A new technique for finding the optical center of cameras

We present a new technique for finding the optical center of a camera. The proposed technique uses spheres as calibration objects. We prove a new key result, that the major axis of the ellipse image resulting from the perspective projection of a sphere would pass through the optical center of the image, and use this result to find the optical center of the camera. Spheres being isotropic, simplify the process of calibration greatly. The proposed technique has been tested on a large number of images and we present the results of some of the test cases