<div dir="ltr">The last I checked the vtkPolyon triangulate methods work pretty well (I've triangulated very complex polygons including the outlines of US states, etc.) In the past I've used this in combination with the triangle area computing routines.<div>
<br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Mar 12, 2013 at 12:07 PM, Moreland, Kenneth <span dir="ltr"><<a href="mailto:kmorel@sandia.gov" target="_blank">kmorel@sandia.gov</a>></span> wrote:<br>
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<div>I might be mistaken, but I thought the triangulation filter correctly handled concave polygons. The advice I usually see on the ParaView mailing list when someone's concave polygons are not rendering correctly is to triangulate them.</div>
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<div>-Ken</div>
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<span style="font-weight:bold">From: </span>Philippe Pébay <<a href="mailto:philippe.pebay@kitware.com" target="_blank">philippe.pebay@kitware.com</a>><br>
<span style="font-weight:bold">Date: </span>Tuesday, March 12, 2013 9:53 AM<br>
<span style="font-weight:bold">To: </span>David Thompson <<a href="mailto:david.thompson@kitware.com" target="_blank">david.thompson@kitware.com</a>><br>
<span style="font-weight:bold">Cc: </span>VTK Developers <<a href="mailto:vtk-developers@vtk.org" target="_blank">vtk-developers@vtk.org</a>><br>
<span style="font-weight:bold">Subject: </span>[EXTERNAL] Re: [vtk-developers] Measuring the area of arbitrary polygons<br>
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<div>Hello D<br>
<br>
Thanks for the prompt answer. So this is what I was concerned about :) Namely that there is no way to generically deal with concave polygons at this point. In fact, just finding a correct triangulation is not trivial. One could for instance compute a CDT and
remove outside triangles. This would be computationally expensive for large meshes composed of such elements, but is there another choice?<br>
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Thanks<br>
P<br>
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<div class="gmail_quote">On Tue, Mar 12, 2013 at 3:31 PM, David Thompson <span dir="ltr">
<<a href="mailto:david.thompson@kitware.com" target="_blank">david.thompson@kitware.com</a>></span> wrote:<br>
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Hi P,<br>
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> Is anyone aware of a routine already available to measure the surface area of arbitrary planar polygons in VTK, including non-convex ones?<br>
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I don't know of anything in VTK to handle concave polygons. For convex ones, I believe the triangulate filter followed by the mesh quality filter should get you the area of a decomposition of the polygon. Assuming that the triangulate filter creates pedigree
IDs, you could sum areas with matching pedigree IDs.<br>
<span><font color="#888888"><br>
David</font></span></blockquote>
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-- <br>
<font color="#888888">Philippe Pébay, PhD<br>
</font><font color="#888888">Director of Visualization and High Performance Computing /<br>
</font><font color="#888888">Directeur de la Visualisation et du Calcul Haute Performance<br>
Kitware SAS<br>
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