ZBrushCentral

Hell of a time UV unwrapping

ZBrush Usage Questions
#1

I have been having an extremely frustrating time dealing with UV unwrapping and generating textures from this model inside Zbrush: http://bjpentecost.deviantart.com/art/Temp-Post-1-153117513 This is a Full Color Sandstone Shapeways 3D printing commission. It was supposed to be pretty simple, an in and out job, but it has become a bloody nightmare.

There have been so many problems. Firstly, unwrapping takes upwards of five minutes… scratch that, TEN minutes… scratch that, FIFTEEN minutes on a model of only 200K polys. Blender unwraps the same model in a few seconds. That wouldn’t be too big a deal if the problem ended there but as soon as I try to create new texture from polypaint, the texture goes bonkers (as seen in last image) and I have no idea what causes this. Sometimes “creating new from polypaint” will also shift the texture around a little as well so it’s off center.

I’m at wits end here. Does anyone know what’s causing this and how I can fix it?

Edit: it took me a while but I found a rather odd solution to the problem… somewhat, though I’m still not entirely sure what caused that weird freak out and I’d like an answer so I can avoid it in the future.

#2

It is normal to take long time with UVs in high poly models. Normally you don’t do that, but have a lower subdivision version of it. UV master is one of the best automatic UV creators for organic models. Has blender a similar quality automatic tool able to handle high poly? Then you perhaps should use blender for that as Zbrush will give you always long times with high poly UVs.

About the other problems I cant tell without looking the 3d model but perhaps another person knows it.

#3

Thanks. For the reply.

Unfortunately, I cannot decimate this model any further. It causes huge problems further down the pipeline. In this case, I have a dynamesh base model and the final print model. I decimate the print model down to 30K, UV unwrap, then subdivide, and project details from the dynamesh base. Unfortunately, that causes some weird issues that can’t be fixed inside of Zbrush. For example, weird wormholes and “impossible to smooth out folds” will start popping up in places where the geometry is complex. So I can’t decimate down to 30K. Lowest I have been able to get to without problems is around 150K.

It’s very frustrating but I found a sort of weird work around. Previously, I had been grouping her anatomy in what I thought was a logical, typical way (arms, legs, tail, head, face etc). I tried grouping her in blocks instead and that seemed to have solved the problem. Strange.

In any case, thanks again.

#4

Man… working with UVs in Zbrush can be a bit wonky sometimes. I think I’ve solved this issue. Sort of… Zbrush REALLY does not like it if you modify the geometry after UV mapping, not even welding points. Yeesh. Touchy.

#5

I guess you will have that problem with any program. UVs are linked to a specific topology, you can move or deform but not weld, add etc. It can change the order of the verts and mess the UVs. I don’t think any of those problems are specific to Zbrush.

#6

I guess you will have that problem with any program. UVs are linked to a specific topology, you can move or deform but not weld, add etc. It can change the order of the verts and mess the UVs. I don’t think any of those problems are specific to Zbrush.

I’m not sure that’s the problem though because I’ve had this same issue even when not messing with the topology and I just found out that welding points wasn’t actually causing the issue after all. I’m so fricking confused. I’ve never had this problem in Maya or Blender. I can go into Blender, mess with the topology, and the UVs won’t freak out. Same in Maya. Blender also unwraps a thousand percent faster (literally) and allows me to reorganize the UVs (when I try to do that in Zbrush, the UVs freak out, shrink, and relegate themselves to a tiny corner which is superly-duperly weird.

The impression I’m starting to get is that UV master is great for simple, very low poly models but gods help ye if your model is complex and 50K+ polys. I’m usually pretty good at troubleshooting things but this one’s got me stumped.

#7

You are right about Uv master