A Comparative Perceptual Study of Soft Shadow Algorithms

Michael Hecher, Matthias Bernhard, Oliver Mattausch, Daniel Scherzer, Michael Wimmer
A Comparative Perceptual Study of Soft Shadow Algorithms
ACM Transactions on Applied Perception, 11(5):5:1-5:21, June 2014.

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Abstract

We performed a perceptual user study of algorithms that approximate soft shadows in real time. Although a huge body of soft-shadow algorithms have been proposed, to our knowledge this is the first methodical study for comparing different real-time shadow algorithms with respect to their plausibility and visual appearance. We evaluated soft-shadow properties like penumbra overlap with respect to their relevance to shadow perception in a systematic way, and we believe that our results can be useful to guide future shadow approaches in their methods of evaluation. In this study, we also capture the predominant case of an inexperienced user observing shadows without comparing to a reference solution, such as when watching a movie or playing a game. One important result of this experiment is to scientifically verify that real-time soft-shadow algorithms, despite having become physically based and very realistic, can nevertheless be intuitively distinguished from a correct solution by untrained users.

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BibTeX

@article{hecher-2014-MH,
  title =      "A Comparative Perceptual Study of Soft Shadow Algorithms",
  author =     "Michael Hecher and Matthias Bernhard and Oliver Mattausch
               and Daniel Scherzer and Michael Wimmer",
  year =       "2014",
  abstract =   "We performed a perceptual user study of algorithms that
               approximate soft shadows in real time. Although a huge body
               of soft-shadow algorithms have been proposed, to our
               knowledge this is the first methodical study for comparing
               different real-time shadow algorithms with respect to their
               plausibility and visual appearance. We evaluated soft-shadow
               properties like penumbra overlap with respect to their
               relevance to shadow perception in a systematic way, and we
               believe that our results can be useful to guide future
               shadow approaches in their methods of evaluation. In this
               study, we also capture the predominant case of an
               inexperienced user observing shadows without comparing to a
               reference solution, such as when watching a movie or playing
               a game. One important result of this experiment is to
               scientifically verify that real-time soft-shadow algorithms,
               despite having become physically based and very realistic,
               can nevertheless be intuitively distinguished from a correct
               solution by untrained users.",
  month =      jun,
  issn =       "1544-3558",
  journal =    "ACM Transactions on Applied Perception",
  number =     "5",
  volume =     "11",
  pages =      "5:1--5:21",
  keywords =   "Perception Studies, Soft Shadows",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/2014/hecher-2014-MH/",
}