[vtkusers] delaunay3d: degenerate triangles encountered

[Amy Squillacote]

Hi John,

To see which filters are causing problems, you could try first 
creating a simple version of your pipeline -- take out filters until 
you don't get errors. Then add them back in one at a time; when you 
get an error message, you know it's caused by the filter you just added in.

- Amy

At 02:34 PM 8/16/2005, John Harris wrote:
>or maybe its something to do with the normals, I wonder if there is 
>any test that I can do to figure out the problem?
>thanks again  :s
>JH
>
>>From: "John Harris" <lost_bits1110 at hotmail.com>
>>To: vtkusers at vtk.org
>>Subject: Re: [vtkusers] delaunay3d: degenerate triangles encountered
>>Date: Tue, 16 Aug 2005 15:01:23 +0000
>>
>>... so do you think that the problem is the way I read in my mesh? 
>>i.e. the way I create my vtkUnstructuredGrid??
>>Are there any filters I should use that could prevent the problems 
>>I'm getting? :s
>>Any suggestions are appreciated,
>>Thanks again..
>>JH
>>
>>
>>>Subject: Re: [vtkusers] delaunay3d: degenerate triangles encountered
>>>
>>>Thanks all for your responses,
>>>
>>>My data is actually from an unstructured grid which is composed of 
>>>tetrahedra, I then use GeometryFilter to convert the tetrahedra to triangles
>>>
>>>Acutally here is my pipeline:
>>>
>>>         GeometryFilter
>>>         DecimatePro
>>>         PolyDataNormals
>>>         Delaunay3D
>>>
>>>My tolerance is also positive and is set to 0.01.
>>>
>>>I even tried passing my decimate object through 
>>>vtkSmoothPolyDataFilter first as someone had suggested in a 
>>>previous post, but this doesnt solve the problem.
>>>
>>>So not only do I get degenerate triangles, but sometimes my 
>>>program will crash due to " *** glibc detected *** double free or corruption: "
>>>
>>>Here is my exact code:
>>>
>>>         GeometryFilter->SetInput( Ugrid );
>>>         DecimatePro->SetInput( GeometryFilter->GetOutput() );
>>>         DecimatePro->SetTargetReduction( 0.9 );
>>>         DecimatePro->PreserveTopologyOn();
>>>
>>>         PolyDataNormals>SetInput( DecimatePro->GetOutput() );
>>>         PolyDataNormals->ConsistencyOn();
>>>         PolyDataNormals->AutoOrientNormalsOn();
>>>
>>>         Delaunay3D->SetInput( PolyDataNormals->GetOutput() );
>>>         Delaunay3D->SetTolerance (0.01);
>>>         Delaunay3D->SetAlpha(0.0);
>>>         Delaunay3D->BoundingTriangulationOff();
>>>         Delaunay3D->Update();
>>>         Delaunay3D->Modified();
>>>
>>>If anyone has any insight that would be great!!
>>>Thank you!!
>>>JH
>>>
>>>
>>>>From: "Kevin H. Hobbs" <kevin.hobbs.1 at ohiou.edu>
>>>>Reply-To: hobbsk at ohiou.edu
>>>>To: Amy Squillacote <amy.squillacote at kitware.com>
>>>>CC: vtkusers at vtk.org, John Harris <lost_bits1110 at hotmail.com>
>>>>Subject: Re: [vtkusers] delaunay3d: degenerate triangles encountered
>>>>Date: Mon, 15 Aug 2005 12:04:30 -0400
>>>>
>>>>On Mon, 2005-08-15 at 08:47 -0400, Amy Squillacote wrote:
>>>> > The error message is being produced by vtkDelaunay3D.  It probably
>>>> > means you have "triangles" in your data set where at least two of the
>>>> > points in a single triangle are coincident.
>>>> >
>>>> > - Amy
>>>>
>>>>I just got the same error with a positive tolerance. The tolerance
>>>>parameter should discard coincident points.
>>>>
>>>>My data are from a regular lattice and so fit the warning in the
>>>>doxygen.  Are yours?
>>>><< signature.asc >>
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>>>
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>>
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>
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