Reflectance field based real-time, high-quality rendering of bidirectional texture functions

Abstract

The bidirectional texture function (BTF) is a suitable representation for the appearance of highly detailed surface structures under varying illumination and viewing conditions. Since real-time rendering of the full BTF data is currently not feasible, approximations of the six-dimensional BTF are used such that the amount of data is reduced and current graphics hardware can be exploited. While existing methods work well for materials with low-depth variation, realism is lost if the depth variation grows. In this article we analyze this problem and devise a new real-time rendering paradigm based on linear interpolation of reflection fields, which provides significant improvements with respect to realism for such highly structured materials without sacrificing the general applicability and speed of previous algorithms. We propose real-time rendering algorithms for this new method supporting either point light sources or image-based lighting and demonstrate the capabilities of our new approach with several examples.