CC3/Zbrush Pipeline: 'Using Polygroups in Zbrush'


https://forum.reallusion.com/Topic399459.aspx
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By e1_scheer - Last Year
I would love for there to be a way to use polygroups in Zbrush and
then send it back to CC3 without it thinking that it is a new mesh but 
I think that polygrouping in ZBrush must change the vertex order in
some way.

OB
By sterlingy - Last Year
Hi gang,

Well, this post was early on in my CC3 pipeline dev learning. Since then, I've discovered the poly groups that CC3 exports to Zbrush (or any 3D program) is locked in. They are based on CC3's UV layout, and ZBrush with automatically interpret the UV layout into Polygroups once imported as a subtool. As we all suspected, 'Auto-Grouping' in ZBrush will mess up CC3's entire format, and break the link from the source CC3 model.
So I've adjusted my workflow to maintain a 'peaceful' pipeline, always allowing for the adjusted Zbrush model to swap out the source CC3 model.

1) I use 'GoZ' for import/export. FBX is fine too. OBJ is probably fine, but I did encounter a few issues with OBJ that I need to explore further.
Bottom line, GoZ works great, always be sure to Open your CC3 program & file before Opening ZBrush for it to work. For some reason, CC3 requires itself to be opened first for Zbrush to be able to communicate correctly.

2) When exporting your avatar from CC3, only select the avatar's mesh's that you need. If you are just sculpting the body, you probably don't need the teeth, eyes, etc. This is not a big deal though,&  just makes for a cleaner Zbrush file  to start with.

3) Once the model is drawn in Zbrush (now a editable subtool), turn on 'Draw Polyframe' (Shift +F). You will see the avatar is reading CC3's UV assignments as Polygroups automatically. No need to 'Autogroup with UV's'.

4) Immediately add Subdivisions to the ZBrush model (I usually go up to level 5) before modifying your mesh.I usually prep the model with masks on a level 5 (for cleaner edges), and then drop down to level 3 to start sculpting (eventually finishing sculpt on Level 5). You can also hide polygroups that you don't want to mess with during the sculpting process here.

5) Once the Zbrush model is finished, unhide any hidden polygroups & remove all masks.

6) Export any maps you have created (Normal = Level 1 SubD export/ AO = Level 5 SubD export / ID = Level 5 SubD export).
Keep in mind, the ZBrush map export process requires each polygroup (UV's) to be exported separately. This takes a little time, as you have to hide polygroups that you don't want exported. 

7) Export your modified Zbrush model back to CC3 (swap out). 
- This must be done at Level 1 SubD. Make sure the poly count matches the source CC3 file. All polygroups must be unhidden.

8) Once in CC3, apply newly created AO & Normal maps from Zbrush into the correct shader texture channels. 

9) If you created ID maps, these can be used in Substance Painter if you want to do your own texturing. I still have some experimenting to do with this, but below is what I think will work:
- ID map creation is the way to 'break free' or override the automatic UV's/Polygroups you are bound to by the source CC3 avatar. In Zbrush, you have the freedom to paint in whatever ID's you like, and import them into Substance Painter.
- Substance Painter will read CC3's 'UVs' & Zbrush's 'Polygroups' as 'Texture Sets'. Each program has a different word for the same thing.
- Use your ID maps as masks for each Texture Set.
- Once you have created your unique Substance Textures, using your proprietary ID maps as mask for each Texture Set, export all of your maps and apply to your CC3 avatar that was modified in Zbrush. 



By Alfonsoantoine - Last Year
I'm having the same problem. has anyone told you how to fix this issue? please let me know, its very frustrating 


By sterlingy - 2 Years Ago
Is it possible to re-link my base CC3 mesh to Zbrush after modifying the model in Zbrush  using the 'Auto Groups with UV' tool? It does come in, but as a new mesh. Alternatively, is there a way to re-project the original mesh's textures onto the updated Zbrush mesh if it cannot swap out with the original?

In the pic, you can see the original mesh as well as the ZBrush version
https://forum.reallusion.com/uploads/images/ec637565-6486-4176-9d53-64cf.jpg

Cheers,
Sterling
By Ascensi - Last Year
sterlingy (2/19/2019)


Well, this post was early on in my CC3 pipeline dev learning. Since then, I've discovered the poly groups that CC3 exports to Zbrush (or any 3D program) is locked in.


You've stated:
sterlingy (2/19/2019)
They are based on CC3's UV layout, and ZBrush with automatically interpret the UV layout into Polygroups once imported as a subtool. "
  On my end Zbrush does not automatically create polygroups from the UVs. Teeth for example, you can't hide the teeth from the gums disappearing what would be the gums. Is there some setting you have on that is safe for CC3 that when models are imported they automatically get poly groups from UVs?


Update: Today I realized that the GoZ export split model feature is the solution to Zbrush Polygroups -the ones that are essential for artists to change -all except for teeth!! Why do some of us why are people making the mistake of using an essential feature like polygroups? because they feel like they need it to do more complex tasks since the part they are working on lacks the ability to be worked efficiently to save time.

If you want more control over your character to customize it I'd Vote for CC3 to be  updated with this https://www.reallusion.com/FeedBackTracker/Issue/GoZ-for-splitting-teeth-as-a-group-separate-from-Gums-needed-for-custom-shapes-and-painting

Also you said:
sterlingy (2/19/2019)
 "Auto-Grouping' in ZBrush will mess up CC3's entire format, and break the link from the source CC3 model.

So if you've only messed up *one* part such as the teeth by using polygroup Uvs and sent it back to CC3 do you mean to say it wrecks the UVs on all other CC3 parts ie; body, nails, eyes etc? The whole character becomes trash?
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I recently made a quick post in a different thread:
I realized something today from destroying my projects so many times, starting from scratch not knowing what's going on, contacting support as to how might I fix this with little to no suggestions.

I realized in the end that maybe its fine to be destructive somewhat, make your polygroups to get the job done faster because when you've finished the dirty work molding it all and have your complete new shape.. maybe, just maybe you can pull out a new character and mix your new creation as a morph for the new character so the new character has perfect UVs?