An empirical fur shader

Many shading models have been proposed for human hair fibers (see, for example, [Marschner et al. 2003]) and they are used successfully in film productions. Not much attention, however, has been paid to animal furs. The models developed for human hair fibers may not be suitable for animal fur since the scale patterns, medullary types, and pigments are different from those of humans, and greatly different between animals [Deedrick and Koch 2004b]. In this paper we propose an empirical shader to reproduce the detailed appearance of animal fur.