Abstract: One of the key steps in 3D optical shape measurement based on the structured light projection is the phase unwrapping. The unwrapping issue about the complicated phase map is also the difficult step of the methods. The temporal phase unwrapping provide a useful tool to obtain the continuous phase map from the complicated wrapped phase map. Along the time direction, the temporal phase unwrapping is independently carried out from a 3D distribution demodulated from grating fringes with different pitches projected on the tested object. Therefore the problem of the error propagation in 2D phase unwrapping algorithm can be avoided. Followed by the comparison among the typical temporal phase unwrapping methods, including the negative exponential method, three pitches unwrapping method, three pitches heterodyne unwrapping method and its improved technique, a segmentation curve fitting method is used to improves the phase calculation accuracy. The computer simulations and experiments are carried out to verify that the phase error is deduced greatly through the segmentation curve fitting.
