Calibration of Nonoverlapping In-Vehicle Cameras With Laser Pointers

This paper introduces a new approach to calibrating inward- and outward-facing in-vehicle cameras using a laser pointer. Since inward cameras, which observe the driver´s behavior, and outward cameras, which observe the driver´s field of view, do not have overlapping views, the conventional calibration methods for stereo cameras cannot be applied directly. A method is presented in which the two cameras can be connected by a laser emitted from a laser pointer. The laser pointer is mounted on a calibration board so that the laser ray´s pose within the calibration board´s coordinate system can be calculated. Two algorithms are presented based on this idea: the coplanar method and the collinear method. We compare the performance of the two proposed algorithms with the conventional mirror-based method through simulations and experiments. Finally, the laser-based collinear method is applied to the calibration of an in-vehicle camera system. In contrast to other methods, the proposed method is simple, practical, and particularly well suited to the calibration of nonoverlapping in-vehicle cameras in a factory or a garage.