Improved Accurate Extrinsic Calibration Algorithm of Camera and Two-dimensional Laser Scanner

Abstract

In the object detecting system composed of a camera and a two-dimensional laser scanner (2DLS), the extrinsic calibration is an essential step to operate properly. However, the edge points of object cannot be detected accurately by 2DLS due to angular resolution limit, which caused loss of accuracy of the extrinsic calibration between camera and 2DLS. In this paper a new algorithm is proposed to solve this problem. Firstly, the least-squares method was applied to linearly fit laser data located on the scanning plane of the three-dimensional rectangular calibration object. Secondly, half of the value of angular resolution was used as the angular incremental component of the laser edge points of object to improve the accuracy of laser data captured by 2DLS. Finally a general optimization was proposed to refine the extrinsic calibration parameters of camera-2DLS by minimizing the re-projection error between those adjusted laser points and their corresponding projections under the image coordinate of the camera. Compared with related methods, experimental results showed that the accuracy of extrinsic calibration between camera and 2DLS was significantly improved