Complementary Gray Code Fourfold-N Step Phase Shift Grating Fringe Projection Profilometry

Complementary Gray code
${N}$
-step phase shift algorithm has been widely used because of its high detection accuracy. In order to solve its low detection efficiency and real-time detection, this article proposes a grating projection profilometry based on the combination of complementary Gray code and fourfold-
${N}$
step phase shift algorithm. When the number of phase shift steps is an integral multiple of four, divide images into
${N}$
/4 groups according to the same phase difference, then get the wrapped phase of each group image, and fuse them. Finally, unwrap phase with complementary Gray code. The algorithm in this article can quickly eliminate periodic phase error and obtain a high-precision unwrapped phase. In order to prove the effectiveness of this algorithm, the algorithm in this article is compared with the
${N}$
-step phase shift algorithm of complementary Gray code and the double
${N}$
-step phase shift algorithm of complementary Gray code with different
${N}$
-values. The experimental result shows that the proposed algorithm can achieve high-precision phase unwrapping and improve the efficiency by 5%–20%.