Nonmetric calibration of camera lens distortion using concentric circles pattern

A method of distortion calibration for camera is proposed. The distortion center and distortion coefficients are estimated separately. The planar concentric circles are used as the calibration pattern. By analyzing the geometrical and projective characters of concentric circles, we deduce that the line connecting the centroids of distorted concentric circles must go through the distortion center. This is utilized to compute the distortion parameters and the solution in the sense of least square are obtained. The proposed approach is entirely noniterative, therefore it keeps away from the procedure of iterative optimization. On the other hand, it is nonmetric, thus it is low cost. Experiments on both synthetic and real image data are reported. The results show our method behaves excellently. Moreover, the capability of our method to resist noise is satisfying.

I. Introduction

Camera calibration is a fundamental component in Computer Vision which extracts geometric information from images. Simply but not exactly, the pinhole model using projective geometry is employed to describe the imaging process. However, the lens distortion is inevitable, which should be corrected in measurement requiring high accuracy. The distortion parameters include distortion center and distortion coefficients. So the basic task of distortion calibration is to make estimation of these parameters.