IOSS: Support for polyhedral meshes

[gsjaardema]

IOSS should support reading and writing arbitrary polyhedral meshes. At a minimum, serial support would be beneficial.

Although not used extensively, there are some groups that are using the exodus arbitrary polyhedral capability extensively. They would like to use ParaView for visualization, but the new IOSS-based reader in ParaView does not support polyhedral capability and they must fall back to the legacy exodus reader. If we want to eliminate the need to maintain both paraview readers, the ioss-based reader needs to support all capabilities of exodus.

Here is excerpt from a user requesting this capability:

Some of these Exodus meshes have polygons and polyhedra, in which case the IOSS reader does not support those topologies, so the Legacy Exodus Reader is used. The problem is that with the Legacy Exodus Reader, if we open a mesh with polygons/polyhedra, and then try to load any "Sets", we get errors like the following:

ERROR: In vtkExodusIIReader.cxx, line 2527
vtkExodusIIReaderPrivate (0x41393300): Unable to fetch side set "detention pond" (10006) node list
 
Warning: In vtkExodusIIReader.cxx, line 1330
vtkExodusIIReaderPrivate (0x41393300): Set wasn't present in file? Working around it. Expect trouble.

If the mesh does not contain any polygons or polyhedra, we are able to load and see "Sets" fine. So we are trying to figure out a way to display sets for Exodus II meshes that contain polygons/polyhedra.

Is this a known limitation of the Legacy Exodus Reader? Do you have a feel as to how much work it would take to get this working with the Legacy Exodus Reader?
Another option might be to add support to reading polygons/polyhedra to the IOSS reader. Again, do you have a feel as to how much work this might entail?
We also thought that converting the Exodus Mesh to a VTK multiblock might let us set the sets. Do you know of an existing tool or script that converts an Exodus mesh to VTK?