Global phase accuracy enhancement of structured light system calibration and 3D reconstruction by overcoming inevitable unsatisfactory intensity modulation

Mainstream fringe projection profilometry (FPP) faces challenges in measuring low signal-to-noise ratio intensity modulation areas, especially in shadow areas on objects and black areas on calibration plates, causing pseudo phases and obvious nonlinear calibration error in 3D measurement. To address these issues concurrently, we proposed a cyclic phase-shifts difference (CPSD) module based on phase-shifting gratings. CPSD uses double-layer circulation difference to retain the pixels with higher light intensity eliminating the influence of ambient light and finally creates a mask removing and correcting black and shadow areas. Without further post-processing and projection operation, we achieved the global phase accuracy enhancement and obtained high-precision 3D point clouds without pseudo points. The method’s efficacy was proven through experiments on three kinds of calibration planes, achieving a significant reduction in mean absolute error (MAE) and standard deviation (STD) in plane reconstruction (up to 50.9% and 56.1% respectively). We believe that CPSD has enormous potential for wide application across various FPP-related fields.