Vertex Painting ( Experimental Workflow ) Issue - 3DCoat and ZBrush

[Laticis]

Hi,

I have been experimenting with a workflow.

Zbrush to Sculpt < 3DCoat to Retopo and UV < ZBrush for Polygroups / Sub-d detailing and polypaint Base Color < Exporting 3.5Mil to 14Mil Polys to 3DCoat for Vertex Painting

So, this does work quite well, but I am having one main issue and then a secondary. 

ISSUE 1:
The exported FBX from ZBrush ( with polygroups ) file is coming into 3DCoat Vertex Room without subgroups/naming convention in the Sculpt Tree.
I have tried exporting a few variations but don't seem to have any luck. The file will successfully import into DAZStudio with the subgroups.
 

ISSUE 2:
So I tried export as an OBJ with successful polygroups and polypaint but........when I try to use a VDM brush this happens to the mesh. ( Mesh vanishes and can't really be undone )
This does not happen with the FBX file though.

The mesh seen here is just the lowpoly version for testing.

MAIN OBJECTIVE: Ideally, I would like the FBX to come in with the polygroups so I can continue to paint isolated areas and add additional details to the mesh and then bake it out.

Please let me know and thoughts, tips or holes in my workflow....thank you
 

[digman]

Without having access to the FBX file and Obj file I can only offer suggestions.  If you want me to test the model files, pm me with a link to download them.

In the import panel which is available in the sculpt room are you selecting "Import as Child" to see if the groups import correctly. Left toolbar under Objects for the import panel.

Disappearing parts of the mesh I do not know why.  Again without having the files, I cannot give a good answer, I would only be guessing.

Also in your pictures I see you are in surface mode so in the import panel choose "Import w/o Voxelization"

[Laticis]

Hi Digman,

Thank you, I have just sent you a PM

Actually, no, I bypass that process. I go File / New / Vertex Painting / Import the FBX file from there.

So I just tested my workflow and that would be a negative, Import as Child is not selected and my process of importing doesn't allow me to click that but I can see the panel.

I'll test your alternative route

 

[digman]

Thanks I downloaded them.

[Laticis]

Just some additional information, the issue on the imported OBJ file seems to be when I use the Stamp Brush.

Trying the alternative route for the import of the FBX file with 'import as child' I still couldnt see groups.

[Laticis]

Awesome, thank you

 

[Laticis]

Findings so far....

3DCoat will read the polygroups on the FBX exported from the Zbrush file if imported for Per Pixel Painting or Microvertex Painting, but I can't get them to show up any other way.

OBJ File works as expected, but regarding the Vertex Painting workflow it breaks when using the Stamp brush.

[digman]

Ok, this is a tricky one so bear with me and my suggestions

First VDM maps are applied using the Extrude tool / brush. Others might work but the VDM alphas are designed to work with the extrude tool / brush. Others can cause glitches.

All below is for testing: Windows Version 2023.41 

I imported the FBX file into Blender and it sees the sub groups as material layers and not sub groups. 3DC importing the FBX into surface mode file only sees the materials as one layer and also no groups.

If Import the FBX into 3DC as Per Pixel painting it does the same as Blender seeing the sub groups as material layers.

Importing the Obj file into Blender gives the vertex colors but no separate groups or materials expect one whole group.

Importing the Obj file into surface mode in 3DC you get the subgroups with the sub-groups materials converted into vertex colors which is what you want. 

The problem appears not completely related to 3DC but Blender as well in reading Zbrush fbx files and how it exports Fbx files.

You said this model is only a low polygon version testing. I can use Multiresolution on it to increase the resolution without losing the vertex colors but I think you already have a high polygon version. 

In the extrude tool panel. Turn off Modify Connected in order to have local sub-division. Do not go by the amount of subdivisions in the panel as I was just testing. I do not know the resolution of your high polygon model. Local Sub-division is so your VDM alpha map can be in high resolution without the entire model having to be so in surface mode.

Side Note: if you use Multiresolution the local sub-division is not available in the Extrude tool / brush panel.  I do not know why at this time, could be something to do with how Multiresolution works. 

