Lofting with scaled ellipses - I want surface but GH creates Brep

I’m lofting two curves. Each is a portion of an ellipse (degree 2) (with no kinks).

When I loft in GH I get a polysurface with two faces. I can rebuild the curves but I’d rather not - I’m keeping the geometry as clean and as lightweight as possible.

They loft happily and as expected in Rhino. Am I missing something obvious here?

See attached GH file. (13.8 KB)


If you used part of an ellipse, the ellipse has 4 kink points, so it is likely that kink is included in some way.

You could use Ruled Surface or Pufferfish plugin’sUnsplit Loft Surface instead.


Good point about the ellipse kinks. However:

  • it lofts without splitting until I scale the ellipses.
  • IsCurveKinky (also from pufferfish) does not find any kinks.

So I’m wondering if there is something else happening here.

Unsplit Loft Surface works perfectly though - thanks @HS_Kim :+1:

1 Like

I did a little test with a C# component and Brep.CreateFromLoft creates a single surface. I suppose the loft component does some extra things.

You can reduce the Rebuild ‘N’ (Count) value from 100 to 5 and still be very close to the original polysurface.

P.S. Any reason to be working so very far from the origin?

Thanks for the reply but 5 control points leads to up to 75mm difference between the curves - much too large.

On curves that are 75853 mm and 129037 mm long. That’s less than 1/10th of one percent.