itkBSplineDeformableTransformInitializer.txx

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/*===================================================================

The Medical Imaging Interaction Toolkit (MITK)

Copyright (c) German Cancer Research Center,
Division of Medical and Biological Informatics.
All rights reserved.

This software is distributed WITHOUT ANY WARRANTY; without
even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE.

See LICENSE.txt or http://www.mitk.org for details.

===================================================================*/

/*===================================================================

This file is based heavily on a corresponding ITK filter.

===================================================================*/

#ifndef __itkBSplineDeformableTransformInitializer_txx
#define __itkBSplineDeformableTransformInitializer_txx

#include "itkBSplineDeformableTransformInitializer.h"

namespace itk
{
  template <class TTransform, class TImage>
  BSplineDeformableTransformInitializer<TTransform, TImage>::BSplineDeformableTransformInitializer()
  {
    this->m_GridSizeInsideTheImage.Fill(5);
  }

  template <class TTransform, class TImage>
  void BSplineDeformableTransformInitializer<TTransform, TImage>::InitializeTransform() const
  {
    // Sanity check
    if (!this->m_Image)
    {
      itkExceptionMacro("Reference Image has not been set");
      return;
    }

    if (!this->m_Transform)
    {
      itkExceptionMacro("Transform has not been set");
      return;
    }

    // If the image come from a filter, then update that filter.
    if (this->m_Image->GetSource())
    {
      this->m_Image->GetSource()->Update();
    }

    typedef typename TransformType::RegionType RegionType;

    typename RegionType::SizeType numberOfGridNodesOutsideTheImageSupport;
    typename RegionType::SizeType totalGridSize;

    numberOfGridNodesOutsideTheImageSupport.Fill(TransformType::SplineOrder);

    totalGridSize = this->m_GridSizeInsideTheImage;
    totalGridSize += numberOfGridNodesOutsideTheImageSupport;

    RegionType gridRegion;
    gridRegion.SetSize(totalGridSize);

    typedef typename TransformType::SpacingType SpacingType;
    const SpacingType &imageSpacing = this->m_Image->GetSpacing();

    typedef typename TransformType::OriginType OriginType;
    const OriginType &imageOrigin = this->m_Image->GetOrigin();
    ;

    const typename TransformType::RegionType &imageRegion = this->m_Image->GetLargestPossibleRegion();

    typename ImageType::SizeType fixedImageSize = imageRegion.GetSize();

    SpacingType gridSpacing;
    SpacingType gridOriginShift;

    const unsigned int orderShift = TransformType::SplineOrder / 2;

    for (unsigned int r = 0; r < SpaceDimension; r++)
    {
      const unsigned int numberOfGridCells = this->m_GridSizeInsideTheImage[r] - 1;
      const unsigned int numberOfImagePixels = fixedImageSize[r];

      gridSpacing[r] =
        imageSpacing[r] * static_cast<double>(numberOfImagePixels) / static_cast<double>(numberOfGridCells);

      // Shift half image pixel to cover the image support
      const double imageSupportShift = -imageSpacing[r] / 2.0;

      // Shift by the number of extra grid cells required by
      // the BSpline order.
      const double gridSupportShift = -1.0 * gridSpacing[r] * orderShift;

      // Combine both shifts. They are both aligned with the coordinate
      // system of the grid. Direction has not been considered so far.
      gridOriginShift[r] = gridSupportShift + imageSupportShift;
    }

    typename ImageType::DirectionType gridDirection = this->m_Image->GetDirection();
    SpacingType gridOriginOffset = gridDirection * gridOriginShift;

    OriginType gridOrigin = imageOrigin + gridOriginOffset;

    this->m_Transform->SetGridRegion(gridRegion);
    this->m_Transform->SetGridOrigin(gridOrigin);
    this->m_Transform->SetGridSpacing(gridSpacing);
    this->m_Transform->SetGridDirection(gridDirection);
  }

  template <class TTransform, class TImage>
  void BSplineDeformableTransformInitializer<TTransform, TImage>::PrintSelf(std::ostream &os, Indent indent) const
  {
    Superclass::PrintSelf(os, indent);

    os << indent << "Transform   = " << std::endl;
    if (this->m_Transform)
    {
      os << indent << this->m_Transform << std::endl;
    }
    else
    {
      os << indent << "None" << std::endl;
    }

    os << indent << "Image   = " << std::endl;
    if (this->m_Image)
    {
      os << indent << this->m_Image << std::endl;
    }
    else
    {
      os << indent << "None" << std::endl;
    }
  }

} // namespace itk

#endif