[vtkusers] How to get the cg of a surface

[An Jiye]

Hi, everyone.

I have used Marching Cubes alogrithm to extract an iso-surface.
It is the surface of some object.
Now I want to get the cg of this surface, how can I?

Or I can calculate the center of gravity myself,
but I need the coordinate of each pixel on the surface to do so.
How to get them?

Any suggestion will be appreciated.
Thank you in advance.

An Jiye