Re: [Libmesh-devel] [Libmesh-users] Fwd: problem with exodusII, hex27 and paraview

[Lorenzo B. <bot...@gm...>]

Ok, I took a look to the vtkExodusIIReader and there is no support for more
than first order WEDGES.
VTK_TRIQUADRATIC_HEXAHEDRON (hex27) requires a different path but the code
is a bit convoluted and I don't understand the numbering.

Thanks for help
Lorenzo

2010/4/27 Derek Gaston <fri...@gm...>

> Ok - this is definitely a bug in Paraview.  I just wrote a Hex27 mesh out
> straight from Cubit and opened it with Paraview... and.... Paraview messes
> it up!  The file looks perfectly fine in Ensight... but Paraview has face
> nodes in an obviously wrong order.
>
> How can this be though?  Paraview and Exodus are both developed at
> Sandia... and I have personally used codes at Sandia to output Hex27 meshes
> and view them in Paraview without trouble (although that was a few years
> ago).  Is it really possible that Paraview has a bug of this magnitude in
> it?  That is really hard for me to believe...
>
> Derek
>
>
> On Apr 27, 2010, at 10:30 AM, John Peterson wrote:
>
>  On Tue, Apr 27, 2010 at 11:19 AM, Lorenzo Botti <bot...@gm...>
>> wrote:
>>
>>> The ordering of mid-face nodes and centroid that works with paraview is
>>> 26,
>>> 20, 25, 24, 22, 21, 23 but it is absolutely non-sense for me.
>>> Your ordering is good for IO but for some reason I don't understand I
>>> need
>>> to do a mesh.prepare_for_use() before adding the mesh to
>>> equation_systems.
>>> Otherwise I get a seg fault.
>>> I'm quite disappointed because even the prism18 is broken in paraview.
>>> I think the problem is the vtk exodus reader.
>>>
>>
>> Maybe we can work around this, perhaps by adding a user-selectable
>> flag in exodusII_io_helper which can switch the Hex27 node ordering
>> when the user knows the exodus files will be read with vtk/paraview?
>>
>> For reading in those same files back to Libmesh, I'm not sure.  We
>> could have it try one ordering, check the Jacobian sign and if
>> negative, try the other ordering?  Seems like a pain ...
>>
>> --
>> John
>>
>>
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>