If you have ever spent hours trying to get realistic lighting and shadows in 3d renders you may well have heard of radiosity, then again you may have not

For those who have not, radiosity is the bouncing of light from one object onto another. Much like the light in a room effects objects directly in it's path but that light is also bounced from object to object

Thus light from say a window will have an effect of objects that are behind other objects due to the former radiating light to the later as well as light bouncing of other objects e.g. the walls

Trying to setup a scene with multiple lights to get a realistic effect is a headache and most good 3d progs have a radiosity option which though time consuming in rendering is well worth investigating

here are some examples :

in this render there is a simple omni light at the end of the room

http://www.black-and-white-to-color.com/stuff/lightinnorad.jpg

pretty boring !!

Ok here it is with raduiosity on

http://www.black-and-white-to-color.com/stuff/lightinrad.jpg

Much better, note the subtle shading at the corners

though radiosity takes some time to render it can be "baked" and then the reultant imnage is used as a texture map, this means that assuming no objects in the scene are moving then you can render an animation with a camera moving through the scene that has radiosity applied and the render times are amazingly short

Now have a look at this

http://www.black-and-white-to-color.com/stuff/lightoutnorad.jpg

interesting but very dull

Now with radiosity

http://www.black-and-white-to-color.com/stuff/lightoutrad.jpg

ah much better

Your BEFORE and AFTER samples were excellent... Made me a believer and I am NOT even into 3D yet...

radiosity and caustics make for much better images but are time consuming to render though there are short cuts and fake radiosity tricks