Three-dimensional (3D) shape measurement of complex surface object using composite fringe patterns

An important and challenging issue associated with fringe pattern profilometry (FPP) is the unwrapping of phase maps from complex object surface shape. Existing methods based on single phase map are very sensitive to unwanted phase disturbances and fail to recover complex phase maps. This article presents a new single phase map based phase unwrapping method, which combines phase shifting profilometry (PSP) and binary coding stripes together. In our approach, sinusoidal fringe patterns for phase detection and two pre-designed binary coding stripes for phase unwrapping are simultaneously projected in different color of red, green and blue (RGB). Then, by decomposing the captured images into respective color-channels, sinusoidal fringe patterns and binary coding stripes can be obtained. Then, wrapped phase map is acquired by PSP method. Unwrapping is performed with reference to the binary coding stripes. Compared with existing algorithms, this approach can provides efficient and accurate measurement of objects with sharp changing surface. Experiment results are presented to confirm the effectiveness of the proposed technique.