A calibration and range-data extraction algorithm for an omnidirectional laser range finder of a free-ranging mobile robot

Abstract

A generalized calibration method and an exact 3D range data extraction algorithm for an omnidirectional laser range finder are described. Firstly, a simple 3D range data extraction is achieved by ignoring the camera's lens distortion and scale factor, using the focal length as it is given by the manufacturer, and introducing some assumptions. The simple extracting equations roughly transform a point on a 2D image plane into a position in a 3D spatial coordinate system. Secondly, the intrinsic parameters of the CCD camera are obtained by an existing camera calibration method based on a pin-hole camera model. Thirdly, the exact design constant of the laser slit emitting device and the extrinsic parameters of the CCD camera are simultaneously obtained by laser range finder calibration, where the previously obtained simple 3D range data extraction equations are modified exactly. Consequently, the simple 3D range data calculation equations can be expanded to the exact one by using the parameters obtained by camera and laser slit emitting device calibration. Finally, the calibration parameters and the exact 3D range data of an omnidirectional laser range finder are obtained by experiment and errors of the measurement distances are calculated. Copyright (C) 1996 Elsevier Science Ltd.