Thanks for your help. I tried to put your code after 
my_polyData-&gt;RemoveDeletedCells();<br>Unfortunately It doesn&#39;t work.<br>I tried to delete lot of cells, they are never really removed.<br><br>My VTK version is 5.2, does it matter? <br>
<br><br><div class="gmail_quote">2009/7/28 Dominik Szczerba <span dir="ltr">&lt;<a href="mailto:dominik@itis.ethz.ch">dominik@itis.ethz.ch</a>&gt;</span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
my_polyData-&gt;Modified()<br>
<br>
Corinne Tith wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div><div></div><div class="h5">
Hi all,<br>
<br>
I get a polydata volume with a vtkContourFilter and a vtkWindowSincPolyDataFilter.<br>
Some cells are not connected to the largest volume. They seem to be &#39;on&#39; the mesh but have no vertice in common.<br>
<br>
I tried the filters vtkCleanPolyData and vtkPolyDataConnectivityFilter, but most of my unconnected cells are not removed.<br>
Finally, I tried to delete them &#39;manually&#39;, but nothing happens.<br>
<br>
How can I really remove my unconnected cells?<br>
<br>
Any help is appreciated, thanks!<br>
<br>
<br>
// generate my volume<br>
my_vtkWindowSincPolyDataFilter-&gt;SetInputConnection(my_vtkContourFilter-&gt;GetOutputPort()); <br>
// no effect on my cells<br>
my_vtkCleanPolyData-&gt;SetInputConnection(my_vtkWindowSincPolyDataFilter-&gt;GetOutputPort()); <br>
my_vtkCleanPolyData-&gt;PointMergingOn();<br>
my_vtkPolyDataConnectivityFilter-&gt;SetInputConnection(my_vtkContourFilter-&gt;GetOutputPort());<br>
my_vtkPolyDataConnectivityFilter-&gt;SetExtractionModeToLargestRegion();<br>
// manual remove<br>
my_vtkPolyDataConnectivityFilter-&gt;Update();<br>
my_polyData = my_vtkPolyDataConnectivityFilter-&gt;GetOutput();<br>
for(int i = 0; i &lt; n; i++){<br>
       my_polyData-&gt;DeleteCell(cellsToRemove[i]);<br>
}<br>
my_polyData-&gt;RemoveDeletedCells();<br>
<br>
<br></div></div>
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</blockquote>
<br>
</blockquote></div><br>