Affine Transform Parameter Order

AffineTtransformParameterOrder.cxx

#include "itkAffineTransform.h"
#include "itkTransformFileWriter.h"

int main( int argc, char * argv[] )
{
  if( argc < 2 )
    {
    std::cerr << "Usage: "
              << argv[0]
              << " outputTransform"
              << std::endl;
    return EXIT_FAILURE;
    }
  const char * outputTransformFile = argv[1];

  const unsigned int Dimension = 3;
  typedef float ScalarType;

  typedef itk::Matrix< ScalarType, Dimension + 1, Dimension + 1 > MatrixType;
  MatrixType matrix4x4;
  for( unsigned int ii = 0; ii < 3; ++ii )
    {
    for( unsigned int jj = 0; jj < 4; ++jj )
      {
      matrix4x4[ii][jj] = ii * 4 + jj + 1;
      }
    }
  for( unsigned int ii = 0; ii < 3; ++ii )
    {
    matrix4x4[3][ii] = 0;
    }
  matrix4x4[3][3] = 1;
  std::cout << "matrix4x4: " << matrix4x4 << std::endl;

  typedef itk::Point< ScalarType, Dimension + 1 > ExtendedPointType;
  ExtendedPointType extendedPoint;
  extendedPoint[0] = 3.3;
  extendedPoint[1] = 2.8;
  extendedPoint[2] = -4.7;
  extendedPoint[3] = 1.0;
  std::cout << "extendedPoint: " << extendedPoint << std::endl;

  const ExtendedPointType transformedExtendedPoint = matrix4x4 * extendedPoint;
  std::cout << "transformedExtendedPoint: " << transformedExtendedPoint << std::endl;


  typedef itk::AffineTransform< ScalarType, Dimension > TransformType;
  TransformType::ParametersType parameters( Dimension * Dimension + Dimension );
  for( unsigned int ii = 0; ii < 3; ++ii )
    {
    for( unsigned int jj = 0; jj < 3; ++jj )
      {
      parameters[ii * 3 + jj] = matrix4x4[ii][jj];
      }
    }
  for( unsigned int ii = 0; ii < 3; ++ii )
    {
    parameters[ii + 9] = matrix4x4[ii][3];
    }
  std::cout << "parameters: " << parameters << std::endl;

  TransformType::Pointer transform = TransformType::New();
  transform->SetParameters( parameters );
  std::cout << "transform: " << transform << std::endl;

  typedef itk::Point< ScalarType, Dimension > PointType;
  PointType point;
  point[0] = extendedPoint[0];
  point[1] = extendedPoint[1];
  point[2] = extendedPoint[2];

  const PointType transformedPoint = transform->TransformPoint( point );
  std::cout << "transformedPoint: " << transformedPoint << std::endl;

  typedef itk::TransformFileWriterTemplate< ScalarType > WriterType;
  WriterType::Pointer writer = WriterType::New();
  writer->SetInput( transform );
  writer->SetFileName( outputTransformFile );

  try
    {
    writer->Update();
    }
  catch( itk::ExceptionObject & err )
    {
    std::cerr << "Error: " << err << std::endl;
    return EXIT_FAILURE;
    }

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required( VERSION 2.8 )

project( AffineTransformParameterOrder )

find_package( ITK REQUIRED )
include( ${ITK_USE_FILE} )

add_executable( ${PROJECT_NAME} ${PROJECT_NAME}.cxx )
target_link_libraries( ${PROJECT_NAME} ${ITK_LIBRARIES} )

include( CTest )
add_test( NAME ${PROJECT_NAME}
  COMMAND ${PROJECT_NAME} ${PROJECT_NAME}.tfm )