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The Ohio State University Center for Mapping
Charles K. TothCharles K. Toth1 1 & Dorota A. Grejner-Brzezinska& Dorota A. Grejner-Brzezinska22
Center for MappingCenter for Mapping11
andandDepartment of Civil and Environmental Engineering and Geodetic ScienceDepartment of Civil and Environmental Engineering and Geodetic Science22
The Ohio State UniversityThe Ohio State University
e-mail: [email protected]://www.cfm.ohio-state.edu/
CLEM 2001 CLEM 2001
Specialist Meeting onSpecialist Meeting on
Centerline Extraction and MaintenanceCenterline Extraction and Maintenance
August 6-7, 2001August 6-7, 2001
Santa BarbaraSanta Barbara
OSU
Integrated GPS/INS/CCD System for Integrated GPS/INS/CCD System for High-Precision Centerline ExtractionHigh-Precision Centerline ExtractionIntegrated GPS/INS/CCD System for Integrated GPS/INS/CCD System for High-Precision Centerline ExtractionHigh-Precision Centerline Extraction
The Ohio State University Center for Mapping
National Consortium for Remote Sensing in Transportation - Flows
Develop, demonstrate, and disseminate cost-effective remote sensing techniques for application to transportation flows
NCRST - FNCRST - FNCRST - FNCRST - F
The Ohio State University Center for Mapping
• Traffic Monitoring
• Traffic Management
• Freight and Intermodal Analysis
From Satellite or Airborne Platforms
NCRST - F Application AreasNCRST - F Application AreasNCRST - F Application AreasNCRST - F Application Areas
The Ohio State University Center for Mapping
• Multi-sensor and multi-platform fusion for flow acquisition and interpretation
• Findings to date– Positioning quality at flight altitude: 2-5cm per
coordinate– Positioning quality on the ground: 20-30cm
from 300m altitude– Strong dependence on system calibration
Progress to DateProgress to DateProgress to DateProgress to Date
The Ohio State University Center for Mapping
Presentation Outline Presentation Outline Presentation Outline Presentation Outline
Problem description – background
Solution/System design
Hardware configuration
Prototype imaging software suite
Performance experiences
Imaging component
(GPS/IMU positioning system)
Summary
The Ohio State University Center for Mapping
cable location
Precision Centerline Mapping Precision Centerline Mapping Precision Centerline Mapping Precision Centerline Mapping
The Ohio State University Center for Mapping
Mapping road lane markers at decimeter-level accuracy while maintaining traffic flow and ensuring safety of survey personnel
Finding the connection between the high-accuracy vehicle navigation and the road surface
Mechanical solutions (early system concept) Accident hazard Strong dependence on driver
Non-contact measurements
Problem Description Problem Description Problem Description Problem Description
The Ohio State University Center for Mapping
Multisensor data fusionHigh speed image acquisition
2D/3D image processing (photogrammetry) Computer vision Real-time processing
Tightly-coupled GPS/INS system Post-processing Real-time relative motion support for the real-time image
processing system
Proposed SolutionProposed SolutionProposed SolutionProposed Solution
The Ohio State University Center for Mapping
Digital Camera
Y
H
ZINS
-YINS
GPS Antenna
INS
Mapping ConceptMapping ConceptMapping ConceptMapping Concept
The Ohio State University Center for Mapping
System Design ConceptSystem Design ConceptSystem Design ConceptSystem Design Concept
Image
Acquisition
Control and
Storage
Image
Acquisition
Control and
Storage
StrapdownNavigation
Solution
TightlyCoupledGPS/INS
Kalman Filter
StrapdownNavigation
Solution
TightlyCoupledGPS/INS
Kalman Filter
User
Interface,
Control &
Display Unit
User
Interface,
Control &
Display Unit
PulnixTMC 6700
Digital Color
Camera
PulnixTMC 6700
Digital Color
Camera
RoverGPS Station
RoverGPS Station
LN-100LN-100
BaseGPS Station
BaseGPS Station
L1 and L2 phase observable
Delta V
Delta
L1 and
L2
Image Data
ExposureControl
Time Tag/Sync
EO Data
Host/SlaveCommunication
ControlSignal
OptimalPosition,Velocity,AttitudeEstimates
Real-timeImage
Processing Block
Real-timeImage
Processing Block
Image Post-processing
Block
Image Post-processing
Block
The Ohio State University Center for Mapping
Digital frame camera used in tests presented here based on Lockheed Martin Failrchild 4K 4K CCD
sensor 60mm by 60mm imaging area (15-micron pixel size) Hasselblad 553 ELX camera body with 50 mm Zeiss
lens 6 second image acquisition rate (0.16 Hz)
