ZBrushCentral

How to Keep Plane Corners Sharp After Subdividing

ZBrush Usage Questions
#1

Hello,

I’m completely new to Zbrush.

I’d like to know how I can go about keeping the corners of a plane sharp when applying Subdivide.

Even after applying the ‘Crease’ function, Subdivide always rounds the corners of the plane.

Is there any way to Subdivide a plane (with smoothing left on) so that the corners are left sharp?

#2

Hi @KT87

Turn off the “Subdivide Smooth Modifier” before you subdivide.
 

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#3

Thanks so much for your prompt response.

The plane I’m working with is curved and I actually want to smooth it. I just want to retain my corners when doing so.

Is this possible in ZBrush?

#4

Not that I’m aware of. I’m not quite sure what you mean by “The plane I’m working on is curved”. A screenshot would help. You would have to subdivide while the plane is flat as I mentioned above then add the bend using SBend (Smooth Bend) in Deformation palette on the highest subdivision level.

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#5

Hello @KT87

Yes, but it requires a bit of set up.

To understand why this happens you need to understand the Catmull-Clark smoothing algorithm. The 2d plane primitive has its edges creased by default, and this keeps the edges from shrinking inward when subdivision smoothing is active.

However, in the case of 2D geometry, there are not enough edge connections to keep the corners anchored. You’ll notice that every other vert on a 2D plane has at least 3 “spokes” coming out of it. The corner verts only have 2, and this is not sufficient to keep them from being smoothed.

So you can either:

  1. Disable subdivision smoothing as @zber2 suggested.

or, in the case of a curved 2D surface when subdivision smoothing is required to smooth part of the mesh:

  1. To keep the corners from smoothing, you must subdivide the plane as part of a 3D mesh instead of a 2D mesh. Extrude the plane into a cube, or a curved 3D solid in this case. This will create a third “spoke” on the corners that will hold those verts in place during subdivision smoothing. The corner edges must also be creased.

Alternatively, you can use the ZModeler > Edge> Edge Extrude> Mesh Border option to extrude a single additional polyloop around the edge of the border, which will also create a third edge at the corners that can then be creased.

Delete any unwanted geometry after subdividing.

:slight_smile:

#6

Hello @Spyndel ,

I extruded my 3D plane after following these steps:

  1. Morph Target >> StoreMT
  2. Deformation >> Inflate
  3. Morph Target >> CreateDiff Mesh

Afterwards, I applied a crease to the extruded mesh and proceeded to subdivide with smoothing on.

It worked like a charm.

What are the steps that I should follow to delete the unwanted geometry?

#7

If you’re familiar with the mesh visibility shortcuts for ZBrush, you can use Geometry> Modify Topology> Delete Hidden function.

If the geometry is fairly low-poly, ZModeler offers additional options.

:slight_smile: