Mobile LiDAR for Ground Applications Spar 2006, March 27 2006 Paul Mrstik, Terrapoint Canada Inc. Craig Glennie, Terrapoint USA LLC
Agenda Introduction to Terrapoint What is mobile LiDAR? Advantages of going mobile Terrapoint s SideSwipe system Development Block Diagram Experience Future of Mobile LiDAR Technology Applications
Introduction to Terrapoint Offices in Houston, Calgary and Ottawa 20+ years of airborne mapping and survey experience 9+ years of LiDAR survey experience Projects in over 40 countries 50+ experts in Physics, Engineering, Geodetics and GIS 7 LiDAR systems: 3 low-altitude high accuracy, 3 high-altitude fixed-wing, 1 system for ground operations
Projects Overview Over 500 LiDAR projects from the air & from the ground Major Markets served:» Oil & Gas/Seismic» Transportation» Land Development» Powerline/Utilities» Mining» Environmental/Flood
Mobile LiDAR 1. The position of the laser is provided by GPS 2. The orientation of the laser is provided by an IMU 3. The scan angles and ranges of the laser are provided by the sensor 1+2+3 data combined in post-flight processing to accurately determine the position of each point Data combination occurs post mission
Advantages of Going Mobile Advantages Speed of acquisition Area covered Safety Homogeneous segments unnecessary to align any clouds Disadvantages Accuracy Point density Access to some areas Shadowing Need accurate Navigation Solution
Low-Altitude LiDAR System LiDAR sensor, GPS & IMU all integrated in modular design Combined with high-resolution digital camera 10 KHz Laser, max 350 m AGL Portable/modular design Easy to install and operate Fly low and slow for high survey point density Millions of survey points per sq km 2 to 20 pts/sq m
Terrapoint s Sideswipe System 2002: Developed a prototype to test the concept of LiDAR on a ground vehicle Solution waiting for a problem for a few years Obstructions were a problem Multiple passes required for good coverage 2004: Requirement in Afghanistan to do a road survey Couldn t find a suitable helicopter Built prototype into a production prototype in about 1 month & tested it on home turf Successful test meant we could send it to Afghanistan Testing was done against ground truth as well as airborne LiDAR Fusing airborne and ground data sets was no problem
SideSwipe LIDAR Take conventional LiDAR Bring it down-to to-earth Turn it on its side
SideSwipe Assembly
SideSwipe LIDAR Test System On the road in Afghanistan 40 survey points per sq m on the pavement
Flexible solution UK SideSwipe Switzerland low-range 1 week later same system
BoatDAR on Mooney s Bay Objectives Test viability of LIDAR mapping of shorelines. Determine whether or not water causes interference due to reflections etc. Net Result Very fast survey Ability to map under canopy along the shoreline Ability to map structural features from the water 5-10 cm accuracy possible
Determining the Accuracy Check airborne LiDAR against SideSwipe Multiple passes of SideSwipe compared to each other LiDAR is a great for checking the accuracy of the GPS/INS, and even the LiDAR itself it provides a long lever arm that amplifies errors Measurement runs in opposite directions provide checks on horizontal accuracy. GPS road profiles GPS spot checks Total station cross sections
Determining the Accuracy Centre Line Ditch Site Edge of Pavement Edge of Shoulder Guard Rail Property Line Toe Slope 100 m AGL: Sample 294 points RMSE 3.74 cm Sample Size 47 68 45 20 30 44 40 RMSE 2.2 cm 3.7 cm 2.8 cm 4 cm 4.9 cm 4.8 cm 4.6 cm LiDAR hill-shade image with cross sections 10 pts / sq. m
SideSwipe Ups and Downs Pros: Cons: Accurate Fast Homgeneous data sets Lots of points Great for wires, clearances Difficult to process (software not designed for long corridors of side scans when you do vegetation removal) Vibration Limited field of view in one pass
Ground Based LIDAR Planimetric View ~1 km ~15 minutes of data collection
Boat LIDAR Planimetric Shoreline View ~1 km ~10 minutes of data collection
Future of Mobile LiDAR Technology GPS (new positioning systems more satellites) INS Longer Stability MEMS? Image coverage & improved LiDAR coverage Additional Sensors Compass & heading Odometer Replacement or enhancement of GPS using Images Triangulation LiDAR (tunnelling projects)
Future of Mobile LiDAR Applications Corridors (Engineering) Highways Railways Power lines Overpasses Urban areas Roads Infrastructure Communication and power wires Curbs Intersections Underground/Indoors Mines Malls? Subways
Questions? Paul Mrstik: paul.mrstik@terrapoint.com (613)-820-4545 Craig Glennie: craig.glennie@terrapoint.com (281)-364-4081