Fast Percentage Closer Soft Shadows using Temporal Coherence

Michael Schwärzler, Christian Luksch, Daniel Scherzer, Michael Wimmer
Fast Percentage Closer Soft Shadows using Temporal Coherence
In Proceedings of ACM Symposium on Interactive 3D Graphics and Games 2013, pages 79-86. March 2013.
[draft]

Information

Abstract

We propose a novel way to efficiently calculate soft shadows in real-time applications by overcoming the high computational effort involved with the complex corresponding visibility estimation each frame: We exploit the temporal coherence prevalent in typical scene movement, making the estimation of a new shadow value only necessary whenever regions are newly disoccluded due to camera adjustment, or the shadow situation changes due to object movement. By extending the typical shadow mapping algorithm by an additional light-weight buffer for the tracking of dynamic scene objects, we can robustly and efficiently detect all screen space fragments that need to be updated, including not only the moving objects themselves, but also the soft shadows they cast.

By applying this strategy to the popular Percentage Closer Soft Shadow algorithm (PCSS), we double rendering performance in scenes with both static and dynamic objects - as prevalent in various 3D game levels - while maintaining the visual quality of the original approach.

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BibTeX

@inproceedings{SCHWAERZLER-2013-FPCSS,
  title =      "Fast Percentage Closer Soft Shadows using Temporal Coherence",
  author =     "Michael Schw{"a}rzler and Christian Luksch and Daniel
               Scherzer and Michael Wimmer",
  year =       "2013",
  abstract =   "We propose a novel way to efficiently calculate soft shadows
               in real-time applications by overcoming the high
               computational effort involved with the complex corresponding
               visibility estimation each frame: We exploit the temporal
               coherence prevalent in typical scene movement, making the
               estimation of a new shadow value only necessary whenever
               regions are newly disoccluded due to camera adjustment, or
               the shadow situation changes due to object movement. By
               extending the typical shadow mapping algorithm by an
               additional light-weight buffer for the tracking of dynamic
               scene objects, we can robustly and efficiently detect all
               screen space fragments that need to be updated, including
               not only the moving objects themselves, but also the soft
               shadows they cast.   By applying this strategy to the
               popular Percentage Closer Soft Shadow algorithm (PCSS), we
               double rendering performance in scenes with both static and
               dynamic objects - as prevalent in various 3D game levels -
               while maintaining the visual quality of the original
               approach.",
  month =      mar,
  address =    "New York, NY, USA",
  booktitle =  "Proceedings of ACM Symposium on Interactive 3D Graphics and
               Games 2013",
  isbn =       "978-1-4503-1956-0",
  location =   "Orlando, Florida",
  publisher =  "ACM",
  pages =      "79--86",
  keywords =   "real-time, temporal coherence, soft shadows",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/2013/SCHWAERZLER-2013-FPCSS/",
}