3D displacement measurement with a single camera based on digital image correlation technique

Abstract

In this paper, a simple speckle technique utilizing a charge-coupled device (CCD) camera and frequency and spatial domain combined correlation, is developed to measure 3D rigid-body displacement of an object. Rigid-body displacement in an arbitrary direction in space consists of both in- and out-of-plane components. On the basis of the pinhole perspective camera model, the presence of in-plane component of displacement results in a shift of the displacement vector center and constant slope of the displacement vector is related to the out-of-plane component. The proposed method facilitates the separation of in- and out-of-plane displacements. Based on the linear distribution features of the displacement vector, digital image correlation (DIC) in global coordinates is employed to locate the displaced position of each point on the object, which has been validated to be more accurate than conventional means. Correlation in frequency domain is combined with the technique in spatial domain to improve the speed and automation in the initial searching process. Simulation and experimental results demonstrate that both in-plane and out-of-plane displacements can be accurately measured with the proposed method.