An Interactive Appearance Model for Microscopic Fiber Surfaces

Modeling and rendering the appearance of fabrics remains one of the most challenging research topics in computer graphics. Today's most advanced models are based on volumetric fiber distributions, obtained from advanced measurement techniques like micro-CT, and only renderable through expensive volume rendering approaches. In this paper, we propose an analytical BRDF model for pile fabrics, i.e., textiles like velvet, plush or Alcantara, that are characterized by open-ended strands of yarn. A fascinating property of many such materials is that they ''memorize'' tactile interaction and that their appearance depends on the last direction in which the surface was brushed. Our reflectance model, inspired by recent microflake models, links the microscopic structure of a material to the interaction that caused that structure, and to the resulting macroscopic reflectance behavior. We present an end-to-end pipeline for fitting the parameters of our model to measured reflectance data, for manipulating fiber distributions using tactile input, and rendering the resulting spatially varying surface appearance in real time.