Research work on Bringing Linearly Transformed Cosines to Anisotropic GGX by Aakash K T under the supervision of Prof. P J Narayanan received the best paper award at ACM SIGGRAPH Symposium on Interactive 3D Graphics and Games (I3D), 2022. The other authors of this paper are Eric Heitz and Jonathan Dupuy from Unity Technologies Grenoble, France.
Research work as explained by the authors: 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 8 4 look-up table that provides a plausible and artifact-free LTC approximation to anisotropic GGX and brings it to real-time area-light shading.
Link to full paper: http://cvit.iiit.ac.in/images/ConferencePapers/2022/Bringing_ggx.pdf
Best paper award announcement: https://i3dsymposium.org/2022/awards.html