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Improving and Filtering Laser Data for Extrinsic Laser Range Finder/Camera Calibration. Sukhum Sattaratnamai Advisor: Dr.Nattee Niparnan. Outline. Introduction LRF-Camera System, Applications Related work LRF-Camera Calibration Method Our Problem Challenge, Propose method
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Improving and Filtering Laser Data for Extrinsic Laser Range Finder/Camera Calibration SukhumSattaratnamai Advisor: Dr.NatteeNiparnan
Outline • Introduction • LRF-Camera System, Applications • Related work • LRF-Camera Calibration Method • Our Problem • Challenge, Propose method • Scope & Work plan
Point Cloud Data • Hard to classify the objects without color information
Color Information • Give rich information about the environment
Laser Range Finder • Give depth data of scan plane, and can be used to generate 3D point cloud
Camera • Camera Model
LRF-Camera Calibration • Problem Definition [Ganhua Li, 2007] • Find the transformation [R |t ] of the camera w.r.t. LRF
Applications • Transportation • Surveillance • Tourism • Robotics
Precision? • “Stanley: The Robot that Won the DARPA Grand Challenge”
Precision? • Accident
Objective • Calibration method can give most accurate result • laser data post-processing method
Related work • Projection Error (2D) • Point to Plane Distance (3D)
Related work (2D) • Wasielewski, S.; Strauss, O.;, "Calibration of a multi-sensor system laser rangefinder/camera," Intelligent Vehicles '95 Symposium., 1995
Related work (2D) • Mei, C.; Rives, P.;, "Calibration between a central catadioptric camera and a laser range finder for robotic applications," ICRA 2006
Related work (2D) • Ganhua Li; Yunhui Liu; Li Dong; XuanpingCai; Dongxiang Zhou;, "An algorithm for extrinsic parameters calibration of a camera and a laser range finder using line features," IROS 2007
Related work (3D) • Qilong Zhang; Pless, R.;, "Extrinsic calibration of a camera and laser range finder (improves camera calibration)," IROS 2004
Related work (3D) • Dupont, R.; Keriven, R.; Fuchs, P.;, "An improved calibration technique for coupled single-row telemeter and CCD camera," 3DIM 2005
Comparison • 2004 vs 2007
Our Problem • Propose an autonomous data improving and filtering method which lead to more accurate calibration result
LRF-Camera System • Laser Range Finder • Camera
Challenge • Sensor Model [Kneip, L.; 2009] • Laser range finder sampling an environment discretely • Laser data are noisy : Mixed pixel
Challenge • Laser beams are invisible • Point-Line constrains • No ground truth available • Autonomous process • Autonomously improve and filter the data
Proposed method • Data improvement : Reduce angular error
Proposed method • Data filtering: Remove outlier • In case of mixed pixel: may select neighbor point instead • In case of moving calibration object: remove data pairs
Scope of the research • Propose an autonomous laser data improving and filtering method for extrinsic LRF/camera calibration • Laser range finder and camera can be placed at arbitrarily position as long as they have a common detection area • An environment is suitable for laser range finder and camera so that they can detect the calibration object
Work Plan • Study the works in the related fields • Develop data improvement method • Develop data filtering method • Test the proposed method • Prepare and engage in a thesis defense
Bundle adjustment • Conceived in the field of photogrammetry during 1950s and increasingly been used by computer vision researchers during recent years • Mature bundle algorithms are comparatively efficient even on very large problems • Bundle adjustment boils down to minimizing the re-projection error between the image locations of observed and predicted image points • Visual reconstruction attempts to recover a model of a 3D scene from multiple images and also recovers the poses of the cameras that took the images