One-shot 3D shape and color measurement using composite RGB fringe projection and optimum three-frequency selection

Abstract

A composite RGB fringe projection and processing method is presented to simultaneously obtain 3D shape and color information of objects from one-shot acquisition. Three fringe sets with optimum fringe numbers are coded into the red, green and blue channels of a digital light projector to generate one composite RGB fringe pattern. The deformed fringes on an object surface are recorded by a three-chip color CCD camera from a different viewpoint. Fourier transform analysis is applied to the obtained fringe patterns in each color channel to retrieve the wrapped phase maps. Absolute phase across the full-field is calculated from the three obtained wrapped phase maps on a pixel-by-pixel basis using the optimum three-frequency method. Color data are also extracted from the same composite RGB fringe pattern image, so there is an exact one-to-one correspondence between the absolute phase and color data. Only one RGB fringe image is required to calculate the shape and color information, thus the proposed method can measure dynamic objects. Experimental results on static and moving objects having discontinuities and/or isolated surfaces show the validity of the proposed method for measuring the shape and color information.