計測対象とカメラの相対位置が変化する場合のデジタル画像相関法によるひずみ計測

抄録

Digital Image Correlation (DIC) is an optical method that employs tracking and image registration technique to measure surface displacement. In general, the relative attitude between the target object and the camera is required to be defined with high accuracy. When the attitude changes, virtual strain is observed since the scale of the taken image varies from place to place. Thus, the application of DIC has been limited. In this study, we propose a method to measure the strain even when the relative attitude changes. First, a strain distribution is calculated with DIC. The observed strain has both true and virtual strain. The virtual strain is estimated using optimized eight parameters in the homography transformation. The true strain is extracted by subtracting the virtual strain the observed strain. This procedure extracts the true strain without a linear component. The effectiveness of the proposed method is verified by measuring the deformation of an aluminum plate with a crack.