[vtkusers] the pronlem of blending two volume by vtkImageBlend

[Yuetian Liu]

Hi vtkusers,



I want to blend the two volumes by vtkImageBlend. And I use vtkMetaImageReader to read two volumes(CT and MR)


Then I use the vtkImageBlend to blend two volumes. And then I use the Ray Casting Algorithm to render the two volumes


after blending. But the result has one color. And it is not the result that I want. My hoping result is that the CT volume is


red and the MR volume was blue.


How can I solve it. Please help me. And my code is attached.


Thank you very much!


Bset 
Yuetian


#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkImageData.h>
#include <vtkSmartPointer.h>
#include <vtkImageBlend.h>
#include "vtkMetaImageReader.h"
#include <string>
#include "vtkPiecewiseFunction.h"
#include "vtkColorTransferFunction.h"
#include "vtkVolumeProperty.h"
#include "vtkVolumeRayCastCompositeFunction.h"
#include "vtkVolumeRayCastMapper.h"
#include "vtkVolume.h"
#include "vtkImageCast.h"
#include <vtkLookupTable.h>


int main ( int argc, char* argv[] )
{
  std::string input1Filename = argv[1];
  std::string input2Filename = argv[2];
 
  vtkSmartPointer<vtkMetaImageReader>Reader1 =
    vtkSmartPointer<vtkMetaImageReader>::New();
Reader1->SetFileName ( input1Filename.c_str() );
 
  vtkSmartPointer<vtkMetaImageReader> jReader2 =
    vtkSmartPointer<vtkMetaImageReader>::New();
Reader2->SetFileName ( input2Filename.c_str() );
  vtkSmartPointer<vtkImageBlend> imgBlender = 
 vtkSmartPointer<vtkImageBlend>::New();
  imgBlender->SetOpacity( 0, 0.2 );
  imgBlender->SetOpacity( 1, 0.6 );
  imgBlender->AddInputConnection( Reader1->GetOutputPort() );
  imgBlender->AddInputConnection( Reader2->GetOutputPort() );


 vtkSmartPointer< vtkImageCast> readerImageCast =  
vtkSmartPointer< vtkImageCast>::New();
  readerImageCast->SetInputConnection(imgBlender->GetOutputPort());
  readerImageCast->SetOutputScalarTypeToUnsignedShort ();
  readerImageCast->ClampOverflowOn();


 vtkSmartPointer< vtkPiecewiseFunction> opacityTransferFunction =
  vtkSmartPointer< vtkPiecewiseFunction>::New();
  opacityTransferFunction->AddPoint(20, 0.0);
  opacityTransferFunction->AddPoint(255, 0.8);
 vtkSmartPointer< vtkColorTransferFunction > colorTransferFunction =  
vtkSmartPointer< vtkColorTransferFunction > ::New();
  colorTransferFunction->AddRGBPoint(0,0.9,0.7,0.5);
  colorTransferFunction->AddRGBPoint(15,1,0.7,0.6);
  colorTransferFunction->AddRGBPoint(255,1,0,0);
  vtkSmartPointer<vtkVolumeProperty> volumeProperty = 
  vtkSmartPointer<vtkVolumeProperty>::New();
  volumeProperty->SetColor(colorTransferFunction);
  volumeProperty->SetScalarOpacity(opacityTransferFunction);
  volumeProperty->ShadeOn();
  volumeProperty->SetInterpolationTypeToLinear();
  volumeProperty->SetSpecular(0.1);
  volumeProperty->SetSpecularPower(8); 
  volumeProperty->SetScalarOpacityUnitDistance(0.8919);
  vtkSmartPointer<vtkVolumeRayCastCompositeFunction> compositeFunction =
   vtkSmartPointer<vtkVolumeRayCastCompositeFunction>::New();
 vtkSmartPointer< vtkVolumeRayCastMapper> volumeMapper =
  vtkSmartPointer< vtkVolumeRayCastMapper> ::New(); 
  volumeMapper->SetVolumeRayCastFunction(compositeFunction); 
  volumeMapper->SetInputConnection(readerImageCast->GetOutputPort());
  volumeMapper->SetNumberOfThreads(3);
  vtkSmartPointer<vtkVolume> volume =
   vtkSmartPointer<vtkVolume>::New();
  volume->SetMapper(volumeMapper);
  volume->SetProperty(volumeProperty);


  vtkSmartPointer<vtkRenderer> renderer =
 vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
 vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
 vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);
  renderer->AddVolume(volume);
  renderWindow->Render();
  renderWindowInteractor->Start();
  return EXIT_SUCCESS;
}





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