<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
</head>
<body bgcolor="#ffffff" text="#000000">
you are right, my bad. burlen<br>
<br>
David E DeMarle wrote:
<blockquote
cite="mid:e85d6c9a0712060953y7354386emd63f0d3c8945860e@mail.gmail.com"
type="cite">
<pre wrap="">On 12/6/07, burlen <a class="moz-txt-link-rfc2396E" href="mailto:burlen@apollo.sr.unh.edu"><burlen@apollo.sr.unh.edu></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap=""> I see where you are coming from, vtk is awesome in that it provides a lot
of well documented very thoroughly debugged functionality. Just a thought...
vtkPolyData is a type(not in the C++ sense) of unstructured grid, in fact
all of the cell types applicable for use with the unstructured grid are
available for use with the polydata. In my experience vtkPolyData class
encapsulates the functionality of the vtkUnstructuredGrid, although they are
not symetrically interchangable. You may be able to use poydata in place of
</pre>
</blockquote>
<pre wrap=""><!---->
You have this point reversed. PolyData cell types are a subset of
those in UnstructuredGrid. PolyData, is tuned for graphics cards and
rendering. PolyData can only represent 0 (point), 1 (line segment) and
2 (polygons, pixels etc) dimensional cells. UnstructuredGrid can also
represent 3 dimensional cells (tetrahedra, voxels etc).
</pre>
<blockquote type="cite">
<pre wrap="">the unstructured grid. & If you couldn't it is very easy to convert between
the two, by taking the point set, cells, and point or cell data from one and
inserting it into the other. So what you might try is to convert your
unstructured grid to polydata clean it then convert back.
</pre>
</blockquote>
<pre wrap=""><!---->GeometryFilter will extract the surfaces of all boundary cells in an
UnstructuredGrid, producing PolyData. I am not aware of any filters
that can reverse that process (taking the 4 triangles that are on the
surface of a tetrahedra and producing the tetrahedra for example.)
</pre>
<blockquote type="cite">
<pre wrap=""> Burlen
Oliver Gloth wrote:
I had a look at vtkCleanPolyData and the classes vtkMergePoints and
vtkPointLocator seem to be good starting points. It is required to clean a
vtkUnstructuredGrid, that's why the vtkCleanPolyData is not directly
applicable - but thanks for pointing me in the right direction.
The links you sent (thanks btw.) are not completely unknown to me and I
might use the Netgen package for this project. It is not a CFD project, but
a mesh generation project (I would not use VTK data structures for a solver
...). I gave some thought to using VTK: it might not be ideal, but
definitely well suited. Tools like, for example, vtkMergePoints, are very
valuable and they can be a real pain to implement and debug. The other thing
I like about VTK is that it is well documented and has a large user
community, and yes visualisation is very easy indeed!
Oliver
-----Original Message-----
From: burlen [<a class="moz-txt-link-freetext" href="mailto:burlen@apollo.sr.unh.edu">mailto:burlen@apollo.sr.unh.edu</a>]
Sent: 06 December 2007 16:28
To: Oliver Gloth
Cc: vtkusers
Subject: Re: [vtkusers] eliminate duplicate nodes
Does the vtkCleanPolyData class do what you want??
Although I supose you could do it, I am not convinced that VTK would be
ideal for CFD project, you might find these links of use:
<a class="moz-txt-link-freetext" href="http://www.andrew.cmu.edu/user/sowen/softsurv.html">http://www.andrew.cmu.edu/user/sowen/softsurv.html</a>
<a class="moz-txt-link-freetext" href="http://www.cs.cmu.edu/~quake/triangle.html">http://www.cs.cmu.edu/~quake/triangle.html</a>
<a class="moz-txt-link-freetext" href="http://www.hpfem.jku.at/netgen/">http://www.hpfem.jku.at/netgen/</a>
On the other hand at least visualization would be easy.
Burlen
Oliver Gloth wrote:
Dear VTK Users,
I am currently working on an open-source project - developing a mesh
generator for CFD simulations. Due to budget and time constraints I have
chosen to use the VTK data structures as a basis, instead of writing my
own
data structures. Furthermore this makes building a GUI (based on Qt) to
modify and visualise the mesh easy. One thing that is required is a filter
to merge two grids and eliminate duplicate nodes. Is such a thing already
part of VTK, or does somebody have a piece of code that would do this? The
implementation is not trivial, because the 3D search can be very time
consuming. If it doesn't exist yet I will implement it myself, but I would
like to avoid double work as much as possible.
Oliver
_______________________________________________
This is the private VTK discussion list.
Please keep messages on-topic. Check the FAQ at:
<a class="moz-txt-link-freetext" href="http://www.vtk.org/Wiki/VTK_FAQ">http://www.vtk.org/Wiki/VTK_FAQ</a>
Follow this link to subscribe/unsubscribe:
<a class="moz-txt-link-freetext" href="http://www.vtk.org/mailman/listinfo/vtkusers">http://www.vtk.org/mailman/listinfo/vtkusers</a>
</pre>
</blockquote>
</blockquote>
<br>
</body>
</html>