[vtkusers] How to make the exterior of an image transparent?

[Istvan Matis]

Hi guys,

can somebody tell me how to  make the exterior of an image transparent? I need only the "middle".

Thanks in advance!
Istvan Matis

Below is my code: -I tried to map an image on a plane as a texture. It will generate an error, that it couldn't find any scalar! What is that?

  vtkPlaneSource * tPlaneSource=vtkPlaneSource::New();
  vtkThresholdTextureCoords * thresh=vtkThresholdTextureCoords::New();
  thresh->SetInput((vtkDataSet *)tPlaneSource->GetOutput());
  thresh->ThresholdByUpper(0.5);
  vtkDataSetMapper *tDataSetMapper_Plane=vtkDataSetMapper::New();
  tDataSetMapper_Plane->SetInput(thresh->GetOutput());
  vtkPolyData *temp=tPlaneSource->GetOutput();
  tDataSetMapper_Plane->SetScalarRange(temp->GetScalarRange()); 
  anActor_Reslice->SetMapper(tDataSetMapper_Plane);
  
  vtkTexture * tTexture=vtkTexture::New();
  tTexture->SetInput(anImageReslice-> GetOutput());
  tTexture->InterpolateOn();
  anActor_Reslice->SetTexture(tTexture);        //nothing will happen, image will be "black", error will be generated
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