Shape measurement by the use of digital image correlation

Abstract

Digital image correlation DIC using a single camera has been widely used for determination of in-plane displacement. However, in order to obtain shape information on an object, one should employ stereo vision systems with multiple cameras. In this paper, a new method using digital image correlation for shape measurement is developed. In the proposed method, an object with a surface profile is given an in- plane translation, and digital image correlation is employed to measure the image displacement. Since the object has a surface height variation, the magnification at each point is different. Thus the image displacement field obtained from the DIC method contains the shape information of the object, which can be retrieved from a pinhole camera model. Principles of the proposed method are described. Experiments conducted to mea- sure a step change and a light bulb show that the method is simple, effective, and suitable for measurement of a step change or a large object. © 2005 Society of Photo-Optical Instrumentation Engineers.