A novel composite-structure-light 3D measurement method for improving accuracy based on two plus one phase shifting algorithm

In this paper, a novel method is proposed from the perspective of restructuring the gratings to be modulated to restrain the spectrum overlap in composite structure light 3D measurement. Previously, kinds of methods are presented to expand the distance between the adjacent carrier channels, but it still cannot eliminate the spectrum overlap in the orthogonal direction. By the new method, three sinusoidal gratings with equal phase shifting in traditional Phase Measuring Profilometry (PMP) are replaced by two sinusoidal gratings with π/2 phase shifting and a uniform flat image. Moreover, set the carrier frequency modulated by the flat image between the frequencies modulated by the phase-shifting sinusoidal gratings. For the flat image, carrier is only modulated by the “DC” component. Therefore the spectrum overlap between adjacent carrier channels is smaller than the traditional composite pattern (CP) projection. Computer simulation and experiment results prove the new method can effectively restrain the effect of spectrum overlap, and improve the measurement accuracy about 1.74 times.