Title
Offline Deep Importance Sampling for Monte Carlo Path Tracing
Abstract
Although modern path tracers are successfully being applied to many rendering applications, there is considerable interest to push them towards ever-decreasing sampling rates. As the sampling rate is substantially reduced, however, even Monte Carlo (MC) denoisers-which have been very successful at removing large amounts of noise-typically do not produce acceptable final results. As an orthogonal approach to this, we believe that good importance sampling of paths is critical for producing better-converged, path-traced images at low sample counts that can then, for example, be more effectively denoised. However, most recent importance-sampling techniques for guiding path tracing (an area known as "path guiding") involve expensive online (per-scene) training and offer benefits only at high sample counts. In this paper, we propose an offline, scene-independent deep-learning approach that can importance sample first-bounce light paths for general scenes without the need of the costly online training, and can start guiding path sampling with as little as 1 sample per pixel. Instead of learning to "overfit" to the sampling distribution of a specific scene like most previous work, our data-driven approach is trained a priori on a set of training scenes on how to use a local neighborhood of samples with additional feature information to reconstruct the full incident radiance at a point in the scene, which enables first-bounce importance sampling for new test scenes. Our solution is easy to integrate into existing rendering pipelines without the need for retraining, as we demonstrate by incorporating it into both the Blender/Cycles and Mitsuba path tracers. Finally, we show how our offline, deep importance sampler (ODIS) increases convergence at low sample counts and improves the results of an off-the-shelf denoiser relative to other state-of-the-art sampling techniques.
Year
DOI
Venue
2019
10.1111/cgf.13858
COMPUTER GRAPHICS FORUM
Field
DocType
Volume
Computer vision,Monte Carlo method,Importance sampling,Computer graphics (images),Computer science,Path tracing,Artificial intelligence
Journal
38.0
Issue
ISSN
Citations 
7.0
0167-7055
0
PageRank 
References 
Authors
0.34
0
4
Name
Order
Citations
PageRank
Steve Bako1562.69
Mark Meyer2366.50
Tony DeRose31152136.22
Pradeep Sen488253.01