Application of a Combinatorial Dic Algorithm in Sub-Pixel Displacement Measurement

Digital image correlation method has higher requirements for search speed and accuracy. Single algorithm is difficult to achieve high speed and high precision. A combinatorial digital image correlation algorithm is proposed in this paper, it quickly obtains the maximum correlation coefficient point of the sub-pixel level based on the genetic algorithm, and uses this point as the fitting window to obtain the sub-pixel displacement value through spline interpolation and quadratic surface fitting. Taking the simulated speckle pattern as the research object, the accuracy and speed of the combined algorithm are compared and analyzed. The results show that the combinatorial digital image correlation algorithm has obvious advantages over a simple algorithm in the search speed and measurement accuracy, and meets the requirements of the speed and precision of the digital image correlation in the sub-pixel micro-displacement measurement.