[Paraview] [Non-DoD Source] XDMF Multiblock limit on number of blocks shown in Hierarchy

[Burns, Andrew J CTR USARMY RDECOM ARL (US)]

For the Xdmf3 reader, does it simply not display anything or does it not display correctly?

From the files you attached, I see the grid/subgrid structure, but there is no data inside each item. I would guess that the Xdmf3 reader sees the empty grid and simply doesn't load it.

Andrew Burns
Software Engineer | Parsons
Phone: 410-306-0409
ARL DSRC
andrew.j.burns35.ctr at mail.mil



-----Original Message-----
From: ParaView [mailto:paraview-bounces at paraview.org] On Behalf Of Andy Smith
Sent: Wednesday, March 08, 2017 3:03 PM
To: Benson Muite via ParaView <paraview at paraview.org>
Subject: [Non-DoD Source] [Paraview] XDMF Multiblock limit on number of blocks shown in Hierarchy

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