[vtkusers] exporting mesh from image data

[John Hunter]

I am trying to generate a mesh for a finite volume solver (gambit,
fluent) from 3D image data (CT, MRI).  To generate the fluent msh
file, you need not only a list of vertices and polygons, much like
what is available in the vtk file format, but also the volume elements
in the mesh that the polygons abut.  Eg for a given triangle in the
mesh, you would have a line like

3 3 2 1 11 0

which is 

numfaces vert0 vert1 vert2 vol1 vol2

where vol1 and vol2 are indices that indicate the volume in the mesh
that the triangle belongs to (vol2 is 0 for triangles on the
surface).

The specific problem at hand involves building a mesh for ventricles
in the brain.  I have no trouble building the isosurface that
surrounds the ventricles using marching cubes and connectivity
filters, but now need to be able to generate a mesh over the interior
and assign volumes to faces.

Does such capability exist in VTK, and if so I would be thankful for
pointers to class docs or examples.  I posted a related question
yesterday but now have a clearer idea of the problem I am trying to
solve so hopefully this post clarifies.

Thanks!
JDH
VTK 4.4