基于分段阶梯相位编码的三维形貌测量方法

Three-Dimensional Shape Measurement Based on Piecewise Step Phase Coding

为了解决基于相位编码的三维形貌测量方法在对高频条纹截断相位进行相位展开时易出现误码的问题,提出了一种分段阶梯相位编码方法。用一级阶梯码字对另一级分段阶梯码字的分段数进行编码,投影两组相位编码条纹分别获取两级码字后,再投影额外的两帧错位格雷码,分别获取与这两级码字错位半个阶梯的码字。利用错位码字与原码字易出现误码位置的不同,选用不同的码字进行互补解码,从而获得更加可靠的条纹级次重建三维结果。实验结果表明,所提方法的码字重建结果不易出错。在使用相同数量辅助图案情况下,所提方法能比互补格雷码编码方法标记更多的投影条纹周期,可以辅助更高频率正弦条纹实现对复杂物体形貌的准确三维面形测量。

In this paper,we proposed a piecewise step phase coding method to solve the error codes occurring in the threedimensional(3D)shape measurement method using the phase coding technique in the phase unwrapping for the wrapped phase of high-frequency fringe.The first step codewords were used to encode the order of the second step codewords.After two groups of phase coding fringes were projected for the recovery of two sets of codewords,two extra misaligned Gray code patterns were projected to obtain two codewords shifted by half period from the two sets of codewords,respectively.By taking advantage of the mismatch between the misaligned and original codewords,we selected different codewords for complementary decoding.Therefore,more reliable fringe orders were obtained for 3D reconstruction.Experimental results reveal that the proposed method is robust in decoding codewords and can label more fringe periods than the complementary Gray code method using the same number of projected auxiliary patterns.Furthermore,the proposed method accurately reconstructs 3D shapes of complex objects with denser high-frequency sinusoidal fringes.