How do I change the interpolation method of a point to soft from hard?

No matter what I do this point is always sharp? :frowning:

And here moved:

Hello- RemoveKnot all but one knot at that location. Fully multiple (Degree number) knots will always be kinked.


Hmmm, I tried that, but it does not seem to work… Here is the curve. I type remove knot and click on it, and it stays the same.

I must be doing something wrong. Rebuild does help tho.

curve.3dm (130.6 KB)

Ah… a closed curve, so that is the seam point - I guess you do not get to remove knots there. If you move the seam (CrvSeam) you can fix that location but it just moves the problem elsewhere.
MakePeriodic will smooth the seam but will, in this case, change the shape of the curve pretty dramatically - InsertKnot on either side of the seam first MidPoints=Yes.


Is that a NURBs limitation or Rhino’s?

I can do closed curves just fine in other software:

Yeah - Nurbs - the AI curves are beziers strung together and very limited except maybe in this respect.


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I think the problem is having a control point exactly on the seam. I moved the seam, then deleted the control point at the new seam, and everything smooth.

Sometimes I also need to remove the knot at the old seam location, but this time the command works just fine because it is no longer a seam.

I still think Rebuild is faster for this type of situations.

If you interpolate a sent of points using CurveThroughPts with Closed=Yes or InterpCrv with PersistentClose=Yes the result will be smooth.

This is not a limitation of NURBS in general but rather a particular method of creating a closed curve.