High-speed, high-accuracy 3D shape measurement based on binary color fringe defocused projection

A widely used method in high-speed 3D shape measurement, color-code fringe projection requires the projection of only one image. In traditional color-code method, the projected fringe is compounded by sinusoidal fringes, grayscale value distribution ranges from 0-255, and projection speed is limited to 120 frames/s. Consequently, measurement speed is restricted, and a nonlinear gamma of the projector exists, as well as high harmonics, which have a great influence on measurement accuracy. Binary color-code fringe defocused projection is proposed to solve the abovementioned problems. With the proposed method, projection speed can switch to tens of K frames/s because it only has two grayscale values (0 and 255). A standard sinusoidal color-code fringe can be generated by properly defocusing the binary color-code fringe, thereby overcoming the influence of nonlinear gamma and ultimately improving measurement accuracy. Experiment results verify the feasibility and superiority of the proposed method.