[Insight-users] Attempt to rotate image resulting in black image.

[Michael Jackson]

Just to follow up with this, If I force my origins to be (0,0) then  
the rotation seems to work. So I guess I am not understanding what  
exactly the origins are? I have reread through several sections of the  
ITK guide and I thought I had it figured out. The origins of where the  
image is taken is actually stored in our data files so I just thought  
I would use that. The values are in Microns and are typically around  
the 48,000 to 50,000 range.

Is there an implicit units (like mm) in vtkImage that I don't know  
about? I just can not get this figured out.

  Explanations are truly appreciated at this point.

_________________________________________________________
Mike Jackson                  mike.jackson at bluequartz.net
BlueQuartz Software                    www.bluequartz.net
Principal Software Engineer                  Dayton, Ohio



On Jun 3, 2009, at 5:50 PM, Michael Jackson wrote:

> I am trying to rotate an image about the "upper left" corner. I had  
> to write my own ImageSource derived class to read the data from and  
> HDF5 file. I am pretty sure the "Hdf5 reader" works as I can create  
> the ImageReader instance from it, read an image and write the image  
> to disk as a tiff file.
>
>  Where my code seems to be failing is in the application of an  
> AffineTransformFilter. I am basically taking the code straight from  
> one of the examples adapting it to use my ImageSource derived reader  
> and running it. And I get the dreaded "black image". Here is the  
> code and the output from the program. Oddly, if I switch the reader  
> back to the usual ImageFileReader and read up a tiff image I get the  
> correct result, so maybe my custom reader class is not quite correct?
>
>
> #define USE_MXA_FILE 1
> int main(int argc, char **argv) {
>  int exampleAction =0;
>  const     unsigned int   Dimension = 2;
>  typedef   unsigned char  InputPixelType;
>  typedef   unsigned char  OutputPixelType;
>
>  typedef itk::Image< InputPixelType,  Dimension >   InputImageType;
>  typedef itk::Image< OutputPixelType, Dimension >   OutputImageType;
>
> #if USE_MXA_FILE
>  typedef itkR3DImageIO  ReaderType;
> #else
>  typedef itk::ImageFileReader< InputImageType >  ReaderType;
> #endif
>  typedef itk::ImageFileWriter< OutputImageType >  WriterType;
>
>  ReaderType::Pointer reader = ReaderType::New();
>  WriterType::Pointer writer = WriterType::New();
>
>  reader->SetFileName( argv[1] );
> #if USE_MXA_FILE
>  reader->SetDatasetPath(argv[2]);
> #endif
>  reader->Update();
>  writer->SetFileName( argv[3]);
>  typedef itk::ResampleImageFilter<InputImageType, OutputImageType >   
> FilterType;
>  FilterType::Pointer filter = FilterType::New();
>  typedef itk::AffineTransform< double, Dimension >  TransformType;
>  TransformType::Pointer transform = TransformType::New();
>
>  typedef  
> itk::NearestNeighborInterpolateImageFunction<InputImageType, double  
> >  InterpolatorType;
>  InterpolatorType::Pointer interpolator = InterpolatorType::New();
>  filter->SetInterpolator( interpolator );
>  filter->SetDefaultPixelValue( 0 );
>  const InputImageType::SpacingType& spacing = reader->GetOutput()- 
> >GetSpacing();
>  const InputImageType::PointType& origin = reader->GetOutput()- 
> >GetOrigin();
>  InputImageType::SizeType size = reader->GetOutput()- 
> >GetLargestPossibleRegion().GetSize();
>  filter->SetOutputOrigin( origin );
>  filter->SetOutputSpacing( spacing );
>  filter->SetSize( size );
>
>  filter->SetInput( reader->GetOutput() );
>  writer->SetInput( filter->GetOutput() );
>
>  std::cout << "Input Size: " << size[0] << "," << size[1] <<  
> std::endl;
>  std::cout << "Input Origin: " << origin[0] << "," << origin[1] <<  
> std::endl;
>  std::cout << "Input Spacing: " << spacing[0] << "," << spacing[1]  
> << std::endl;
>
>  TransformType::OutputVectorType translation1;
>  translation1[0] =   -origin[0];
>  translation1[1] =   -origin[1];
>  transform->Translate( translation1 );
>
>  const double degreesToRadians = atan(1.0) / 45.0;
>  transform->Rotate2D( -10.0 * degreesToRadians, false );
>
>  TransformType::OutputVectorType translation2;
>  translation2[0] =   origin[0];
>  translation2[1] =   origin[1];
>  transform->Translate( translation2, false );
>  filter->SetTransform( transform );
>  try
>    {
>    writer->Update();
>    }
>  catch( itk::ExceptionObject & excep )
>    {
>    std::cerr << "Exception caught !" << std::endl;
>    std::cerr << excep << std::endl;
>    }
>
>  return EXIT_SUCCESS;
> }
>
>
> output:
> GenerateData()
> GenerateData()
> Input Size: 1292,968
> Input Origin: 46978.9,48347.8
> Input Spacing: 0.207987,0.207987
> GenerateData()
>
> Any help would be great.
> _________________________________________________________
> Mike Jackson                  mike.jackson at bluequartz.net
> BlueQuartz Software                    www.bluequartz.net
> Principal Software Engineer                  Dayton, Ohio
>
>
>