Smooth UV hull in one direction?

Picture explanation:

What I’ve tried so far:

  1. Select V
  2. Move UVN
  3. Smooth V

But the smooth slider in the Move UVN dialog only gets you so far.

Anyone else have any better tricks, while managing to stay within a reasonable surface tolerance?

Can you post an example .3dm file?

Best practice for smooh surfaces is to have the minimum number of control points needed for the desired shape. The number of control points in one direction can be reduced using RebuildUV, RemoveControlPoint or RemoveKnot. RemoveKnot usually changes the overall shape less than RemoveControlPoint.

Here is a file:

1.3dm (69.6 KB)

I’ve already Rebuilt the surface and reduced the points and spans quite a bit, because this surface was created by merging six other surfaces, and Rhino tried to conform the control points to the original iso curve placements, which were a bit offset.

Have you considered creating a new surface based on the geometry requirements, constraints and required tolerances?

move uvn will be your go to here.

if you change the scale setting you can get larger or smaller edits-

you’ll want to use the move tools not the smoothing tools and move the cv’s as needed. I’d recommend making a copy of the surface so you can compare to your original after you edit-

Hello - it works pretty well to select a rectangle of points (SelControlPointRegion) then smooth in U and V both, alternately


@eobet, @theoutside, @davidcockey - just in case it helps: (4.4 KB)

To use the Python script use RunPythonScript, or a macro:

_-RunPythonScript "Full path to py file inside double-quotes"

Pre-select the surface control points.
Set U or V
Set the smooth strength.

You can just type a number and Enter to set the strength, and you can type ‘u’ or ‘v’ or ‘t’ (for ‘toggle’) to set the direction.

Best to set a low strength and hit enter a few times and watch it smooth in stages.

Currently, Esc to exit…

Any use at all? I’m not sure it is very different from just using the MoveUVN smoothing…



Thank you so much for the effort, but I’m afraid it’s not accurate enough. It’s rather easy to see that it actually lifts all control points in the normal direction in addition to smoothing out the UV direction, which isn’t acceptable to me:

So while the smoothing works great, is there any way of getting rid of the distortion in the normal direction?