Blender<->Zbrush OBJ import/export

[Roja]

I’ve been testing out importing/exporting obj files back and forth between Blender & Zbrush. What I’ve found is that sometimes it works, sometimes it doesn’t. It doesn’t work when you create any geometry in Zbrush, such as adding edge loops to your mesh. If you don’t add any edge loops, or do not create a mesh from Zspheres, it works fine.
I’d really like to get any input and help on exactly why it’s not working under some circumstances if anyone knows or has any ideas at all as to why.

Here are my notes:

Using Zbrush 2, and Blender 2.42 RC1

what works:
Scenario #1
-import an existing obj file into zbrush(mine were created in blender)
-work on mesh, have many subd’s, lots of detail using proj. master, move vertices around, etc.-but do not add edge loops.
-export obj at subD1 (having options obj, txr, qud, mrg checked)
-import obj into blender, make uv changes
-export obj from blender
-import obj into Zbrush at subD 1.
Model works just fine, all subd’s are intact, and new UV’s are working as well!

what works:
Scenario #2
-work on Zbrush model, doing ANYTHING to it(including edgeloops)
-export model as .dxf from zbrush
-import into blender, fix UV’s.
-export from blender as obj
-import into zbrush as obj
Model works! All subD’s intact and uv’s have been fixed!

what works:
Scenario #3
-create a mesh in Zbrush from a sphere 3d, or one of the primitives, making them a polymesh.
-adding detail, subD’s, anything but edgeloops.
-import into blender, fix UV’s.
-export from blender as obj
-import into zbrush as obj
Again, it all works!

What doesn’t work:

-work on imported mesh in Zbrush, creating edge loops. OR creating a mesh from Zspheres(then using adaptive skin to make it a real mesh).
–tried making the subd1 a polymesh, doesn’t work either
-export as obj(same settings as above)
-import obj into blender, reUV map.
-export obj from blender
-import into Zbrush…mesh is all messed up when I change subD lvl’s. Looks like vertices are just scrambled up.

So it seems like something is messed up in the area of exporting an OBJ from Zbrush and importing it into Blender, but only if edgeloops are added to the mesh or the model is created from Zspheres. Maybe some Zbrush data that the obj format or Blender is misinterpretting?

Of course, there are a ton of variables in this issue, and I don’t have time to test them all. But if anyone wants to add their testing notes to this I’m sure it would be helpful!

Attached image shows my blender/zbrush import/export settings. I tried to check/uncheck many different combinations in them. These settings I found to work best overall so far however.

Attachments

[aminuts]

Sounds like for whatever reason in your doesn’t work scenario that blender is changing the vertex order and that would explain the weird behavior.

am assuming it was originally mapped in blender?

am curious why in scenario 2 you exported as dxf when all other times obj from zb…just testing to see what works?

also you say fix uv’s in a couple scenarios but in doesn’t work scenario you remap…which will cause a reordering of vertex me thinks specially if you added geometry so again explains the problem.

[Roja]

Hi,

Actually I originally UV mapped the mesh in Zbrush using GUV tiles, to which I then regretted doing that and wanted to UV map it normally so that I can edit the actual texture file in a 2d program(so that it’s “readable”).

I exported it as a dxf as a test, yes. It worked!

I reuvmapped in EVERY scenario, also, I tried not touching the UV’s as well in the “it doesn’t work” scenario". Basically all I did was import/export the file, and the messed up mesh still did happen.

I also did not edit or touch the mesh when i was working with it in Blender in any scenario. The only thing I ever did touch was the UV’s.

[system]

Sounds like for whatever reason in your doesn’t work scenario that blender is changing the vertex order and that would explain the weird behavior

YES Blender changes the order - I took me 2 hours to solve but here is the

SOLUTION: When importing AND exporting obj with Blender use the “Morph Target” button

This way everything stays in tact and it works.
The second thing is that you might have to switch U and V when exporting normal and displacement maps. (and i had to rotate the images 90degrees).

So its not simple but I know the tricks now and I wanted to share it.

[Bladka]

I’ve been testing out importing/exporting obj files back and forth between Blender & Zbrush. What I’ve found is that sometimes it works, sometimes it doesn’t. It doesn’t work when you create any geometry in Zbrush, such as adding edge loops to your mesh. If you don’t add any edge loops, or do not create a mesh from Zspheres, it works fine.
I’d really like to get any input and help on exactly why it’s not working under some circumstances if anyone knows or has any ideas at all as to why.

Here are my notes:

Using Zbrush 2, and Blender 2.42 RC1

what works:
Scenario #1
-import an existing obj file into zbrush(mine were created in blender)
-work on mesh, have many subd’s, lots of detail using proj. master, move vertices around, etc.-but do not add edge loops.
-export obj at subD1 (having options obj, txr, qud, mrg checked)
-import obj into blender, make uv changes
-export obj from blender
-import obj into Zbrush at subD 1.
Model works just fine, all subd’s are intact, and new UV’s are working as well!

what works:
Scenario #2
-work on Zbrush model, doing ANYTHING to it(including edgeloops)
-export model as .dxf from zbrush
-import into blender, fix UV’s.
-export from blender as obj
-import into zbrush as obj
Model works! All subD’s intact and uv’s have been fixed!

what works:
Scenario #3
-create a mesh in Zbrush from a sphere 3d, or one of the primitives, making them a polymesh.
-adding detail, subD’s, anything but edgeloops.
-import into blender, fix UV’s.
-export from blender as obj
-import into zbrush as obj
Again, it all works!

What doesn’t work:

-work on imported mesh in Zbrush, creating edge loops. OR creating a mesh from Zspheres(then using adaptive skin to make it a real mesh).
–tried making the subd1 a polymesh, doesn’t work either
-export as obj(same settings as above)
-import obj into blender, reUV map.
-export obj from blender
-import into Zbrush…mesh is all messed up when I change subD lvl’s. Looks like vertices are just scrambled up.

So it seems like something is messed up in the area of exporting an OBJ from Zbrush and importing it into Blender, but only if edgeloops are added to the mesh or the model is created from Zspheres. Maybe some Zbrush data that the obj format or Blender is misinterpretting?

Of course, there are a ton of variables in this issue, and I don’t have time to test them all. But if anyone wants to add their testing notes to this I’m sure it would be helpful!

Attached image shows my blender/zbrush import/export settings. I tried to check/uncheck many different combinations in them. These settings I found to work best overall so far however.

For an other solution I recommend this:

http://blood2oo1.atw.hu/obj/

But I dont try with blender I hope this will work.

BlooD2oo1