Modelling and Removing Radial and Tangential Distortions in Spherical Lenses

Abstract

Spherical cameras are variable-resolution imaging systems and promising devices for autonomous navigation purposes, mainly be cause of their wide viewing angle which increases the capabilities of vision-based obstacle avoidance schemes. In addition, spherical lenses resemble the primate eye in their projective models and are biologically relevant. However, the calibration of spherical lenses for Computer Vi sion is a recent research topic and current procedures for pinhole camera calibration are inadequate when applied to spherical lenses. We present a novel method for spherical-lens camera calibration which models the lens radial and tangential distortions and determines the optical center and the angular deviations of the CCD sensor array within a unified numerical procedure. Contrary to other methods, there is no need for special equipment such as low-power laser beams or non-standard nu merical procedures for finding the optical center. Numerical experiments, convergence and robustness analyses are presented.