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Maya Obj's Exploding in Zbrush

ZBrush Usage Questions
#1

First, im not that new to Zbrush and i have dealt with the “Exploding mesh” problems before, but this is a bit differnt. Usually, exploding mesh means someone has move some Verts around while they were in Max / Maya / SXI, whichever, and after they import, everything explodes because its really not the same model.

First attempt 1. Anyway, i finished detailing my tool, dropped to the lower SubD, exported, brought the OBJ into Maya, Re-Uv’d it, exported it back out and after i Imported into Zbrush, all the high SubD’s on the tool Explode.

Second attempt 2. I figured i had accidentally moved a vert or something, so i ReExported the Level 1 SubD, Transfered the UV’s to the newly Exported OBJ and imported again…Still the model Explodes. At this point im a little annoyed.

3rd Try. Thinking something with the import Export options are wrong (Some times “FlipX on Export” is on) i checked Zbrush settings and nothing is on. Nothing gets flipped on Imp or Exp. So i export a new OBJ, and then i Import it right back into Zbrush. It works. So its not Zbrush’s issue

Then i take the new OBJ, bring it into Maya, DO NOTHING, and just export it back out, Then try to import it into my Zbrush tool. This Explodes the mesh.

my conclusion is that something in Maya isnt working. Anyone that knows Maya that can offer a suggestion, Please do.

Sry for the long Read. Thanks for the help.

#2

I have had this happen to me more times than i can count. it kind of reminds me of algebra 3 in highschool, it just sucks. i actually believe that it is not necessarily a zbrush issue or a maya issues, but an issue when they meet up. kind of like Jim Breuers’s take on alcohol and tequila. I have tried many many methods in the past on this, and it is the same issue. Import obj, detail, export for uv adjustment (make some stuff better for zmapper etc.) reimport and boom! just nasty and frustrating. the best i can figure is that it is mainly to do with the texture button in the tool palette. there’s a button that says uv’s on or off or something. usually, from some successful trys i have had, before i reimport my model, i make sure that button is turned off. when you bring it back into zb, it will automatically turn it back on. i have done that a few times with no problems. other times it doesn’t work and i have tried reconstructing and reprojecting in the geometry palette. sometimes that does the trick. other times i say aw hell and just start all over. i’ve never really found a good answer for this topic either, so i will keep an eye out to try and learn something.

#3

I have the same problems with Modo and have come to the conclusion that it’s down to changing point order. The only workflows which so far haven’t given me problems are

1 Finish model in Modo, UV in Modo, export to ZB, sculpt, export to Modo.

2 Finish Model in Modo, export and UV in ZB, Sculpt, export to Modo.

Any deviation from those can cause exploding meshes so no tweaking of UVs, no export to Modo/Maya and reimport to ZB. ZB seems really fussy about this and there’s no room any variation of workflow.

I can’t promise this is the answer but it seems to be working for me!

#4

I’ve somewhat come to this conclusion as well. since i dont Edit the model in any shape or form…Workflow as follows…

  1. Export from Zbrush at lowest Sub D (OBJ format).
  2. Import to Maya (OBJ).
  3. Export from Maya (OBJ). Just to be clear, as a Control Test, nothing was done between step 2 and 3. No XYZ movement, No UV editing, No Vertex Editing.
  4. Import to Zbrush (OBJ)
  5. Move slider to level 2 Detail and BOOOM. Explode!

So something chages between the Zbrush OBJ and the Maya OBJ. all i can think of is Point order. Any furter Help from the Zbrush Gods would be awesome! Thx again

#5

yeah, maybe the problem is in maya while exporting the OBJ. I notice that UV map and polygon normal in maya and zbrush is fliped
umm, may be if we flip back the UV map or the polygon normal it will work.
I just guessing, cause I don’t have zbrush here in my office :stuck_out_tongue:

#6

Solution Update!!!

First off, This has been driving me INSANE for the past 3 days. Not being able to Import UV’s is such a pain in the ass. the below solution may of been common knowledge for most, but i found no mention of this anywhere.

Anyway, I hope this helps a lot of people cause god knows i searched for a solution for hours and didnt find one.

Updating UV’s - Zbrush to Maya and back to Zbrush Work Flow as Follows.

  1. From Zbrush - Export OBJ mesh from Lowest Subd Level.
  2. Within Maya - Import OBJ mesh using the follow options (THIS IS WHERE ALL MY PROBLEMS WERE)…
    Import OBJ.jpg
    It appears as though, simply leaving it to maya and the default options wont always import certain Very important Vertex Imformation. Telling Maya that the imported File type is Specifically on OBJ will import those Proper vertex points.
  3. within Maya - Adjust your UV’s as needed, Remember not to XYZ move any verts or this wont work.
  4. Within Maya - Export your new Mesh with Good UVs as an OBJ. Also under the Box options, select OBJ File type before exporting.
  5. Zbrush - on the Same SubD level as you exported, Import your new OBJ and your DONE!

I hope this helps as the only reason im posting is to help others avoid the head ache i just went through.

Have a good one guyz

#7

Worked for me - thanks.

I had a zbrush scene I needed to rescale in Maya.

I exported the subd01’s into maya, scaled and back into zbrush
with the mesh exploding when doing a subdivision command.

:E

#8

I have a question about how you import an OBJ back into subdivision levels. What I have been doing is importing the OBJ back into ZBrush (Blank document) and assuming that I have to re-sculpt all the higher levels. or rebuild all the lower levels. The rebuild of lower levels doesn’t always work and re-sculpting, well that isn’t fun either. I am sure this is rudimentary but i have missed it somehow.
thanks.

#9

im glad i managed to help a few people. anyway, for the above. After you have adjusted the UV’s on your mesh in maya and saved it back out as an OBJ, open your Original Tool, with the old UV’s in Zbrush. Set your division level to that, where you exported it before. (usually this is lvl 1) Now with your Old mesh, on its Lowest SubD lvl, [Import] - your Mesh from Maya with your new UV’s.

This will always work if no Vertex imformation has been changed. when any of those vertices are moved, you start running into Exploding meshes like i was in the OP. GL!

#10

Thanx Demonfrost. You saved me alot of headache.

#11

DemonFrost, thank you so much for your help. I’m a beginner and swore I had all my UVs laid out and whatnot, but when I went to export a normal map, my UVs apparently disappeared. So I tried re-importing them only to get the exploding mesh. Your solution worked perfectly. Again, thank you so much!

#12

thanks man, it was the Import settings that were giving me the trouble…

#13

I think I found another reason why model collapsing happens: vertex point order.

I had a zbrush LVL1 model that I had manipulated in Maya. I was fixing the eye sockets so that they would wrap around the eyeballs. Once I fixed one eye, I just copies the polygons there and replaced the polygons of the other eye. The poly count is identical, however, because some polys got deleted, the vertices are numbered differently. Here’s what happens:

Open my Zbrush file. Go down to level 1 and import Maya manipulated .OBJ.

Everything goes swimmingly.

Then I go from lvl 1 to lvl 6 in the subdivision.

Switching lvl 6 morph targets of the original detailed model helps a bit, but doesn’t resolve the issue.

#14

DemoFrost, thanks for starting this thread-- followed your instructions (along with digiegg) and the exploding stopped!