A model of skylight and calculation of its illuminance
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.
Keywordsskylight direct sunlight spatial coherence penumbra
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