[vtkusers] extracting exterior bone surfaces

[Will Newman]

We import volumetric CT data into VTK to create bone surfaces using
marching cubes.  We are looking for ways to extract only the external
bone surfaces, but are having problems eliminating the inside bone
surface. There are two main surfaces, the endosteal and periosteal
surfaces of the bone.  We have used thresholding to isolate a nice
binary image but because of small interconnections between the surfaces
we are unable to isolate the periosteal (exterior) surface by using the
connectivity filter.  Is there any way we can further preprocess the
image data to obtain just the exterior ring of voxels *before* running
marching cubes?  Or, are there other strategies we can use to isolate
just the exterior surface *after* running marching cubes?

Thanks.

--
Will Newman
Musculoskeletal Research Laboratories
University of Utah
wjn1 at utah.edu   http://hodad.bioen.utah.edu/~weiss/mrl