Ambient Occlusion help

helldiver

Hello again averyone, I've stumbled onto another issue.

I'm not too experienced when it comes to Ambient Occlusion maps and game art making.

Some questions:
What do I do with my AO map?
I've baked the map, it looks good, and it looks good when put in the Diffuse or Specularity slots on my shader in max.

But then what? This is where I'm confused.

What happens next?

Am I suppose to blend it into my Diffuse map? Is it suppose to be blended into my Specularity map?

Is it a seperate map altogether? Meaning I need to get a DX 9 shader with an AO slot?

If the latter, anyone have a good technique to apply an AO into a Diffuse? Or AO to a specularity? Tutorial perhaps (I tried doing things like overlay and so on in PS but didn't turn out good)

If the former, anyone have a DX9 shader that also does AOs seperately?

Sorry for all the noob questions, but I'm still learning some of this extended stuff. I come from game development that was just low poly, single 256 texture models, guraud shaded, and now I'm trying to learn to do the more advanced stuff (Normals, Specularity, AO, parallax mapping, etc).

Thanks in advance.

Ben Apuna

Depending on the situation what you probably want to do is multiply the AO as a layer in photoshop over your diffuse and possibly specular map as well.

In some cases however the AO needs to be a separate map, for example when you've done a lot of tiling and stacking with the diffuse and spec maps to keep the texture's pixel density high but the object has lots of unique areas of shading.

helldiver

Ben Apuna wrote: »

Depending on the situation what you probably want to do is multiply the AO as a layer in photoshop over your diffuse and possibly specular map as well.

In some cases however the AO needs to be a separate map, for example when you've done a lot of tiling and stacking with the diffuse and spec maps to keep the texture's pixel density high but the object has lots of unique areas of shading.

Ok perfect this is what I wanted to know.

So if it's a seperate map, than the engine or shader will have an AO map "slot" I guess I'd call it that?

So would it be reasonable if I said; I need to find a shader for Max that allows me to load an AO as a seperate texture. I suppose this might be the case for large objects maybe? I guess it isn't really needed since the cases for a seperate AO is rare?

again thanks for the reply

Ben Apuna

I believe different engines will have various ways to integrate a separate AO map into your material.

I think there are some exotic Max shaders out there that have separate AO slots as well as a bunch of other nifty stuff. Though I don't have much experience with them, I usually just try to get my objects into whatever engine I'm using as soon as possible that way I can see what it'll really look like in game.

Here's one of said shaders that seems to be pretty popular:

Xoliul's 3DS Max Viewport Shader

and this one

Free Maya/max cgfx/fx Shader

Needing separate AO maps is actually fairly common with large objects, I guess it really depends on what you end up working on a lot.

EDIT:

Sometimes when the texture budget for an asset doesn't allow for a nice perfect AO map I'll just give the areas I can get away with AO multiplied with the diffuse and spec maps and then let the rest go without.

kodde

Assuming you have some form of ambient lighting you want to multiply that lighting with the ambient occlusion map. Making the AO-map exluding ambient lighting in the dark areas of the AO-map, exactly as the name implies. This way the AO-map won't affect directly lit areas either, meaning you won't ever get "dark colored" areas from the AO map even though you have a bright light source hitting the sampled surface.

kodde

Since I love you so much I made you a video explaining what I wrote in text above.

[ame]http://www.youtube.com/watch?v=iTCq-bE9urE[/ame]

To be more honest I also want to use this for teaching my students about how this works

Peris

It's just a texture you can use to simulate ambient lighting on your model. Use it as a layer in photoshop, paint over it or do whatever you want with it!

helldiver

Thanks everyone for all of the replies, AOs are now part of my pipeline. Lots of things now make sense. I'd been wondering how to get shadows in those spots that normally wouldn't be lit. I was doing it by hand for years.
-The areas under the armpits, between thighs, ears for heavens sakes... Spots under gun clips, nooks and crannies. For years I'd been doing all that stuff by just manipulating the texture. Now with AO life is much better.

Although it seems to me to get a good AO I'd want to bake it using hi-res versions of my models, which has been a slow process for me thus far. Takes me about a week to two weeks to put together a high res version. Think it's time to invest in Z-brush or something.