How do I bake/transfer AO maps?

lewist

I've been working on a model for the past several days to strengthen my understanding of the high poly/low poly process. I’ve (unfortunately) had the experience of attending a university where despite its claims I received little in the way of help or direction in creating game art, so polycount has become my go-to place to find answers. Baking normals was a breeze thanks to the excellent write ups on the wiki and the boards. Currently though, I’m having a tough time with transferring AO maps. If I might ask some beginner questions:

1) Should I even be transferring AO from low to high or should I just generate AO for my low poly model?

2) How should my mesh be set up for transferring or baking AO? Should it be exploded, individual pieces? A combined mesh?

3) I’ve gotten a lot of artifacting from my test bakes, though I’ve made sure to remove overlapping UV space. What else could be causing it?

I’m a Maya user for the most part, which hasn’t helped given that the mentalray render is extremely slow. Because of that, I’m trying to learn xNormal. I'd appreciate any advice!

throttlekitty

1/2) Whenever possible, use AO from your exploded high poly. Sometimes you may want to capture AO from an unexploded view, some of us also do one from the low-poly as well, mixing that into the main.

3) Hard to say without pictures. This guy had some artifacts on a rotated model, resetting or applying them fixed the bake. So, there's one possibility.

I recommend using xNormal for doing AO, it's much faster than using Maya.

gsokol

1) At least from the high. That way you get some nice occlusion from areas where you may not have geo (such as recessed sections that are in your normal map on a flat plane). Some people suggest mixing a bake from the high poly with one of the low poly, but I never really tried so I'm not sure of the benefit...maybe somebody else can clue you in there.

2) With AO...you don't want to get any self shadows on moving objects...for instance...a Tire on a car would get shadow from being under the car...but when the tire rotates...that shadow will rotate with it too and look silly.

That is where doing an exploded view..or baking separately helps.

3) Really would be beneficial to see your model and the ao map...not sure what would be causing it. Could be issues with your cage...could be render settings for AO, not sure.