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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>You are right: vtkPolygon:: PointInPolygon is also for 3D polygons. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>But a surface mesh (obtained via marching cubes) does not correspond to a polygon! Also the projection on the plane defined by the normal n (which you provide to PointInPolygon) in general is not a (single) polygon. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>To test inside/outside you will need to <o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>-<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>project the surface mesh onto a plane, <o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>-<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>obtain the outer edges/points defining the silhouette boundary, <o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>-<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>put these points into the vtkPolygon as a list of ordered points (oriented polygon ring).<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Jothy [mailto:jothybasu@gmail.com] <br><b>Sent:</b> Monday, July 25, 2011 11:07 AM<br><b>To:</b> Bryn Lloyd<br><b>Cc:</b> VTK Mailing List<br><b>Subject:</b> Re: [vtkusers] PointInPolygon returns 1 for all points within bounds<o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal style='margin-bottom:12.0pt'>Thanks for your reply Bryn!<br><br>vtkPolygon is meant to be used for 2D polygons, but the pointInPolygon uses a ray-tracing to find the points inside the polygon so why it will work only for 2D polygons. The arguments are [x,y,z].<br><br>I want to calculate the dose-volume histograms from these meshes.<br><br>I will make a new post with a more appropriate subject.<br><br>Thanks again<br><br>Jothy<o:p></o:p></p><div><p class=MsoNormal>On Mon, Jul 25, 2011 at 7:03 AM, Bryn Lloyd <<a href="mailto:lloyd@itis.ethz.ch">lloyd@itis.ethz.ch</a>> wrote:<o:p></o:p></p><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Hi Jothy<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Since you are using vtkDiscreteMarchingCubes, I assume your mesh is a 3d surface mesh.<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>vtkPolygon is meant to used for 2D polygons (e.g. a triangle in the xy-plane). Unless you project your 3D mesh to a 2d plane, and obtain the silhouette, this will not work.<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><a href="http://www.vtk.org/doc/nightly/html/classvtkPolyDataSilhouette.html" target="_blank">http://www.vtk.org/doc/nightly/html/classvtkPolyDataSilhouette.html</a><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Also, it seems dangerous or even wrong to cast the points and polygons to a double pointer like this. First, the points could also be floats. Second, I doubt the polys in your mesh can be cast to <double*>.<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Instead, you should probably use one of the cell locators, e.g. vtkOBBTree or vtkCellLocator to test if your point is inside the mesh in 3D.<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>You could have a look at the code in “vtkSelectEnclosedPoints” to see how to do this in a robust way. You can even use this filter directly, via the function “vtkSelectEnclosedPoints::IsInsideSurface”.<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><a href="http://www.vtk.org/doc/nightly/html/classvtkSelectEnclosedPoints.html" target="_blank">http://www.vtk.org/doc/nightly/html/classvtkSelectEnclosedPoints.html</a><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Cheers<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Bryn<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;color:#1F497D'> </span><o:p></o:p></p><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span style='font-size:10.0pt'>From:</span></b><span style='font-size:10.0pt'> <a href="mailto:vtkusers-bounces@vtk.org" target="_blank">vtkusers-bounces@vtk.org</a> [mailto:<a href="mailto:vtkusers-bounces@vtk.org" target="_blank">vtkusers-bounces@vtk.org</a>] <b>On Behalf Of </b>Jothy<br><b>Sent:</b> Friday, July 22, 2011 4:39 PM<br><b>To:</b> VTK Mailing List<br><b>Subject:</b> [vtkusers] PointInPolygon returns 1 for all points within bounds</span><o:p></o:p></p></div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Hi all,<br><br>I have a mesh generated from vtkDiscreteMarchingCubes and processed through vtkDecimatePro and vtkWindowedSincPolyDataFilter. Now, I want to find the points/voxels inside this mesh. I am using vtkPolygon::PointInPolygon. But, the result is "1! for the all the points whichever falls with the bounds.<br><br>Here is the piece of code that I am using<br><br>(smoother is vtkWindowedSincPolyDataFilter)<br><br> int npts=smoother->GetOutput()-> GetPoints()->GetNumberOfPoints();// test point <br> //double n[3]={0.707, 0.707, 0};<br> double n[3];<br><br> vtkSmartPointer<vtkPolygon> polygon =<br> vtkSmartPointer<vtkPolygon>::New();<br> <b><span style='color:#CC0000'>polygon->ComputeNormal(mapper->GetInput()->GetPoints()->GetNumberOfPoints(),<br> static_cast<double*>(mapper->GetInput()->GetPoints()->GetData()->GetVoidPointer(0)), n); </span></b> <br><br> double bds[6];<br> smoother->GetOutput()->GetBounds(bds); <br> qDebug()<< polygon->PointInPolygon(testIn,npts,<b><span style='color:red'>static_cast<double*>(mapper->GetInput()->GetPolys()->GetData()->GetVoidPointer(0)</span></b>),bds,n)<<"Result";<br><br>Are these two highlighted lines correct?<br><br>Many thanks<br><br>Jothy<br> <o:p></o:p></p></div></div></div></div></div></div><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>