Function GetHomogeneousMatrix

Examples/ConvertTransformFile.cxx:162–258

 */
template <typename TTransform, typename TMatrix>
bool
GetHomogeneousMatrix(const typename TTransform::Pointer & transform, TMatrix & hMatrix, bool outputRAS)
{
  const unsigned int ImageDimension = TTransform::InputSpaceDimension;

  using ScalarType = typename TTransform::ScalarType;

  hMatrix.Fill(itk::NumericTraits<ScalarType>::ZeroValue());

  bool done = false;

  // Get the NxN matrix
  typename TTransform::MatrixType matrix;
  if (!GetMatrix<TTransform>(transform, matrix, outputRAS))
  {
    return false;
  }
  for (unsigned int i = 0; i < ImageDimension; i++)
  {
    for (unsigned int j = 0; j < ImageDimension; j++)
    {
      hMatrix(i, j) = matrix(i, j);
    }
  }

  // Set the lower-right corner to 1
  unsigned int corner = ImageDimension;
  hMatrix(corner, corner) = itk::NumericTraits<typename TTransform::ScalarType>::OneValue();

  //
  // Get the offset
  //

  // Identity
  {
    using CastTransformType = itk::IdentityTransform<ScalarType, ImageDimension>;
    typename CastTransformType::Pointer castTransform = dynamic_cast<CastTransformType *>(transform.GetPointer());

    if (castTransform.IsNotNull())
    {
      // Nothing more to do here.
      return true;
    }
  }

  typename TTransform::OutputVectorType offset;
  offset.Fill(itk::NumericTraits<typename TTransform::ScalarType>::ZeroValue());

  // Matrix-offset derived
  {
    using CastTransformType = itk::MatrixOffsetTransformBase<ScalarType, ImageDimension, ImageDimension>;
    typename CastTransformType::Pointer castTransform = dynamic_cast<CastTransformType *>(transform.GetPointer());

    if (castTransform.IsNotNull())
    {
      offset = castTransform->GetOffset();
      done = true;
    }