InsertControlPoint inserts a control point (and presumably a corresponding knot) without moving the original control points. It may not be possible to obtain the exact original shape by moving the control points.
InsertKnot adds a knot and corresponding control point. The curve/surface shape is not changed but some of the original control points will be moved.
The choice of which to use depends in large part on how important preserving the original control point locations is compared to preserving the original curve/surface shape.
since i had forgotten to switch on my brain i did not even think about an insert knot. but one thing is for sure i would never use InsertControlPoint, at least not until somebody can explain it, because the following statements dont seem to be true.
not correct i guess, actually all initial control points circumscribing the insert in closer proximity get moved in both directions at least on that example from Modeler, which then again underlines my doubts about a useful application of it.
also not fully true, if you are close to an isocurve it only inserts a knot (isocurve) without control points.
Can you provide an example of using InsertControlPoint changes the original control points? I can’t find one. It does change some of the “edit points”.
What is “Modeler”?
Can you provide an example of where using InsertKnot does not also insert control point(s)? I can’t find one. The displayed isocurves do change.
the creator of this thread 