I have a closed polycurve with 8 points, I try to convert it to a Nurbs curve but I can't get it closed it seems that I have a tangency problem on the “last point” . I'm not sure if I made myself clear Does anyone know how to solve this ?
If you drew the curve with a Curve SOP, you should be able to change the “Primitive Type” from Polygon to Nurbs which should solve your problem, right?
However if you're looking to convert, you can use either of the following SOPs: Fit SOP or PolySpline.
I have the best result with a PolySpline SOP (Spline Type: BSpline) to which I appended a Convert SOP.