The Constant Radiance Term

Information

• Publication Type: Technical Report
• Workgroup(s)/Project(s): not specified
• Date: April 1996
• Number: TR-186-2-96-13
• Keywords: radiosity, constant radiance step

Abstract

The proposed method accelerates the computation of multiple interreflections in non-diffuse environments or the solution of the rendering equation. The method is suited for closed environments. It is a generalization of the 'constant radiosity step' introduced for diffuse environments and does not require geometrical or visibility information, nor the calculation of form factors. A constant radiance is extracted from the solution in every surface point and every direction. We choose this constant value so that the average self emitted power of the residuum problem is zero. The self emitting term of the residuum problem can either be positive or negative. Direction dependency is determined by the albedo function of the characteristic BRDF of the surface. This function can easily be pretabulated and it is used frequently throughout this paper. The residuum problem can be solved faster or with reduced variance by all known non-diffuse methods: different versions of distribution ray tracing, proper methods of radiosity, and hybrid solutions. The acceleration achieved by the proposed method can be significant for bright environments.

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BibTeX

@techreport{Neumann-1996-CRS,
  title =      "The Constant Radiance Term",
  author =     "L\'{a}szl\'{o} Neumann",
  year =       "1996",
  abstract =   "The proposed method accelerates the computation of multiple
               interreflections in non-diffuse environments or the solution
               of the rendering equation. The method is suited for closed
               environments. It is a generalization of the 'constant
               radiosity step' introduced for diffuse environments and does
               not require geometrical or visibility information, nor the
               calculation of form factors. A constant radiance is
               extracted from the solution in every surface point and every
               direction. We choose this constant value so that the average
               self emitted power of the residuum problem is zero. The self
               emitting term of the residuum problem can either be positive
               or negative. Direction dependency is determined by the
               albedo function of the characteristic BRDF of the surface.
               This function can easily be pretabulated and it is used
               frequently throughout this paper. The residuum problem can
               be solved faster or with reduced variance by all known
               non-diffuse methods: different versions of distribution ray
               tracing, proper methods of radiosity, and hybrid solutions.
               The acceleration achieved by the                 proposed
               method can be significant for bright environments.",
  month =      apr,
  number =     "TR-186-2-96-13",
  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 =   "radiosity, constant radiance step",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/1996/Neumann-1996-CRS/",
}