In Proceedings of SIGGRAPH 2005. Held in Los Angeles, California, July 2005.
Wood coated with transparent finish has a beautiful and distinctive appearance that is familiar to everyone. Woods with unusual grain patterns, such as tiger, burl, and birdseye figures, have a strikingly unusual directional reflectance that is prized for decorative applications. With new, high resolution measurements of spatially varying BRDFs, we show that this distinctive appearance is due to light scattering that does not conform to the usual notion of anisotropic surface reflection. The behavior can be explained by scattering from the matrix of wood fibers below the surface, resulting in a subsurface highlight that occurs on a cone with an out-of-plane axis. We propose a new shading model component to handle reflection from subsurface fibers, which is combined with the standard diffuse and specular components to make a complete shading model. Rendered results from fits of our model to the measurement data demonstrate that this new model captures the distinctive appearance of wood.
This paper is available as a 6.2M PDF file or as a 856K PDF file.
To really appreciate the results you need to see the associated video, which is available as a 40M QuickTime movie or as a 8.1M QuickTime movie. Both are encoded using MPEG 4.
The data that is available on the proceedings DVD-ROM can also be downloaded here as a 20M tar/gzip archive. It contains the four texture maps (diffuse color, fiber direction, fiber color, and highlight width) for each of the samples shown in the paper and video, stored in 16-bit linear TIFF files. It also contains the RenderMan shader that was used to render Figure 10 in the paper and some sequences in the video.