[vtkusers] How to find Normal vector ?

[Kiran, P (CORP, GEITC)]

Hi all:

I have a set of 3D points. And I have generated a triangulated surface from
these points.
Now, I want to find normal vector at each point on the surface.  How I can
do this in vtk?
Are there any available methods to do this kind of stuff?

Can someone through some light on how to do this..

Thanks in advance for help.
Kiran