A fast reconstruction method for three-dimensional shape measurement using dual-frequency grating projection and phase-to-height lookup table

Phase-to-height mapping is indispensable part of three-dimensional (3D) shape measurement system based on phase analysis, which guarantees the accuracy of 3D reconstruction. In this paper, a fast 3D shape reconstruction method based on dual-frequency grating projection and phase-to-height lookup table is proposed. In this proposed method, the reference plane is moved with known interval along the measurement depth direction to establish the mapping lookup table between the phase of the high and low frequency projected grating and their corresponding spatial height pixel by pixel respectively. Then, two methods to establish the lookup table with the unwrapped and the wrapped phase have been respectively introduced according to the characteristics of dual-frequency grating. The actual experimental results show that the two methods can effectively extend the measurement range of the current wrapped phase-to-height lookup method, and the reconstruction accuracy is better than the traditional phase-to-height quadratic fitting method. At the same time, the consumed time for 3D shape reconstruction of the tested object by the two methods is compared and analyzed. Finally, combining the high performance parallel computation of GPU, the fast 3D shape reconstruction is realized with the speed of 60fps.