Well, the shadows are pretty much all that\'s affected by GI. It simply takes all the black shadows and pushes them up to a certain value, emulating light bouncing around. It\'s best to keep it relatively low (since having pretty black shadows can be good for contrast), and use point/spot lights for all your lighting.
:emerald:
You\'re very wrong. Unless you are using a really bad unknown algorythm, global illumination algorythms are not limited to pushing up light on shadows. Hard shadows are only an effect caused by black bodies direct light, but in computer terms shadows are created by subtracting an area from the light calculation. Global illumination has no intention of enhancing shadows, it simulates inter-reflection on bodies reflecting direct light. For example, this is a quick image of a light inside a cube, and absolutely no shadow ever in the scene. The first is without GI, the second is with GI:
http://i2.photobucket.com/albums/y26/Kamashii/radinoradi.jpgGI reflects the indirect light all around the scene, not limiting to where shadows are present. The fact that shadows are usually black unless you have a light from behind is the reason they are usually the first thing noticed when GI is enabled, but the GI function goes far, far beyond it.
If an area has shadows but is in somewhere where light cannot reach because it gets absorbed before, then GI will not \"push it up\", but it will surely push up the non-shadowed areas before reaching the point of zero light.
The fact that 100% of CGI movies and animations within live action moves use GI since Toy Story (and back then, they didn\'t even have a good way to implement per-pixel GI, the guys developed a pretty nasty way of turning every pixel on screen in a vertex to simulate per-pixel effects), plus 100% of professional games\' cinematics hould be a good hint that GI is not a bad attempt at making lights look pre-calculated but a technology needed to simulate real-life scenes (unless you\'re a true master on fakeosity). GI algorythms are the next step being implemented on new generations\' video cards (you can see the new HDRI half-life 2 map or the \"gas station\" demo at nvidia site) and even Planeshift city models has GI baked at the textures.