A model of skylight and calculation of its illuminance

  • Eihachiro Nakamae
  • Guofang Jiao
  • Katsumi Tadamura
  • Fujiwa Kato
Session CG2a — Image Synthesis
Part of the Lecture Notes in Computer Science book series (LNCS, volume 1024)


It has still been extremely expensive to make outdoor scenes illuminated by direct sunlight and skylight because of the limited models of these light sources and expensive algorithms of rendering. In this paper, a multi-layered parallelepiped is proposed for representing skylight and direct sunlight sources; the total energy of their light is regulated due to time and the position of a scene to be rendered. With this model, the illuminance on a calculation point is calculated. Then two methods for reducing the calculation cost, grouping and classifying obstacles, are discussed. This model makes a good trade-off between the cost and accuracy of rendering, and gives solar penumbra effects with a low cost.


skylight direct sunlight spatial coherence penumbra 


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Copyright information

© Springer-Verlag Berlin Heidelberg 1995

Authors and Affiliations

  • Eihachiro Nakamae
    • 1
  • Guofang Jiao
    • 2
  • Katsumi Tadamura
    • 1
  • Fujiwa Kato
    • 3
  1. 1.Hiroshima Prefectural UniversityShoubaraJapan
  2. 2.Sanei Giken Co., LtdHiroshimaJapan
  3. 3.Tokyo Electric Power CompanyYokohamaJapan

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