[vtkusers] vtkDistanceWidget and surface placement

[Barry Hathaway]

I'm trying to measure a wound area where the skin surface is represented 
by a 3D point cloud.
When I place the endpoints of the vtkDistanceWidget and then rotate the 
object the endpoints
are place somewhere in the air.  Any ideas how to make the endpoints of 
the widget snap to
the closest surface point?  Thanks in advance.

Barry Hathaway