Direct fitting of center collinear circles for equidistant fish-eye camera calibration

An equidistant fish-eye camera can be calibrated using a single image of two sets of parallel lines in the scene, which is very convenient for practical applications. The core of the calibration procedure is the fitting of center collinear circles that intersect at two vanishing points. A fast and accurate fitting method that can be used for equidistant fish-eye camera calibration is presented. First, the fitting problem is formulated as a nonlinear least square problem and solved using Levenberg-Marquardt optimization. The objective function is also derived, as well as the Jacobian required by the Levenberg-Marquardt algorithm. It is also demonstrated how to determine the initial estimations. Experimental results on synthetic data have demonstrated the superiority of our method to two existing approaches in terms of speed and accuracy. Results on real data have also demonstrated its effectiveness for fish-eye camera calibration. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. [DOI: 10.1117/1.JEI.22.1.013004]