title: VTK : how to read grid cells' lenth, width and height?
body: <p>I have a huge grid in <code>*.pvd</code> format. I would like to ensure some cells size specification have been respected when building said grid. To do so, I should get a cell data array with (dx,dy,dz)</p>
  
  <p>I first tried to check this in Paraview with very little success. Then I resolved to export the mesh in various format (vtk, vtu, ex2) and import things into python using the <code>vtk</code> module, as in the code below. Unfortunately, the size of the mesh forbids it and I get various error messages stating "Unable to allocate n cells of size x".</p>
  
  <pre><code>import vtk
  reader = vtk.vtkXMLUnstructuredGridReader()
  reader.SetFileName("my_mesh.vtu")
  reader.Update()
  </code></pre>
  
  <p>Finally, in Paraview there is a python-shell that allows me to open the grid file in either <code>pvd</code> or <code>vtk</code> format:</p>
  
  <pre><code>&gt;&gt;&gt; from paraview.simple import *
  &gt;&gt;&gt; my_vtk = OpenDataFile("my_mesh.vtk")
  &gt;&gt;&gt; print dir(my_vtk)
  </code></pre>
  
  <p>Despite my browsing the methods and attribute of this reader object, I remain clueless about where to fetch any geometry information on the grid. I also browsed through the <a href="https://www.paraview.org/ParaView/Doc/Nightly/www/py-doc/paraview.simple.html" rel="nofollow noreferrer"><code>simple</code> module documentation</a> and I can't really wrap my head around it.</p>
  
  <p>So how can one retrieve information regarding the geometry of cells from a <code>paraview.servermanager.LegacyVTKReader</code> object?</p>
  
  <p>Any clue about how to achieve this with through the paraview GUI, or any kludge to load the vtk object into python vtk despite the memory issue is also very welcome. Sorry for such a hazy question, but I don't really know where to get started... </p>