Visualization of 3-dimensional grid from X_Y_Z(seperate datasets) on Paraview without using xdmf

问题

Reading netcdf files with Paraview using xdmf

I used to parse netcdf files with an xdmf script in order to create 3DSMesh on paraview. On top of it, I was adding scalar or vector fields. (So 3DSMesh provides physical coordinates).

I never though if it is best way to do that actually. It works, so I was OK. Please let me know if there is more convenient way.

I am able to create a 3-dimensional grid with the following script.

<?xml version="1.0" ?>
<!DOCTYPE Xdmf SYSTEM "Xdmf.dtd" []>
<Xdmf xmlns:xi="http://www.w3.org/2001/XInclude" Version="2.0">
   <Domain>
      <Grid Name="gridxyz">
        <Topology TopologyType="3DSMesh" NumberOfElements="0032 0032 0063">
        </Topology>
<!-- Read Coordinates -->
        <Geometry GeometryType="X_Y_Z">
           <DataItem Name="X" Format="HDF" NumberType="Float" Precision="8" Dimensions="0032 0032 0063">
                       grid_x.nc:/gridx
           </DataItem>
           <DataItem Name="Y" Format="HDF" NumberType="Float" Precision="8" Dimensions="0032 0032 0063">
                       grid_y.nc:/gridy
           </DataItem>
           <DataItem Name="Z" Format="HDF" NumberType="Float" Precision="8" Dimensions="0032 0032 0063">
                       grid_z.nc:/gridz
           </DataItem>
        </Geometry>
<!-- Read Scalar -->
<!-- Here I have bunch of scalars stored in different netcdf files -->
     </Grid>
   </Domain>
</Xdmf>

Pros

• xdmf scripts are great when someone needs repetitive tasks.

Cons

• this script(s) needs to be generated somehow, or typed by hand. And required to be updated, when the dimensions or variable names are changed

• if I want to read another scalar, I need to add a line

• grid can be uniform in 2 directions and not uniform on the third one, no need to create 3D grid files, but geometry type dx_dy_dz is not enough to achieve that.

What I am looking for

Recently I realize, I can open netcdf files with paraview just by clicking open(Paraview4.3). So, I do not need these xdmf scripts anymore (few years ago I was not able to open netcdf files on Paraview).

How can I create 3DSMesh via Paraview GUI. Is that possible? Or is there any other simple/faster way (instead of writing a python script) ? Is there any way read 1D coordinates and create 3D geometry using them ?

回答1:

That's how I manage to do that. Certainly it's not the fastest way, but it works for me.

When you open a NetCDF file, paraview asks you to choose a reader, I always use NetCDF files generic and CF conventions .

After that, before hitting "Apply" button you have to select the appropriate "Dimensions" in the dropdown menu.

Your data now must be displayed as a UniformGrid, with your data(X,Y,Z) as scalars fields so you must transform to a grid to be more specific a StructuredGrid. In order to do that, apply the "ImageDataToPointSet" filter.

After that, apply a "Calculator" filter check "Coordinate Results" field and do the following:

If your data appears as X, Y , Z colummns put in the calculator field the expression

(X * iHat) + (Y * jHat) + (Z * kHat)

if your data appears with other names, substitute x, y, z with those names

The expression means that x is in the direction of the î vector, y is in the direction of the j vector and so on

Hope it helped!

来源：https://stackoverflow.com/questions/30616741/visualization-of-3-dimensional-grid-from-x-y-zseperate-datasets-on-paraview-wi