[vtkusers] Re: file format conversion (XML <-> simple legacy format)

[Amy Squillacote]

Hi Martin,

You need to get all the array data into your vtkUnstructuredGrid 
before you write it out. The easiest solution is to read your data 
with vtkPDataSetReader (in VTK/Parallel). With this reader, you don't 
have to specify which array name is "scalars", "vectors", etc; all 
the arrays in the data file are read and added to your data set. Once 
your vtkUnstructuredGrid has all the arrays, then you should have no 
trouble writing out the data using the vtkXMLUnstructuredGridWriter.

- Amy

At 06:04 PM 5/25/2006, Martin Baumann wrote:
>Hi Amy,
>
>as I read legacy files and write xml files this is good news.
>I still cannot see a function that lets me append data on a xml file.
>
>   vtkXMLUnstructuredGridWriter* _xml_grid_writer = 
> vtkXMLUnstructuredGridWriter::New();
>
>   _grid_reader->SetScalarsName("Data1");
>   _grid_reader->Update();
>
>   _xml_grid_writer->SetFileName("camenbert.hvs.xml");
>   _xml_grid_writer->SetInput(_grid_reader->GetOutput());
>   _xml_grid_writer->SetDataModeToAscii();
>   _xml_grid_writer->Write();
>
>   _grid_reader->SetScalarsName("Data2");
>   _grid_reader->Update();
>
>   _xml_grid_writer->Write(); // WRONG
>
>By the last command the file is overwritten and only contains Data2.
>How can the data be appended to the file?
>
>Regards, M.B.
>
>
>Amy Squillacote schrieb:
>>Hi M.B.,
>>
>>Using the legacy VTK writers (e.g., vtkPolyDataWriter, 
>>vtkUnstructuredGridWriter, etc.), if you want to have more than one 
>>scalar, vector, etc. array, arrays beyond the first one must be 
>>stored in field data. Try calling GetNumberOfFieldDataInFile(); it 
>>should account for your "missing" arrays.
>>
>>(At the time these writers were written, this mirrored the 
>>structure of vtkPointData / vtkCellData.) Using the VTK XML 
>>writers, you can certainly store more than one of any given type of array.
>>
>>- Amy
>>
>>At 01:20 PM 5/25/2006, Martin Baumann wrote:
>>>Is it generally possible to save more than one scalar / vector 
>>>into one file using vtk's writers?
>>>It seems to me as if one could only save ONE scalar / vector.
>>>
>>>Regards, M.B.
>>>
>>>
>>>Martin Baumann schrieb:
>>>
>>>>Hi,
>>>>
>>>>I just realized, that I have the same problem using 
>>>>vtkUnstructuredGridReader and vtkUnstructuredGridWriter:
>>>>
>>>>  // read orginal file
>>>>  vtkUnstructuredGridReader*    _grid_reader      = 
>>>> vtkUnstructuredGridReader::New();
>>>>  _grid_reader->SetFileName(in_file.c_str());
>>>>  _grid_reader->Update();
>>>>  cout << "#Points : " << 
>>>> _grid_reader->GetOutput()->GetNumberOfPoints() << endl;
>>>>  cout << "#Scalars: " << 
>>>> _grid_reader->GetNumberOfScalarsInFile() << endl;
>>>>
>>>>  // writer new file
>>>>  vtkUnstructuredGridWriter* _grid_writer  = 
>>>> vtkUnstructuredGridWriter::New();
>>>>  _grid_writer->SetFileName("camembert.new.hvs");
>>>>  _grid_writer->SetInput(_grid_reader->GetOutput());
>>>>  _grid_writer->Write();
>>>>
>>>>  // read new file
>>>>  _grid_reader->SetFileName("camembert.new.hvs");
>>>>  _grid_reader->Update();
>>>>  cout << "#Points : " << 
>>>> _grid_reader->GetOutput()->GetNumberOfPoints() << endl;
>>>>  cout << "#Scalars: " << 
>>>> _grid_reader->GetNumberOfScalarsInFile() << endl;
>>>>
>>>>
>>>>This makes the following output:
>>>>
>>>>  #Points : 400
>>>>  #Scalars: 3
>>>>  #Points : 400
>>>>  #Scalars: 1
>>>>
>>>>Hmmm....
>>>>
>>>>Regards, M.B.
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