[Paraview] Display integration point centered data

[Burlen Loring]

Hi Eduardo,

As far as I know VTK's XML data format is the only format that currently 
has support for quadrature points (both reading and writing). To make 
use of these features in ParaView the quadrature scheme definitions and 
offsets need to be embedded in your vtu datafile, the writer would that 
for you if you embed the offsets and dictionary. The doc is slightly 
outdated, the offsets array is mentioned, and below screen shot in pv. 
If you were not using vtk's xml data format, you'll have to look into 
adding support to the reader/writer.

Alternatively, you can write a PV filter plugin that will insert the 
definitions. this would be fairly easy to do, copy code from the 
vtkQuadratureSchemeDictionaryGenerator, modify wieghts and xml from PV's 
filters.xml, and post questions about writing plugins on the list.

While refreshing my memory on how this all works I have noticed that vtk 
xml file format changed the handling of vtkIdType introducing a bug 
which breaks the PV filters. The vtk part of that fix is on 
gerrit(http://review.source.kitware.com/#/c/9216/), and a small patch to 
pv removing the id type qualifier from the gui xml will follow. This bug 
doesn't affect the dictionary generator, you could make use of that 
while we're in the process of merging the fix, or apply the patch 
yourself, if so I'll send you the pv part.

Hope it helps
Burlen

if reader supports quadrature points:


if using dictionary generator:


xml elements:
...
</FieldData>
...
<DataArray type="Float64" Name="pressure" NumberOfTuples="6088" 
format="appended" RangeMin="-0.9990888746" RangeMax="1.1125756259" 
offset="440936">
   <InformationKey name="QUADRATURE_OFFSET_ARRAY_NAME" 
location="vtkQuadratureSchemeDefinition" value="QuadratureOffset" />
</DataArray>
</FieldData>
...
   <CellData>
...
     <DataArray type="Int64" Name="QuadratureOffset" format="appended" 
RangeMin="0" RangeMax="6084" offset="752856">
       <InformationKey name="DICTIONARY" 
location="vtkQuadratureSchemeDefinition">
         <vtkQuadratureSchemeDefinition>
           <CellType value="24"/>
           <NumberOfNodes value="10"/>
           <NumberOfQuadraturePoints value="4"/>
           </NumberOfQuadraturePoints>
           <ShapeFunctionWeights>
             1.5625000000000000e-01 -9.3750000000000000e-02 
-9.3750000000000000e-02 -9.3750000000000000e-02
             3.1250000000000000e-01 6.2500000000000000e-02 
3.1250000000000000e-01 3.1250000000000000e-01
             6.2500000000000000e-02 6.2500000000000000e-02 
-9.3750000000000000e-02 7.0312500000000000e-02
             -1.1718750000000000e-01 -9.3750000000000000e-02 
2.8125000000000000e-01 4.2187500000000000e-01
             9.3750000000000000e-02 6.2500000000000000e-02 
2.8125000000000000e-01 9.3750000000000000e-02
             -9.3750000000000000e-02 -1.1718750000000000e-01 
7.0312500000000000e-02 -9.3750000000000000e-02
             9.3750000000000000e-02 4.2187500000000000e-01 
2.8125000000000000e-01 6.2500000000000000e-02
             9.3750000000000000e-02 2.8125000000000000e-01 
-9.3750000000000000e-02 -5.4687500000000000e-02
             -5.4687500000000000e-02 3.7500000000000000e-01 
3.1250000000000000e-02 1.5625000000000000e-02
             3.1250000000000000e-02 3.7500000000000000e-01 
1.8750000000000000e-01 1.8750000000000000e-01
           </ShapeFunctionWeights>
           <QuadratureWeights>
             6.9231905580894400e-310 6.9231905580894400e-310 
0.0000000000000000e+00 0.0000000000000000e+00
           </QuadratureWeights>
         </vtkQuadratureSchemeDefinition>
       </InformationKey>
     </DataArray>
,,,


On 01/04/2013 11:51 AM, Eduardo wrote:
> Burlen:
>
> I got the paper and it seems to be what I need. I was just wondering
> though if there is any example that can be opened with Paraview. As
> far as I can understood, there is a code example. But what I really
> would like to have is a file example with data at integration point
> (let say a scalar or vector) to be displayed.
>
> Many thanks,
> Eduardo
>
> On Wed, Jan 2, 2013 at 3:07 PM, Burlen Loring <bloring at lbl.gov> wrote:
>> Hi Eduardo,
>>
>> You could visualize data on quadrature points, see
>> http://www.vtk.org/Wiki/File:VTK-Quadrature-Point-Design-Doc.pdf for some
>> details. There is a ctest that demonstrates the functionality, and those
>> filters are found in ParaView. There may be some newer features that I don't
>> know of, but this should get you started.
>>
>> Burlen
>>
>>
>> On 01/02/2013 06:07 AM, Eduardo wrote:
>>> Hi all,
>>>
>>> I am looking for how I can display data that is centered at
>>> integration quadrature point of elements in a mesh. Is that possible
>>> or I can only display data that is centered at vertices and elements?
>>>
>>> Can someone give some pointers on how I can do that. I couldn't find
>>> googling the web.
>>>
>>> Thanks in advance,
>>> Eduardo
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