Tang Tao, Zhang Yu, Wan Yingying, Peng Jianping, Li Jinlong, Luo Lin
Department of Physical Science and Technology, Southwest Jiaotong University, Chengdu, 610031, China.
Sci Rep. 2024 Oct 23;14(1):24992. doi: 10.1038/s41598-024-76453-3.
Phase shifting profilometry (PSP) is widely used in three-dimensional (3D) optical metrology applications such as mechanical engineering, industrial monitoring, computer vision, and biomedicine because of its high measurement accuracy. In PSP, multi-frequency temporal phase unwrapping (TPU) plays a dominant role due to its high-accuracy measurement of surfaces with discontinuities and isolated objects. However, it requires a large number of fringe patterns. To reduce the number of required patterns, a new dual-frequency composite-pattern TPU method is developed, which needs only three patterns. The new method combines two fringe patterns of different frequencies into three composite fringe patterns, reconstructs rough 3D points by demodulating the low-frequency fringe pattern using geometric constraints, and reprojects it to obtain a rough low-frequency absolute phase, which is then refined to correct edge errors. Finally, the high-frequency wrapped phase is unwrapped under the guidance of the refined low-frequency phase, thereby the accurate 3D points are reconstructed based on stereo-vision technology. Experimental results demonstrated that the proposed method can achieve 3D surface measurement with only three images, which greatly improves the measurement efficiency. The proposed method has great application potential for the rapid 3D measurement of discontinuous surfaces and isolated objects.
相移轮廓术（PSP）因其高测量精度而广泛应用于三维（3D）光学计量应用中，如机械工程、工业监测、计算机视觉和生物医学。在PSP中，多频时间相位展开（TPU）由于其对具有不连续性的表面和孤立物体的高精度测量而发挥着主导作用。然而，它需要大量的条纹图案。为了减少所需图案的数量，开发了一种新的双频复合图案TPU方法，该方法只需要三个图案。新方法将两个不同频率的条纹图案组合成三个复合条纹图案，利用几何约束对低频条纹图案进行解调来重建粗糙的3D点，并将其重新投影以获得粗糙的低频绝对相位，然后对其进行细化以校正边缘误差。最后，在细化后的低频相位的引导下对高频包裹相位进行展开，从而基于立体视觉技术重建精确的3D点。实验结果表明，该方法仅用三张图像就能实现3D表面测量，大大提高了测量效率。该方法在不连续表面和孤立物体的快速3D测量方面具有很大的应用潜力。
