If all the dimensional data Radiosity receives are solid, it is not that problem whether front or back of the surfaces. The function to automatically reverse the surface in Radiosity calculation can be easily added to OptGraph Radiosity Library as well under the assumption that all the input dimensional data are solid. Practically, however, the data which is not solid has to be treated. Radiosity is the method to physically simulate inter-reflections of light in a three-dimensional space. Therefore, if the object is not solid, for example, a polygon existing as a single object, it essentially has to have both front and back colors (energy). Because this process is difficult, users need to decide which surface is the front (surface to be calculated). For non-solid objects, the function to generate front or back surface date (double-surface mode function) is available.

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1. What is Radiosity ?
2. The Radiosity calculation result doesn't become brighter even though light sources are increased in the scene.
3. What is an important reminder to generate model data for Radiosity calculation ?
4. Why is it a problem, whether front or back of the surface, in Radiosity calculations ?
5. Why some surfaces were displayed as black after Radiosity calculation ?
6. When is the completion point of Radiosity calculation ?
7. How to deal with the texture-mapping or the bump-mapping in Radiosity calculations.
8. What is the relation between Radiosity and Ray Tracing when using them together ?