XDMF saved from ParaView is incompatible with DOLFIN

[Chris Richardson]

When viewing a mesh in ParaView, it can be saved with "Save Data" as format XDMF (.xmf) This should be possible to read in to DOLFIN, but currently fails.

[Prof Garth Wells]

Any idea what the issue is?

[Chris Richardson]

Yes. Dolfin XDMF assumes certain names for topology and geometry datasets. It will require some reorganisation, but it's basically just crunching the right strings in XML.

[Chris Richardson]

Another issue is that ParaView does not save the CellType in HDF5, so the XML has to be queried to differentiate, for example, between a mesh of tetrahedra, and a mesh of quads in R^3.

[Lawrence Mitchell]

FWIW, what is the CellType in a mixed element mesh?

[Prof Garth Wells]

Different cell groups can be stored in different groups (it should at least in principle be fine, whether or not it works in practice . . .).

[Chris Richardson]

There is a TopologyType "Mixed" defined in XDMF, where you have to define the cell type of each cell. It should work in principle, but could cause problems to read in parallel, as the topology dataset becomes a serial stream in that case. I guess some more metadata will be needed, maybe indicating where the stream can be split.

[Chris Richardson]

Fix in next

[Anders Logg (Chalmers)]

Removing milestone: 1.7 (automated comment)