基于条纹光流的物体面形测量技术

Surface Shape Measurement Technique Using Fringe-Based Optical Flow

提出一种运用条纹光流实现物体面形测量的新技术。介绍光流法测量面形的原理,从光流的视角分析投影条纹的变化,建立平行投影条件下光流与被测面形高度及相位分布之间的理论关系。对建立的球冠几何模型进行数值模拟,验证光流法直接计算面形高度的可行性;对实际物体面形的测量与相移法测量结果对比,证明光流法能够准确恢复物面相位,并且对物面空洞区引入的噪声有较好的稳健性。不同于传统的面形测量技术,光流法仅需要二帧图像就可精确恢复高度分布或相位分布。由于光流法方法本身含有时间因子,且仅需两幅图像就能直接得到面形分布,所以比相移法更适合动态测量。

This study proposes a new technique for surface measurement by using fringe-based optical flow.The principle of measuring surface shape by optical flow method is introduced,and the changes of projected fringes are analyzed from the perspective of optical flow.The theoretical relationship among the optical flow,height distribution,and phase distribution of the measured surface is established under parallel projection.A numerical simulation conducted with an established spherical crown geometric model shows that the optical flow method can be used to directly calculate the height of the measured object.Practical measurement of the object and comparison of the measured results with those of the phase shift method reveal that the optical flow method can accurately restore the object′s phase;in addition,it demonstrates good robustness to the noise emanating from the void area of the measured object.Unlike traditional surface shape measurement techniques,the optical flow method only needs two frames to accurately restore height or phase distributions.Because the optical flow method itself contains the time factor and only requires two images to directly obtain surface shape distribution,it is more suitable for dynamic measurement than the phase shift method.