AW: [vtkusers] Urgent!how to get data about cells,points and data attributes of vtkPolyData

[Hendrik Belitz]

Hi Gao,

After

>    skinExtractor->SetInputConnection(v16->GetOutputPort());
>    skinExtractor->SetValue(0, 500);

you need to call skinExtractor->Update() to actually run the filter. Otherwise

>   vtkPolyData *td= skinExtractor->GetOutput();

just returns an empty vtkPolyData object, since no processing has occured.

hope this helps,
 Hendrik




>Dear all,
>      I am using the sample Medical.cxx ,which is in the 
>Examples\Medical\Cxx in vtk-5.0.0.zip. I need to write the data about cells 
>, points and data attributes of  vtkPolyData to a file in server side, and 
>then read these data from the file to rebuild the objects of same 
>vtkPolyData in client side.I do not know which member functions of the 
>classe vtkPolyData I could use to read these data about cells,point ,data 
>attribute of dataset. the snippet of Medical.cxx is as follows.
>
>vtkVolume16Reader *v16 = vtkVolume16Reader::New();
>    v16->SetDataDimensions (64,64);
>    v16->SetImageRange (1,93);
>    v16->SetDataByteOrderToLittleEndian();
>    v16->SetFilePrefix (argv[1]);
>    v16->SetDataSpacing (3.2, 3.2, 1.5);
>
>  vtkContourFilter *skinExtractor = vtkContourFilter::New();
>    skinExtractor->SetInputConnection(v16->GetOutputPort());
>    skinExtractor->SetValue(0, 500);
>   vtkPolyData *td= skinExtractor->GetOutput();
>
>I need to get data about cells,points and data attributes of object td.So  I 
>wrote:
>    vtkPoints* pt=td->GetPoints();
>But I found pt is NULL.
>
>When I wrote:
>     vtkCellArray *vert=td->GetVerts();
>     vtkCellArray *poly=td->GetPolys();
>     vtkCellArray *line=td->GetLines();
>     vtkCellArray *strip=td->GetStrips();
>    cout <<"numofvert="<<vert->GetSize()<<endl;
>      cout <<"numofpoly="<<poly->GetNumberOfCells()<<endl;
>    cout <<"numofline="<<line->GetNumberOfCells()<<endl;
>     cout <<"numofstrip="<<strip->GetNumberOfCells()<<endl;
>
>All the printed results are 0.
>
>I am confused.Is there anyone who could help me?Many thanks in advance.
>
>Gao Shu
>
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