Method and apparatus for radiometrically accurate texture-based lightpoint rendering technique

Abstract

A method and apparatus for rendering lightpoints is provided. For the method of the present invention, a programmer creates a series of texture maps. Each texture map approximates the lobe of a lightpoint at a respective distance from the lightpoint. Each texture map includes transparency texture information. This allows the lightpoint to correctly model fog and other atmospheric conditions. The series of texture maps are encoded in a mipmap associated with the lightpoint. During use, a simulation environment renders the lightpoint using a billboarding technique. The billboarding technique keeps the lobe of the lightpoint oriented towards the eye point. The simulation environment dynamically tracks the distance from the lightpoint to the eye point. Each time the distance changes, the simulation environment selects an appropriate texture map from the mipmap. The appropriate texture map is the texture map that correctly depicts the lightpoint at the distance between the eye point and the lightpoint. In cases where no appropriate texture map exists, the simulation environment generates an interpolated texture map. The simulation environment then applies the selected or generated texture map during rendering of the lightpoint. The result is that the lightpoint is realistically depicted over a wide range of distances.

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