Abstract: In three-dimensional shape measurement, the existence of the indirect reflection declines the three-dimensional measurement precision. In order to separate the indirect reflection, an improved structured light projection method is proposed. This method uses the phase difference between the direct and indirect reflection and to design phase difference for 90° structure light modulation based on the gray codes. Using positive and negative structure light projection, it detects the structure light edge and edge sub-pixel localization. The experimental results show this method not only effectively improves the separation of indirect reflection and three-dimensional measurement accuracy of the measured object, but also expands the range of three-dimensional measurement.

Key words: three-dimensional shape measurement, direct-indirect reflection separation, passive-negative projection

摘要： 针对光学三维形状测量中间接反射的存在导致三维测量精度下降的问题，提出一种分离直接反射和间接反射的改进结构光投影方法。该方法反向利用直接反射和相互反射间的相位差异，以格雷码结构光为基础设计出相互相位差为90°的调制结构光，将它投射到被测物体，以此分离出直接反射和间接反射；并加上改进结构光的正-反投影，来检测结构光条纹图像中的结构光边缘亚像素定位。实验结果表明，该方法不仅有效地分离出了间接反射，而且提高了被测物体的三维测量精度，扩大了三维测量范围。

关键词: 三维形状测量, 直接-间接反射分离, 正-反投影