数字图像相关法(DIC)在位移测量中对搜索速度和测量精度均有较高的要求。在亚像素级测量中,一些不错的算法在速度和精度上很难兼顾。提出了一种组合式DIC算法,即以自适应遗传算法为基础快速得到亚像素级的最大相关系数点,然后以该点为拟合窗口,通过样条插值和二次曲面拟合得到亚像素位移值。以模拟散斑图为研究对象,对组合式DIC算法的测量精度、测量稳定度、搜索速度进行分析。结果表明:组合式DIC算法在搜索速度、测量精度、测量稳定性上比单独一个算法有明显的综合优势,可以满足DIC在亚像素级微小位移测量上对速度、精度的要求。

Digital image correlation method (DIC) has higher requirement for search speed and measurement accuracy in displacement measurement. Some good algorithms in sub-pixel level measurement are difficult to take account of speed and accuracy. Therefore, a combinatorial DIC algorithm is proposed in this paper. It is based on an adaptive genetic algorithm to rapidly obtain the maximum correlation coefficient point at the sub-pixel level. Then,this point is used as a fitting window, and a sub-pixel displacement value is obtained by spline interpolation and quadric surface fitting. Taking the simulated speckle image as the research object, we analyze the measurement accuracy, measurement stability, and the search speed of the combinatorial DIC algorithm. The results show that the combinatorial DIC algorithm has obvious comprehensive advantages over a single algorithm in search speed, measurement accuracy, and measurement stability. It can meet the speed and accuracy requirements of DIC in sub-pixel micro displacement measurement.