A two-step phase-shifting method is proposed. The method realized the rapid measurement of the three-dimensional (3D) contour of some objects using mean envelope denoising based on the striped structured light. First, Butterworth low-pass pre-filtering in the frequency domain was performed on the two deformed fringe images containing the height information of the objects. It reduced the influence of higher harmonics. Then the peak and valley values of fringes with sub-pixel accuracy were obtained through numerical interpolation and point-by-point comparison. Furthermore, the mean envelope was accurately obtained and removed. After removing the mean envelope, the rectangular low-pass filtering was used to thoroughly filter out the remaining background signal. Finally, the fast reconstructions of the 3D contour of the objects were realized. The 3D contour reconstructions of the objects were simulated and experimentally measured using the method proposed. The calculation speed and accuracy were compared with the traditional four-step phase-shifting method and other two-step phase-shifting methods. The method has the advantages of fast calculation speed and high calculation accuracy. It is a valuable method for quickly measuring the 3D contour of some objects.

中文翻译：

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用于测量物体三维轮廓的快速两步移相法

提出了一种两步相移方法。该方法利用基于条纹结构光的平均包络去噪实现了一些物体三维（3D）轮廓的快速测量。首先，对包含物体高度信息的两幅变形条纹图像进行频域中的巴特沃斯低通预滤波。它减少了高次谐波的影响。然后通过数值插值和逐点比较得到亚像素精度的条纹峰谷值。此外，平均包络被准确地获得并去除。去除平均包络后，使用矩形低通滤波彻底滤除剩余的背景信号。最后，实现了物体3D轮廓的快速重建。使用所提出的方法对对象的 3D 轮廓重建进行了模拟和实验测量。将计算速度和精度与传统的四步移相方法和其他两步移相方法进行了比较。该方法具有计算速度快、计算精度高的优点。它是快速测量某些对象的 3D 轮廓的一种有价值的方法。