The Visual Computer

, Volume 10, Issue 1, pp 19–33 | Cite as

Efficient, complete radiosity ray tracing using a shadow-coherence method

  • Arjan J. F. Kok
  • Frederik W. Jansen
  • Charles Woodward
Original Articles


Most two-pass rendering methods calculate a radiosity shading for each patch or element in a scene in the first pass. This shading contains two components: one for the light received directly from the main light sources and one representing the intensity of the light received indirectly by means of diffuse and specular interreflection between patches. However, it is very difficult to achieve accurate representation of the distribution of this radiosity shading over the patch, particularly where clearly visible shadow boundaries exist. A better approach is to store only the indirect reflection component in the form of radiosity shading, and to calculate the direct reflection component during the second pass by casting shadow rays. This approach normally requires that many shadow rays must be cast. However, the number of rays for shadow testing can be kept low by selecting only those light sources that substantially contribute to the shading of a patch and applying an adaptive image refinement technique in combination with a shadow coherence method.

Key words

Rendering Radiosity Ray tracing Source selection Shadow coherence 


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Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • Arjan J. F. Kok
    • 1
  • Frederik W. Jansen
    • 1
  • Charles Woodward
    • 2
  1. 1.Faculty of Technical Mathematics and InformaticsDelft University of TechnologyDelftThe Netherlands
  2. 2.Institute of Industrial AutomationHelsinki University of TechnologyEspoo 15Finland

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