四步相移结合互补格雷码的快速相位展开

Fast phase unwrapping of four-step phase shift combined with complementary Gray code

为提高相移条纹投影测量系统的精度与效率,提出了一种四步相移结合互补格雷码的快速相位展开方法,有效消除了相位展开误差,并能够显著提升计算效率。引入的互补格雷码与传统格雷码的条纹阶次存在半周期错位,利用这种错位与中值滤波结合可完全消除相位展开误差。首先,采用大津法对全亮图案进行二值化生成掩码图像;其次,以掩码图像非零区域为路径引导四步相移与互补格雷码解码得到包裹相位与条纹阶次;最后,利用条纹阶次对包裹相位进行相位展开。实验结果表明:提出的快速相位展开算法比原算法速率提升了36%。

In order to improve accuracy and efficiency of phase shift fringe projection measurement system, a four-step phase shift combined with complementary Gray code fast phase unwrapping method is proposed, which effectively eliminates the phase unwrapping error and can significantly improve calculation efficiency. There is a half-period misalignment between introduced complementary Gray code and fringe order of traditional Gray code. The combination of this misalignment and median filtering can completely eliminate phase unwrapping error. Firstly, the Otsu method is used to binarize full-bright pattern to generate a mask image;Secondly, the non-zero area of mask image is used as a path to guide four-step phase shift and complementary Gray code decoding to obtain wrapped phase and fringe order;Finally, the fringe order phase unfolds wrapped phase. The experimental results show that the speed of proposed fast phase unwrapping algorithm is 36% higher than that of original algorithm.