Sweep 2 Not Producing Smooth Surface

Rhino Rhino for Windows
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1

Im trying to sweep2 these curves to form a sort of distorted and warped surface, but the surface produced from the sweep always comes out not smooth, and with many creases. i tried rebuilding the ellipse in the middle and making it 5 deg but to no avail. would like some help :slight_smile:

Screenshot 2026-08-06 163736
Screenshot 2026-08-06 1637361396×739 122 KB

Screenshot 2026-08-06 163758
Screenshot 2026-08-06 163758664×368 152 KB

Screenshot 2026-08-06 163743
Screenshot 2026-08-06 1637431420×741 98.6 KB

2

if possible within your constraints, best is to over-build the surface and trim it.
See attached example

image
image1002×596 69.4 KB

overbuilt-trimmed.3dm (373.4 KB)

3

You may also give it a try with Loft, and fyi.

Loft.zip (1.7 MB)

4

How did you do that?

5

Roughly these steps:

  1. started with a ellipse in top plane
  2. gumball - extrude with scale handle in top plane
  3. rebuild surface to higher degree and point count
  4. the rest is CP manipulation
6

Hi @Shan_Ning
If sub-d is an option (or you can settle for a polysurface), you can use the plugin StructuralDesigner3D (free and available via the PackageManager) to create a mesh version that can easily be converted to sub-d (and then to a polysurface with ToNURBS).


via StructuralDesigner.3dm (2.2 MB)

HTH, Jakob