Nonlinear self-calibration method based on phase registration in phase-shifting profilometry

In phase-shifting profilometry, the nonlinearity of the projector is the main error source which undermines the 3D reconstruct accuracy. Most calibration algorithms mainly focus on calibrating the nonlinear responses and compensating for the related errors. However, it requires a tedious pre-calibration process. In this paper, a phase registration algorithm based on Gray code guidance is proposed, Hough transform and majority voting are performed to accurately locate the boundary of Gray code, two strategies are introduced to select correct phase matching pairs. In addition, to eliminate mismatched points and improve the accuracy of the fitting, outlier detection technology is used to iteratively fit phase matching pairs. Finally, the error is compensated point by point using the fitting curve. Experimental and simulation results demonstrate the effectiveness of the proposed method. It has the advantages of simple deployment, no photometric pre-calibration, high accuracy, strong robustness, and can handle the projector's nonlinearity that changes with time.