Transcript
Development of a Portable Mobile Laser Scanning System with Special Focus on the System Calibration and Evaluation MCG 2016, Vichy, France, 5-6th October
Erik Heinz, Christian Eling, Markus Wieland, Lasse Klingbeil and Heiner Kuhlmann University of Bonn, Germany
Motivation
Growing importance of spatial 3D data… • mapping, documentation, visualization, planning, inspection, …
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Mobile laser scanning, but… • limitations in terms of weight, size, costs, access, safety, …
[4] Erik Heinz
[5] Machine Control and Guidance 2016, Vichy, France
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Motivation
Development of portable systems • improved mobility and flexibility in challenging situations: soft ground, narrow passages, access limitations, security aspects
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[12] Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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Motivation
Development of portable systems • improved mobility and flexibility in challenging situations: soft ground, narrow passages, access limitations, security aspects
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Erik Heinz
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Machine Control and Guidance 2016, Vichy, France
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Portable system
Portable laser scanning system (IGG Bonn) • direct georeferencing unit (GPS, IMU, magnetometer) and 2D laser scanner (Hokuyo UTM-30LX-EW) • weight < 1.5 kg (w/o frame & batteries) and size < 1 m
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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Direct georeferencing unit
Position and attitude of the mobile platform • small, lightweight (240 g, w/o antennas & batteries), real-time • pose estimation with σPos < 5 cm, σAtt < 0.5° ̶ 1° and 100 Hz
RTK-GPS (L1+L2) GPS compass (L1) GPS/IMU integration
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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2D laser scanner
Mapping of the environment • Hokuyo UTM-30LX-EW (TOF principle)
• maximum (guaranteed) range 30 m • FOV 270° with resolution of 0.25° • 2D points, intensities, multi-echo
• scanning rate 40 Hz • weight: 210 g (w/o cable) • small, low-cost (~ 5,000 $) • accuracy mm to cm Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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System architecture
Fusion of the sensors • time synchronization with trigger pulses (PPS + SCS) • system calibration, i.e. lever arms and boresight angles between direct georeferencing unit and 2D laser scanner
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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System architecture
Fusion of the sensors • time synchronization with trigger pulses (PPS + SCS) • system calibration, i.e. lever arms and boresight angles between direct georeferencing unit and 2D laser scanner
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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System calibration
Problem formulation • 6 DOF transformation • 3 lever arms Δx, Δy, Δz • 3 boresight angles α, β, γ
• transformation (position and orientation) between direct georeferencing unit and 2D laser scanner is unknown
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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System calibration
Calibration approach • calibration field with differently oriented reference planes (georeferencing by TLS and ground control points) • static scanning of the planes with the mobile system from different stations
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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System calibration
Calibration approach • scan points of the mobile system must satisfy the plane equations ↔ planes are defined by the 3D TLS points
• adjustment of g1 and g2 in a total least squares approach • estimation of the six calibration parameters with covariances (variance component estimation)
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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System calibration
Calibration results Parameter accuracies about 4 mm and 0.1°
Parameter correlations smaller than 15 %
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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Simulations
Analysis/optimization of the calibration • network configuration in the calibration field is crucial for the quality of the results
• quality criteria accuracy and correlation of the parameters reliability, i.e partial redundancies of the observations
sensitivity of the planes towards the parameters efficiency, i.e. minimal number of planes and scans
Implementation of a simulation environment! Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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Simulations
Exemplary simulation results • two calibration fields: 7 reference planes, 4 stations of a MSS with [σxyz, σϕθψ, σd, σa] = [0.01 m, 0.05°, 0.002 m, 0.02°] P7
P1 P2
MSS1,2,3,4
P6
P3,4,5
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
Field 1 Parameter
Accuracy
Δx
0.0050 m
Δy
0.0050 m
Δz
0.0050 m
α
0.0551°
β
0.0258°
γ
0.0256° Page 15
Simulations
Exemplary simulation results • two calibration fields: 7 reference planes, 4 stations of a MSS with [σxyz, σϕθψ, σd, σa] = [0.01 m, 0.05°, 0.002 m, 0.02°] P7
P1 P2
MSS1,2,3,4
P6
P3,4,5
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
Field 2 Parameter
Accuracy
Δx
0.0050 m
Δy
0.0050 m
Δz
0.0050 m
α
0.0282°
β
0.0258°
γ
0.0251° Page 16
Simulations
Partial redundancies of the observations • Refinement of the network configuration improves the quality of the calibration results • weakly controlled pitch angles θ of the mobile platform affect the boresight angle α negatively!
