2022/03/24 by Aakash KT, Eric Heitz, Jonathan Dupuy +1
Computer Science · Engineering · Mathematics · #3D Shape Modeling and Analysis #Algorithm #Anisotropy #Applied mathematics #Artificial Intelligence in Games #Artificial intelligence #Computer Graphics and Visualization Techniques #Computer graphics (images) #Computer science #Computer vision #Curse of dimensionality #Direction cosine #Geometry #Isotropy #Linear subspace #Mathematical optimization #Mathematics #Optics #Physics #Rendering (computer graphics) #cs.GR
paper · pdf · doi:10.1145/3522612
ACM SIGGRAPH Symposium on Interactive 3D Graphics and Games (I3D), 2022
arxiv created 2022/03/24 · arxiv updated 2022/03/25 · openalex publication_date 2022/05/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Linearly Transformed Cosines (LTCs) are a family of distributions that are used for real-time area-light shading thanks to their analytic integration properties. Modern game engines use an LTC approximation of the ubiquitous GGX model, but currently this approximation only exists for isotropic GGX and thus anisotropic GGX is not supported. While the higher dimensionality presents a challenge in itself, we show that several additional problems arise when fitting, post-processing, storing, and interpolating LTCs in the anisotropic case. Each of these operations must be done carefully to avoid rendering artifacts. We find robust solutions for each operation by introducing and exploiting invariance properties of LTCs. As a result, we obtain a small 84 look-up table that provides a plausible and artifact-free LTC approximation to anisotropic GGX and brings it to real-time area-light shading.