Digital image correlation for structural measurements

Digital image correlation is an optical imaging technique that compares images taken of a structure and is well established for laboratory measurements. By processing pairs of images under different loading conditions, the full-field deformation of the structure can be measured. Using modern high-resolution digital cameras, in-plane displacement resolutions can approach 5 parts per million of the horizontal field of view. With the ready availability of low-cost computing resource, digital image correlation is now useful for full-field deformation measurements of civil engineering structures and can help identify suitable sites for installation of continuous-measurement deformation sensors. Examples of its use in civil engineering are described and some of the practical problems of deploying the technique in situ are discussed.