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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System evaluation
Precision of the system • cloud-to-mesh differences δ between two kinematic scans
• good repeatability: no systematic deviations, cm-precision
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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System evaluation
Accuracy of the system • cloud-to-mesh differences δ: kinematic scan ↔ TLS scans
• systematic deviations (due to GPS), cm to dm accuracy
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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System evaluation
Accuracy of the system • cloud-to-mesh differences δ: kinematic scan ↔ TLS scans
• systematic deviations (due to GPS), cm to dm accuracy
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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System evaluation
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Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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Conclusion and outlook • Portable laser scanning system with cm to dm accuracy – small and lightweight – improved mobility and flexibility
• System calibration with plane-based approach – accuracy of the parameters about mm and decidegree – simulations to analyze and optimize the calibration
• Future work – refinement of the calibration based on simulations – integration of intrinsic calibration parameters – test field for mobile laser scanning systems for calibration and evaluation purposes
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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Thank you for your attention Questions or comments? M.Sc. Erik Heinz Institute of Geodesy and Geoinformation University of Bonn, Germany Tel.: +49 228 / 73-3034 Email:
[email protected]
Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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List of figures [1] [2]
http://mundogeo.com/blog/2014/09/15/artigo-trata-sobre-o-futuro-do-bim-e-geo-aliadosou-concorrentes/ (20/07/2016). http://www.renishaw.com/media/img/gen/da846af7bf7f4c09a1a6f13403244707.png (20/07/2016)
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http://www.xyht.com/wp-content/uploads/2016/01/arsenal_rails.gif (20/07/2016) https://rieglusa.files.wordpress.com/2015/02/uls_ricopter_productimage_002.jpg (20/07/2016)
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http://leica-geosystems.com/products/mobile-sensor-platforms/capture-platforms/leicapegasus_two (20/07/2016) http://www.terra.ch/de/gleismessungen.html (20/07/2016)
[6] [7] [8] [9]
Kukko, A., Kaartinen, H., Hyyppä, J., Chen, Y., 2012. Mobile Laser Scanning: Usability and Peformance. Sensors 12, 11712-11733. http://www.ingenieur.de/Arbeit-Beruf/Gruenderlounge/Finanzierungsrunden/HTGFinvestiert-in-3D-Laservermessung-p3d-Systems (20/07/2016) http://leica-geosystems.com/products/mobile-sensor-platforms/capture-platforms/leicapegasus-backpack (20/07/2016)
[10] http://www.auto-map.co.uk/sectors/marine/coastal-mapping/ (20/07/2016)
[11] http://www.trailsoffroad.com/trails/533-devil-s-lane (20/07/2016) [12] https://cams.ukb.uni-bonn.de/hkom/album/Gebaeude%20und%20Museen/Poppelsdorfer %20Schloss%20und%20Botanische%20Gaerten/index.html#Studierende_41_LR.jpg (20/07/2016) [13] http://host.madison.com/red-and-white-wind-cone-istock/image_3308a013-2b19-5f298151-635b89de2807.html (20/07/2016) [14] http://www.mena3d.com/unmanned-aerial-vehicle.html (20/07/2016) [15] https://cams.ukb.uni-bonn.de/hkom/album/Gebaeude%20und%20Museen/Luftbilder/slides /02_LR.jpg (21/07/2016). Erik Heinz
Machine Control and Guidance 2016, Vichy, France
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