3D shape measurement based on color-encoded sinusoidal fringe projection

In three dimensional (3D) shape measurement based on fringe projection, a serial of well designed color strips is used to encode each period of the projected sinusoidal fringe. It is considered one of the most reliable techniques for recovering 3D shape of a tested objects, even with spatially isolated surface. The sinusoidal fringe intensity is used to extract the phase information of the tested object, and the color strips with known order is assisted to recover its corresponding natural phase distribution. Principles of this technique and three color encoding methods with difference color codification are described in this paper. Some experimental results are also presented. In each method, each fringe order only depends on its own corresponding color information, has nothing to do with the neighborhood fringes in space, thus, unwrapping error is limited in a small area and won't expand to other pixels. It takes great convenience for 3D measurement of an object with spatially isolated surface. With only one image, 3D shape of the tested object can be exactly reconstructed, thus the speed is limited only by the frame rate of camera, so these methods can also be used in 3D shape measurement for dynamic object.