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SOLVED. Importing an OBJ into lowest subdivision level. 3dsMax >ZB3 NO EXPLODE/CRASH

ZBrush Usage Questions
#1

There have been a lot of threads concerning this, but i could never find a true answer, so after weeks of searching on and off these forums and others (some not involving zbrush at all), ive come to an answer… and its VERY weird. Even still its not 100% perfect (for instance your model will end up upside down) but i plan on doing some more tests and getting it 100% by the end.

Im using 3dsmax 8 (ill assume this also works with 9 though) and Zbrush3

  1. Export the lowest subdivision of your highres, zbrush tool. I used the default export options in zbrush3 with OBJ, QUD, TXR, GRP all checked and a scale of 1.
  2. Import the OBJ into max and make any changes to the UV’s or position of the verts.
    NOTE - do not create any new edges or verts, or delete any from your model. If you dont know if youd be changing the geometry, i suggest just changing the UV’s
  3. Export your changed model from max as an OBJ. Once again i just used the default settings.
  4. Heres where it gets weird. Import the OBJ you just exported from max, BACK INTO MAX! im not quite sure why you have to do this, but im assuming it has to do with max mirroring all the verts. Export it as an OBJ right away again.
  5. Now bring the OBJ you exported from max into ZBrush3 as a seperate tool. (make sure you bring in the 2nd OBJ file from max and not accidently the first)
  6. Now export the new tool as an OBJ again (this is because max and Zbrush have different ways of dealing with normals. If you dont export it from Zbrush again, it will crash your model when you try and sub it in for your lowest subdivision level)
  7. Now load your original high res Zbrush3 tool, and go down to the lowest subdivision level. You can now import your corrected UV mesh in without it exploding when you try and subdivide.

HERES THE CATCH! your model will be upside down, and anywhere you have more than 4 edges goin into a vert will be twisted a small bit. You can easily just smooth out the twists though, so the cleaner the mesh the better (quads quads quads!!! :stuck_out_tongue_winking_eye: )
Im assuming you can rotate your model 90 degrees in max to fix the upside down part, but im too exhausted to try today and im happy enough that i found out this fix after weeks of doing tests.

#2

to fix the upside down problem, just rotate your model 90 degrees in max before you export it the 2nd time. :wink:

#3

hi Cenelder

So far … it doesn’t work here on 9 …
the strange thing is , if i started from max the base model >> i don’t encounter this problem ! but a Zbrush base mesh makes the Explosions and stuff

now , i can’t seem to get this working on any of the Zbrush included models !
the Best results i’m having till now is a “Spikey” model and the Spikeness increases with subdivisions !

#4

I posted this thought in another forum–For some reason Zbrush by default flips models and textures and normals on imports. This is the reason for alot of problems for people pipelines.I think if they just make the Default import to industry standards it would help resolve alot of issues.

#5

I too have encountered the exciting undocumented feature of exploding re-imported OBJ’s, and can confirm that Z3 will flip the normals of any OBJ from XSI. It leads to these Kafka-esque export-reimport-export scenarios - undoubtedly stimulating to track in terms of mental gymnastics - but not so much fun if all you want to do is tweak a few UVs and get back to work.
(For fear of being churlish, I’ll note that Z3 is great to model in however, and unsurpassed in that regard)

#6

I observed this difference too back in ZB2. I have not tested in ZB3 though.
For meshes created in ZB you could try the FBX solution that garycrumb posted in this thread:
Imported Mesh Exploding. THE FIXX.

I posted my setting on page 2 of that thread.

-Andrea