Real-Time Antialiased Area Lighting Using Multi-Scale Linearly Transformed Cosines

Abstract

We present an anti-aliased real-time rendering method for local area lights based on Linearly Transformed Cosines (LTCs). It significantly reduces the aliasing artifacts of highlights reflected from area lights due to ignoring the meso-scale roughness (induced by normal maps). The proposed method separates the surface roughness into different scales and represents them all by LTCs. Then, spherical convolution is conducted between them to derive the overall normal distribution and the final Bidirectional Reflectance Distribution Function (BRDF). The overall surface roughness is further approximated by a polynomial function to guarantee high efficiency and avoid additional storage consumption. Experimental results show that our approach produces convincing results of multi-scale roughness across a range of viewing distances for local area lighting.