An adaptive fringe projection method for measuring three-dimensional profile of surface with high reflectivity using sub-pixel coordinate mapping

Fringe projection profilometry (FPP) is a popular three-dimensional (3D) shape measurement technique and has been widely used in industry. However, measuring surface with high reflectivity is still challenging because image saturation leads to absolute phase errors and reconstruction errors. In this paper, a novel adaptive fringe projection method is proposed. First, a projection intensity model is built. Adjusting the exposure time only once can easily calculate the low projection intensity. Then, using fringe patterns with low intensity we can get the coordinate mapping relationship. By mapping and filtering the sub-pixel coordinates in the projector image, we can obtain more accurate coordinate correspondence and gray value correspondence of the projector and the camera. Finally, the parameters of the projection intensity model are fitted to calculate the optimal intensity and generate accurate adaptive fringe patterns. The measurement experiments demonstrate that the proposed method is effective in obtaining high-precision and complete 3D profile of surface with high reflectivity.