ACM Transactions on Graphics
We present a novel method for devising a closed-form analytic expression to the light transport through the bulk of inhomogeneous optically anisotropic media. Those optically anisotropic materials, e.g., liquid crystals and elastic fluids, arise in a plethora of established applications and exciting new research, however current state-of-the-art methods of visually deducing their optical properties or rendering their appearance are either lacking or non-existent. We formulate our light transport problem under the context of electromagnetism and derive, from first principles, a differential equation of the transmitted complex wave fields that fully accounts for the complicated interference phenomena that arise. At the core of our proposed rendering framework is a powerful mathematical representation, carefully crafted to enable us to produce highly accurate analytic approximative solutions for the light transport. This approach is previously unused in computer rendering, and our framework is capable of rendering accurately optically anisotropic materials with varying optically properties at orders of magnitude faster than existing methods. We demonstrate a few practical applications of our method and validate it against polarized photos of liquid-crystals as well as numerically against numerical solvers and qualitatively against brute-force renderings.
Presented at SIGGRAPH 2020