign locations are analyzed through comparison to sign library Semi-automated (due to non-standard signs) Sign compiler available

36 Asset Images are Linked to Asset Images are Linked to GIS using ArcGIS Server