Robust Shadow Mapping with Light Space Perspective Shadow Maps

Michael Wimmer, Daniel Scherzer
Robust Shadow Mapping with Light Space Perspective Shadow Maps
In ShaderX 4 -- Advanced Rendering Techniques, pages 313-330, March 2006

Information

Abstract

In this paper, we present a new shadow mapping technique that improves upon the quality of perspective and uniform shadow maps. Our technique uses a perspective transform specified in light space which allows treating all lights as directional lights and does not change the direction of the light sources. This gives all the benefits of the perspective mapping but avoids the problems inherent in perspective shadow mapping like singularities in post-perspective space, missed shadow casters etc. Furthermore, we show that both uniform and perspective shadow maps distribute the perspective aliasing error that occurs in shadow mapping unequally over the available depth range. We therefore propose a transform that equalizes this error and gives equally pleasing results for near and far viewing distances. Our method is simple to implement, requires no scene analysis and is therefore as fast as uniform shadow mapping.

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BibTeX

@incollection{Wimmer-2006,
  title =      "Robust Shadow Mapping with Light Space Perspective Shadow
               Maps",
  author =     "Michael Wimmer and Daniel Scherzer",
  year =       "2006",
  abstract =   "In this paper, we present a new shadow mapping technique
               that improves upon the quality of perspective and uniform
               shadow maps. Our technique uses a perspective transform
               specified in light space which allows treating all lights as
               directional lights and does not change the direction of the
               light sources. This gives all the benefits of the
               perspective mapping but avoids the problems inherent in
               perspective shadow mapping like singularities in
               post-perspective space, missed shadow casters etc.
               Furthermore, we show that both uniform and perspective
               shadow maps distribute the perspective aliasing error that
               occurs in shadow mapping unequally over the available depth
               range. We therefore propose a transform that equalizes this
               error and gives equally pleasing results for near and far
               viewing distances. Our method is simple to implement,
               requires no scene analysis and is therefore as fast as
               uniform shadow mapping.",
  month =      mar,
  booktitle =  "ShaderX 4 -- Advanced Rendering Techniques",
  editor =     "Wolfgang Engel",
  isbn =       "1-58450-425-0",
  publisher =  "Charles River Media",
  series =     "ShaderX",
  volume =     "4",
  keywords =   "real-time rendering, shadows",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/2006/Wimmer-2006/",
}