[vtkusers] vtkContourFilter produces no data as its output

[David Doria]

On Mon, Jan 4, 2010 at 8:14 AM, Bill Lorensen <bill.lorensen at gmail.com> wrote:
> ContourFilter produces isosurfaces from the scalar data in a dataset.
> Your unstructured grid has no scalar data as far as I can see.
>
>
> On Mon, Jan 4, 2010 at 4:56 AM, Rakesh Patil <rakeshthp at in.com> wrote:
>> Hello there
>>
>> After debugging for a long time, i found out that data exists till this part
>> of code
>>
>>
>> vtkPoints *pts = vtkPoints::New();
>> pts->SetData(scatter_data); // scatter_data is an instance of vtkDoubleArray
>> with three components
>>
>> unsigned int num_ids = scatter_data->GetNumberOfTuples();
>>
>> vtkPolyVertex *poly = vtkPolyVertex::New();
>> poly->GetPointIds()->SetNumberOfIds(num_ids);
>>
>> for ( unsigned int i = 0; i < num_ids; i++ )
>> poly->GetPointIds()->SetId(i,i);
>>
>> vtkUnstructuredGrid *ugrid = vtkUnstructuredGrid::New();
>> ugrid->Allocate(1);
>> ugrid->InsertNextCell (poly->GetCellType(), poly->GetP ointIds());
>> ugrid->SetPoints(pts);
>>
>> vtkDelaunay2D *del = vtkDelaunay2D::New();
>> del->SetInput(ugrid);
>> del->SetTolerance(0.001);
>>
>> Once i execute, the following code,
>>
>> vtkContourFilter *cf = vtkContourFilter::New();
>> cf-&g t;SetInputConnection(del->GetOutputPort());
>> cf->GenerateValues(10, -5, 20);
>> cf->Update();
>>
>> all data vanishes..
>>
>> I mean to say that, initially, the grid had, 22,000 points.. After
>> traingulating, i got 20000 of cells..
>>
>> But after executing the contour filter class, i get 0 cells and 0 points as
>> output.. Where the data disappears all of a sudden, i'm not able to
>> understand.. Please i need a guidance from the most experienced and senior
>> person.. My mind is totally blank..
>>
>> Thanks in advance
>>
>>
>>
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As Bill said, the vtkContourFilter does this:
http://www.vtk.org/doc/nightly/html/classvtkContourFilter.html#_details

Maybe you can come up with a very simple data set and describe exactly
what you are expecting to happen and maybe someone can point you to a
filter that does what you're looking for.

Thanks,

David