Phase unwrapping method based on discrete phase shifting fringes for 3D measurement

Abstract Temporal phase unwrapping (TPU) methods are extensively employed due to their superior performance characteristics. Nevertheless, conventional TPU methods necessitate the projection of supplementary patterns to facilitate phase period determination, thereby compromising measurement speed and efficiency. To overcome the above challenge, a phase unwrapping method based on discrete phase shifting fringes (DPSFs) for 3D measurement is presented. The DPSF method utilizes three specific sinusoidal patterns with initial phase values around π to calculate the wrapped phase. Two of these patterns are selected for binarization, with the selection criterion governed by the value of N . The periodically distributed phase periods are obtained by comparing these two phase shifting patterns with a certain phase shift amount. Then, a stepped grayscale image is used to correct the phase periods, thereby achieving phase unwrapping and completing the measurement of the target. The entire projection process only uses four patterns. The feasibility of the DPSF method was validated through measurements on a plastic ball and a human statue. Measurement results indicate that the method enables reconstruction of the surface contours of the objects. As phase shifting step size increases, the method exhibits a faster measurement speed and higher measurement efficiency.