High-speed 3-D reconstruction based on phase shift coding and interleaved projection

Fringe projection profilometry (FPP) based on temporal phase unwrapping (TPU) is one of the most important three-dimensional (3-D) structured light (SL) reconstruction techniques. However, there is an inevitable contradiction between the number of auxiliary coded patterns and the measuring speed. To mark a large number of fringe order in high-frequency fringe projection or wide-field scenes, commonly-used strategy is to add more coded patterns, which compress heavily the ratio of phase-shifting patterns carrying the 3-D shape information of object. In this paper, a phase shift coding method is developed to mark fringe order, in which three phase-shifting patterns and one auxiliary coded pattern can obtain high-quality wrapped phase and fringe order at the same time. In addition, an interleaved projection can provide two fringe order with different densities to extend the coding range of fringe order, while ensuring the measuring speed. Experiments with various static and dynamic objects demonstrated that the proposed method with the advantages of flexibility, high-efficiency coding can achieve the reconstructing rate of 30 fps for 8-bit fringe projection. This method should be highly meaningful for practical applications of 3-D face modeling, industrial inspection, intelligent recognition, virtual reality, and so on.