<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Hi,</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">A polyhedron could be treated as a closed polygonal surface (or conversely a closed polygonal surface could be considered an arbitrary polyhedron).  If you look at vtkPolyhedron.cxx you can see how it is using MeanValueCoordinates to interpolate the function values inside the cell, and then compute the derivatives.  So if your mesh contains polyhedral cells, vtkCellDerivatives should work.</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, May 8, 2017 at 5:38 PM, Kurt Sansom <span dir="ltr"><<a href="mailto:kayarre@gmail.com" target="_blank">kayarre@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">I do not understand your answer.<div><br></div><div>~Kurt</div></div><div class="gmail_extra"><div><div class="h5"><br><div class="gmail_quote">On Mon, May 8, 2017 at 10:26 AM, Jeff Lee <span dir="ltr"><<a href="mailto:jlee1549@gmail.com" target="_blank">jlee1549@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto">Vtkpolyhedron uses mean value coordinates.</div><div class="gmail_extra"><br><div class="gmail_quote"><div><div class="m_-5272415516126766825h5">On May 8, 2017 1:13 PM, "Kurt Sansom" <<a href="mailto:kayarre@gmail.com" target="_blank">kayarre@gmail.com</a>> wrote:<br type="attribution"></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="m_-5272415516126766825h5"><div dir="ltr">Hi,<div>  Does anyone have suggestions to take cell derivatives from a  polyhedral/polytopal surface mesh because the VTK documentation says that, "<span style="color:rgb(0,0,0);font-family:roboto,sans-serif;font-size:14px">derivatives calculated for polygons with more than 4 vertices are inaccurate in most cases"</span></div><div><font color="#000000" face="roboto, sans-serif"><span style="font-size:14px"><br></span></font></div><div><font color="#000000" face="roboto, sans-serif"><span style="font-size:14px">from: <a href="http://www.vtk.org/doc/nightly/html/classvtkCellDerivatives.html#details" target="_blank">http://www.vtk.org/doc/nightly<wbr>/html/classvtkCellDerivatives.<wbr>html#details</a></span></font></div><div><font color="#000000" face="roboto, sans-serif"><span style="font-size:14px"><br></span></font></div><div><font color="#000000" face="roboto, sans-serif"><span style="font-size:14px"><br></span></font></div><div><font color="#000000" face="roboto, sans-serif"><span style="font-size:14px">Regards, </span></font></div><div><font color="#000000" face="roboto, sans-serif"><span style="font-size:14px">~Kurt<br></span></font><div><div><br></div>-- <br><div class="m_-5272415516126766825m_3165154598143680089m_4978611642611960298gmail_signature">Kurt Sansom<br></div>
</div></div></div>
<br></div></div>______________________________<wbr>_________________<br>
Powered by <a href="http://www.kitware.com" rel="noreferrer" target="_blank">www.kitware.com</a><br>
<br>
Visit other Kitware open-source projects at <a href="http://www.kitware.com/opensource/opensource.html" rel="noreferrer" target="_blank">http://www.kitware.com/opensou<wbr>rce/opensource.html</a><br>
<br>
Please keep messages on-topic and check the VTK FAQ at: <a href="http://www.vtk.org/Wiki/VTK_FAQ" rel="noreferrer" target="_blank">http://www.vtk.org/Wiki/VTK_FA<wbr>Q</a><br>
<br>
Search the list archives at: <a href="http://markmail.org/search/?q=vtkusers" rel="noreferrer" target="_blank">http://markmail.org/search/?q=<wbr>vtkusers</a><br>
<br>
Follow this link to subscribe/unsubscribe:<br>
<a href="http://public.kitware.com/mailman/listinfo/vtkusers" rel="noreferrer" target="_blank">http://public.kitware.com/mail<wbr>man/listinfo/vtkusers</a><br>
<br></blockquote></div></div>
</blockquote></div><br><br clear="all"><div><br></div></div></div><span class="HOEnZb"><font color="#888888">-- <br><div class="m_-5272415516126766825gmail_signature" data-smartmail="gmail_signature">Kurt Sansom<br></div>
</font></span></div>
</blockquote></div><br></div>