[Solved] ZBrush: Edges around open faces are warping when subdividing, please help

AlbinoEgg

Hi all,
When subdividing in ZBrush, the edges around open faces are warping pretty bad. Im modeling a building and wanted to sculpt all of the surface detail in ZBrush and then bake the low and high poly mesh in Substance Painter.  My workflow has been: delete all unnecessary faces in Maya-open it up in ZBrush- put a CreaseAll on the low poly mesh, and then start subdividing.

Low Poly mesh, before beginning to subdivide:

What happens to my mesh after subdividing:

cryrid

Creasing normally does the trick, though it's possible you've missed some faces or the control edges are throwing it off. A building like this doesnt look like it needs any smoothing though, so you might have better luck turning off the SMT toggle next to the divide button. 

Alex_J

I think not all your verticess are not welded. You can run a weld points operation in tool > mod topology > weld points. Or for a better look at what is going on, you can also take it into your main 3d application, apply a smooth mesh preview, and look for any verts getting pulled out of place. Those would be the ones not welded. They will be the ones your edges are getting pinched towards.

If you aren't clear on how subdivision surface modeling works, reading up on that will help you understand what is happening (assuming my diagnosis is correct.)

musashidan

Somewhere along the line in the last few releases the creasing on open borders got broken and doesn't work as expected. Disabling the Smooth modifier as @cryrid suggested will work. However, using dynamesh for this would be much better. It will give you optimal sculpting topology. The topology on your basemesh is unsuitable for sculpting and will subdivide unevenly. Duplicate you mesh and dynamesh to a high resolution. You can use the dupe to project back the hard edges if needed.

Also, a little tip on creasing: you can crease by polygroup(setup polygroups quickly using polygroups by normal) and you can crease by angle threshold.

cryrid

If you go the dynamesh route then you'll probably want to close the holes or restore the deleted faces before using it. Dynamesh prefers the model to be 'water tight', otherwise the results can be more unexpected. 

AlbinoEgg

Thank you! @cryrid and @musashidan
Turning off Smt (subdivide smooth modifier) worked like a charm! Also, Dynameshing the model was the better rout for this particular project, thanks for the info!

musashidan

cryrid said:

 Dynamesh prefers the model to be 'water tight', otherwise the results can be more unexpected. 

Just for posterity, this also applies 100% to Zmodeling.