Possible Bug with Zsphere retopo

[SugarViper]

Hi there, first time posting but I think I ran across a bug that was introduced yesterday October 26th, 2022.

I am currently doing a practice project for hard surface modeling within Zbrush and using Zspheres to create wireframes around a sculpt and using the preview to generate PolyMeshes and insert them as new subtools for panels by using Zmodler.

So I noticed the issue when I wasn’t able to preview a simple triangle (which had not been an issue until 4:00 pm on the specified date) then I realized that I could not preview a simple quad either. I can only preview if there are two or more polygons.

The major issue, is that when I generated the Polymesh and tried to use Zmodler on it, the faces become extremely flipped. Normally I just flip all the faces, but it will flip random faces and some of the polygons just vanish. Flipping and doubling doesn’t fix the issue either, and I am not able to select single faces and flip them.

I was concerned (and still am) that I must have accidentally hit something and caused this issue. I have however been able to replicate the issue on several other people’s Zbrushs as well.

I managed to try and eliminate possible causes for it. I was wondering if it was possibly Zmodler that was the issue, so I brought in a plane and Qmeshed it back and it did it normally. So I think the issue might reside within the Zspheres as the preview messing up is where I first saw there was a problem.

I am not stuck on my project, as there are many ways to skin a cat. However I fear that there might be some bug within the Zshperes themselves and that could affect other people.

[Spyndel]

Hello @SugarViper ,

It’s been a while since I’ve worked with ZSphere retopology for manual retopologizing. That feature has largely been superseded by newer retopology features.

However to the best of my recall that has always been a limitation of ZSphere retopology. It needs a certain minimal amount of polygon information to make accurate decisions about a surface. Lacking that, it may not be able to draw the surface accurately and you may end up with flipped polygon normals.

This was a common problem when trying to retopologize digits like fingers and toes. If you drew the topology with minimal quads–a simple quad box extrusion with a single poly on each side–the feature would be unable to to accurately parse the surface, and polygon normals along the finger would invert. It is necessary to draw an additional edge loop down the length of the digit to give the feature enough information about the surface.

This is in addition to the possibility of missed connection targets. If two edge lines merely terminate near each other and aren’t actually connected, or if an extraneous point along an edge would result in an ngon, the polygon may not be created, depending on settings in the Rigging palette.

[SugarViper]

Thank you I appreciate the link to other methods. I switched to using topological brush for my needs, but I was just wondering if anyone else has had this issue come up.