Target sensor Pulnix color digital camera (TMC 6700) 9 mm by 6 mm imaging area 30 images per second max acquisition rate (30 Hz)
Imaging ComponentImaging ComponentImaging ComponentImaging Component
The Ohio State University Center for Mapping
RGB to STransformation
Median Filter Binary Conversion
Boundary PointsCenterline Extraction
RGB to STransformation
Median Filter Binary Conversion
Boundary PointsCenterline Extraction
Feature Point Extraction
Feature Point Matching
Affine Model Formation
Centerline Strip Formation
Image n
Centerline PositionRefinement
Export to GIS/CAD
Post-processing
Stereo Image Processing
Data Acquisition
ImagePreprocessing
Feature Point Extraction
Image n-1
Final Navigation Data
Relative Motion Estimates
Image Processing ConceptImage Processing ConceptImage Processing ConceptImage Processing Concept
The Ohio State University Center for Mapping
Typical Road/Line PatternsTypical Road/Line PatternsTypical Road/Line PatternsTypical Road/Line Patterns
The Ohio State University Center for Mapping
B/W Image of Low-quality Road SurfaceB/W Image of Low-quality Road SurfaceB/W Image of Low-quality Road SurfaceB/W Image of Low-quality Road Surface
The Ohio State University Center for Mapping
Sobel Edge OperatorSobel Edge OperatorSobel Edge OperatorSobel Edge Operator
The Ohio State University Center for Mapping
Color SeparationColor SeparationColor SeparationColor Separation
RGB to IHS transformation
The Ohio State University Center for Mapping
Color TransformationColor TransformationColor TransformationColor Transformation
The Ohio State University Center for Mapping
Scanline
Centerline
Intersection
noise
Centerline Extraction (1)Centerline Extraction (1)Centerline Extraction (1)Centerline Extraction (1)
SL
RL
CL
P
The Ohio State University Center for Mapping
Centerline Extraction (2)Centerline Extraction (2)Centerline Extraction (2)Centerline Extraction (2)
Monoscopic solution moderate accuracy
High accuracy solution 3D processing
The Ohio State University Center for Mapping
Feature Point ExtractionFeature Point ExtractionFeature Point ExtractionFeature Point Extraction
R(x, y) = det[C] – k trace2[C]
^
2^
^^2
yyx
yxx
III
IIIC
Corner detector:
The Ohio State University Center for Mapping
Feature Point MatchingFeature Point MatchingFeature Point MatchingFeature Point Matching
s1
s2
s3
m2m1
1
m21
m13
m23
n
i
m
j
vuIjviuIvuIjviuImsscore1 1
22222211111111 ]),(),([]),(),([),(
)()(),:,()()(
1
iji
ik
kn
l
klk
klk
iji
iji mspmspmsmscmsp
The Ohio State University Center for Mapping
Strip FormedStrip FormedStrip FormedStrip Formed
Pairwise affine transformation (6-parameter model)
The Ohio State University Center for Mapping
StatusStatusStatusStatus
Prototype system implemented in C++
Experiences Two sets of images (~15-20) with various
road/centerline conditions Computation-intensive algorithms with
convincing performance (post-processing)
Remaining tasks Real-time data acquisition (camera interface
and navigation data from GPS/IMU system) Software reengineering (multithreading) Performance tuning (dual P-IV @ 1.7 GHz)
The Ohio State University Center for Mapping
System Calibration ComponentsSystem Calibration ComponentsSystem Calibration ComponentsSystem Calibration Components
GPS
CameraCalibration
Lever ArmCalibration
INS OTFCalibration
GPSBase
INS
Sensor Mount
CCD
BoresightMisalignment
The Ohio State University Center for Mapping
Digital camera
GPS antenna
LN 100
Test Hardware ConfigurationTest Hardware ConfigurationTest Hardware ConfigurationTest Hardware Configuration
The Ohio State University Center for Mapping
Performance Analysis TestsPerformance Analysis TestsPerformance Analysis TestsPerformance Analysis Tests
Single side-looking camera, tilted downwards by 5°, 4K by 4K B/W imagery
50-mm focal length
Imagery collected along the surveyed road (edge/center line location)
Stereo-pairs formed by subsequent images
7-8 m object distance for boresighting
8-20 m object distance for ground control points (check points)
The Ohio State University Center for Mapping
Vehicle TrajectoryVehicle TrajectoryVehicle TrajectoryVehicle Trajectory
-83.0418 -83.0416 -83.0414 -83.0412 -83.041 -83.0408 -83.040639.997
39.9975
39.998
39.9985
39.999
39.9995
40
longitude [deg]
latit
ude
[deg]
Start
-83.052 -83.05 -83.048 -83.046 -83.044 -83.042 -83.0439.997
39.998
39.999
40
40.001
40.002
40.003
longitude [deg]
latit
ude
[d
eg]
Start/end
Calibration range
Centerline test range
The Ohio State University Center for Mapping
Positioning AccuracyPositioning AccuracyPositioning AccuracyPositioning Accuracy
