Ahh... the venerable and all-important "filler" inside the hot dog required to make them "plump when you cook 'em". ;-)

And not so easy to understand:


Knots and Control Points
A common misconception is that each knot is paired with a control point. This is true only for degree 1 NURBS (polylines). For higher degree NURBS, there are groups of 2 x degree knots that correspond to groups of (degree+1) control points. For example, suppose we have a degree 3 NURBS with 7 control points and knots 0,0,0,1,2,5,8,8,8. The first four control points are grouped with the first six knots. The second through fifth control points are grouped with the knots 0,0,1,2,5,8. The third through sixth control points are grouped with the knots 0,1,2,5,8,8. The last four control points are grouped with the last six knots.





Maybe what I need to ask for is a way to remove control points.

Hi Mike,

> Maybe what I need to ask for is a way to remove control points.

That could be possible, but there are some complications - the number of knots and control points are related, so if you remove a control point you also have to remove a knot as well and then you have to decide do you want the other control points to shift in position or do you want the other control points to stay where they were which instead could make the surface kind of mutate strangely in shape with a shifted knot vector.

If you want to do a lot of surface control point manipulation, sub-d modeling tends to be a better tool for that...

- Michael