ZBrushCentral

why is this happening? polygroup/subD problem

ZBrush Usage Questions
#1

polyG1.jpg

in the image, on the left on top- these shapes have assigned polygroups and creases where i want them.
on the left, lower- it shows them after 4 levels of subdivision.

on the right however- it shows the shapes after i either delete the highest subD level and then reconstruct the levels,
or if i merge them with another subtool.
it not only ruins the polygroup assignments, but it actually changes the lowest subdivision’s shape between the left cylinder and the right on (they were symmetrical).
i don’t have any idea why this is happening. i’ve tried remaking them from scratch and it still happens.
i tried exporting as an OBJ, then importing, but it still happens.
none of the other other subtools in my project are doing this.
i’m completely stumped.
any help is greatly appreciated!

Attachments

polyG1.jpg

#2

Zbrush is reconstructing your mesh incorrectly, as you noted.
I don’t believe there is a way to tell Zbrush what edge to keep when reconstructing subD levels.

As a work around simply don’t combine this mesh with another so you can keep all your SubD levels and correct polygoups.
eh, my 2 cents.

#3

if no one else knows what’s going on, i’m thinking that’s what’s gonna have to happen.
thanks!

#4

There are some other options you have to help force the reduction you want.

On your lowpoly cage if you add another edge loop in the center of the inner loop and break that edge so it isn’t welded together it will basically force your edge rings to stay correct. Chances are this will also have the same effect on getting your mesh to maintain the proper edge loops as well. But it might not. As your mesh has radial symmetry this probably won’t matter if it messes it up though.