[Paraview] advice on saving outputs

[Felipe Bordeu Weldt]

Hi,

If you know the structure of the binary file, you can use xdmf format  
file to read your binary data.


for the binary part use something like this:
<DataItem ItemType="Uniform"
  Format="Binary"
  Dimensions="64 128 256"
  Seek="1234">
   PressureFile.bin
</DataItem>

if you grid does not change over time you can use XPath:
"XPath, allows for elements in the XML document and the API to  
reference specific elements in a document"
http://www.xdmf.org/index.php/XDMF_Model_and_Format



I use xdmf all the time, I think is very flexible (ascii, binary, HDF5  
heavy data storage), time, grids, extra data using "Information" tag.   
And all kinds of topologies and geometries.


Le 20 mai 12 à 13:47, Hal Canary a écrit :

> On 05/19/2012 06:30 PM, Mohammad Mirzadeh wrote:
>> Hi guys,
>>
>> I need a little bit of advice on how I'm outputting data. So far I  
>> have
>> been using a simple legacy VTK format and dumping my grid and all
>> sclaar/vectors into that single file. Basically I start with  
>> writing the
>> grid and then append as many as variables that I like to the file.  
>> This
>> has the problem that it was ascii and slow for large data sets,
>> especially fro a parallel code where the solver was taking only 5 sec
>> but the IO was around 20!!
>>
>> So I want to turn into binary and I have learned how to output binary
>> vtu files. The issue is, since the cluster I'm working with has kill
>> times (Max 24 hr) I also need to be able to save and resume my
>> simulation. So, what I do right now is dump my variables in binary  
>> form
>> into a single file that does not have any xml tag or anything -- just
>> raw binary data. This is a preferred method since when I want to  
>> resume,
>> I do not need to parse the xml code; I just read the binary file and
>> that's it. Besides, I save on the grid information I'm writing to  
>> disk.
>> For a 23M grid point, the grid information (which basically is a
>> quadtree saved as a general unstructured grid with
>> cell connectivity information etc) file is about 1GB whereas my  
>> actual
>> data is only about 150MB. In most cases my grid does not change with
>> time, so I really only need to save it once and that's enough.
>>
>> Now, the problem is, I want to be able to use or refer to these  
>> binary
>> files using the xml tags. Here are the questions:
>>
>> 1) Is this supported in .vtu format? How can I refer to a binary file
>> instead of dumping all the binary information in the file?
>> 2) If this is not supported in .vtu, is it something xdmf can do?  
>> If so
>> how? Can you please point me to a tutorial?
>> 3) Is there any plan or strategy that would be better than what I  
>> have
>> in mind right now? Please remember that retaining the raw binary  
>> format
>> of the files is a must for me (well I do not see convincing reasons  
>> to
>> give up on it, but if there is one, please let me know)
>>
>> Thanks
>> Mohammad
>
>
>
> Just this week, I wrote a Python program that uses the  
> numpy.fromfile function and ParaView's  
> paraview.vtk.dataset_adapter.numpyTovtkDataArray and  
> paraview.vtk.io.vtkXMLPolyDataWriter functions to convert a large  
> binary file to .vtp format.  It is reasonably fast.  Maybe you can  
> use something like that as a post-processing step.
>
> This separates the tasks of producing data and converting it to VTK  
> format.
>
>
> -- 
> Hal Canary
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