Three-dimensional shape measurement method based on composite cyclic phase coding.

Phase coding is widely used in 3D measurement due to its good anti-interference and robustness. However, the measurement accuracy is affected by the limitation of the number of codewords. To solve this problem, we propose a 3D shape measurement method based on composite cyclic phase coding. The traditional phase coding is quantized cyclic without adding extra patterns, further adopting composite coding, using the composite cyclic phase coding grayscale values to distinguish the same cyclic codewords, and finally integrating them into a new fringe order sequentially for phase unwrapping to achieve effective expansion of codewords. The related experimental results show that the proposed method stably achieves high accuracy 3D reconstruction, which overcomes the misjudgment of codewords caused by traditional phase coding under high-frequency fringes due to system nonlinearity and noise. Meanwhile, compared with the improved phase coding method of temporal domain combined with spatial domain information, such as the method of quantized phase coding and connected region labeling, it can effectively avoid the phenomenon of error propagation, with high robustness and low algorithm complexity.