[Paraview] No volume representation for cell-centered data with center-to-point filter

[David E DeMarle]

Xdmf's 3DRectMesh maps to VTK's vtkRectilinearGrid.

But, ParaView only has volume rendering representations for
vtkImageData and vtkUnstructuredGrids.

So, convert your data from a rectilinear grid to an unstructured grid,
and then volume render that. You could go the other way but you'd
loose the variability in the cell size.

One way to convert is to apply the threshold filter and keep the
entire data range inside the threshold to keep all of the cells.

David E DeMarle
Kitware, Inc.
R&D Engineer
21 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-881-4909


On Wed, May 16, 2012 at 4:36 PM, Bao Kai <paeanball at gmail.com> wrote:
> Hi, everybody,
>
> Recently, we are trying to output our simulation results (  some
> scalars ) with cell-centered scheme and xmdf format.
>
> The problem now is that with the center-to-point filter, we can get
> the contour(seems not work with cell-centered representation), while
> we still can not use the volume representation.
>
> The file header is provided as the following. We use some rectangular
> mesh, while due to some requirements, the sizes of the mesh cells can
> be different. So we have to output the coordinates (X, Y, Z ) of the
> nodes to represent the mesh.
>
> Could anybody tell me how I can do the volume rendering with our data?
>
> Thank you very much.
>
> Best Regards,
> Kai
>
> <?xml version="1.0" ?>
> <!DOCTYPE Xdmf SYSTEM "Xdmf.dtd" []>
> <Xdmf xmlns:xi="http://www.w3.org/2001/XInclude" Version="2.0">
> <Domain>
>  <Topology TopologyType="3DRectMesh" Dimensions=" 33 33 33 ">
>  </Topology>
>  <Geometry Type="VXVYVZ">
>  <!-- VX -->
>  <DataItem Format="XML" Dimensions=" 33 ">
>   0.000   0.031   0.062   0.094   0.125
>   0.156   0.188   0.219   0.250   0.281
>   0.312   0.344   0.375   0.406   0.438
>   0.469   0.500   0.531   0.562   0.594
>   0.625   0.656   0.688   0.719   0.750
>   0.781   0.812   0.844   0.875   0.906
>   0.938   0.969   1.000
>  </DataItem>
>  <!-- VY -->
>  <DataItem Format="XML" Dimensions=" 33 ">
>   0.000   0.031   0.062   0.094   0.125
>   0.156   0.188   0.219   0.250   0.281
>   0.312   0.344   0.375   0.406   0.438
>   0.469   0.500   0.531   0.562   0.594
>   0.625   0.656   0.688   0.719   0.750
>   0.781   0.812   0.844   0.875   0.906
>   0.938   0.969   1.000
>  </DataItem>
>  <!-- VZ -->
>  <DataItem Format="XML" Dimensions=" 33 ">
>   0.000   0.031   0.062   0.094   0.125
>   0.156   0.188   0.219   0.250   0.281
>   0.312   0.344   0.375   0.406   0.438
>   0.469   0.500   0.531   0.562   0.594
>   0.625   0.656   0.688   0.719   0.750
>   0.781   0.812   0.844   0.875   0.906
>   0.938   0.969   1.000
>  </DataItem>
>  </Geometry>
> <Grid Name="soln_1PhFlw.xmf" GridType="Collection" CollectionType="Temporal">
>  <Grid  Name="Grid at time  25.0000000000000000 " GridType="Uniform">
>  <Time Value=" 25.0000000000000000 "/>
>  <Topology Reference="/Xdmf/Domain/Topology[1]"/>
>  <Geometry Reference="/Xdmf/Domain/Geometry[1]"/>
>  <Attribute Name="conc" Center="cell">
>  <DataItem Format="Binary" Endian="Big" DataType="Float" Precision="8"
> Dimensions=" 32 32 32 ">
>  soln_conc1
>  </DataItem>
>  </Attribute>
>  <Attribute Name="velx" Center="cell">
>  <DataItem Format="Binary" Endian="Big" DataType="Float" Precision="8"
> Dimensions=" 32 32 32 ">
>  soln_velx1
>  </DataItem>
>  </Attribute>
>  <Attribute Name="vely" Center="cell">
>  <DataItem Format="Binary" Endian="Big" DataType="Float" Precision="8"
> Dimensions=" 32 32 32 ">
>  soln_vely1
>  </DataItem>
>  </Attribute>
>  <Attribute Name="velz" Center="cell">
>  <DataItem Format="Binary" Endian="Big" DataType="Float" Precision="8"
> Dimensions=" 32 32 32 ">
>  soln_velz1
>  </DataItem>
>  </Attribute>
>  <Attribute Name="density" Center="cell">
>  <DataItem Format="Binary" Endian="Big" DataType="Float" Precision="8"
> Dimensions=" 32 32 32 ">
>  soln_density1
>  </DataItem>
>  </Attribute>
>  <Attribute Name="pressure" Center="cell">
>  <DataItem Format="Binary" Endian="Big" DataType="Float" Precision="8"
> Dimensions=" 32 32 32 ">
>  soln_pres1
>  </DataItem>
>  </Attribute>
>  </Grid>
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