Draft from Graphical Models and Image Processing , vol . 58 , no . 5 , September 1996 Reflectance Analysis for 3 D Computer Graphics Model Generation Running head : Reflectance Analysis for 3 D CG Model Generation

For synthesizing realistic images of a real three dimensional object, reflectance properties of the object surface, as well as the object shape, need to be measured. This paper describes one approach to create a three dimensional object model with physically correct reflectance properties by observing a real object. The approach consists of three steps. First, a sequence of range images and color images is measured by rotating a real object on a rotary table with fixed viewing and illumination directions. Then, the object shape is obtained as a collection of triangular patches by merging multiple range images. Secondly, by using the recovered object shape, color pixel intensities of the color image sequence are mapped to the object surface and separated into the diffuse and specular reflection components. Finally, the separated reflection components are used to estimate parameters of the Lambertian reflection model and a simplified Torrance-Sparrow reflection model. We have successfully tested our approach using images of a real object. Synthesized images of the object under arbitrary illumination conditions are shown in this paper.