Study on a full field of view laser scanning system

To meet the requirement of accurate and convenient 3-D measurement for some large parts in reverse engineering, a full field of view scanning system that is mainly composed of a CCD camera, a galvanometer and a laser projector is proposed in this paper. The camera model is firstly established according to the mapping between the world coordinate system and the computer image. A planar target engraved with square patterns is adopted to calibrate the camera. Based on the rule of cross-ratio invariability, the calibration points are extracted from the square patterns and the lens distortion coefficients are simultaneously acquired. The unknown parameters in camera model are solved using these points. For obtaining the 3-D coordinate of a point in a laser plane, the orientation and position of the laser plane are computed according to the angle of the galvanometer and the intersected lines on the target. And based on the laser orientation and position, the three coordinates of a point in the laser plane can be represented by two of them. Hence, two coordinates can be directly obtained from the camera model. Experiments show that the developed system possesses good accuracy. It can identify the fine structure on a large part, also it is portable and convenient for field measurement.