Joint Calibration of Structured-Light Measurement Systems via 3-D Offset Modeling and Phase-Consistent Optimization

Abstract

Structured light (SL) systems are widely used as optical 3-D measurement instruments, where calibration accuracy plays a critical role in ensuring reliable metrological performance. However, practical calibration targets often exhibit nonnegligible surface deformations due to manufacturing or handling imperfections, which introduce systematic measurement errors and degrade the accuracy and traceability of 3-D measurements. This article presents a joint optimization framework that integrates 3-D offset modeling with phase-consistent subpixel feature matching to address these challenges. Each target point is associated with a deformation-compensated 3-D offset vector, constrained by a global zero-mean prior to suppress scale ambiguity and spatial drift. The optimization jointly refines camera and projector parameters by minimizing bidirectional reprojection errors (REs). Experimental results on both simulated and real-world datasets demonstrate that, in simulation, the proposed method reduces deformation-induced reprojection-error growth by 69 % for the camera and 71 % for the projector. In real-world experiments, relative to traditional calibration, the mean camera/projector REs are reduced by 82.7 %/77.0 % for the globally deformed target and by 89.7 %/92.3 % for the localized Gaussian-shaped target, while the accuracy of downstream 3-D reconstruction is substantially improved. The method enables high-precision calibration using low-cost or flexible targets without requiring additional measurement hardware, making it suitable for field deployment and portable SL instruments.