采用二元二次多项式曲面拟合方法进行精确亚像素定位,这种数字散斑相关方法具有计算简单、求解效率高等优点。然而传统方法通常选取整像素周围的9个像素点进行曲面拟合,为此提出了曲面拟合的改进方案,采用整像素周围最近的6个像素点和相关系数,直接求解二元二次多项式。采用计算机模拟产生散斑图样,分别模拟了刚体平移和单向拉伸实验。实验结果证明,改进方案具有计算效率高、计算误差小的优点。

The digital speckle correlation method based on bivariate quadratic polynomial curved surface fitting method for precise sub-pixel localization has the advantages of simple calculation and high efficiency. The original method usually selects nine pixels around the integer pixel for surface fitting. We use the nearest six pixels around the integer pixel and the correlation coefficient to directly solve the bivariate quadratic polynomial through analyzing the possible improvement schemes of surface fitting. The speckle patterns are generated by computer simulation, as well as the rigid body translation experiments and uniaxial tension experiments are simulated respectively. Experimental results show that the improved scheme has the advantages of high computational efficiency and small computational error.