gnss/ins for high accuracy mobile mapping · lidar mobile mapping mm – cm 0.1° challenging !...
TRANSCRIPT
GNSS/INS for High Accuracy Mobile Mapping
Olaf Gross 11th Terrasolid European User Event 15.02.2012
Kittilä, Finland
• Founded 1978
• 25 staff – about half in R&D
• More than 380 customers in 60 different countries
• World-wide technical support
IGI office in Kreuztal
IGI mbH
IGIs Modular Sensor Systems
• Missionplanning • Navigation • GNSS/IMU • Sensor Management
IGIs Mobile LiDAR Solutions
point cloud
Georeferencing Workflow
Measure lever arms &
Determine Misalignments
Apply misalignments and lever arms
Is the Result satisfactory?
Scanner data
Navigation data
Pointcloud
yes
Calibration
Office/Lab Calibration
Missalignment Calibration workflow
• Drive suitable site with buildings: Good visibility to walls
Clean, vertical walls
Right driving pattern
• Search tie lines on building walls automatically
• Solve HRP misalignment angles
Calibration Mobile
• Large building with open area (parking lot)
Calibration driving pattern 1
Calibration driving pattern
Calibration of Train/Tram Data?!
Engineers installing a RailMapper calibration field …
point cloud
Airborne Lidar & “Mobile Mapping”
Same sensor technologies
• LiDAR, GNSS/INS, different kind of cameras
Similar calibration and orientation strategies Differences:
• Kinematic conditions • GNSS conditions • Distance to the object
Kinematic Conditions - Standstill
GNSS conditions: Air vs. Ground
point cloud
Distance to the Object of interest Airborne LiDAR / Photogrammetry
focal length: 100mm pixel size: 6µm FOV (one pixel) = 0.0034°
LiDAR Mobile Mapping
distance: 5m accuracy: ~1cm angular error = 0.1°
Resulting Requirements
Application Position Orientation
Airborne LiDAR or Airborne Photogrammetry
cm – dm 0.01° – 0.001°
Airborne Thermography dm 0.1° – 0.01°
LiDAR Mobile Mapping mm – cm 0.1°
Challenging ! Easy !
The IMU is 10 to 1000 times better than needed for Orientation of
LiDAR Mobile Mapping
But: Exceptional good IMU is a must to be able to provide required
Position accuracies!
IMU
Kalman Filter
Position Velocity Attitude
Differential GNSS
TERRAcontrol – Technology
GPS vs. GPS & GLONASS
GPS vs. GPS & GLONASS
GPS only
GPS vs. GPS & GLONASS
GPS & GLONASS
GPS vs. GPS & GLONASS
GPS & GLONASS
GPS only
IMU
Kalman Filter
Position Velocity Attitude
Differential GNSS Odometer
Direct Inertial Aiding
TERRAcontrol – Technology
Direct Inertial Aiding
without inertial aiding with inertial aiding
Direct Inertial Aiding
Direct Inertial Aiding
Navigation – ZUPT
Navigation – ZUPT
TERRAoffice V5.2 compared to V5.3
Trajectory
TERRAoffice 5.2 Trajectory
TERRAoffice 5.3
TERRAcontrol Technologie
TERRAoffice V5.2 compared to V5.3
Trajectory
TERRAoffice 5.2
Trajectory
TERRAoffice 5.3
TERRAcontrol Technologie IV
Forward/Backward Processing
GNSS gap
IMU Performance
GPS only
IMU Performance
TERRAcontrol IMU-IIe
• Fiber optic gyros
• MEMS Accelerometers
• Data rate 400Hz
• Gyro Drift 0.03°/h
TERRAcontrol Technologie
TERRAcontrol with IMU-IIe
• Integrated GNSS receiver with DIA+ (GPS/GLONASS)
• IMUIIe
• Real time navigation
TERRAcontrol Technologie
System accuracy (dGPS):
Position: <0.05m
Velocity: 0.005m/s
Roll/Pitch: 0.003°
Heading: 0.007°
TERRAcontrol Technology
StreetMapper Control Rack
Thermal camera option for StreetMapper and RailMapper
point cloud
Georeferencing Workflow
Measure lever arms & Determine
misalignments and
Apply misalignments and lever arms
Is the Result satisfactory?
Scanner data
Navigation data
Pointcloud
Apply global or local adjustments no
yes
Matching based on intensity or xyz features in LIDAR
Matching based on linear features in images
Terrasolid – Tie Lines
Typical control points
Geometric Correction
GCP-Marker
e.g. 25cm x 25cm
Example: Tram System Helsinki
TERRAcontrol Technologie IV
Example: Tram System Helsinki
TERRAcontrol Technologie IV
Problem: Strong GNSS shadowing effects due to vegetation and buildings.
TERRAcontrol Technologie IV
Examples
Recent project on UK Highway - Results
Conclusion
• A careful system calibration is a prerequisite for high accuracy Mobile
Mapping.
• Local adjustments are generally much more important for Mobile
Mapping than for airborne LiDAR.
• Combining a high performance GNSS/INS with a state of the art LiDAR
and the current calibration and adjustment techniques allows for cm
accuracies for a wide range of project conditions.