Path Guiding for Wavefront Path Tracing: A Memory Efficient Approach for GPU Path Tracers

TL;DR

This paper introduces a memory-efficient path-guiding algorithm for wavefront path tracers on GPUs, utilizing a single global sparse voxel octree to reduce memory usage while maintaining high rendering quality.

Contribution

It is the first to integrate path guiding into wavefront path tracers, significantly reducing memory requirements with a novel on-the-fly PDF generation method.

Findings

Reduces scene memory usage compared to existing techniques

Produces comparable or better rendering results

Efficiently guides rays using a single global data structure

Abstract

We propose a path-guiding algorithm to be incorporated into the wavefront style of path tracers (WFPTs). As WFPTs are primarily implemented on graphics processing units (GPUs), the proposed method aims to leverage the capabilities of the GPUs and reduce the hierarchical data structure and memory usage typically required for such techniques. To achieve this, our algorithm only stores the radiant exitance on a single global sparse voxel octree (SVO) data structure. Probability density functions required to guide the rays are generated on-the-fly using this data structure. The proposed approach reduces the scene-related persistent memory requirements compared to other path-guiding techniques while producing similar or better results depending on scene characteristics. To our knowledge, our algorithm is the first one that incorporates path guiding into a WFPT.