Recovery of contour deformation using steerable filters

A motion-based approach is presented to recovering the nonrigid deformation of free-form curved objects. Protrusions and indentations of contours are typically the results of altering curvature structure along the symmetry axes. The recovery task is formulated as a search for a set of lines of curvature on the spatiotemporal surface. These lines of curvature correspond to the tracings of curvature extrema of the plane contour as it is drawn across the time axis. Three-dimensional steerable filters are developed to compute the lines of curvature. The filters analyze the gradient of Gaussian curvature, remove noise by angularly adaptive filtering, and select the dominant orientation direction of the lines of curvature