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List: vtk-developers
Subject: RE: [vtk-developers] Geodesics on polygonal surfaces
From: "Rasmus Reinhold Paulsen" <rrp () oticon ! dk>
Date: 2007-02-07 13:37:03
Message-ID: 8CC17F724B8992438D91F16D2EF784D901879A31 () KBNNT70 ! emea ! demant ! com
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Hi Karthik,
I have not done any work on the Geodesics routines since June 2005, so
unfortunately I do not have any hidden golden nuggets :)
Cheers,
Rasmus
PS. As can be seen I am gradually changing my academic email address
into my new one rrp@oticon.dk
________________________________
From: vtk-developers-bounces+rrp=oticon.dk@vtk.org
[mailto:vtk-developers-bounces+rrp=oticon.dk@vtk.org] On Behalf Of
Karthik Krishnan
Sent: 7. februar 2007 00:01
To: vtk-developers@vtk.org
Cc: rrp@imm.dtu.dk
Subject: [vtk-developers] Geodesics on polygonal surfaces
Hi,
I'm writing a widget that can draw on polygonal datasets. So an need an
algorithm that can trace geodesics on surfaces. I dug up an old thread :
http://public.kitware.com/pipermail/vtkusers/2005-June/080306.html
I played around with Rasmus Paulsen's code that computes the Dijkstra's
shortest path between two vertices (Graph geodesics). [
http://www2.imm.dtu.dk/~rrp/VTK/ <http://www2.imm.dtu.dk/~rrp/VTK/> ],
hoping to get the shortest path using Dijkistra and then try to smooth
the resulting zig-zagged curve.
It sort of works if the mesh is very dense. Often, it gives
non-intuitive results.
Attached is an example:
- The input polydata is
http://public.kitware.com/pub/itk/UsersITK/vtkDijkstra/ellipsoid.png
- The result is :
http://public.kitware.com/pub/itk/UsersITK/vtkDijkstra/DijkstraGeodesic1
.png
The curve ends up hugging the latitudes of the ellipsoid for a while to
get to its final destination, instead of zigzagging its way through the
latitudes and longitudes.
Any thoughts. Anybody else using geodesics for similar purposes ?
Thanks
--
Karthik Krishnan
R&D Engineer,
Kitware Inc.
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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Hi Karthik,</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I have not done any work on the Geodesics
routines since June 2005, so unfortunately I do not have any hidden golden
nuggets :)</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Cheers,<br>
Rasmus</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>PS. As can be seen I am gradually changing
my academic email address into my new one rrp@oticon.dk</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> \
vtk-developers-bounces+rrp=oticon.dk@vtk.org \
[mailto:vtk-developers-bounces+rrp=oticon.dk@vtk.org] <b><span \
style='font-weight:bold'>On Behalf Of </span></b>Karthik Krishnan<br> <b><span \
style='font-weight:bold'>Sent:</span></b> 7. februar 2007 00:01<br> <b><span \
style='font-weight:bold'>To:</span></b> vtk-developers@vtk.org<br> <b><span \
style='font-weight:bold'>Cc:</span></b> rrp@imm.dtu.dk<br> <b><span \
style='font-weight:bold'>Subject:</span></b> [vtk-developers] Geodesics on polygonal \
surfaces</span></font></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Hi,<br>
<br>
I'm writing a widget that can draw on polygonal datasets. So an need an
algorithm that can trace geodesics on surfaces. I dug up an old thread :<br>
<a
href="http://public.kitware.com/pipermail/vtkusers/2005-June/080306.html">http://public.kitware.com/pipermail/vtkusers/2005-June/080306.html</a><br>
<br>
I played around with Rasmus Paulsen's code that computes the Dijkstra's
shortest path between two vertices (Graph geodesics). [<a
href="http://www2.imm.dtu.dk/~rrp/VTK/"> http://www2.imm.dtu.dk/~rrp/VTK/</a>],
hoping to get the shortest path using Dijkistra and then try to smooth the
resulting zig-zagged curve.<br>
<br>
It sort of works if the mesh is very dense. Often, it gives non-intuitive
results.<br>
<br>
Attached is an example:<br>
<br>
- The input polydata is <a
href="http://public.kitware.com/pub/itk/UsersITK/vtkDijkstra/ellipsoid.png">http://public.kitware.com/pub/itk/UsersITK/vtkDijkstra/ellipsoid.png
</a><br>
- The result is : <a
href="http://public.kitware.com/pub/itk/UsersITK/vtkDijkstra/DijkstraGeodesic1.png">ht \
tp://public.kitware.com/pub/itk/UsersITK/vtkDijkstra/DijkstraGeodesic1.png</a><br> \
<br> The curve ends up hugging the latitudes of the ellipsoid for a while to get to
its final destination, instead of zigzagging its way through the latitudes and
longitudes. <br>
<br>
Any thoughts. Anybody else using geodesics for similar purposes ?<br>
<br>
Thanks<br>
<br>
<span class=sg>-- </span><br>
<span class=sg>Karthik Krishnan</span><br>
<span class=sg>R&D Engineer,</span><br>
<span class=sg>Kitware Inc. </span></span></font></p>
</div>
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