[Insight-users] Problem with vtk RayCasting: volume to be of pixel type unsigned char or unsigned short

[sara meghellati]

Hi all,
I have segmented 3D image using region growing method (using itk) and I want to display the original volume(float type) using vtk. I got an error at run time stating that vtk raycasting requires the volume to be of pixel type unsigned char or unsigned short. I'm converting the vtkimport that I use to unsigned char using the function SetDataScalarTypeToChar() but I still get the error.  The code is bellow.
Any help is very appreciated.
Thank you for  your time
Sara
 
 
#include "itkConfidenceConnectedImageFilter.h"
#include "itkImage.h"
#include "itkCastImageFilter.h"
#include "itkCurvatureFlowImageFilter.h"
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkVTKImageExport.h"
#include "itkVTKImageImport.h"
#include "vtkImageImport.h" 
#include "vtkImageExport.h"
#include "vtkImageReader.h"
#include "vtkPiecewiseFunction.h"
#include "vtkVolumeProperty.h"
#include "vtkVolumeRayCastMapper.h"
#include "vtkVolumeTextureMapper3D.h"
#include "vtkFixedPointVolumeRayCastMapper.h"
#include "vtkVolumeRayCastCompositeFunction.h"
#include "vtkVolume.h"
#include "vtkRenderer.h"
#include "vtkRenderWindow.h"
#include "vtkRenderWindowInteractor.h"
// This function will connect the given itk::VTKImageExport filter to the given vtkImageImport filter.
template <typename ITK_Exporter, typename VTK_Importer>
void ConnectPipelines(ITK_Exporter exporter, VTK_Importer* importer)
{
importer->SetUpdateInformationCallback(exporter->GetUpdateInformationCallback());
importer->SetPipelineModifiedCallback(exporter->GetPipelineModifiedCallback());
importer->SetWholeExtentCallback(exporter->GetWholeExtentCallback());
importer->SetSpacingCallback(exporter->GetSpacingCallback());
importer->SetOriginCallback(exporter->GetOriginCallback());
importer->SetScalarTypeCallback(exporter->GetScalarTypeCallback());
importer->SetNumberOfComponentsCallback(exporter->GetNumberOfComponentsCallback());
importer->SetPropagateUpdateExtentCallback(exporter->GetPropagateUpdateExtentCallback());
importer->SetUpdateDataCallback(exporter->GetUpdateDataCallback());
importer->SetDataExtentCallback(exporter->GetDataExtentCallback());
importer->SetBufferPointerCallback(exporter->GetBufferPointerCallback());
importer->SetCallbackUserData(exporter->GetCallbackUserData());
}
int main( )
{
//typedef unsigned short InputPixelType;
typedef float InputPixelType;
typedef unsigned char OutputPixelType;
const unsigned int Dimension = 3;
typedef itk::Image< InputPixelType, Dimension > InputImageType;
typedef itk::Image< OutputPixelType, Dimension > OutputImageType;
typedef itk::CastImageFilter< InputImageType, OutputImageType > CastingFilterType;
typedef itk::ImageFileReader< InputImageType > ReaderType;
typedef itk::ImageFileWriter< OutputImageType > WriterType;
typedef itk::CurvatureFlowImageFilter< InputImageType, InputImageType > CurvatureFlowImageFilterType; 
typedef itk::ConfidenceConnectedImageFilter<InputImageType, InputImageType> ConnectedFilterType;
CastingFilterType::Pointer caster = CastingFilterType::New(); 
ReaderType::Pointer reader = ReaderType::New();
WriterType::Pointer writer = WriterType::New();
CurvatureFlowImageFilterType::Pointer smoothing = CurvatureFlowImageFilterType::New(); 
ConnectedFilterType::Pointer confidenceConnected = ConnectedFilterType::New();

reader->SetFileName( "c:/images/Patient01.mhd" );
writer->SetFileName( "c:/images/3DConfidenceConnectedSegmImg.mhd" );
smoothing->SetInput( reader->GetOutput() );
confidenceConnected->SetInput( smoothing->GetOutput() );
caster->SetInput( confidenceConnected->GetOutput() );
writer->SetInput( caster->GetOutput() );

smoothing->SetNumberOfIterations( 5 );
smoothing->SetTimeStep( 0.125 );

confidenceConnected->SetMultiplier( 2.5 ); 
confidenceConnected->SetNumberOfIterations( 2 );
confidenceConnected->SetReplaceValue( 255 ); 
InputImageType::IndexType index; 
index[0] = atoi( "256" );
index[1] = atoi( "256" );
index[2] = atoi( "16" );
confidenceConnected->SetSeed( index ); 
confidenceConnected->SetInitialNeighborhoodRadius( 2 );
try
{
writer->Update();
}
catch( itk::ExceptionObject & excep )
{
std::cerr << "Exception caught !" << std::endl;
std::cerr << excep << std::endl;
}
//----------------------------------------------
// -------------------- vtk Display----------------
//----------------------------------------------
typedef itk::VTKImageExport< InputImageType > ExportFilterType;
ExportFilterType::Pointer itkExporter = ExportFilterType::New(); 
itkExporter->SetInput(reader->GetOutput()); 
vtkImageImport* vtkImporter = vtkImageImport::New(); 
ConnectPipelines(itkExporter, vtkImporter);
vtkImporter->SetDataScalarTypeToUnsignedChar();

// Define opacity transfer function
vtkPiecewiseFunction *opacityTransferFunction = vtkPiecewiseFunction::New();
vtkVolume *volume = vtkVolume::New();
vtkVolumeProperty *volumeProperty = vtkVolumeProperty::New();
vtkVolumeRayCastMapper *VolumeMapper = vtkVolumeRayCastMapper::New();
vtkVolumeRayCastCompositeFunction *RayCastFunction =vtkVolumeRayCastCompositeFunction::New();

// Volume property 
opacityTransferFunction->AddPoint(0,0.001);
opacityTransferFunction->AddPoint(255,0.2);
volumeProperty->SetScalarOpacity(opacityTransferFunction);
volumeProperty->SetInterpolationTypeToLinear();
volumeProperty->ShadeOff();
// Volume mapper
VolumeMapper->SetVolumeRayCastFunction(RayCastFunction);
VolumeMapper->SetSampleDistance(1.0);
VolumeMapper->SetBlendModeToMaximumIntensity();
VolumeMapper->SetInput(vtkImporter->GetOutput() ); 

// The volume 
volume->SetMapper(VolumeMapper);
volume->SetProperty(volumeProperty);

// Create a renderer, render window, and render window interactor to display the results.
vtkRenderer *Renderer = vtkRenderer::New();
vtkRenderWindow *RenWin = vtkRenderWindow::New();
vtkRenderWindowInteractor *RenWinInterc = vtkRenderWindowInteractor::New();
RenWin->AddRenderer(Renderer);
RenWinInterc->SetRenderWindow(RenWin);
Renderer->AddVolume(volume);
Renderer->SetBackground(1,1,1);
RenWin->Render();
RenWinInterc->Initialize();
RenWinInterc->Start();
// Release all VTK components
RenWinInterc->Delete();
RenWin->Delete(); 
Renderer->Delete();
volume->Delete();
VolumeMapper->Delete();
volumeProperty->Delete();
opacityTransferFunction->Delete();
 
return 0;
}


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