[vtk-developers] vtkDelaunay2D fails to tesselate a partially complex geometry with one hole

[wyldckat]

Greetings Will and David,

@David: I don't believe it's 100% related to the bug you posted, since
vtkDelaunay2D hasn't crashed with us (yet).

@Will: Thank you for the link and we'll start on that ASAP. But could you
please also provide the link or references for the textual information about
the currently implemented code?
Because it feels that the current code fails sometimes only because it uses
an absolute referential for finding the triangles, instead of using various
relative referentials for each relevant section of the geometry. So, by
using multiple referentials, the numerical precision errors could be
minimized/eliminated with some additional heuristic. And without some
paper/text/document as reference for the current code, it will harder to
analyze the current implementation.

Best regards,
Bruno


David Doria-2 wrote:
> 
> On Tue, Aug 10, 2010 at 2:44 PM, Will Schroeder
> <will.schroeder at kitware.com> wrote:
>> Hi Bruno-
>> I'm sorry about your problem with Delaunay2D, although it
>> not totally unexpected. Due to numerical precision, the implemented
>> algorithm can be made to fail. To really fix this we would have to
>> rewrite
>> the algorithm using arbitrary precision methods. (See for
>> example http://www.cs.cmu.edu/~jrs/jrspapers.html as a starting point.)
>> In the short term, you can sometimes work around the algorithm
>> by injecting the points in a different order, e.g., randomizing them or
>> changing into a more spatially dispersed order. Try that and if it
>> doesn't
>> work let me know and we will try to fix the existing code to swallow
>> numerical degeneracies. Then one day will figure out how to get arbitrary
>> precision into these algorithms and do it right...
>> Will
> 
> I submitted a bug the other day that may be related to this?
> 
> http://public.kitware.com/Bug/view.php?id=11102
> 
> Thanks,
> 
> David
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