Clipping data only on area selected

I have an image of a human that I need to clip the selected area only(e.g. an arm or leg). My methodology:

  • First pick two points on the area I want to cut.
  • Calculate the plane normals that will be perpendicular to the line connecting the two points.
  • Use the normals from the plane to set vtkPlanes normal (2 normals, one the negative of the other)
  • and add the two selected points to vtkPlanes
  • I used vtkClipPolyData and set the clip function to the above-mentioned vtkPlanes.

So the problem is that the plane is never-ending and thus also cuts the rest of the body and not just the selected arm (as seen from the picture). I was thinking of adding some bounds but how do I do that? Is there perhaps a different kind of clipper I should use?

I thank you in advance.