Photorealistic material learning and synthesis

Abstract

Light transport simulations are the industry-standard way of creating convincing photorealistic imagery and are widely used in creating animation movies, computer animations, medical and architectural visualizations among many other notable applications. These techniques simulate how millions of rays of light interact with a virtual scene, where the realism of the final output depends greatly on the quality of the used materials and the geometry of the objects within this scene. In this thesis, we endeavor to address two key issues pertaining to photorealistic material synthesis: first, creating convincing photorealistic materials requires years of expertise in this field and requires a non-trivial amount of trial and error from the side of the artist. We propose two learning-based methods that enables novice users to easily and quickly synthesize photorealistic materials by learning their preferences and recommending arbitrarily many new material models that are in line with their artistic vision. We also augmented these systems with a neural renderer that performs accurate light-transport simulation for these materials orders of magnitude quicker than the photorealistic rendering engines commonly used for these tasks. As a result, novice users are now able to perform mass-scale material synthesis, and even expert users experience a significant improvement in modeling times when many material models are sought. Second, simulating subsurface light transport leads to convincing translucent material visualizations, however, most published techniques either take several hours to compute an image, or make simplifying assumptions regarding the underlying physical laws of volumetric scattering. We propose a set of real-time methods to remedy this issue by decomposing well-known 2D convolution filters into a set of separable 1D convolutions while retaining a high degree of visual accuracy. These methods execute within a few milliseconds and can be inserted into state-of-the-art rendering systems as a simple post-processing step without introducing intrusive changes into the rendering pipeline.