Phase error correction based on chord distribution and spectral analysis

To address the saturated phase error caused by the local specular reflection of the object, and the nonlinear error resulting from the gamma effect of the projector and the cameras in fringe projection three-dimensional (3D) measurement, a phase error correction method based on the string distribution and spectrum analysis was proposed. First, the saturated signal model was theoretically analyzed, and the characteristics of the saturated phase error were derived. Then, spectral analysis was performed on the saturated image signal, and the saturated phase correction was completed using Fourier transform. Finally, a phase error correction algorithm based on chord distribution equalization was employed to reduce the nonlinear error induced by the gamma effect. This method can simultaneously mitigate both saturated and nonlinear phase error in fringe projection 3D measurement without requiring any additional fringe image. Simulation and experimental results demonstrated the effectiveness of the proposed method.