Zbrush export<>reimport offset issue

jibowski

Hi guys,

I encountered some offset problems when reimporting an .obj file into zbrush...

I exported my subtool at level 1 to unwrap UVs in modo(as usual), then when I reimported it in zbrush, I noticed it didn't appeared at the same position...there was a small offset on the Y axis. I first thought it was a modo<>zbrush import/export issue..
But i tried to simply export and reimport the obj file from zbrush(without loading it in modo) and i got the same problem!! I searched on zbrushcentral but didn't find anything that can really help me...
If i keep exporting/reimporting it in zbrush the mesh keep moving on Y.. i'm really getting crazy...

If anyone can help it would be GREATLY appreciated!

thx

rossco1111

Is your Object offset in ZBrush prior to export?
check the preview tab and ensure its centered before export

jibowski

hmm i don't know what do you mean by centered... here is what i have in the Preview tab :


By "Zbrush prior" you mean if my subtool is in the top of the subtools list ? If yes, it's not..

MoP

I've always had tons of trouble importing/exporting models from ZB3.1 and getting them to stay positioned when re-importing.

Exporting is always fine, they always line up correctly in Max/Maya, but even if you just immediately re-export the mesh from your 3D app and re-import into ZBrush it always ends up higher/lower/forward/back from where it was when you exported it.

I still haven't found a proper solution to this. I swear it never happened on ZBrush 2.5.
Currently what I tend to do is just manually move it back into position before deleting the "old" subtool. It's even worse with asymmetrical meshes since they end up offset on your mirror axis and it can really screw with using mirror/resym tools.

I asked the same question ages ago on ZBrushCentral forums and the few solutions I was presented with never worked fully, and mostly it was just other people saying "yeah, I also have this problem".

I tried messing with the "Preview" palette stuff like rossco1111 mentioned here, but it never seemed to make any difference at all

Renaud Galand

Hey Julien, as I told you on msn before, I won't be able to help that much on your specific problem, but if you don't mind I'll take the chance to speak about another import/export related problem (and potential solutions) :

I Had a kind of similar problem (= import problem) a few days ago with a fresh new retopology mesh imported in Zbrush to rebake all the details from the old highpoly. The new mesh which had the same scale in max was like 0.45 smaller in ZBrush. I had to export the highpoly (highest subd) and reimport it as obj. then reimport the new lowpoly as subtool, and it worked. I had both models lined up and I did my project all without any problem. After a quick search on ZbrushCentral I found a part of solution about this specific problem (and WHY).

http://www.pixolator.com/zbc/showpost.php?p=546514&postcount=23 (aurick is providing another solution to solve the above problem).

Another problem I also got lately, was exporting a few subtools (at lower level) to make UVs in max and reimport them back to Zbrush one by one. Using the EXACT same obj export/import setup in both max and Zbrush, some subtools was exploding in Zbrush, some other not... Still didn't figure out what happened... The solution I found for the meshes which was exploding was to use a small external "Uv Specialized" software which doesn't seem to alter the obj (?) and then reimport in Zbrush and it worked so far. I could use this little app for all my Uvs, but I'd like to get why the bridge between max and Zbrush isn't seamless, sometimes.

It looks like, every scale/offset problems seems to be due to the fact that Zbrush is "reinitializing" the pivot and the scale of an object when you're importing it using their very own Zbrush unit setup. They should definitly fix that

//edit : here's another solution from aurick about scale/offset problems :

http://www.zbrushcentral.com/zbc/showthread.php?t=47511 (solution > post #4) weird...

MoP

Thanks for the tips and links, Renaud.

It'd mad. I honestly don't understand why the program re-scales and assigns the pivot to the centre of the geometric mesh bounds... it's a totally unnecessary operation. I'm fairly sure this didn't happen in ZBrush 2.5, certainly I don't recall having any problems with it.

It's totally useless for a mesh which has some symmetry (eg. symmetrical torso, head and legs, but asymmetrical arms) because ZBrush just throws the centre point somewhere slightly off the middle of the model, breaking symmetry completely unless you manually position it correctly.
I've got into the habit of cloning my asymmetrical meshes, mirroring them, and exporting both the mirrored version and the original version, just so that the centre point will actually be where I set it in Max/Maya/whatever. Then I just delete the mirrored version in ZBrush using DelHidden and bingo, I have an asymmetrical mesh working with symmetry.

It's stupid to have these workarounds though, it should just preserve whatever pivot and scale you set originally, would make life so much easier
I hope they fix it in ZBrush 3.5 or whatever the next release is.

FAT_CAP

Importing/ exporting between MAX 2009 and ZBRUSH 3.1 is a real pain. I was getting exploding meshes every time using the exact same workflow that I used with MAX 9 and ZBRUSH 3.1 - even using the new ZBRUSH export settings in 2009.

After looking around on ZBRUSHCENTRAL I found that a fix was (after turning off the optimize checkboxes in the exporter) turn the object into an editable mesh, then back into an editable poly then export it back into ZBRUSH. This seemed to work for most objects but a few still would explode after I had changed the UVs > editable mesh > editable poly. I set up a script to convert to mesh > convert to poly > export and then repeat the process straight away - seems wierd but this has fixed any exploding mesh export problems I was having.

kunglao

Renaud would appreciate a link for that Uv Specialized

Ft cap wuld you mind sharing that script.

I have a problem in that i would build a basemesh in max,export to zb 3.1,store morph target.Sub divide and sculpt for my normal.Drop to sub div 1 and import in Max,using pelt map i get an ok wire but really get great results exporting to Deep UV and using the relax tool.However if i export back to max and onto ZB or stright to ZB my model explodes.Guess it's to do with point order changing.
Really need a sloution.Right now i hae to save out wire bitmap from Deep UV and use that as a texture in max (unwrap UV ) and move the poiints from on model prior to exporting to Deep UV just to get a good layout,trdious and annoying bit only way i know how,Would appreciate any help

FAT_CAP

Hi Kunglao - I'm not sure if I would be able to share the script as it has been worked on by a few people at work and so could come under te company NDA - I will ask though.

Basically all it does is converts the object into a mesh, then back into a poly and export into a predetermined path with a button click instead of having to do it manually. There are still some annoying objects which still only work when I go through that process manually, even though the script does exactly the same thing only automated.

MoP

OK, I'm an idiot.

aurick (from post that Renaud linked) wrote:

But if you export a model that is a SubTool of another model, ZBrush will apply the scaling of the top-most SubTool.

So yeah... I never realised this before, but if you just Append a "PolyMesh3D" tool to your existing tool (the star default thing), then using Import of any arbitrary geometry works and replaces the PolyMesh3D with the OBJ import and keeps the scaling correct relative to all your other objects.

I guess I never realised you could actually append the PolyMesh3D object, and then import the OBJ - I was always switching to a new PolyMesh3D tool, importing my OBJ, then using Append to add this new tool as a sub-tool - which is why my scaling was always messed up.

Well, that solves that, I guess. I'm a bit slow...

Costin

When it happened to me, I wanted to destroy my computer.
to reslove the problem I merged the subtool that has problems with export to an subbtoll that doesnt have these problems, and it worked!!

cheers

Costin

by the way, I merged my subtools with sub tool master itegrated in ZB 3.5 plugin