Surface shape reconstruction of a nonrigid transport object using refraction and motion

The appearance of a pattern behind a transparent, moving object is distorted by refraction at the moving object´s surface. An algorithm for reconstructing the surface shape of a nonrigid transparent object, such as water, from the apparent motion of the observed pattern is described. This algorithm is based on the optical and statistical analysis of the distortions. It consists of four steps: extraction of optical flow, averaging of each point trajectory obtained from the optical flow sequence, calculation of the surface normal using optical characteristics, and reconstruction of the surface. The algorithm is applied to both synthetic and real images to demonstrate its performance