At a loss on how to polygroup and mask these simple surfaces of a ring

[RickFlorida]

Hello everyone. I’m really loving Zbrush so far and think it’s amazing.

Can someone please take a look at this simple ring I made and tell me how would I create polygroups for these simple surfaces?

I import my models from Rhino so they are one surface so I need to make polygroups for each of the “faces” or surfaces of this ring for me to continue working on it in Zbrush.

Because the “Drag Rectangle” mask brush does not allow backfacemasking, I don’t know a good way to get clean, crisp masking on one one side of each surface. The inside surface of the ring is wider than the outside surface of the ring, so I can’t use drag rectangle masking. I don’t think autogrouping is working right. When you import a Rhino STL, you have to remesh the model to get quads and it ends up being high poly but that is not the problem.

I just don’t know how to make crisp, single sided masks for polygrouping.

I’m attaching the model if anyone wants to see how simple the surface edges are. (Each edge makes 90 degrees) So you would think autogroup would work. But because it’s high poly I think Zbrush doesn’t autogroup it correctly.

I would be extremely grateful if anyone has an idea how to polygroup this. This particular ring is simple and I could make it in Zbrush. But many other items I will create will have to be made in Rhino so I would need to know this workflow anyways.

Here is the Ring file: https://www.dropbox.com/s/ivosrcp2boii2mi/pimmys%20channel%20ring.ZPR?dl=0

Attachments

[beta_channel]

That looks too dense for what you actually want to do. Personally I would use a low res version that is easy to manipulate and mange your polygroups.

That said, you can try to use polygroups by normals. This should get you an easy way to select your Y facing polygons and then you can just combine your X and Z manually. This will allow you to easily start to use the deformers and edgeloop functions to get clean breaks from one polygroup to the other.

My 2cents

[RickFlorida]

Thank you, but how can I make a low resolution version if when you import from rhino I think I must first remesh to make the triangles into quads? (The triangles are really bad when you import from Rhino, so first thing people do is remesh but then you have millions of polygons). I don’t know how to reduce it after this step.

Is there a way to reduce the polygons after I remesh it? The only thing I can think of is decimation master to reduce the polygons. Because the dimensions must stay nearly the same, I am probably limited to how I can reduce the polgons of a remeshed STL that I imported from Rhino.

[beta_channel]

Try using Zremesher. With fairly low polygon counts. It should do an alright job.

[RickFlorida]

ok, great idea. thanks

[RickFlorida]

Zremesher wouldn’t work. Every time I tried it, it badly distorted the ring. It distorted it less if I increased the polygon count, but was still bad. I think there might be a Zremesher setting to keep crisp edges?

In the end, Decimation Master reduced the polygons a lot and the ring looks the same. I already had quads, so I guess Zremesher isn’t need as badly as if I had a weird dynamesh topology.

[RickFlorida]

I found a solution.

I simply hide half of the ring, then I can cleanly mask the inside of the ring, make a polygroup there… and after that it’s easier to cleanly mask the other surfaces since I can now start hiding some of the other surfaces.

Group by normals doesn’t work on high mesh, like you said. And Zremesher actually gave me worse quads while at the same time, distorting the crisp edges even with 25 or 35 thousand poly settings.

In the end, this workflow is fine for me as long as I decimate the model whenever I’m done.

I’m still confused as to why there is no way to tell Zbrush or even Rhino to take a high poly mesh and reduce the polys without distorting edges. I would think the software is smart enough to find the edges but changing the maximum angle setting didn’t completely help group the edges.