Obtaining external parameters of an omnidirectional camera with a fish-eye lens using contour matching

This paper presents a novel omnidirectional camera calibration technique based on automatic contour matching. In this proposed method, the initial parameters, translation and rotation, are computed using the epipolar constraint from matched feature points. By using a normal vector to a 3-D plane connecting the contour with the center of the camera projection model, after contour segmentation, candidate contours are chosen to establish a correspondence between views. In order to find the corresponding end points of the contours among the views, the initial parameters and their active matching windows are utilized. Finally, the camera motions are estimated by minimizing the angular error function between the epipolar plane and the backprojected end-point vectors of the corresponding contours. Experiments on synthetic and real images demonstrate that the proposed algorithm obtains more precise camera parameters than previous methods.