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Advantages and Disadvantages.

The largest single advantage of the radiosity method for computer
image generation is the highly realistic quality of the resulting images. 
No other method accurately calculates the diffuse  interreflection of
light energy in an environment.  Soft shadows and color bleeding are
natural by-products of this method, just as hard shadows and
mirror-like reflections are natural by-products of a typical ray-tracing
algorithm.

In addition to being visually pleasing, the method can be quite
accurate in its treatment of energy transport between surfaces. The
viewpoint independence of the basic radiosity algorithm provides the
opportunity for interactive 'walkthroughs' of environments, as one
intensity solution for an environment will serve as the base for any
particular view of the environment.

The costs associated with the radiosity method are substantial. The
'full matrix' radiosity method requires a large amount of storage and
long computation times for form factor calculation and matrix solution. 
The 'progressive' method must also calculate a large number of form
factors, many more than once.

Accuracy in the resulting intensity solution requires preprocessing the
environment, subdividing large surfaces into a set of smaller
surfaces, and more surfaces means more storage and computation.