<div dir="ltr">For a surface mesh, in the vtkFeatureEdges terminology :<br> - a boundary edge belongs to exactly one cell<br> - a manifold edge belongs to two cells<br> - a non-manifold edge belongs to 3 or more cells.<br>
A simple close surface has only manifold edges.<br><a class="el" href="http://www.vtk.org/doc/nightly/html/classvtkFeatureEdges.html#d1db4f83238d8c67e1947d49b9cde809">BoundaryEdgesOn</a> ()<br><a class="el" href="http://www.vtk.org/doc/nightly/html/classvtkFeatureEdges.html#f500d450d2858feff66bf6d8ea445789">NonManifoldEdgesOn</a> ()<br>
<a class="el" href="http://www.vtk.org/doc/nightly/html/classvtkFeatureEdges.html#39683205bb877df465d166029307cbb8">ManifoldEdgesOff</a> ()<br><a class="el" href="http://www.vtk.org/doc/nightly/html/classvtkFeatureEdges.html#bbe4158f8c4a8a29131e7e32637f563d">FeatureEdgesOff</a> ()<br>
should return an empty set.<br><br>A simple open surface has boundary edges and may has manifold too. <br>Having non-manifold edges means the surface intersects itself. It could still be close, but I guess you don't want to deal with...<br>
<br> <br><div class="gmail_quote">2008/10/9 Dominik Szczerba <span dir="ltr"><<a href="mailto:dominik@itis.ethz.ch">dominik@itis.ethz.ch</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hmmm. Is a boundary edge of an open surface a non-manifold edge? It does not<br>
seem so, at least with the default settings.<br>
<br>
Dominik<br>
<div><div></div><div class="Wj3C7c"><br>
On Friday 03 October 2008 07:14:51 pm Marie-Gabrielle Vallet wrote:<br>
> I think there is a easier way of checking the surface closeness. I mean<br>
> using vtk facilities, instead of writing a (yet another) new algorithm.<br>
><br>
> VTK library has algorithms to extract a mesh boundary, i.e. the set of<br>
> faces (in 3D) or edges (in 2D) that are not shared by two cells. See<br>
> vtkFeatureEdges. The mesh is close if and only if this set is empty. If it<br>
> not, you can visualize the holes that must still be closed.<br>
><br>
> Pamela is trying to do the same thing today. Have a look at the thread "get<br>
> boundary triangles from a mesh" on this mailing list.<br>
><br>
> By the way, Charles, are you sure you are not re-inventing the wheel ?<br>
><br>
> Marie-Gabrielle<br>
><br>
> > Date: Fri, 3 Oct 2008 08:17:31 +0200<br>
> > From: Dominik Szczerba <<a href="mailto:dominik@itis.ethz.ch">dominik@itis.ethz.ch</a>><br>
> > Subject: Re: [vtkusers] Proving a surface mesh of closeness<br>
> > To: <a href="mailto:vtkusers@vtk.org">vtkusers@vtk.org</a><br>
> > Message-ID: <<a href="mailto:200810030817.31796.dominik@itis.ethz.ch">200810030817.31796.dominik@itis.ethz.ch</a>><br>
> > Content-Type: text/plain; charset="utf-8"<br>
> ><br>
> > If it is manifold then pick the 1st element and make sure each one it<br>
> > has<br>
><br>
> the<br>
><br>
> > proper number of neighbors (for triangles: 3). Mark the element as<br>
><br>
> 'visited'<br>
><br>
> > and visit all his neighbors, repeating the procedure. At the end, if<br>
><br>
> number<br>
><br>
> > of visited elements equals to number of elements in the mesh and all<br>
> > have their expected neighbors the mesh is closed.<br>
> ><br>
> > DS<br>
> ><br>
> > On Friday 03 October 2008 02:48:59 am Charles Monty Burns wrote:<br>
> > > Hello,<br>
> > ><br>
> > > I repaired a surface mesh and want to prove whether the mesh is<br>
> > > totally closed or not. Save is save ...<br>
> > ><br>
> > > How can I do this?<br>
> > ><br>
> > > Greetings<br>
> ><br>
> > --<br>
> > Dominik Szczerba, Ph.D.<br>
> > Computational Physics Group<br>
> > Foundation for Research on Information Technologies in Society<br>
</div></div>> > <a href="http://www.itis.ethz.ch" target="_blank">http://www.itis.ethz.ch</a> <<a href="http://www.itis.ethz.ch/" target="_blank">http://www.itis.ethz.ch/</a>><br>
<font color="#888888"><br>
<br>
<br>
--<br>
</font><div><div></div><div class="Wj3C7c">Dominik Szczerba, Ph.D.<br>
Computational Physics Group<br>
Foundation for Research on Information Technologies in Society<br>
<a href="http://www.itis.ethz.ch" target="_blank">http://www.itis.ethz.ch</a><br>
</div></div></blockquote></div><br></div>