[vtk-developers] Issue found in the vtkDelaunay2D filter?

Will Schroeder will.schroeder at kitware.com
Fri Mar 15 14:18:31 EDT 2013


Philippe-

At some point can you send me the code / data files / whatever you use to
generate some of these tests (particularly the star). I'll be using them to
test the Delaunay code of course. Thanks,

W


On Sat, Mar 9, 2013 at 7:18 AM, Philippe Pébay
<philippe.pebay at kitware.com>wrote:

> Hello all,
>
> I think that I just ran into a numerical instability of the Delanauy 2D
> triangulator, when used with a specified boundary constraint. For those
> interested in this issue, please look at the attached picture: the boundary
> constraint is in the upper left corner, which also includes the generators
> in red. The CDT is shown in the upper right corner, where I indicated the
> problematic edge: clearly, the 2 adjacent triangles do not satisfy the
> empty ball property, and that edge should be flipped. This is confirmed by
> the Voronoi diagram underneath where we see one cell protruding into
> another.
>
> In fact the highlighted edge should be flipped to obtain a correct CDT,
> and this what happens indeed when I nudge on of the points with a tiny
> epsilon. See the correct picture attached (where the "forced edges" for the
> sake of the constraint have been removed).
>
> By the way I observed similar instabilities, but with *slightly different
> generators*, when calling the Delaunay 2D from ParaView.
>
> I intend to work on the Delaunay 2D triangulator, but in collaboration
> with whoever is interested in this. Please let me know.
>
> Thanks
> P
>
> --
> Philippe Pébay, PhD
> Director of Visualization and High Performance Computing /
> Directeur de la Visualisation et du Calcul Haute Performance
> Kitware SAS
> 26 rue Louis Guérin, 69100 Villeurbanne, France
> +33 (0) 6.83.61.55.70 / 4.37.45.04.15
> http://www.kitware.fr <http://www.kitware.fr/>




-- 
William J. Schroeder, PhD
Kitware, Inc.
28 Corporate Drive
Clifton Park, NY 12065
will.schroeder at kitware.com
http://www.kitware.com
(518) 881-4902
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/vtk-developers/attachments/20130315/fa605dbd/attachment.html>


More information about the vtk-developers mailing list