改进的三频三步相移结构光三维重建方法

针对结构光三维重建中的传统三频三步相移方法需要投影过多编码图像、效率低的问题，提出了改进的三频三步相移结构光三维重建方法。该方法与传统三频三步方法均需要3种频率的正弦条纹图，但条纹图数量只需5张，即最高频率的条纹图3张，但初始相位不同，剩余频率的条纹图各1张。较传统方法的9张条纹图投影效率提高44.44%。随后推导了该方法的求解原理，由最高频的3张条纹图直接求得重建所需包裹相位，另外两张条纹图用于对包裹相位进行展开，理论上该方法与传统三频三步算法具有相同的精度。最后进行了4组实验，验证了该方法的重建精度、复杂不连续模型重建能力、不同光照环境中的重建稳定性以及对彩色物体重建能力。结果证明该方法在有效提高测量速度的同时保证了和传统三频三步方法一致的精度和适应性。

Modified three-dimensional reconstruction based on three-frequency three-step phase shifting algorithm

Aiming at the problem that the traditional three-frequency three-step phase shifting algorithm in structured light three-dimensional measurement needed to project too many fringe patterns and has low efficiency, the modified three-frequency three-step phase shifting algorithm was proposed. The proposed algorithm and traditional one both required sinusoidal fringe patterns of three frequencies, but the number of fringe patterns was reduced to 5, that was, 3 fringe patterns of the highest frequency, and one for each of the other two frequencies. Compared with 9 fringe patterns of the traditional algorithm, the projection and capture efficiency was increased by 44.44%. The principle of the proposed algorithm was derived. Three fringe patterns of the highest frequency were used to directly obtain the wrapped phase, and the other two fringe patterns were used to unwrap the phase. In theory, the proposed algorithm owned the same accuracy as the traditional one. Finally, four sets of experiments were conducted to verify the reconstruction accuracy of the algorithm, the reconstruction ability of complex discontinuous models, the reconstruction stability in different illuminations, and the reconstruction ability of color objects. The experimental results prove that the algorithm can effectively improve the measurement speed while maintaining the accuracy and adaptability consistent with the traditional three-frequency three-step phase shifting algorithm.