Recursive estimation of illuminant motion from flow field and simultaneous recovery of shape

Abstract

We present a scheme based on the total least squares estimator to track the motion of a point source, by observing a sequence of images of an object illuminated by it. The initial shape of the object is estimated from any one of the existing shape and source from shading schemes from a single image frame. The total least squares formulation is used that considers this estimate of shape as being a noisy measurement of the actual shape. The method tracks the illuminant motion between successive frames from the flow field. Using the data only from two successive frames, an approach is developed to estimate the underlying illuminant motion between those two frames. This approach is then extended and a recursive method which uses the data from all previous image frames is developed to track the illuminant motion. An incremental shape recovery scheme using the proposed illuminant motion estimator is also presented. The method is then extended to deal with the presence of ambient light and the motion of multiple illuminants. We present typical simulation results to validate the proposed illuminant motion and shape update schemes. No feature point correspondence is required between the successive frames. Also the method is applicable to any general reflectance map.