Spline equation

[blazejpop]

Hello guys

I'm wondering if it is possible to get the spline equation created in NX.
Does anyone know something about this?

 

[BubbaK]

Using NX/Open or SNAP functions, you can get the degree of a spline and its poles (control points) and knots. Then, if you know about b-splines, you can write down its equation.

 

[blazejpop]

It isn't what I was expecting, but thanks for the response.

 

[cowski]

Using NX/Open or SNAP functions, you can get the degree of a spline and its poles (control points) and knots.

You can also get this from the Information -> spline command.


blazejpop,
If you were expecting a simple polynomial equation such as 3x^2+4x-1, then you will be disappointed. A NURBS curve is actually composed of several equations blended together. If NX were to report the equation used it would look more like what you see on the Wikipedia page (in the General form of a NURBS curve section, about 3/4 way down the page).

www.nxjournaling.com

 

[blazejpop]

Hello.

I thought that spline is just spline, not B-spline or NURBS.

Thanks for your response.

 

[cowski]

All splines created in NX are Non Uniform Rational B-splines (NURBS).

www.nxjournaling.com

 

[BubbaK]

The Wikipedia page is a good reference.

You will see that the general equation of the spline involves some things called basis functions. To construct these, you need some numbers called "knots" (or, collectively, the "knot vector" or "knot sequence").

As far as I know, you can't get the knots from within interactive NX, you have to use SNAP or NX/Open. You can get "knot points" from Information --> Spline, but knots and knot points are not the same thing. The former are numbers, and the latter are points.