Tim Nikias v2.0 wrote:

> Additionally, it might be of interest to know that using
> actual lightsources gives sharper shadows (though using
> area-lights to get soft shadows is a must for realistic lighting,
> somewhat paradox). BUT, it must be said that shadows
> produced by pure radiosity lighting are VERY soft.

It really depends on the circumstances. With a sufficiently low 
error_bound and high count, and the right environment, I have seen 
radiosity produce some pretty sharp shadows. The "problem" is that the 
scenes where radiosity typically has the greatest obvious impact vs. 
normal point lighting are those where there are large lit areas (skies, 
well-lit rooms with white walls, etc) and naturally when light is coming 
from everywhere, you're going to have some pretty soft shadows.

If you want sharper shadows in such a scene, you'll have to set it up so 
that the "main" light sources in the scene are much brighter than the 
lit objects around them (or else reduce the radiosity brightness, which 
provides much the same effect). I think you'll see this as you start 
playing with outdoor scenes with full sun, although an indoor 
environment could also work if you're using a bright, naked light bulb 
for lighting.

-Xplo

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