[vtkusers] some help please with raycasting!

[Benjamin King]

Hi Christos!

> I have a 3D volume and I want to select points on its surface. What I 
> thought to do is to cast rays from the centre of mass of the volume for 
> set angles in all directions and save they intersections as the points.

How is that volume defined? If you have a polygonal representation of it's 
surface, you could try a vtkCutter. It takes an implicit surface, e.g. a 
plane and computes the intersection of the volume with that plane.
If your volume is a "real" volume, i.e. a threedimensional image, then I'm 
not sure if your problem is well defined, because you'd have to decide 
which voxels belong to the surface. If you do, you could try to adapt one 
of the vtkVolumeRayCastFunctions, but that will require a lot of hacking.

cu,
  Benjamin


-- 
Benjamin King
Institut für Medizinische Informatik
Medizinische Hochschule Hannover
Tel.: +49  511  532-2663