A simple camera calibration method based on sub-pixel corner extraction of the chessboard image

In view of the limitations revealed in detecting some special types of corners such as chessboard corners (orthogonal X- corners), the authors of this paper improve the SUSAN operator by adding two ring-shaped masks within the SUSAN circular mask. The improved SUSAN operator also includes sub-pixel positioning of the corners by using the center of the gravity about brightness. Moreover, according to the imaging characteristics of optical lens about distortion distribution, we propose a simple camera calibration method in which the intrinsic and extrinsic parameters of the camera and the distortion coefficients are calibrated separately, that is, the camera intrinsic and extrinsic parameters are linearly calibrated firstly using calibrating points near the center of the image, and then the distortion coefficients are calculated using calibrating points in the whole field of view. The experimental results show that the proposed algorithm obtains good results both in calibrating precision and speed.