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Old 11-24-2008   #1
TofurkeyMan
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Unhappy Nightmare on Maya Street

Hello All, this is my first post here. Gnomon workshop has been extraordinarily helpful for the project I'm doing in school. We were given a "studio project", essentially the instructors said "here's 3 months, go do something productive, we'll tell you if it's good enough". So I decided to model a human head (with a tutorial from gnomon they have in the library), and zbrush in the details.

Here's where I mucked everything up.

I imported the .obj into zbrush3.1, and sculpted away. When I had finished, I had 5.35 million polys on the highest level. I tried generating a displacement map, it all went fine, and then I applied the map to the model in Maya. Maya software would render, but mental ray wouldn't. It would render the scene, but the head would just be gone. And mentalray the renderer I need to make the displacement map visible.

Does the model in zbrush have to have the exact same number of points as the model in maya? I know it does if you want to replace the lowest mesh in zbrush with a newly uv mapped one.

So, essentially, my first question is, why won't my model render in mentalray when I have a displacement map applied with the approx. editor?

After this spectacle of 3d work, I decided to try a normal map. That worked better, but doesn't look as good as displacement I hear. I had artifacts in the map, due to overlapping UVs. So I fixed the uvs, went back into zbrush to replace the lowest poly mesh with my newly uv mapped one, and that's when zbrush decided to crash.

So, in defeat, I decided to just start from scratch and test a normal map on the model in a fresh Zbrush document. I subdivided it 4 times, sculpted some jargon on it, and created a normal map. The first few times the map exploded, but on the 3rd try it worked beautifully (i'm just assuming I had some settings wrong).

So my second question is, why is it when I replace my mesh in zbrush with a newly mapped one, zbrush crashes when I try and go up a division?

And they do have the same number of points as far as I know, the first time I tried they didn't, and zbrush wouldn't let me import it. Now it's imported, just, it's pooped.

Any help is greatly appreciated, and I apologize for this novel I have written here. I'm stumped and I really don't want to re-sculpt all this, since this project is due next thursday, but I think I might have to.

P.S. there are overlapping uvs on the new mesh, but in places that aren't visible, will that cause problems for a normal or displacement map?

Thanks!
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Old 11-24-2008   #2
GTpix
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Hi and welcome!
I don't know what are the mentalray settings for this case.
Did you try to import directly your final obj on a maya scene (not as displacment or normal map)?
I got the same problem when I modelled the "ghost and ghouls" project on my maya scene as a displacment map. I decided to just import it. The rendering time was a bit too long but it worked!
Let's try. Hope it helps.
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Old 11-24-2008   #3
TofurkeyMan
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I don't know if I could import the whole object into maya. That's over 5 million polys. And I once tried a 2 million poly object and maya crashed on me. I'm going to try moving it into max, see if that does anything.

And thanks for the welcome
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Old 11-25-2008   #4
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Ok so I loaded everything into 3ds max, and haven't figured out how to do displacement yet. So I decided to try it again in maya, and the same thing happened even with new UVs. The mesh just disappears when rendered with mental ray. normal maps work fine, but displacement maps just don't wanna cooperate. Any ideas as to why this keeps happening?

There are a few overlapping uvs in unnoticeable areas. Could that be the problem?
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Old 11-25-2008   #5
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I think the problem is that your model is at a too high resolution. Did you try to export it as intermediate zbrush poly? I mean, not the final resolution. Don't know if it is possible.
In Maya, did you have a look at the object surface? Perhaps it is not visible in 2 faces? After that, I cannot help you more. Sorry.
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Old 11-26-2008   #6
deakinduperly
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Hi,
Are u using maya 2008 or 8.5? cuz the 2008 has some problems with the new ccmesh changes when rendering with mental ray. It was done to speed renders but in the end they screwed up the relation with zbrush and it's displacement maps.
Make sure not to have any UVs overlapping that may cause some funky stuff...
remember to regenerate a new displacement map in zbrush when importing your model and activate the uv's before importing again in zbrush... i mean: have your lowest subd in zbrush, activate UV setting in the texture pallete, export your mesh, layout your uvs again, imoprt your mesh back and it shoud work... this was a new feature (if i'm not wrong) witht he 3.1 cuz if treid it in the 2.03 version and nothing... then when checking everything is working regenerate your displacement map, normal and cavity and whatnot... and then go to maya... if your using the 2008 be sure to use the approximation editore script (found in zbrushcentral by scott spencer) and then everything else (tick displacement off the attribute, change to a .map file... ect....) and do a render.. it should work... if your in 8.5 forget the script part...

hope it helps...
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Old 11-26-2008   #7
TofurkeyMan
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Thanks for the info man, I really appreciate it. That's alot of work!

But just so I'm clear, these are the steps I take:

1. Import mesh into zbrush and switch to lowest subd
2. Activate UV setting
3. Export back to maya
4. Layout UVs again
5. Import my mesh back into zbrush

Then to render out the displacement map, I generate it, take it into maya, change it to a .map file, and load the script by scott spencer and it should work?

And yes I'm in 2008 :P
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Old 11-26-2008   #8
TofurkeyMan
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HA! IT WORKED! I could kiss you deakinduperly. You saved me! THank you so much!
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Old 11-26-2008   #9
deakinduperly
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LOL!!!!!!! well at least it's good to know it's working for someone lol!!!! i'm using the script but for some reason i got somethign different in my maya and it's giving me holes in my renders LOL o well...

hey dude i'm glad it helped and just in case u get maya 2009... keep using the script, i've gotten some feedback that they still have that bug in maya 2009...

good luck and hope to see some nice stuff now that u don't have an excuse LOL peace!!!!!
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Last edited by deakinduperly; 11-26-2008 at 22:34 PM.
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