it doesn´t help ;o( but thanks !!!
thx help:lol:
I’m struggling with this problem too and I don’t believe it is a problem with vert order.
Yesterday I did some sculpting in ZB, the model I worked on was created and UVd in Modo. I exported from Modo and imported to ZB. Even at this stage 2 verts were moved way off into the distance but I carried on anyway. I stored the morph target, subdivided to level 6 and did my sculpting. All OK so far, back down to level one and swapped to the original mesh and exported my displacement map. Still all OK. The thinking I might tweak the sculpt a bit more I increased the subdivision level and the mesh explodes. Back down to level 1 and even that is now messed up with a chunk of geometry in the wrong place. Note I haven’t reimported so the vert order cannot have changed.
This is driving me nuts!
The same thing happend to me. The only solution I found was to install Zbrush on a fresh installed Windows XP. Very, very weird, but it worked.
I mostly have no problems with reimporting my UV-layouted Subd-1-obj that I UVed with Roadkill, but sometimes it happens (exploding meshes after the reimport).
But I think you are not right saying the fault lies in ZB3.1, I think it’s a fault of the UV-Layout-Apps.
I personally think most apps including C4D have lumpy programmed obj-import/export-routines, that’s the reason why the Riptide-Plugin exists for C4D-Users. It’s the only way for us C4D-Guys to get a proper handled wavefront-file.
And ZBrush 3.1 seems to be a little critical with unpropper created wavefront-files.
Anyhow, a very easy solution in that cases for me is, that I export two subd-1 obj from ZBrush 3.1.
One is used for the UV-work in Roadkill, the other one is left untouched.
Then I load both meshes via the Riptide-plugin in Cinema 4D.
I can then easily take the UV-Tag from my RoadKill-obj and transfer it to the untouched mesh, then I store this one again via the Riptide-Plugin.
Now I can import the obj with the transferred UV-Layout into ZBrush 3.1 without problems and all works fine.
senario: For whatever reason your mesh ‘frags’ when re-imported into Z3.1, how do you fix this?..quite simply! 
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import your obj and add it as a subtool to the original model.
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subdivide it to the same level as original, then go back to the 1subD lvl.
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With the obj as the selected subtool and on it lowest subd lvl hit the “project all” button, do this for each subd lvl.
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If you get stray verts use the “project” brush to fix.
99% of the time this works off the bat, except when the orig model have holes in it or overlapping geometry or many seperate pieces i.e a car or character with clothes.
If this is the case then clone all the pieces and insert into one mesh then deal with the strays.
Also you could retypo the mesh once it is all in one piece to make it airtight but this would be an extreme case.
Cheers
I’ve been fighting with this problem, as I know a lot of people have. It’s certainly not specific to any external UV prog. I don’t know what the issue is, but I tried all the solutions above and got explosions ( the original idea works, but I would love to find a way with just Zbrush3.1 . I do enough importing/exporting as it is ).
I have a semi-solution where you WILL NOT get an exploding mesh. Doubt it is to do with point order, since, in Maya, I chopped the model in half to save time doing UVs then mirrored geometry. even added a couple lines which I removed later.
The problem with my method, is you lose your xyz position relative to your other subtools, which sucks I know. But some stuff it’s not so bad to use the transpose tool to move it back into place. Other than that, it works great. Maybe someone knows something I can change to make that happen too.
These are the steps:
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exported subD1 to Maya2008. Went crazy doing the UVs with little regard for point order and such.
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Export as .obj and bring into Zbrush3.1
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Divide your Low Rez UV mapped model to have the same amount of SubD as the detailed model.
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Unify both models. Obviously this is what messes up the xyz co-ordinates ( and sometimes scaling ), but it’s also what will keep your model in one piece.
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Append the one model as a subtool on the other model ( it doesn’t matter which one is appended, just which you have selected when you do the next step ).
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Put both models on highest subD, and hit ProjectAll.
You should now have the UV mapped model with your High Res detail intact.
Add it as a subTool onto your main model, and use the old non UV piece of the model as a reference for scale and position.
A tip for anyone who will touch the Deformations menu and use that for scale or positioning. Make sure all your subtools are on lowest subD ( easily done with subTool Master plugin ) and Zbrush won’t crash every time you touch one of those dials. I used the Deformations menu to scale, and the transpose tool to move, but it doesn’t really matter, whatever you like best.
Anything to add, change, correct, improve, is most welcome. At least I can paint on my model now. I would be quite happy with just using AUV in Zbrush to do UVs, but this model is for my reel, for modeling and texturing, so I gotta do it oldschool ( the long way ).
[i]“The problem with my method, is you lose your xyz position relative to your other subtools”
[/i]1.Export all subtools to ext 3D app (in my case maya).
2.Create 8 cubes in maya and place them around your tools, like a bounding box.
