3D shape measurement method for high-reflection surface based on fringe projection

3D measurement methods based on fringe projection have attracted extensive research. However, it is a challenge to deal with overshooting on a high-reflection or specular surface. To eliminate the saturated pixels caused by overshooting, we propose a projection intensity adaptive adjustment method. First, we project three uniform gray-level images and estimate the projection intensity of the measured surface through the captured uniform gray-level images. Then we can obtain the optimal projection fringes in the camera coordinate system. Second, a set of horizontal and vertical gray-coded patterns are used to establish a coordinate matching relationship between the projected image and the captured image. To check the decoding result of the gray-coded patterns, a set of horizontal and vertical sinusoidal fringes are used to calculate the high-reflection mapping area(HRMA) in the projector coordinate system. Through the distribution of HRMA, we can check whether the decoding is reliable or not. Finally, we project the optimal intensity fringes and obtain the measurement results. We develop a measurement system to verify the validity of the proposed method. Experimental results show that the proposed method can effectively avoid overshooting and obtain measurement results with a minimum rms error. (C) 2021 Optical Society of America