Light Space Perspective Shadow Maps

Information

• Publication Type: Conference Paper
• Workgroup(s)/Project(s):
  • UrbanViz
• Date: June 2004
• ISBN: 3-905673-12-6
• Publisher: Eurographics Association
• Organization: Eurographics
• Location: Norrköping, Sweden
• Lecturer: Michael Wimmer
• Editor: Alexander Keller and Henrik W. Jensen
• Booktitle: Rendering Techniques 2004 (Proceedings Eurographics Symposium on Rendering)
• Conference date: 21. June 2004 – 23. June 2004
• Pages: 143 – 151
• Keywords: shadows, real-time rendering

Abstract

In this paper, we present a new shadow mapping technique that improves 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 z-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

@inproceedings{Wimmer-2004-LSPM,
  title =      "Light Space Perspective Shadow Maps",
  author =     "Michael Wimmer and Daniel Scherzer and Werner Purgathofer",
  year =       "2004",
  abstract =   "In this paper, we present a new shadow mapping technique
               that improves 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
               z-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 =      jun,
  isbn =       "3-905673-12-6",
  publisher =  "Eurographics Association",
  organization = "Eurographics",
  location =   "Norrk\"{o}ping, Sweden",
  editor =     "Alexander Keller and Henrik W. Jensen",
  booktitle =  "Rendering  Techniques 2004 (Proceedings Eurographics
               Symposium on Rendering)",
  pages =      "143--151",
  keywords =   "shadows, real-time rendering",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/2004/Wimmer-2004-LSPM/",
}