Photon Splatting Using a View-Sample Cluster Hierarchy

Pierre Moreau
Lund University

Erik Sintorn
Chalmers University of Technology

Viktor Kämpe
Chalmers University of Technology

Ulf Assarsson
Chalmers University of Technology

Michael Doggett
Lund University

High Performance Graphics, 2016

Abstract

Splatting photons onto primary view samples, rather than gathering from a photon acceleration structure, can be a more efficient approach to evaluating the photon-density estimate in interactive applications, where the number of photons is often low compared to the number of view samples. Most photon splatting approaches struggle with large photon radii or high resolutions due to overdraw and insufficient culling. In this paper, we show how dynamic real-time diffuse interreflection can be achieved by using a full 3D acceleration structure built over the view samples and then splatting photons onto the view samples by traversing this data structure. Full dynamic lighting and scenes are possible by tracing and splatting photons, and rebuilding the acceleration structure every frame. We show that the number of view-sample/photon tests can be significantly reduced and suggest further culling techniques based on the normal cone of each node in the hierarchy. Finally, we present an approximate variant of our algorithm where photon traversal is stopped at a fixed level of our hierarchy, and the incoming radiance is accumulated per node and direction, rather than per view sample. This improves performance significantly with little visible degradation of quality.

News

  • 2017-11-21:
    • Add a direct link to the paper's Eurographics DigitalLibrary webpage;
    • Add the BibTeX entry;
    • Some slight HTML formatting and fixes.
  • 2016-08-01: Update the author generated version of the paper to include a direct link to the corresponding diglib page.

Downloads

Paper
BibTeX entry

@inproceedings {hpg.20161194,
  booktitle = {Eurographics/ ACM SIGGRAPH Symposium on High Performance Graphics},
  editor = {Ulf Assarsson and Warren Hunt},
  title = {{Photon Splatting Using a View-Sample Cluster Hierarchy}},
  author = {Moreau, Pierre and Sintorn, Erik and Kämpe, Viktor and Assarsson, Ulf and Doggett, Michael},
  year = {2016},
  publisher = {The Eurographics Association},
  ISSN = {2079-8679},
  ISBN = {978-3-03868-008-6},
  DOI = {10.2312/hpg.20161194}
}
Slides
Presentation at HPG 2016 in Dublin
Code
  • Archive with binaries for Windows (coming soon)
  • Source code (coming soon)
Videos

Videos

All videos were captured in real-time using OBS Studio on an NVIDIA Titan X GPU (with 12 GB of VRAM).

On the left (or top): Moving objects in Sponza using the cluster-trivial method and 200k photons of radius 3;    On the right (or bottom): Moving caustics in Sponza using the cluster-trivial method
Fly-through of Sponza using the cluster-trivial method; 200k photons of radius 1.2 on the left (or top), 50M photons of radius 0.2 on the right (or bottom)
Fly-through of Sibenik using the cluster-trivial method; 200k photons of radius 1.2 on the left (or top), 50M photons of radius 0.2 on the right (or bottom)
Fly-through of San Miguel using the cluster-trivial method; 200k photons of radius 2 on the left (or top), 50M photons of radius 0.2 on the right (or bottom)

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