[Paraview] Field Divergence: vtkImageDivergence and XML

[Chad Glendenin]

I'm looking for a way to color isosurfaces by the divergence of a  
velocity vector field. It looks like the vtkImageDivergence class is  
the one I need.[1] Please correct me if I'm wrong about that.

To add the vtkImageDivergence class to the ParaView GUI, I tried to  
modify the XML files from the vtkCellDerivatives example in the Wiki. 
[2] My XML files (GUI and SM) are below. They do give me a  
"Divergence" entry in my Filters menu, and the filter will allow me  
to choose an input and Accept. But there is no apparent output from  
the filter. Is this just a syntax error in my XML, or is there  
another problem?

Thanks,
ccg

[1] http://www.vtk.org/doc/release/5.0/html/a01515.html
[2] http://www.paraview.org/Wiki/ParaView:Extend

---- vtkImageDivergence.xml ----

<ModuleInterfaces>
   <ServerManagerFile name="vtkImageDivergence.pvsm" />

   <Module name="ImageDivergence"
           menu_name="Divergence"
           root_name="Divergence"
           module_type="Filter"
           long_help="Compute divergence of a field."
           short_help="Compute divergence of a field.">
     <Filter class="vtkImageDivergence">
       <Input name="Input"
              class="vtkDataObject"/>
     </Filter>
     <InputMenu trace_name="Input" label="Input" property="Input"
                help="Set the input to this filter."
                input_name="Input"/>
     <Documentation>
Compute the divergence of a field.
     </Documentation>
   </Module>
</ModuleInterfaces>

---- vtkImageDivergence.pvsm ----

<?xml version="1.0"?>
<ServerManagerConfiguration>
   <ProxyGroup name="filters">
    <SourceProxy name="ImageDivergence" class="vtkImageDivergence">
      <InputProperty
         name="Input"
         command="SetInput">
           <ProxyGroupDomain name="groups">
             <Group name="sources"/>
             <Group name="filters"/>
           </ProxyGroupDomain>
           <DataTypeDomain name="input_type">
             <DataType value="vtkDataObject"/>
           </DataTypeDomain>
      </InputProperty>
    <!-- End ImageDivergence -->
    </SourceProxy>
   </ProxyGroup>
</ServerManagerConfiguration>