[Insight-users] a question about using itkImageToVTKImageFilter

[Karthik Krishnan]

LI XIN wrote:

>Hello, insight users
>
>I have a question when I use itkImageToVTKImageFilter.
>  
>
This class propagates its metadata (spacing info) etc via callbacks 
which *will not* be triggered unless you make an Update() call... You 
were just missing the line

connector->Update();

[The image itself is available since it is passed around as a raw pointer.]

HTH
karthik

>I tried to use itkImageFileReader to read a 3D raw image file, change it to VTK image data using itkImageToVTKImageFilter, and then display one slice of the image using vtkImageViewer. But the slice could not be displayed properly. 
>
>I found that the data spacing are 1 ,1 ,1 and the dimensions are 0 , -1 , 0 after ITK image data changed to VTK image data.
>
>My code is:
>
>                     typedef float     PixelType;
>	const   unsigned int   Dimension = 3;
>
>	typedef itk::Image< PixelType, Dimension >   ImageType;
>	typedef itk::ImageFileReader< ImageType >    ReaderType;
>	typedef itk::RawImageIO<PixelType, Dimension>	ImageIOType;
>	typedef itk::ImageToVTKImageFilter< ImageType > ConnectorType;
>
>	ReaderType::Pointer reader = ReaderType::New();
>	ImageIOType::Pointer rawIO = ImageIOType::New();
>	ConnectorType::Pointer connector = ConnectorType::New();
>	
>	reader->SetImageIO(rawIO);
>	reader->SetFileName( "brain.raw" );
>
>	rawIO->SetFileDimensionality(3);
>                     rawIO->SetOrigin(0,0.0);
>	rawIO->SetOrigin(1,0.0);
>	rawIO->SetOrigin(2,0.0);
>
>	rawIO->SetDimensions(0,256);
>	rawIO->SetDimensions(1,256);
>	rawIO->SetDimensions(2,50);
>
>	rawIO->SetSpacing(0,0.9609375);
>	rawIO->SetSpacing(1,0.9609375);
>	rawIO->SetSpacing(2,2.2);
>
>	try
>	{
>		reader->Update();
>	}
>	catch (itk::ExceptionObject & err)
>	{
>		cout << "ExceptionObject caught!" << endl;
>		cout << err << endl;
>		return -1;
>	}
>                     
>                    connector->SetInput(reader->GetOutput());
>
>                    vtkImageViewer *viewer=vtkImageViewer::New();
>	vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
>
>	viewer->SetInput(connector->GetOutput());
>
>	float max=(((vtkDataSet *)(connector->GetOutput()))->GetScalarRange())[1];
>
>	viewer->SetZSlice(10);
>	viewer->SetColorWindow(max);
>	viewer->SetColorLevel(max/2.0);
>
>	viewer->SetupInteractor(iren);
>	viewer->Render();
>  
>	iren->Initialize();
>	iren->Start();
>
>
>I tried a .png image file and it worked very well. I couldn't find out the reason why the parameters of VTK image data changed. How should I do?
>
>Thank you very much!
>
>xin
>
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