High-Order Time-Domain DIC Algorithm Based on a Nonlinear Optical Flow Equation

Abstract

To resolve high-precision deformation from low-quality speckle images, a high-order time-domain digital image correlation algorithm is proposed. This algorithm is based on the nonlinear optical flow equation for low-quality speckle images collected in extreme testing environments. A subpixel displacement image containing Gaussian white noise is established by using the simulated speckle method. The displacement of the high-order time-domain digital image correlation algorithm is solved by the least squares iteration method, and the test accuracy of the proposed algorithm is analyzed. The results show that the nonlinear optical flow equation can describe the time continuity of pixel gray level changes before and after deformation. The proposed algorithm can also analyze the velocity and acceleration term of deformation. The high-order time-domain digital image correlation algorithm is insensitive to the change in image grayscale and has high measurement accuracy. Therefore, this method can solve the problem of resolving high-precision deformation from low-quality speckle images.