High-precision light plane calibration via cross-structured light correction and its application in a swinging 3D scanning system with online calibration

Abstract The calibration of the light plane in line-structured light directly impacts the accuracy of subsequent three-dimensional (3D) measurement. This paper presents a novel light-plane calibration method based on the correction of the cross-structured light center. First, the positions of the intersection points are optimized by using Gaussian curve fitting, so as to improve the extraction accuracy of the intersection points. Taking the corrected intersection points as anchor points, an iterative straight-line fitting method for laser stripes is proposed. This method is driven by an adaptive threshold determined according to the manufacturing accuracy of the planar target. Subsequently, the equation of the light plane of line-structured light in the camera coordinate system is established by leveraging the straight-line clusters fitted from the intersection points and the 3D direction vectors of the laser stripes. Experimental results demonstrate that the corrected intersection points obtained by this method greatly improve the accuracy of straight-line fitting, thereby enhancing the fitting accuracy of the light plane. To evaluate the accuracy improvement brought about by the proposed calibration method, a system for high-precision online calibration of the swinging measurement structured light is proposed, which is based on auxiliary structured light. Ultimately, through comparison with the fixed-line scanning system, an approximately equivalent effect is achieved.