Image Correlation techniques have proven to be a flexible and useful tool for deformation analysis. With the use of two cameras, even three-dimensional studies can be carried out. The principle of this technique is quite easy to understand and opens a nearly unlimited range of applications.
In classical image correlation, the deformation of an object is determined by observation with a CCD camera. Then, a digital image correlation process determines the shift and/or rotation and distortion of small facet elements determined in the reference image. Such correlation algorithms can determine the maximum of the displacement with an accuracy of up to 1/100 pixel. This procedure allows the determination of the object deformation in a plane parallel to the image plane of the camera.