Sphere from nurbs curve?

[Marc]

Using the sphere tool I created a sphere, then used the convert to nurbs command. The result seems to be a single surface from a single curve. How does this happen and why can't I recreate this starting from a single nurbs curve?

Also there are 45 vertices and the U and V values are 2.

Is it really three curves laid one on top of the other with a rotation? Or something like that?

Thanks M

[Biplab]

The Convert to NURBS command in this case creates a NURBS surface - the same if you revolve a circular arc around an axis. The degrees are 2 (quadratic) in both edirections. Turn on show vertices in OI Palette and you will see the 45 vertices and how they are arranged in a lattice on a cube. Thw wireframe representation looks a litle weird, as the sphere is represented by 3 circles, one in xy plane, one in yz and the other in zx plane. The dark aemi-circle is the hard edge (you can think of the sphere being created by revolving this semi-circle by 360 degrees0 and rest are all created just for wireframe drawing in grey color.