Influence of imaging configurations on the accuracy of digital image correlation measurement

Abstract

Compared to other approaches to improving digital image correlation (DIC) measurement accuracy, improving image quality is becoming increasingly effective. Image noise level, which is the main indicator of image quality, is very sensitive to the configurations of an imaging system and affects DIC measurement accuracy. However, the mechanism by which the imaging configurations affect accuracy is unclear. In this study, the influence of imaging configuration on DIC measurement accuracy was investigated using the common factor of noise. Firstly, the type and levels of noise introduced into actual images by different imaging system configurations were investigated. Next, the effect of noise on DIC measurement accuracy was determined using simulated images. Finally, the effects of imaging configuration on DIC measurement accuracy were experimentally investigated using actual measurements. The results show that both camera-related and lens-related configurations affect DIC measurement accuracy. In particular, lengthening the exposure time and reducing the f-number of the lens achieve similar improvement in DIC measurement accuracy, and a prime lens with high light transmittance is recommended for full-field optical measurements. In contrast, the imaging gain does not affect the accuracy of DIC measurements.