Baking an AO pass

Ravenok

Hey everyone,

I'm working on a model currently, I got the character modeled in high poly, the mesh is decimated - and I retopologized the decimated mesh for an in-game resolution one.

After I did that, I thought, maybe I can bake out an AO pass from the high poly model and put it on the final game res model. I usually bake things out first, when the high and low poly models share the same UV, and clean up the mesh after I have the texture - but this time it was a last minute call.

So my question is, once I'm done with cleaning the mesh, I expect I'll have a problem baking out an AO map considering the high poly mesh doesn't have the same UV as the low poly one. But I'm not sure about this one, since I don't really know the inner mechanics of xNormal...

So, will it be a problem? and if it will, is there a way around it that doesn't involve making my game mesh all quads, project the details on it from the high poly, bake an AO map and then rework the model for game res?

Thanks!

Bigjohn

Nah, you're fine. The highpoly mesh doesn't need to have UVs at all. It's only the low-poly mesh where the UVs matter.

You can bake off of any object, or any number of objects, UVs or not.

The only time UVs on the highpoly matter is if you're baking the highpoly's textures into a lowpoly. But I never personally had to do that.

Mark Dygert

The UV's on the high don't matter. You will be projecting the surface of the high poly onto the low poly. It will be looking at whatever is on the surface of the model it won't be looking at the UV's.
The only thing that matters is the UV layout of the low poly.

Typically you don't want to get into materials and baking until your mesh is rock solid and set in stone. Anytime you change the low poly mesh, technically you should rebake. There are spots and places where the edits might not show up and it might be ok to let it slide without rebaking, but technically its broken, just not enough to tell.

Ravenok

That's awesome. I was always very strict about my workflow that I never gave thought to this, I just assumed UVs have to be impeccable before I bake out anything. I keep getting nervous about things not working out.

Thanks a lot, u've been very helpful.

Mark Dygert

Oh yea sure. This also opens up to the high poly being UV'ed however you need it to be. If you apply a bump map or a normal map to your high poly model that will also capture and bake. This is good for things like skin details or stone patterns in a statue. It can even be insanely helpful for things like a wood pattern. You apply it to the high in whatever way it looks best, then capture it in the bake. Suddenly the wood pattern translates to your jumbled up UV pieces pretty well without a lot of work on the seams.

That way you're not stuck having to model and stamp all that detail into a really dense high poly and hope that it holds up, you can just bump the high poly and it captures in the projection. Very very useful.

You can use UVMaster to unwrap the high poly to a really large map then paint in some base colors for the diffuse... It opens the door to some interesting techniques.

Ravenok

Yeah it really frees you up, I suddenly realize I always thought there was no freedom in these things, but this really makes things easier... I can actually give up a basemesh altogether, just go freestyle in ZBrush and use Topogun for reto, and it's all done.

I really need to sharpen up.. my techniques are pretty crude.

Thanks again m8, this is great.


PS. I checked out both your sites - you got some awesome work. Keep it up