ZBrushCentral

Polygroups lost after importing a updated mesh, how do I retain them?

ZBrush Usage Questions
#1

Hello.

My character has a Uv map in which has three targeted body parts to occupy the same uv space so 3 maps arm made from one. Its essencial that my Polygroups remain based on Uvs. I used the Polygroup Uv to get them polygrouped.

Now I needed to make some edits to the mesh in a external application then import the base back which works fine. Problem is, my polygroups are gone.

Due to the nature of what I need these polygroups for they have to match the Uv spot on but now the polygroup to uv wont work any more?

Does anyone know how I can retain or save a polygroup set, or even a mask set to allow me to make new polygroups again?

Thanks.

#2

Make sure that Tool>Export>Grp is turned on and then use the Tool>Export>Export button. This will export your polygroups when you export the model.

#3

Unfortunatly I cant have this turned on as Hexagon literaly breaks the model up in the groups. When I export the point order is altered. I could use Modo but was hoping there was a way to get the polygroups back from uv groups again somhow.

Thanks.

#4

hey there… just ran into this recently.

exporting with GRP on causes some real problems! i masked the area (mind you i only had two major poly groups, if you have more, perhaps another method?) but i just masked the group, imported, then hid the selection, and grouped visible.

If you have more groups, try saving your masks as alpha’s, then use them to isolate the mesh to group visible. may seem complicated, but was the way i worked around it :slight_smile: hope it helps?

#5

Hi there.

Masking could well be the answer, ,now how do you save a masked area?

Thanks

#6

Tez, use the Tool/Masking Subpalette to save a mask. The Create Alpha button enables you to save a mask as an alpha and the Mask By Alpha button to load it back on again.

#7

Not working for my situation as it uses Uvs to project the mask and (Create alpha) wont work with hidden parts.

Because my Uv map has overlapping body parts, each part must only be visable while making any maps that use Uvs. Shame as this would be so handy otherwise.

I did also try using Guv tiles to make new uvs based on one uv set space and the alpha thats made from a mask dont work either, it sellects the areas plus odd random polys.

For anyone just reading this thread for the first time, I want to convert each poly group into a mask that I can save.

With this mask I want to apply it and hide everything outside this mask to then use (Group visable) from the Polygroups menu.

Thanks.

#8

Have you thought of using Tool>SubTool>GrpSplit prior to making the alphas? That would get around the need to hide parts of the mesh.

#9

I had try had this before but I need to beable to sculpt the mesh as one.

If there was a way to bring the model in ZB and use grpSplit, then say export the arms and do some editing in another app and bring it back, then merge all parts back retaining their sub-d levels, then yes, that would sort things out, as I know the Uvs still work fine.

As I dont do this as my job, I may be not doing all things the traditional way but where is my workflow.

Make base with all topology present in external application. Uv map in Modo giving the character 3 full uv areas of the body to occupy, for assisting in getting more uv space for better detail. Id split like this.

Head, Torso, limbs. Bring into Zbrush and instantly greate a polygroup set based off the 3 uv group sets.

I sculpt, add detail and later on delete the first Sub-d level, and create a cage on the base. While cage is on, il make displacment maps, but hiding each of the three body parts so one map can be created per group. Create the textures, flip em and export the cage and both maps. Render in Modo.

With the current character ,iv had to make edits to the base in another app that would take too long in ZB. As iv said at the beginnig of this post, Its essencial that the polygroups remain for making maps.

Im thinking its time to stop using Hexagon as this dont happeen with Modo. What I mean is if I export with Grps to be exported Modo will not split the mesh in seperate parts like Hexagon does.