Paracatadioptric camera calibration using sphere images

The problem of calibrating paracatadioptric camera from sphere images is still open. In this paper, we propose a calibration method for paracatadioptric camera based on spheres. We notice that, under central catadioptric camera, a sphere is projected to two conies on the image plane, which can also be seen as the projections of two parallel circles on the viewing sphere by a virtue camera. These two conies are called a pair of antipodal sphere images. Firstly, we study properties of K(K >; 3) pairs of antipodal sphere images under paracatadioptric camera. Then, they can be estimated using these properties. Finally, paracatadioptric camera can be calibrated by three pairs of antipodal sphere images or more. The method only requires the projected contour of parabolic mirror is visible on the image plane in one view. Experimental results on both simulated and real image data have demonstrated the effectiveness of our method.