Loft Deformities

I have a trimmed surface that I am trying to rebuild in GH so that I can use isotrim. Therefore I split my shape into a series of curves and tried to loft between them to make the shape again. However there always seems to be a deformity in the center of the shape. I checked my list order and played around with the loft options but I have no idea how to fix it. Any help would be much appreciated, thank you.

lofting (29.3 KB)


I tried several ways to fix your problem, but none of them worked. Rebuilding the curves helps, and so does specifying Align for the Loft options, but ultimately nothing I tried produced good results.

I think a big part of the problem is the point at the bottom of your base geometry. Try changing that point into a very short (like 0.01 or even 0.01) length edge and see if that helps.

The attached file is close but not totally right. I think you need help from someone who knows more about how Loft works and how it deals with the details of it’s input curves.

lofting (34.7 KB)


yea I’m sure the base curves are messed up. Thank you for trying though.
But about what you said about shortening the bottom of my base curve, which part are you specifically referring to?

What I meant was what I accomplished by removing the bottom 0.1 (or whatever length I specified for the cylinder) from your base geometry. Doing this changes the point to a very short straight line, and this adds one more corner to the bottom edge curve. This, in turn, gives the bottom edge curve the same number of corners as the rest of the curves that serve as Loft control curves. Doing this makes the Loft algorithm much happier and better behaved.

I really thought doing this would fix the problem - I have made many 3D printed objects by Lofting a series of stacked closed curves, and never had a problem. But all my curves were made from scaling a single base curve, so they all had the same number of corners. So I really don’t understand what is causing the problem with your situation.

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Oh yes I see what you mean. I might try to make some changes in my base geometry and see if that helps. Thanks again for your help.