ambient light? Yes or No?

[lazzhar]

Lighting using regular Ambient lights is cheating and may give a very bad results. Better avoid them as possible, but if you need them it's ok to cheat, in the end the cg is a cheating all the time.

>>cgarchitect tutorials, the guy uses light source's ambient pass only and the scene is much much more realistic than those that does not use ambient light.

It's just a point of view :)

[azazel]

I tend to use colored ambient light, just to tint the shaded areas a bit. IMO it's the grey ambient light that is dangerous. Subtle colored ones can be quite useful.

[balistic]

I will sometimes use subtle, colored ambient light to keep my darks from looking too sterile, particularly in brightly-lit shots.

The risk you run with ambient lights is that you'll lose your crevice and contact shadows, but the addition (or rather, multiplication) of an ambient occlusion pass can easily remedy that.

[jeremybirn]

If you have a scene where you're really, really tempted to add ambient light, try this instead: Add a set of very dim, non-shadowing directional (or infinite) lights , one facing each of 6 directions (up, down, north, south, etc.) It'll look almost like some ambient light has been added to the scene, except that you can tweak the colors and brightness a little:
- tint the one coming from below to match the ground color
- make the one from above a little brighter and sky colored
- tint the one opposite from the key light to match the key and make it a little brighter than the other NSEW ones
That way you'll have something like ambient, but with a little bit of variation simulating real bounce. Of course, this is still a cheap oversimplified substitute for real bounce light, and turning on Final Gather or adding some more carefully aimed bounces would be better, but it's still a step up from ambient with very little work.

-jeremy

[cpnichols]

I believe that the Ambient Light that is being refered to in the CGarchitect tutorial is from the HDRI lighting, or skylight. This is actually very different then the old fashion ambient light that you may be thinking. Do you have a link to the tutorial so that we can see what it is refering to?

If you don't have access to a good GI renderig engine, but can still create an Ambient Occlusion pass, what you can do is take the Ambient Light and multiply it by the ambient occlusion. This attempts to give you the skylight look.

[TerryHan]

here's the link to the tutorial which I'm talking about

http://www.cgarchitect.com/resources/tutorials/smoke3d/tutorial1.asp

Initially, I also thought that the guy uses hdri fill lighting, but the tutorial clearly describes as lights using ambient pass only (3ds max).

I 've tried using omin lights with ambient pass only, but the result I get is a very unrealistic flat lighting...

The images that he rendered using ambient lights are much more realistic, in a way that the room gives an atmosphere that there are noise and dust floating around. 3d images usually have the problem of appearing too clean and everything appears to be in focus.

[cpnichols]

Ok... I see now... These are still using Radiosity lighting that is very different type of lighting technique then you will see people talking about on cgtalk (as opposed to cgarchitect). Radiosity gives every wall surface energy that emits light. This light can result in very high contrasts which is why you need an extra "exposure" control. The Ambient light, while it acts similar to traditional lighting, will serve the artist differently. It will help tint the shadows, and soften the extreme contrast. If you have not used Radiosity lighting I would urge you to try it and see how ambient lighting acts just a little differently under this lighting techniques. BTW, I would not necessarily advise this to other GI rendering solutions. This are not purvey to the whole exposure thing.

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