Is it worth the gain to use full over ambient, and if so when does it become worthwhile? Is indirect lighting in general only good when you have a small number of lights?

Full and Amient Occlusion are actually very different.

"Full" is more real - it actually creates the effect by tracing the light rays from object to object. It takes longer to render because of all the calculations, although.

Ambient Occlusion is best described as a "good guess" and takes less time to render. However, it is less realistic because it simply reduces the quantity of light at the locations where objects intersect or touch each other.

Now, to answer your question, use the one that best suites your desired image results. For example, if you have a red ball sitting on a white floor, "Full" will reflect some red from the ball onto the white floor where they come close to each other. Ambient Occlusion will only reduce the quantity of light making it darker but not reflecting the color. If you have similar colored objects or a lot of texture or bumps, AO can be a good choice because texture and bumps can obscure reflected color. Additionally it takes longer to calculate bumpy textures because bumps redirect the rays of light which requires more calculation time from the computer.

Mark

Message edited on: 03/06/2006 06:06

I have to say in my personal experience it is worth the extra time... but then again, I'm always chasing the realism monster. Or maybe I was bitten by it? ;)

Most images--of anything--are usually only looked at for parts of a second by a viewer. The clever fine detail washing over thier perceptions! I know it may sound lazy but I think top notch rendering is only needed when the end imagery is so artisticy superior. Then the work deserves rendering at a quality and size that would be for, at least, an A4 300ppi print.

which is why I use indirect lighting.. most of my images are for print... but I agree that it really depends on what you are working towards as to whether the extra time is worth it.

I am always working toward the most subtle and accurate lighting in my work - the printouts I use are usually combed over for realistic effects - or at least a convincing approximation of realism. My projects in real life use subtle relationships of surfaces (color, texture, reflection etc) and lighting. Bounced illumination and the color that it carries is everything! Ever noticed the ceiling of a large meeting room? Chances are that it will show the color of the carpet - which can be either good or bad..... Interior scenes are more responsive to subtle accurate global illumination than outdoor ones. Outdoors, one or 2 bounces max is enough. Accurate lighting is a must for me, whatever time it takes. Thats why I bought the 'Pro' version of Carrara 5.
wb

Message edited on: 03/08/2006 07:40