View Full Version : Creating AO maps in 3DS Max and tri-optimization
01-24-2008, 07:15 PM
I had two questions (I'm pretty new to ambient occlusion maps and optimizing by creating tris). I got a quick overview of how to do AO maps in 3DS Max (set the renderer to MR, Render to Texture, and create an AO map from there). I was curious about other techniques that you guys use to create your AO maps.
I also wanted to know this: I finally understand that tris are okay in a model because a game engine will triangulate the mesh anyway. My question is regarding a mesh that is all quads, you take into ZBrush/Mudbox, sculpt, and then bring back at the lowest subdiv to optimize. Where should tris usually go? Most tutorials/project overviews I see have tris in the joints (back of the knees, elbows) and the sharp points of a character (armor, toenails, claws, etc). Thanks for all your help in advance guys.
01-24-2008, 11:08 PM
Another question, this would be regarding 3DS Max and ZBrush issues....I recently dual booted my Mac Pro with Windows XP SP2 32 Bit in efforts to run both 3DS Max and ZBrush. I'm having problems with both: With Max, I can't use DirectX---I have to use Open GL. With ZBrush, everytime I try to generate a normal from ZMapper, I get an error saying that the graphics card isn't set up right. My system specs are as follows:
Processor:2x 2.66 GHZ Dual-Core Intel Xeon
Memory: 4 GB RAM 667 MHZ DDR2 FB-DIMM
Graphics Card: ATI Radeon X1900 XT, 512 MB
It seems like I should just buy a PC....or learn to understand computers more....any advice is greatly appreciated..
01-24-2008, 11:22 PM
Well, in regards to your second question, a lot of "how to's" I've seen online actually start by making the hires figure first, THEN building the low res version around it with proper game topology once they're done. This prevents Zbrush from goin' wonky with the poles and things.
01-24-2008, 11:51 PM
Yeah, that's usually what I see as well (create the high poly, scuplt it, then optimize it). I guess a better more specific question is where do you put the tri if you building say, an organic character? Most character wires I see have tris mostly in the joints and areas where quads just don't fit the silhouette (fingers, toes, face shape,etc).
01-25-2008, 07:03 AM
[ QUOTE ]
I was curious about other techniques that you guys use to create your AO maps.
[/ QUOTE ] Personally I find mental ray a pain in the ass for this type of thing and I tend to get limited results from doing a MR-AO bake not to mention some low poly cage clipping issues that always seem to require work arounds.
I like to use scanline render, a sky light (with light lister on) or light dome and a default gray or white material. I have greater control. For environmental shadow bakes and even sometimes characters, I even apply negative lights and sometimes use gobo's in areas I want specific types of shadows. Like if I wanted to capture shadows from slightly closed Venetian blinds but didn't have each blind modeled out, a gobo would work well to get the shadows where I wanted. The same idea can be applied to characters just not as often.
With MR-AO its kind of a crap shoot, you hit a button and hope it comes out ok. I think the important thing to remember is that you don't need MR to get a nice soft, highly customized shadow pass.
01-25-2008, 08:45 AM
Xnormal is fast and easy, for both the AO and the normalmap. CrazyBump is also easy and fast for AO, though less precise.
About tris, it's easier to work in quads where possible, adding/removing edge loops. No need to stay strictly quads, it all goes into tris in the end as you say. But the loops/rings definitely help with modeling.
About where to put topology, deformation/joints are the first concern. 2nd is silhouette. Some would say they're in the opposite order, depends on how the model is used. Some good threads/tuts...
shoulders from japan. (http://boards.polycount.net/showflat.php?Cat=0&Number=172375&an=&page=0&vc=1)
Limb Deformations (http://boards.polycount.net/showflat.php?Cat=0&Number=30519&an=0&page=0&vc=1)
Ancient-Pig's basic deformation tutorial (http://www.pig-brain.com/tut02/tut02_01.htm)
01-25-2008, 11:31 AM
Vig: Sorry if this is a "dumb" question, but what are gobo's? From the way you say light dome, I believe you're referring to fake GI (lights arrayed in a dome around the object) but I've never heard of gobos
Eric: What's xnormal?
01-25-2008, 11:34 AM
01-25-2008, 11:38 AM
Thanks for the link Eric!
01-25-2008, 12:29 PM
Sorry about that, gobo's are go-betweens either objects you place in front of your lights or maps you put in your light to effect the type of shadow/light it casts. Great for faking things like foliage shadows, window blinds, light filtering in through a paneled window ect...
As for light dome, Max has a nice sky light system that gives good results but can take a while to render. Or you can could use a light dome by either setting one up or using a script that does it for you. A good one I like is E-Light Dome.
xnormal is great and I highly suggest checking it out, but it can be a little rough the first few times you use it.
01-26-2008, 01:44 AM
Ah, gobos. Thanks for that Vig. So what's the process/settings for rendering out AO maps? Create the lighting and set up the scene...from there I could just guess: Unwrap the model, render the UV template as a shadow map?? Again, I'm just guessing--all help is appreciated. :-)
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