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combine these cubes so it is one object. Now duplicate the bounding cubes for as many tools you have and combine them to their respective tools.
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Export each new tool back into zbrush and in will maintain its origin and placement.
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When done delete the cubes.
When a mesh frags it is due to the vertex order, where why and how seems to still be a mystery. Considering the problem happens randomly and when all precautions have been taken and then to make it more confusing it doesn’t happen every time, which makes it hard to pinpoint the where, why and how.
Morph Division,
Very clever. Thanks
Grrrr, still having problems. If I sculpted my high res model. Now I have made UV’s on the low res model in Maya.
If I use cubes, it will not be able to ProjectAll with the original mesh ( that has no cubes ). Plus, It still brings the problem with scale ( or placement ) comparing to the high res mesh. Unless I do all my high res detail after I UV my stuff, which is not what I am trying to do. A feature of Zbrush is to worry about UVs later right ?
I do appreaciate the idea though, since it helps with other issues. Maybe I’m just being a dork. Let me know if I missed something vital.
Anyone seeing the light ?
Sounds pretty extreme,
Maybe…You might have to retypo 
or
Cut your original model into small pieces and convert to subtools (head,arms,body etc), then export them at low rez to maya to do uvs.
Import back to ZB and project all for each subtool. If you need them to be one single mesh do the cubes trick on the new subtools afterwards to bring it together.
Also you can mask/hide to only effect specific areas of the mesh when you project all
I have run into this issue so many times now that I simply test each model before I get to the hirez stuff. Export the model to maya, open it and export straight back to zbrush just to see if it frags or not.
All the methods I have suggested have either worked trial by error or in combination for me, in other words you got to beat it into submission
I really don’t think it is the UVing which is causing the issue but more likely the model is corrupted and maya ‘fixes’ the problem by assigning a new vertex order?..my two cents
Good luck
essclock
Just a thought,
Try taking your orig model to the highest subd lvl and delete all lower, then convert to polymesh and reconstruct the lower subd lvls, then export lowest lvl and see if it will import back into ZB without fraging.
The idea being to create a stable vertex order within ZB so maya has no need to make a new one.
很好很强大，呵呵～
Many people here refer to headus for uv’s. I went to their site and saw there is a commercial version and a non-commercial one. Can this non-commercial version do all you need to do? I’m not talking about very high-end specific tasks, but simply unwrapping uv from zbrush.
thanks.
Thanks to everyone who has been adding to this thread. It is one of my only Zbrush related “thorns in the side”.
I have taken a little break from the problem the last few days, and just got on with modeling more stuff. Tomorrow, I’m gonna play around and will definitely use this thread for ideas. I’ll let you guys know what happens.
Erik Heyninck,
Thanks for the suggestion. I have played with Headus briefly at my old job. It seemed very powerful, but I didn’t have time to learn it very well. I will check out their non-commercial version. Thanks.
Gonna try it in combination with Zbrush and see if I still have any hassles.
Thanks guys.
The non-commercial version will let you un-warp a mesh and flatten it, the extra stuff is very useful but you could get by without it by importing the mesh back into your ext 3D app and using its uv tools to layout the flattened UV in 0-1
Today I have spent some hours on this topic… I had a high detail mesh in Zbrush 3.1 with 7 subd levels and wanted to export the lowest level to maya to create UV´s.
When reimporting the UV-layouted mesh to ZBrush, the painted polys changed, and when I switched to a higher subd level, the geometry “exploded”.
I tried some of the approaches from this thread, but it didn´t fix the problem.
*** I forgot to uncheck the “create multiple objects” option in maya 2008 import ***
:lol:
update:
i am getting the exploded meshes again, no matter what i am importing and exporting between maya 2008 and zbrush (also with a simple cube with one subd level)
:mad:
cheers m°
It seems like people are afraid of getting theirs hands dirty with regard to fragging meshes on import (including work collegues who let out a big D’oh when I explain the solution to them) even to the point of having two versions of maya installed.
I can honestly say I have over come the problem and lost no detail/work on any mesh and it was all on jobs with tight deadlines!
The best method is to develop a sixth sense and make sure your model is clean before you go and do all the fun hi rez detailing.
The techinque is to export and import, if it frags then fix it! And get the UVs out of the way while your at it. You know your good to go when there is no issue with the import. (D’oh)
All of the problems so far have a similar tune, la la la la la la, oh no no please god NO! WHY! TAKE ME INSTEAD! followed by calm acceptance and then denial and then blame (ooh ZB shouldn’t be so buggy)
Then again maybe I’m preaching to n–bs:rolleyes:
lol good one
Ok.
I seem to get good results if:
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I take the Un-UV’d model back down to SubD1.
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Create Morph Target.
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Import UV’d model ( it is waaaaay too big )
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Switch Morph Target
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( this is the step I think leaving out was the problem ) Click Reproject Higher SubD.