Hi Hector,
Personally, I don't think the material setup is very difficult in viz. If you use your standard materials in viz, you got very weird results, I agree, but the radiosity override material is really good if you DO NOT use the defaults values of course!
One reason why standard materials are not useful is because it uses the color as a reflectance scale. This means that white surface reflect more light than black surface, which is absolute nonsense because a highly pollished dark floor does reflect lots of light.
So that's it for using standard materials...
Just take a standard material and add a radiosity override material. Keep the existing material as a sub-material. Than change all the following parameters!
Reflectance scale: (this is the amount of light that gets reflected): set this value not higher than 0.85, because most surfaces don't reflect more than 85% of the incoming light.
(If you set this value higher than 1 (max 5), you got a very strange fx because the surface reflects more light than it receives... Only usuable for unreal/inhuman worlds)
DO NOT use this control to increase self-illumination! Use Luminance scale instead (see later)
Color bleed: I usually set this value to 0.5 or 0.6 for most materials and up to 0.85 for colored surfaces that you do want to color bleed.
Transmittance scale: this is the amount of light that gets transmitted through transparant surfaces. Be careful if you use this value, because the sum of transmittance scale and the
reflectance scale cannot exceed 1 in real life, because otherwise you'd end up having more energy after the light hits the surface than before!
tip: It's better to make the total sum around 0.95
(The default settings for these two values are both 1, with means that if a certain amount of light hits a surface, the same amount is AND reflected a 100% AND transmitted a 100%. So basicly you'll end up having twice the amount of light after the beam hits the surface...
see why the default settings are ludicrous?)
Luminance scale: use this for self-illumination. Around 500-1000 should be ok.
Indirect Light Bump Scale: again the default of 1 is very bad. Better use something between 0.1 and 0.5
So this is it about the material setup.
Another rule of thumb is to reduce the RGB Level for a bitmapped material. (I hardly do this myself, but the user guide keeps pinpointing this)
A final very usual tip might be to read the manual/user guide. There is lots of very usefull information in there.
rgds
nisus