Physically-Based Interactive Bi-Scale Material Design

Abstract  We present the first physically-based interactive system to facilitate the appearance design at different scales consistently, through manipulations of both small-scale geometry and materials. The core of our system is a novel reflectance filtering algorithm, which rapidly computes the large-scale appearance from small-scale details, by exploiting the low-rank structures of the Bidirectional Visible Normal Distribution Function and pre-rotated BRDFs in the matrix formulation of our rendering problem. Our algorithm is three orders of magnitude faster than a ground-truth method. We demonstrate various editing results of different small-scale geometry with analytical and measured BRDFs. In addition, we show the applications of our system to physical realization of appearance, as well as modeling of real-world materials using very sparse measurements.