Avoiding Offset Surface artifacts

Rhino Rhino for Windows
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1

I’m going through the following process:

  • Create a grid of polygons
  • Create a reference plane, roughly 12" x 12" & rebuild @ 20x20
  • Create a curved plane about the same size & rebuild @ 20x20
  • Use Flow Along Surface to get the polygons in place on the curved plane
  • Split curved surface with polygons
  • Offset Surface on curved surface (in this case, outward, .25"

I am getting geometry artifacts all over the place after offsetting (see below) - are there some settings / workflow I can change to eliminate this?

thanks!

artifacts
artifacts837×1082 188 KB

2

Also: Not sure if it’s related.

As a test, I tried offsetting the surface of the polygons flowed on the surface; it failed to do them as a group (some of them offset properly), but I found I could select and offset them individually after cancelling the offset on all of them.

offset-fail
offset-fail978×418 174 KB

3

Look at the iso-curves of your original surface.
This surface is waaaaay to heavy on controlpoints and probably for this reason prone to these kind of errors.
Simplyfying and cleaning up the underlying curves and surfaces is allways a good idea when offset and shell gives you trouble.
If you post a file we could help you on the specifics.

4

Thanks norbert -

I was following a tutorial that recommended using more divisions to help keep the flowed polygons from distorting too much.

The work wasn’t saved, but I’ll try it again with fewer divisions.

(edit) A million times better. Thanks.

5

I would do it this way:

  1. Create the curved surface and make a polysurface from it with the desired thickness using “Offset surface”:
  2. Create 5-sided vertical extrusions along the reference plane;
  3. Use “Flow along surface” to place the 5-sided extrusions along the original curved surface (the one used to offset the opposite wall);
  4. “! _BooleanDifference” is my best friend in the last step.
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