ZBrushCentral

Polygroups rearanging UV's problem.

ZBrush Usage Questions
#1

I’m trying to create some polygroups for my model, but I noticed every time I hide and unhide a group, polygons keep changing color, so I end up with polygroups that are all over the place and weird patches in my displacement map.

But the weirdest thing about this is that when I then export the tool to check it’s UV’s, the UV’s of the polygons that ended up in the wrong polygroup also changed their place in the UV map.

I know it sounds confusing, and I don’t know if I’m doing a good job explaining. Maybe some images will help :

polygrp_01.jpg

Has anyone seen this before, and is there a known solution or workaround ?

Thanks.

Attachments

polygrp_02.jpg

#2

You don’t need to keep exporting the OBJ to check the UVs in an external app. UV Check in ZBrush will do this. Just bear in mind that the appropriate way to use it is to view one UV region at a time. Use your poly groups that you generated from UVs to hide everything except the UV region (say 0,1) you want to check out, then do a UV check. Then you can unhide all geometry, and and hide everything except the polygroup from 0,2 and check that region, and so on. The only difference is you don’t get a master view of all UV regions in a grid.

It sounds to me like the problems you’re having may stem from unwelded UV points. Or perhaps you’re trying to create edge loops between two UV regions, in which case the resulting geometry is going to span across the two regions and give you some wonky results. Go in the app where you made your UVs and check for anomalies. You should have a tool in there that will check for overlapping UVs and crap like that.

#3

Hey thanks Dustin.

I did not change anything to the geometry in Zbrush. No edgeloops, nothing.
Also no anomalies in the UV’s, all vertices are merged, everything looks okay.

All I do is create polygroups and hide/unhide them. That’s all it takes to make Zbrush rearrange my UV’s.

I’ve been testing it a bit further, and it smells like a bug to me.

  • I load the tool I’ve been working on. And the UV’s are still fine ( no tiles, all UV’s within the 0 - 1 range )
  • I create some polygroups (I found out it doesn’t matter how)
  • Ctrl+Shift LMB click hide a group, toggle hide/unhide
  • voila ! Rearranged polygroups and UV’s

I’m surprised nobody has had this problem so far, because I can repeat it every time.

#4

Any solution to this issue before? I have not found anything in any documentation so far that gives a solution or work around to this - seems like a bug to me since I have had it happen randomly to various objects.

any ideas anyone?

[youtubehd]7fm8BfxxRUk&hd=1[/youtubehd]

#5

I submitted a ticket, so I suppose it’s logged as a bug. But so far there’s no solution that I know of.

#6

I just found a work around - sort of -

On an object that has this issue - if you subdivide up and move up those subdivisions you can select properly - move down and the issue persists.

This solves the problem for every issue that I have encountered other than creasing where you specifically need to get your polygroup selections at the first level before any subdivisions have occurred.

Thanks for submitting the ticket.

#7

Correction - my “work around” works sometimes, but other times I still have to wrangle it so at least it is easier to deal with this issue now that I have a few options - still persists though.