[vtkusers] casting?? (vtkImageData* -> vtkDataSet*)

[Christos Panagiotou]

hi guys

i am getting a compilation error at the following block of code:

  //read the data from the files
  vtkImageReader2 *reader1 = vtkImageReader2::New();
 
  reader1->SetFileDimensionality(2);
  reader1->SetNumberOfScalarComponents(1);
  reader1->SetFilePrefix("/home/christos/VIVE02/data/countour1/ABDL 
15436 one contour");
  //reader1->SetFilePrefix("/home/christos/VIVE02/data/data1/ABDL 14427 
binary.lhd/ABDL14427");
  reader1->SetFilePattern("%s.l%.2d");
  //reader1->SetFilePattern("%s.L%.2d");
  reader1->SetDataByteOrderToBigEndian();
  
reader1->SetDataScalarTypeToUnsignedChar();                                                      
  reader1->SetDataExtent(0,245,0,245,0,78);
  reader1->SetDataSpacing(1.1211,1.1211,2.5);
  reader1->SetDataOrigin(0, 0, 0);
                      
  //rendering stuff
  vtkContourFilter *dataExtractor = vtkContourFilter::New();
  dataExtractor->SetInput(reader1->GetOutput());

  vtkPolyDataNormals *dataNormals = vtkPolyDataNormals::New();
  dataNormals-> SetInput(dataExtractor->GetOutput());
  dataNormals->SetFeatureAngle(60.0);

  vtkPolyDataMapper *dataMapper = vtkPolyDataMapper::New(); *//LINE 88*
  dataMapper->SetInput(dataNormals->GetOutput());
  dataMapper->ScalarVisibilityOff();



the compilation error is the following:


asm3d_rawloader.cpp: In member function `void asm3D_RawLoader::reader()':
asm3d_rawloader.cpp:81: no matching function for call to 
`vtkContourFilter::
SetInput(vtkImageData*)'
/usr/include/vtk/vtkDataSetToPolyDataFilter.h:44: candidates are: 
virtual void
vtkDataSetToPolyDataFilter::SetInput(vtkDataSet*)

do I have to cast the reader1->GetOutput() to type vtkImageData*?
is there another way to do this?
i ve tried casting... it compiled but then it has thrown an error at the 
next block of code during run time
(error follows)

runtime error:

ERROR: In /home/bellet/rpm/BUILD/VTK/Graphics/vtkPolyDataNormals.cxx, 
line 88
vtkPolyDataNormals (0x80c2710): No data to generate normals for!

so i am thinking if by casting the vtkImageData* to vtkDataSet its 
causing it to throw this error...
i would appreciate any help
christos