A universal method for the calibration of swing-scanning line structured light measurement system

Abstract

As a non-contact, low cost and efficient method for three dimensional (3D) measurements, the swing-scanning line structured light measurement system has a more compact structure than the linear scanning system. In measuring process, the laser line projector is driven by a step motor with the laser plane intersecting the object sequentially. To obtain the intersection profiles, the corresponding laser plane equations need to be real-time calculated. Moreover, the laser plane can be an arbitrary relative position with the swing axis due to the mount error of laser projector. These would make the calibration model and the solution rather difficult. To address these problems, a universal calibration method is proposed which bridges the swing angle and the coefficients of laser plane with a constant mapping matrix directly. This matrix is determined by use of several (three at least) specific laser planes. The whole calibration process can be achieved by one freely moved checkerboard and is very convenient to use. Several experiments are carried out to validate the proposed method including the measurement of the planar surface, the steps and the sculptured surface.