High-speed 3-D shape measurement based on digital fringe projection

A high-speed 3-D shape measurement technique based on digital fringe projection has been developed and experimented. This technique uses a computer-generated color fringe pattern whose red, green, and blue channels are sinusoidal fringe patterns with a 120-deg phase shift between neighboring channels. When this color fringe pat- tern is sent to a digital-micromirror-device (DMD) based video projector with no color filter, three gray-scale fringe patterns are repeatedly pro- jected to an object surface in sequence with a cycle time of approxi- mately 10 ms. The three phase-shifted fringe patterns deformed by the object surface are captured by a CCD camera with proper synchroniza- tion between the camera and the projector. The 3-D shape of the object surface is reconstructed by using a phase wrapping and unwrapping algorithm and a phase-coordinate conversion algorithm. Experimental results demonstrated the feasibility of this technique for high-speed 3-D shape measurement with a potential measurement speed up to 100 Hz.