A practical microcylinder appearance model for cloth rendering

This article introduces a practical shading model for cloth that can simulate both anisotropic highlights as well as the complex color shifts seen in cloth made of different colored threads. Our model is based on extensive Bidirectional Reflectance Distribution Function (BRDF) measurements of several cloth samples. We have also measured the scattering profile of several different individual cloth threads. Based on these measurements, we derived an empirical shading model capable of predicting the light scattering profile of a variety of threads. From individual threads, we synthesized a woven cloth model, which provides an intuitive description of the layout of the constituent threads as well as their tangent directions. Our model is physically plausible, accounting for shadowing and masking by the threads. We validate our model by comparing predicted and measured light scattering values and show how it can reproduce the appearance of many cloth and thread types, including silk, velvet, linen, and polyester. The model is robust, easy to use, and can simulate the appearance of complex highlights and color shifts that cannot be fully handled by existing models.