Im modelling two skirts that are meant to look as if they’re blending into each other and as if they are spinning around. I’m using the loft command to create a flowing movement and they both meet at a perfect circle. FilletEdge only works for small diameters but it would be great to model a more seamless connection between the two, i.e a curved line instead of straight lines for the loft movement.
Is there a good command, modelling method or grasshopper component for creating a seamless connection between the two while keeping the flowing movement of a skirt?
Thanks for any help in advance!
New to Rhino Forum so please direct me if I should tag this question in a specific way.
This looks to me like a much better task for SubD. You could simply create the top and bottom profiles, create a SubD loft between them, add some rows across the loft, and scale and twist those. As @theoutside always says - in SubD’s you get your blends for free.
The complexity of that surface is due to the complexity of the input curves, not the use of NURBS and Loft.
With simpler input curves the surface can be much simpler. For example:
The behavior in the middle of the object is far more controllable and editable as a SubD. If I have some spare time today I’ll cook up a SubD version. And yup those input curves are too dense, and the point count and parameterization don’t match across the three sections.
Hi David, thank you so much for the input. Can I ask, when you say simpler input curves the surface can be much simpler, do you mean rebuilding the original curves to fewer points then lofting? Just wondering how you did the one in the screenshot.
Thank you so much, this was pretty much it! I’ll have a play with SubD modelling too just out of curiosity but I’ve noted your comment about it not specifically being about NURBS / loft.
Also it appears the input curves were originally based on circular arcs with only tangency continuity between the arc. At some point became degree 3 curves with curvature continuity but very abrupt changes in curvature. For the second version I simplified the input curves as degree 2 curves but of course that is not possible using SubD. Degree 3 curves would either deviate more from the input curves or require more control points.
I created a set of simplified degree 3 curves with 24 control points each/ This is the minimum number of control points needed to maintain the 12 lobes of the upper curve. These curves are SubD friendly.
Loft with natural option using the degree 3 curves:
The shapes of the Loft and SubDLoft using the same degree 3 input curves differ because the SubDLoft has zero curvature along the isolines at the edges.
The Loft surface has 120 control points.
The SubD surface has 72 vertices.
The SubDLoft converted to NURBS surface has 350 control points.
Another version with 72 control points. I used RemoveKnot to remove the knot at mid-height and reduce the number of control points. RemoveKnot changes the surface less than RemoveControlPoint. 240305_Blending Top and Lower Skirts DC03.3dm (4.5 MB)