4.165 4.17 4.175 4.18 4.185 4.19 4.195 4.2 4.205x 105
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
GPS time [sec]
RM
S [
m]
The Ohio State University Center for Mapping
Attitude AccuracyAttitude AccuracyAttitude AccuracyAttitude Accuracy
4.165 4.17 4.175 4.18 4.185 4.19 4.195 4.2 4.205
x 105
0
5
10
15
20
25
30
35
GPS time [sec]
RM
S [
arc
sec]
The Ohio State University Center for Mapping
Boresight Calibration Test RangeBoresight Calibration Test RangeBoresight Calibration Test RangeBoresight Calibration Test Range
The Ohio State University Center for Mapping
Boresight Misalignment PerformanceBoresight Misalignment PerformanceBoresight Misalignment PerformanceBoresight Misalignment Performance
PointID
E [m] N [m] H [m] E residual[m]
N residual[m]
H residual[m]
14 553789.008 221908.411 212.473 -0.003 -0.001 0.00215 553789.426 221909.427 212.448 -0.006 0.002 0.00024 553788.985 221908.418 211.366 0.010 0.000 -0.00225 553789.407 221909.438 211.356 0.009 -0.002 -0.00134 553788.974 221908.415 210.272 -0.006 0.002 0.00135 553789.390 221909.437 210.248 -0.004 0.000 0.000
0.007 0.001
Boresight performed by comparison of GPS/INS results with AT solution
Accuracy of the boresight components
1-2 cm for offsets
17-22 arcsec for attitude
The Ohio State University Center for Mapping
Centerline Test RangeCenterline Test RangeCenterline Test RangeCenterline Test Range
The Ohio State University Center for Mapping
Ground coordinate difference for check points measured from different stereo-pairs
Statistic Easting [m] Northing [m] Height [m] Mean 0.015 0.004 0.008
Median 0.006 0.003 0.006 Maximum 0.050 0.025 0.035
RMS 0.019 0.007 0.010 Ground coordinate difference for check points measured
on stereo-pairs from different passes
Statistic Easting [m] Northing [m] Height [m] Mean 0.015 0.014 0.044
Median 0.013 0.011 0.045 Maximum 0.050 0.034 0.130
RMS 0.020 0.018 0.052
Testing Positioning PerformanceTesting Positioning PerformanceTesting Positioning PerformanceTesting Positioning Performance
The Ohio State University Center for Mapping
GPS Losses of LockGPS Losses of LockGPS Losses of LockGPS Losses of Lock
The Ohio State University Center for Mapping
Units Gap 1 Gap 2 Gap 3 Gap 4East [m] 0.19 0.12 19.0 131.0North [m] 0.40 0.06 33.4 209.2Total errorHeight [m] 0.58 0.18 7.2 162.4
Gap duration [sec] 84 140 320 1200INS calibration [sec] 236 723 860 1050
Positional Error Growth Positional Error Growth during GPS Outageduring GPS Outage
Positional Error Growth Positional Error Growth during GPS Outageduring GPS Outage
The Ohio State University Center for Mapping
Summary Summary Summary Summary
Multisensor all-digital mapping systemReal-time image processing needed
Automatic extraction of centerlines is a reality Real-time implementation is feasible
Direct orientation can be achieved with high accuracy Strong GPS-dependency in urban areas INS support needed (attitude less critical) Proper system calibration is crucial
The Ohio State University Center for Mapping
LIDAR/Digital Image DataCourtesy of
The EarthData Group
Baltimore, MDBaltimore, MDBaltimore, MDBaltimore, MD
The Ohio State University Center for Mapping
Panchromatic Image and LIDAR Panchromatic Image and LIDAR Elevations Plotted as IntensityElevations Plotted as Intensity
Panchromatic Image and LIDAR Panchromatic Image and LIDAR Elevations Plotted as IntensityElevations Plotted as Intensity
The Ohio State University Center for Mapping
+ + + + + + + +
+ + + + + + +
+ + + + + + + +
+ + + + + + + +
The Ohio State University Center for Mapping
Image 1 pixel tessellation
Image 2 pixel tessellation
LIDAR footprint
Image/LIDAR Sampling PatternImage/LIDAR Sampling PatternImage/LIDAR Sampling PatternImage/LIDAR Sampling Pattern
0.4-0.8 1.064
The Ohio State University Center for Mapping
LIDAR Spots Overlaid in the Nadir AreaLIDAR Spots Overlaid in the Nadir Area LIDAR Spots Overlaid in the Nadir AreaLIDAR Spots Overlaid in the Nadir Area
The Ohio State University Center for Mapping
Misalignment of LIDAR Spots and ImageryMisalignment of LIDAR Spots and Imagery Misalignment of LIDAR Spots and ImageryMisalignment of LIDAR Spots and Imagery
The Ohio State University Center for Mapping
What Could Be the Problem?What Could Be the Problem?What Could Be the Problem?What Could Be the Problem?
Sensor modeling of the camera (interior orientation)
LIDAR sensor modeling (scan angle error)
Digital camera boresight misalignment
LIDAR boresight misalignment
Varying navigation performance
Mechanical flex of the sensor mount
Etc.