Survey on Omnidirectional Cameras: Camera Models, Calibration, and Reprojection
Most cameras in computer vision applications comply with the pinhole camera model of perspective projection. Cameras with bigger fields of view however don't necessarily comply with that model as
Cameras with extended field of view are however useful in many robotics applications like inspection, exploration, navigation, and obstacle avoidance. This type of cameras include dioptric/fish eye, catadioptric, and general, non-central omnidirectional cameras. They require extended modeling and ad hoc (intrinsic/extrinsic) calibration methods.
At the Institute of Robotics and Mechatronics we largely use central cameras that comply with the pinhole camera model. For these we possess extended knowledge and software for calibration and 3-D inference. However, our experience with omnidirectional cameras is limited.
- projection may not be central anymore,
- the camera system may include external reflecting surfaces (catadioptric cameras),
- severe lens distortion may differ from regliar distortion models, or
- the projecting surface may not be flat anymore.
In this internship the student will conduct a study on the modeling of omnidirectional cameras, in consideration of their eventual ease of use and calibration. In particular:
- Literature review on perspective cameras and their calibration.
- Evaluation of external calibration toolboxes on actual images of a catadioptric camera.
- Software implementation of methods for reprojection and general 3-D inference.
- Accuracy evaluation of the former calibration using the latter implementation.
- (Optional:) Conception and implementation of a novel calibration method (intrinsic, extrinsic) for catadioptric cameras in the context of the camera calibratio toolbox DLR CalDe and DLR CalLab.
- Undergraduate studies in computer science or electrical engineering degrees.
- Preferentially prior knowledge of computer vision and robotics.
- Strong knowledge of mathematics and programming (C++, Matlab, IDL).
K. H. Strobl and G. Hirzinger. "More Accurate Camera and Hand-Eye Calibrations with Unknown Grid Pattern Dimensions." Proceedings of the IEEE International Conference on Robotics and Automation (ICRA 2008), Pasadena, California, USA, pp. 1398-1405, May 2008. Sections I and II.
K. H. Strobl and G. Hirzinger. "Optimal Hand-Eye Calibration." Proceedings of the IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2006), Beijing, China, October 2006.
C. Geyer and K. Daniilidis, "A unifying theory for central panoramic systems and practical applications." European Conference on Computer Vision (ECCV), pp. 445–461, june 2000.
B. Micusik, "Two View Geometry of Omnidirectional Cameras." PhD thesis. Center for Machine Perception, Czech Technical University in Prague, 2004.
D. Scaramuzza. "Omnidirectional Vision: from Calibration to Robot Motion Estimation." ETH Zurich Thesis no. 17635. Thesis advisor: Prof. Roland Siegwart. Zurich, February 22, 2008.
K. H. Strobl, W. Sepp, S. Fuchs, C. Paredes, and K. Arbter. "DLR CalDe and DLR CalLab." Institute of Robotics and Mechatronics, German Aerospace Center (DLR). Oberpfaffenhofen, Germany. [Online]. Available: http://www.robotic.dlr.de/callab/