[vtkusers] How to remove edges/faces not belonging to the konvex hull from Delaunay3D?

[Bryn Lloyd]

Maybe I misunderstand you, but I think you simply need to extract the 
triangle surface from the tetrahedral mesh (obtained with Delaunay3D).

This will only leave the triangles, which are used by only one 
tetrahedron, so only those on the surface.


Try vtkDataSetSurfaceFilter.

http://www.vtk.org/doc/nightly/html/classvtkDataSetSurfaceFilter.html

/Bryn







David Doria wrote:
> On Fri, Jan 15, 2010 at 2:50 AM,  <lynx.abraxas at freenet.de> wrote:
>> Hello!
>>
>>
>> I  want  to get the convex hull of points lying on a sphere. I used Delaunay3D
>> for that. My problem now is the inner connection of points created during  the
>> Delaunay  triangulation (eg a line between opposite points of a octaedron). Is
>> there a way to remove the edges and faces that do not  belong  to  the  convex
>> hull?  I  found  vtkHull  but  that seems not to be the right filter for this,
>> since the Delaunay result contains the hull already,  it  would  just  need  a
>> clean up.
>>
>> Thanks for any help or hints.
>> Lynx
> 
> This is a good point. I don't believe this example is correct:
> 
> http://www.cmake.org/Wiki/Convex_hull
> 
> because it potentially contains surfaces that are "inside" the convex hull.
> 
> I had to do this one time and I used my synthetic lidar scanner:
> http://www.midasjournal.org/browse/publication/695
> 
> To shoot a bunch of rays from a bunch of different directions at the
> object and kept only the surfaces which were hit. This seemed like a
> VERY outrageous way to do this, but it worked :)
> 
> Anyone have a better/easier suggestion?
> 
> Thanks,
> 
> David
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-- 
-------------------------------------------------
Bryn Lloyd
Computer Vision Laboratory
ETH Zürich, Sternwartstrasse 7, ETF C110
CH - 8092 Zürich, Switzerland
Tel: +41 44 63 26668
Fax: +41 44 63 21199
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