Your tool of choice for AO generation?
EDIT: Thanks for the many, many suggestions everyone. I can't say thanks enough, you've given me a ton of options to work with! I'll make sure to post up my results soon 
Hi, I'm trying to figure out the best way to do an AO pass on a low poly (7000 tri) star wars ship model. A Z-95 head hunter to be specific.
I've used Xnormal's simple AO in the past, it's ok but I feel like I could be getting better bakes as it tends to wash things out. Upping the contrast helps but it starts looking a little funny if you go to far with it.
I tend to avoid Maya's baking system due to it's sheer ungainliness.
So I was curious what you, the polycount community typically use for AO bakes, especially pertaining to low poly models that lack a highpoly to bake down from?
If you have any tips for improving the quality of bakes from Xnormal's simple AO generator I would appreciate it as well!
Thanks in advance.
Hi, I'm trying to figure out the best way to do an AO pass on a low poly (7000 tri) star wars ship model. A Z-95 head hunter to be specific.
I've used Xnormal's simple AO in the past, it's ok but I feel like I could be getting better bakes as it tends to wash things out. Upping the contrast helps but it starts looking a little funny if you go to far with it.
I tend to avoid Maya's baking system due to it's sheer ungainliness.
So I was curious what you, the polycount community typically use for AO bakes, especially pertaining to low poly models that lack a highpoly to bake down from?
If you have any tips for improving the quality of bakes from Xnormal's simple AO generator I would appreciate it as well!
Thanks in advance.
Replies
So one thing I do when using the low AO tool in xnormal is, I sub-divide my mesh a couple times(without smoothing, tessellate its called in most apps?). This will result in less mesh-normal type artifacts.
Ah I see, that's an interesting way to deal with it. I'll try that out. Thank you for the suggestion.
I'll have to test out using mudbox for the process. Thanks.
What's your process for setting up a bake in a case like that?
Do you usually setup a plane under your mesh, or do you use bowl shape for light bouncing?
Depends on what I'm making. If it's a static object that's just going to be sitting on a flat floor or propped in some corner, then I'll add some similar geometry like that for the AO to take into account in order to get a more grounded effect. If its more of a dynamic object that could move or see a number of different placements/orientations in the scene and the AO is going to be baked into the diffuse, then I wont use any additional geo to help keep it weaker.
Alright, adding it to my list of tryouts.
Thanks!
And yeah as earthquake noted Xnormal does support gpu acceleration which is great
CUDA power!
Ah ok, makes sense, thanks for the tip. Since this ship will be flying around I guess I'll be using method 2 more.
Alright, thanks for the input.
http://www.rusteddreams.net/faogen.html
Oh, nice
Thanks a lot for the link. I'll definitely check it out.
http://www.zhangy.com/main/blog/id/22
in max you can smooth a mesh using its smoothing groups to created hard creases. perhaps maya has something similar.
No problem! I know it's been mentioned and you have been using it, i'm stating what I normally use =\
Yeah I guess I've just been worried that maybe I'm setting up my scenes wrong before putting them into Xnormal. It definitely doesn't like low poly stuff much since it'll create a lot of faceting, but I liked earth quakes solution of tessellating the mesh till those are less of an issue.
Do you have any tips as far as setting you use to get the best bake results?
I've been under the impression you have to have a plane floating somewhere under your mesh to get proper light bounce. Otherwise I just crank up the contrast on the AO bake till I get a full spectrum from near black to white. Not the best solution in my opinion. It seems like on default settings everything gets really washed out and you don't really see much AO happening.
Ah I didn't see that you had re-edited this.
Maya doesn't have smoothing groups per-se, at least not that I'm aware of. You can harden edge normals and faces individually though, which I would tend to think yields similar results...maybe
I can certainly try it out anyway, looks like a fun tool, thanks.
in my retardedness i posted a max plugin
Ha, well I figured I'd find out once I downloaded it this evening. I had a suspicion it was a Max plugin from looking at the video but I was hopeful
Thanks for trying anyway.
