[Paraview] XDMF Multiblock limit on number of blocks shown in Hierarchy

[Andy Smith]

We use XDMF to output multiple unstructured blocks from our CFD code within
a Spatial Collection.

If 998 or fewer blocks are output in the collection all of the individual
blocks are displayed in the Blocks and Hierarchy tabs in the main
Properties tab when loading the grid.  This allows the user the select only
the blocks of interest.

If 999 or more blocks are output in the collection, only the containing
collection grid is shown in the Blocks and Hierarchy tabs.  In this case
the user cannot select the individual blocks of interest.

I've attached two simple XDMF grids for reference.

The same limitations on block selection occur when using Python to read the
grid.

Is this a limitation for all multiblock readers in ParaView or XDMF
specific?  Is there anyway to extend this limit to a higher value?

A typical use case is to define a spatial region of interest in a Python
script, read the XDMF file directly to determine the datasets that contain
the grids (in HDF5 format) then loop over these datasets and query each
block's bounds using h5py to see if they lie within the region of
interest.  If they do, then we load them in Paraview by setting the
GridStatus to the appropriate list of grids.  As mentioned above, this
fails when the main grid collection has more than 998 blocks in it.
A workaround could be to write out a temporary XDMF file based on the list
of grids required, but hopefully there is a simpler solution.

As a final note, for all of these cases we use the XDMF2 reader.  With the
XDMF3 reader neither of the supplied grids display the block hierarchy that
we require.

Thanks,
Andy
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/paraview/attachments/20170308/7accdfd1/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: grid_with_00998_blocks.xmf
Type: application/octet-stream
Size: 51163 bytes
Desc: not available
URL: <http://public.kitware.com/pipermail/paraview/attachments/20170308/7accdfd1/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: grid_with_00999_blocks.xmf
Type: application/octet-stream
Size: 51214 bytes
Desc: not available
URL: <http://public.kitware.com/pipermail/paraview/attachments/20170308/7accdfd1/attachment-0001.obj>