Orientation Lightmaps for Photon Radiosity in Complex Environments

Information

  • Publication Type: Technical Report
  • Workgroup(s)/Project(s): not specified
  • Date: April 1999
  • Number: TR-186-2-99-11
  • Keywords: lightmaps, complex scenes, photon radiosity, global illumination

Abstract

We present a method that makes the use of photon radiosity methods feasi ble for complex scenes when a totally accurate solution is not essential. This is accompl ished by using {\em orientation lightmaps}, which average the illumination of complex obj ects depending on the surface normal. Through this averaging, they considerably reduce th e variance of the stochastic solution. For the use of these specialised lightmaps, which consume comparatively small amounts of memory, no changes have to be made to the actual p hoton tracing algorithm. Also, they can be freely mixed with normal lightmaps and inserte d at any point in the scene description graph. This gives the user good control over the amount of inaccuracy he introduces by their application. The area computations necessary for their insertion are performed using a stochastic sampling method that performs well f or highly complex objects.

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BibTeX

@techreport{wilkie-1999-ORI,
  title =      "Orientation Lightmaps for Photon Radiosity in Complex
               Environments",
  author =     "Alexander Wilkie and Robert F. Tobler and Werner Purgathofer",
  year =       "1999",
  abstract =   "We present a method that makes the use of photon radiosity
               methods feasi ble for complex scenes when a totally accurate
               solution is not essential. This is accompl ished by using
               {\em orientation lightmaps}, which average the illumination
               of complex obj ects depending on the surface normal. Through
               this averaging, they considerably reduce th e variance of
               the stochastic solution. For the use of these specialised
               lightmaps, which consume comparatively small amounts of
               memory, no changes have to be made to the actual p hoton
               tracing algorithm. Also, they can be freely mixed with
               normal lightmaps and inserte d at any point in the scene
               description graph. This gives the user good control over the
               amount of inaccuracy he introduces by their application. The
               area computations necessary for their insertion are
               performed using a stochastic sampling method that performs
               well f or highly complex objects.",
  month =      apr,
  number =     "TR-186-2-99-11",
  address =    "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria",
  institution = "Institute of Computer Graphics and Algorithms, Vienna
               University of Technology ",
  note =       "human contact: technical-report@cg.tuwien.ac.at",
  keywords =   "lightmaps, complex scenes, photon radiosity, global
               illumination",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/1999/wilkie-1999-ORI/",
}