Estimation of the Torrance-Sparrow reflection model from a single multi-band image
A method is proposed for estimating various reflection parameters from images of an object taken by a multi-band CCD camera. The Torrance-Sparrow model is used for modeling light reflection on an object surface composed of inhomogeneous dielectric materials. First, we examine the validity of the Torrance-Sparrow model based on the spectral reflectance data. Next, we propose algorithms for estimating model parameters from images by a six-color camera. The parameters estimated from a single image are: 1) surface-spectral reflectance, 2) illuminant spectral distribution, 3) illumination direction, 4) surface roughness, and 5) ratio of body to interface intensity. The feasibility of the proposed method is demonstrated in an experiment using a painted object. The estimation accuracy of the whole model is confirmed based on computer graphics images. The method can be applied to objects with general shapes.