[vtkusers] Interactive 2D curve creation in VTK Window

[Wu Ruoyun]

Dear All,

I am trying to let the user create NURBS curves over 2D medical images, then construct smooth surface by skinning over a stack of these 2D curves. User can interactively add, move, delete control points, and the curve will be generated/updated by passing through these control points. 

I was thinking about using vtkActor2D to represent the 2D curves. However, it make me uncomfortable as the curves are in fact 3D objects rather than just 2D annotations. And I don't want to manually control the size of the 2D curves when zooming the VTK renderer.

Now the question is: if I want to use normal vtkActor to represent a curve, what is the best way to interact with that curve, or in another words, the control points on the curves? If the curve and the medical image slice are in the same renderer, the curve may not be always displayed over the image as they are exactly on the same plane, so how to display the curve to make sure that it is always visible over the image slice?

Your help will be greatly appreciated!

Best Wishes!
Ruoyun