But since 1.5 years or so i have switched back to mental ray. I find the result superior. I use a high spread value most of the time to give a really nice deep AO effect. I found that faogen downside is the lack of options for the AO.
Also a skylight bake with groundplane can be really nice and gives superior results sometimes.
See that groundplane method was one of the few alternatives to Xnormal I was aware of. Since you mentioned Faogen too, I'll put that towards the top of my list for now to experiment on tonight. Thanks.
Alright thanks for the tips.
Good to know thanks for letting me know your process.
works great for me this method, fairly fast too.
Have you tried baking Final Gather for that? even with 5-7 bounces its still faster than light tracer. It lacks the fine detail, but you can get that back with a cavity map.
I did some tests on my current model, a 1k Light tracer/skylight bake with hammersley took me 5 minutes.
1k Mental Ray FG with 5 bounces, and a MR ambient Occlusion map (16 samples distance:1 spread 1) took 3 minutes.
When i bake AO in Xnormal i find i get large splotches in the map, they look similar to photo mapping. anyone experience this/have a fix?
I do this in modo, but it should be a universal technique. What's great about this as well, at least in modo, is I get a great AO map in about 2 minutes.
Hey Chronic - If your reading this - I bought Topogun some time ago, primarily because of the AO bake capabilities - and I was never able to get a decent AO bake out of it. I've seen a few images along the way of Topogun AO bakes, and they looked great, but I could never make it happen. If you could offer up a screenshot or explanation of how you do it, that would be awesome.
Well it depends on the object. Is it static? If so you can probably be safe to do a Low Poly AO bake setting a plane underneath your object and using Global Illumination.
Sometimes I use both, but for my high poly AO generation I typically use xNormals, up the rays and play with the bias, render real fast on a low resolution (ie 256). Then i'll multiply a Low Poly AO (by this I mean I use the low poly asset in Max, throw a white material with No Spec/Gloss, add Skylight and increase rays per sample, throw a plane underneath about 5m under but not touching, and then Render to Texture).
I know the AO faceting can be nasty in xNormals, some solutions are the way you export your objects. Typically I try to avoid exporting an OBJ while the object has a turbosmooth stacked on it.
When i'm ready to export, I kill turbosmooth and convert to mesh smooth and adjust smoothing, then export so it preserves the full topology (turbosmooth can export out in obj with some wierd topology sometimes)
Turn off isoline display. I wrote a little script that replaces export/export selected. It just turns off isoline and then exports. simple but a life saver.
Good call, that explains why models are jacked up with Isoline on
You got a link to your script?
Without using a high poly model, what would be suggested methods for doing AO map bakes something like tank models for pc rts games ?
then bringing it into photoshop set to multiply.
I generally just use mental ray and a flat plane beneath but wondered if there was a better method without having to create the high poly version too.
Sounds similar to the tessellation method mentioned earlier. Personally I'm using Maya, however some of that is definitely still applicable. Thanks alot!
I think I'm going to try rendering out an AO in several of the suggested programs and post of the results. Thanks
I may consider doing a quick smoothed mesh just so i can have something in that slot, not sure yet.
Excellent Tip!
i can set up mental ray material and change all these settings in maya but thats such a hassle, too much time.
i personally enjoy the simple way it does stuff, and free
http://www.bigbuckbunny.org/index.php/approximate-ambient-occlusion/
Basically, it's the AO technique that was developed for Dead Man's Chest:
http://features.cgsociety.org/story_custom.php?story_id=3889
I used it a lot on a low poly recreation of Shanghai Expo recently, was definitely nice to be able to chuck out these clean AO bakes quite fast, since I was doing a huge amount of assets in a short amount of time.
Tried FAOGEN, nice speed and good results. But lack of options to tweak the results. Doesn't seem to be developed further since some while.
I usually use xNormal or Mental Ray.