中文摘要：

为了提高数字图像相关曲面拟合法亚像素定位精度，经研究发现，在实际应用中，曲面拟合法在亚像素位移为0．5像素左右时会发生较大的波动，与实际亚像素位移发生一定偏离，导致此位置位移的不连续。本文通过分析曲面拟合法亚像素位移偏离真实位移的原因，给出了具体修正方法，用模拟平移实验讨论了修正系数k和子区大小对修正结果的影响，用三点弯曲实验验证了修正方法在复杂变形情况下的有效性，提高了曲面拟合法在实际应用中的测量精度。

英文摘要：

In order to improve subpixel positioning accuracy of quadratic surface fitting in digital image correlation, it is found that large subpixel displacement fluctuation occurs round 0.5 pixels in practical application which leads to the deviation of calculation result from actual subpixel displacement and the displacement discontinuity at this position. A specific correction method is proposed in this paper by analyzing the cause of subpixel displacement deviation in surface fitting. The effects of correction factor k and suh-rigion size on the correction results were studied by simulation translation experiment. Correction method effectiveness in complex deformation was verified by three point bending experiment. Above results improve the measurement precision of curved surface fitting in practical application.