Stable 3D measurement method for high dynamic range surfaces based on fringe projection profilometry

Fringe projection profilometry (FPP) is widely used because of its simple structure and high robustness. Most existing FPP methods consider the surface of a measurement object to be diffuse, and objects with a high dynamic range (HDR) surface usually violate the assumption that the object is a Lambert surface. As a result, the reconstruction results of many shiny objects will have missing 3D point clouds. To solve this problem, this paper proposes a polarization-plus-phase-shift coding strategy that can stably reconstruct 3D geometric objects under bright light conditions. This method replaces the traditional gray code patterns with polarization code patterns to assist the phase-shift patterns for phase unwrapping. Although the measurement object has an HDR surface, the corresponding phase period can be obtained accurately, which effectively suppresses the phase edge jump error caused by the highlight and improves the robustness of the phase unwrapping. Comparative experimental results show that the method can reliably obtain 3D information under the influence of highlights.