A novel coarse-fine search scheme for digital image correlation method

As a well-established technique for measuring surface deformation, the digital image correlation method (DICM) has received wide application in experimental mechanics and structural analysis in recent years. One of the major challenges in practical applications of this technique is how to achieve the lowest probability of mis-identification and reduce computation cost simultaneously. Based on this understanding, a novel coarse-fine search method for correlation analysis is developed in this paper. This method is based on an affine transform and a new technique of fine searching called "nested fine search method" which is for accelerating calculation. Additionally, a special algorithm is developed for generating simulated images. The proposed method is validated by comparing measured displacements with those of simulated images, and proved to be much faster than the existing ones if the same accuracy is assumed. As the rigid displacements and the elastic displacements induced by deformation can be directly calculated by the affine transform, the proposed method can efficiently measure the full-field displacements of large displacement or finite deformation.