[vtkusers] How to extract area of (triangle) Cells?

[Bill Lorensen]

Vince,

I think the code is fine. The bug was in the user's code.

Sorry for the noise,

Bill

On Fri, Dec 18, 2009 at 11:32 AM, Magnotta, Vincent A
<vincent-magnotta at uiowa.edu> wrote:
> The quality array is set near line 730 in my version of vtkMeshQuality
> (5.2). It appears that the quality->Delete(); method should be removed from
> line 445 and moved to line 745.
>
> Vince
>
>
> ----------------------
> Associate Professor
> Department of Radiology
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> E-mail: vincent-magnotta at uiowa.edu
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>
>
>
> -----Original Message-----
> From: vtkusers-bounces at vtk.org on behalf of Bill Lorensen
> Sent: Fri 12/18/2009 10:01 AM
> To: David Doria
> Cc: vtkusers at vtk.org
> Subject: Re: [vtkusers] How to extract area of (triangle) Cells?
>
> David,
>
> I looked at the source for vtkMeshQuality and I think you have
> uncovered a bug. I see vtkDoubleArray named "Quality" added to the
> cell data, but I do not see where any data is added to the array.
>
> I noticed that that Graphics/Texting/Cxx/MeshQuality does not access
> the CellData.
>
> If it's not tested it's broken,
>
> Bill
>
> On Fri, Dec 18, 2009 at 8:10 AM, David Doria <daviddoria+vtk at gmail.com>
> wrote:
>> On Thu, Dec 17, 2009 at 11:14 AM, Bryn Lloyd <blloyd at vision.ee.ethz.ch>
>> wrote:
>>>
>>> David,
>>>
>>> Not sure, but it works in paraview doesn't it?
>>>
>>> 1. Maybe inverted triangles (there was an issue in the past with inverted
>>> tets).
>>>
>>> 2. Maybe you don't have triangles, but strips?
>>>
>>> /Bryn
>>>
>>
>> Bryn,
>> Hmm, I tried it with a sphere source run through vtkTriangleFilter. This
>> should produce good triangles, right?
>>   vtkSmartPointer<vtkSphereSource> sphereSource =
>> vtkSmartPointer<vtkSphereSource>::New();
>>   sphereSource->Update();
>>
>>   vtkSmartPointer<vtkTriangleFilter> triangleFilter =
>> vtkSmartPointer<vtkTriangleFilter>::New();
>>   triangleFilter->SetInputConnection(sphereSource->GetOutputPort());
>>   triangleFilter->Update();
>>
>>   //vtkPolyData* mesh = sphereSource->GetOutput();
>>   vtkPolyData* mesh = triangleFilter->GetOutput();
>>   cout << "There are " << mesh->GetNumberOfCells() << " cells." << endl;
>>
>>   vtkSmartPointer<vtkMeshQuality> qualityFilter =
>> vtkSmartPointer<vtkMeshQuality>::New();
>>   qualityFilter->SetInput(mesh);
>>   qualityFilter->SetTriangleQualityMeasureToArea();
>>   qualityFilter->Update();
>>
>>   vtkDataSet* qualityMesh = qualityFilter->GetOutput();
>>   vtkSmartPointer<vtkDoubleArray> qualityArray =
>>
>> vtkDoubleArray::SafeDownCast(qualityMesh->GetCellData()->GetArray("Quality"));
>>
>>   cout << "There are " << qualityArray->GetNumberOfTuples() << " values."
>> <<
>> endl;
>>
>>   for(unsigned int i = 0; i < qualityArray->GetNumberOfTuples(); i++)
>>     {
>>     double val;
>>     qualityArray->GetValue(i);
>>     cout << "value " << i << " : " << val << endl;
>>     }
>> The output is still
>> ...
>> value 90 : 5.77804e-269
>> value 91 : 5.77804e-269
>> value 92 : 5.77804e-269
>> ...
>> Any thoughts?
>> Thanks,
>>
>> David
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