Dynamic Diffuse Global Illumination Resampling

TL;DR

This paper introduces a novel resampling technique combining screen-space reservoir resampling and sparse world-space probes to improve the efficiency of global illumination rendering in complex scenes, enabling interactive performance.

Contribution

It extends unidirectional path tracing with a new resampling method that enhances sample efficiency for diffuse transport, outperforming traditional methods.

Findings

Significant improvement in sample efficiency for diffuse transport

Achieves interactive rendering in complex scenes

Outperforms baseline methods at equal time and quality

Abstract

Interactive global illumination remains a challenge in radiometrically- and geometrically-complex scenes. Specialized sampling strategies are effective for specular and near-specular transport because the scattering has relatively low directional variance per scattering event. In contrast, the high variance from transport paths comprising multiple rough glossy or diffuse scattering events remains notoriously difficult to resolve with a small number of samples. We extend unidirectional path tracing to address this by combining screen-space reservoir resampling and sparse world-space probes, significantly improving sample efficiency for transport contributions that terminate on diffuse scattering events. Our experiments demonstrate a clear improvement -- at equal time and equal quality -- over purely path traced and purely probe-based baselines. Moreover, when combined with commodity denoisers, we are able to interactively render global illumination in complex scenes.