Deformation Measurement of Scaling and Rotation Objects Based on Digital Image Correlation Method with Color Information

Abstract

The digital image correlation (DIC) method is widely used in deformation measurement due to the advantages of being non-contact, high precision, full field measurement, and requiring simple experimental equipment. Traditionally, the grayscale speckle patterns captured by a monochromatic camera are used in the DIC method. With the growing development of consumer color cameras, there is a great potential for developing color information in the DIC method. This paper proposes a scaling- and rotation-invariant DIC (SRI-DIC) method based on the color speckle patterns. For the integer-pixel matching stage, the scaling- and rotation-invariant color histogram feature is used to estimate the initial value of the deformation parameters. For the sub-pixel matching stage, a new error function using the three-channel information of color camera is proposed to avoid the influence of illumination changes. In addition, this paper proposes a reverse retrieve strategy instead of the forward search to reduce the search time. Experiments show that the proposed SRI-DIC algorithm not only has scaling and rotation invariance, robustness, and high efficiency, but also that the average accuracy of the strain result can reach 0.1%.