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Suggestions:

Use the import panel as it generally gives you more options either for surface mode or voxel.

Import your high polygon model into 3DC as an obj file as it gives you the sub-groups. Can use Multiresolution but again you lose local subdivision with the extrude tool / brush.  

VDM  alphas apply them with the Extrude tool / brush. 

Side note: Not sure why if I use increase resolution by resampling the model in surface mode it glitches out in pieces. I would suggest sending the file to support at 3dcoat.com for the developers took look at to see why This does not happen with Multiresolution. 

VDM alphas shown not for quality but as examples. I hidden all other sculpt tree layers but the one shown.

 

[Laticis]

Firstly, a very big thank you for your efforts and feedback regarding this.

Small update too, I managed to get the OBJ File working with the VDM brush, it was based on the resolution of the skin that was initially imported and 3DCoat had it set at [0.5] changing this to 1.0 has fixed that aspect.

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I imported the FBX file into Blender and it sees the sub groups as material layers and not sub groups. 3DC importing the FBX into surface mode file only sees the materials as one layer and also no groups.

Regarding this, I did test three versions when exporting from ZBrush and all yielded the same result when it comes to importing for Vertex Painting:
Also Exported as 2020 / 2019 Versions ( the 2020 version really bloated the file size )

Export Polygroups as Mats
Export Polygroups as Selcetion Sets
Exported with neither selected

Funny, I have only recently started seriously trying to get comfortably with Blender and had been experimenting importing the original test files.

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The problem appears not completely related to 3DC but Blender as well in reading Zbrush fbx files.

Yeah, I have a feeling it's got a bit to do with the outgoing ZBrush FBX

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You said this model is only a low polygon version testing. I can use Multiresolution on it to increase the resolution without losing the vertex colors but I think you already have a high polygon version. 

I discovered that too...very cool. I was also testing Fracture painting on this low poly version...that was cool too.
Correct, and based of initial test, I could get away with using the 3.5Mil but will more than likely use the 14Mil Polys and just do some fine level detailing in ZBrush before the final export.

Some preliminary baking test seem to be successful too. I really wanted to make sure I could hide that tongue and eyes before going too far.

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Thank you for the tips about the extrude tool and the Multi resolution.

Also for the suggestions as well.

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Side note: Not sure why if I use increase resolution by resampling the model in surface moe it glitches out in pieces. I would suggest sending the file to support at 3dcoat.com for the developers took look at to see why This does not happen with Multiresolution. 

No probs, I'll send off the two files and a link to this thread.

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At least now, I get get back to the job at hand....two days of messing trying to find a workflow  - but it will be worth it.

[Laticis]

Oh, just to add one other factor to this story regarding workflow....trying to polypaint in Zbrush while using layers and hiding Subtools produces this......needless to say, very troublesome working conditions....

[Carlosan]

On 3DCoat fbx file format have some limitation. Cant import/export blendshapes/shapekeys as example.

Please also send the files and request to Andrew at andrewshpagin@gmail.com

[Laticis]

11 hours ago, Carlosan said:

On 3DCoat fbx file format have some limitation. Cant import/export blendshapes/shapekeys as example.

Please also send the files and request to Andrew at andrewshpagin@gmail.com

 

Hey Carlosan,

Thank you for the additional input, I'll send an email to Andrew. I have also already sent one to support.

 

[Laticis]

Some additional information regarding the workflow.

The exported OBJ file from Zbrush Level 6 - 1.07 GB ( Imports fine - lost polypaint information on the eyeballs though not important )
The exported OBJ file from Zbrush Level 5 - 268 MB ( Imports fine - lost polypaint information on the eyeballs though not important )

Visible differences between these two were negligible, only some micro details.

The exported FBX file from Zbrush Level 5 - 157 MB ( Imports fine, retained all polypaint information - but missing the poly groups )

The biggest difference was in the file size, FBX was much smaller on disk.

In conclusion, would be great to use FBX files and have the sub-groups available.