View Full Version : Baking multiple object's AO in 3ds Max: I keep getting black BGs
12-24-2011, 09:16 AM
Hey guys, I'm learning how to bake texture maps at the moment. So in max 2012, when I hit 0 for render to texture and select several different meshes, add an Ambient Occlusion output and hit render, the first map always comes out right (with a white BG). Subsequent maps come out with black BGs and are harder to use. This doesn't happen when I do it seperately for each mesh. Why is this? Also, is there any way to render a single image output for multiple meshes? It'd help me skip a step compiling them in Photoshop. Thanks for your time =)
12-24-2011, 11:45 AM
Well without seeing some pics of your process I can't really help you. The question about having multiple meshes on a single out put image can be done. If you have each mesh UV unwrapped and then select all of them. You can place a single UVW Unwrap modifier on it all. The UVs will be placed on a single sheet this way. The only issue is you will have to plan for this ahead of time to allot for correct spacing on the UV sheet. What I mean by this is that as you unwrap each object you would have them outside the UV space so that when you throw that unifying UVW unwrap you won't have overlapping UVs. You would then play the puzzle game that is UV unwrapping for placement. If there are a ton of meshes though you will end up reducing the resolution of the UVs to get them to fit which wouldn't be as good as out putting them individually.
12-24-2011, 12:07 PM
RTT Assist (http://www.polycount.com/forum/showthread.php?t=81405&highlight=rtt+assist) is a nice script for max that streamlines the baking process and even combines the maps for you in post, automatically. I've used it for some work before.
As for the black meshes, that could be a lot of things. Might want to search for black RTT meshes on the forum, I know it's definitely been discussed before.
Could be a lot of things. Corrupt mesh, in need of reset xform, etc. You can try resetting xform on the problem meshes. You can also make a new plane or box or whatever, then convert that to epoly and attach the problem mesh to it, then delete the box out. Can also try merging all content into a new max file. Finally, exporting the whole scene out as 3DS or OBJ and reimporting.
12-24-2011, 01:53 PM
I think its a bug myself. seems to just get it into its head to ignore rtt background colours sometimes and there's bugger all you can do to persuade it otherwise.
its usually fixable in photoshop by selecting according to alpha, copying to a new layer and then defringing/dematteing over a plain white layer but its a toss up as to whether that takes longer than making the bakes individually
if they all share uvs then i attach everything together and bake off that
12-24-2011, 02:38 PM
Hi, you need to try the Exploded Mesh Baking process.
But i would advice you try simple baking first than move to multiple bakes at same time. Normal and AO is a big subject with too many 3rd party scripts and apps to do this process alone.
here check Poly wiki before asking ... helps alot.
Hope it helps
12-24-2011, 02:53 PM
Did you guys actually read the question? No offence intended btw. and i didn't watch the video so apologies if it soles the actual problem.
he's getting a black background colour on AO bakes when he is baking multiple objects despite setting the background colour to something else (ill assume white). I've seen this under max2012 as well so its highly unlikely its the fault of anything in the meshes or technique (8 years as a tech artist ought to put me in good standing technically speaking)
12-24-2011, 03:02 PM
Yep, you're right, by AO I assume the actual AO in mental ray, which is pretty much kaput in Max for baking out stuff properly. Bad pad streaking, insane amount of cranked up options just to get it right, slow, and extremely flimsy.
I also suggest baking it out in one mesh format.
You have to be real lucky to get AO to baked out properly in Max, I suggest xNormal or Blender for free. If not, and you still insist in Max, VRay is your only other solution for Max.
I think Max 2009 is the only one that didn't have these problem (apart from streaking, but a simple dilate of your layers is all you need at that point in PS).
12-24-2011, 03:08 PM
I miss max 2009 :(
12-24-2011, 03:19 PM
U can try Skylight Lightracer with high settings, works for me in most cases otherwise i do AO in Xnormal. As for background issue well i have notice way too wierd stuff both in Normal and AO process, like pure pink color, black spots squares, jagged lines despite high AA etc on the background. The reason i found for this in most cases, too much curved surfaces, 90 degree edges (hard surface stuff), Bad Cage setup or Auto Cage padding too low and mesh (low/ high) interseting etc.
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