High-accuracy two-dimensional full field strain measurement method using camera array

Abstract

In recent years, the digital image correlation technique, due to its full-field, non-contact and large measurement, play an important role in non-contact large deformation measurement in many fields. Because of the strain resolution is limited by the camera resolution, compared with the strain gauges, the strain measurement accuracy of digital image correlation is not enough. To make the digital image correlation measurement technology in the strain resolution has big breakthrough, rely on hardware technology, will be a long waiting. In this paper, a camera array, combined with image stitching technology, was used to realize the high-resolution image acquisition and improve the strain measuring resolution of digital image correlation, so as to provide a high-accuracy strain measurement. Moreover, a novel calibration based image stitching method was proposed. The proposed method can maximize the use of spatial resolution of digital camera, and three-dimensional reconstruction of the overlapped areas can be achieved using the calibration results, this can be used to reduce the impact of out-of-plane motion on strain measurement.