itkIdentityTransform.h

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

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkIdentityTransform.h,v $
  Language:  C++
  Date:      $Date: 2009-04-09 09:23:21 $
  Version:   $Revision: 1.18 $

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even 
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/
#ifndef __itkIdentityTransform_h
#define __itkIdentityTransform_h

#include "itkObject.h"
#include "itkPoint.h"
#include "itkVector.h"
#include "itkCovariantVector.h"
#include "vnl/vnl_vector_fixed.h"
#include "itkArray.h"
#include "itkArray2D.h"
#include "itkTransform.h"

#include "itkObjectFactory.h"


namespace itk
{
  
template <class TScalarType,
          unsigned int NDimensions=3>
class ITK_EXPORT  IdentityTransform  : public Transform<TScalarType,NDimensions,NDimensions>
{
public:
  typedef IdentityTransform                                 Self;
  typedef Transform<TScalarType,NDimensions,NDimensions>    Superclass;
  typedef SmartPointer< Self >                              Pointer;
  typedef SmartPointer< const Self >                        ConstPointer;

  itkNewMacro(Self);

  itkTypeMacro( IdentityTransform, Transform );

  itkStaticConstMacro(InputSpaceDimension, unsigned int, NDimensions);
  itkStaticConstMacro(OutputSpaceDimension, unsigned int, NDimensions);

  typedef  TScalarType     ScalarType;

  typedef  typename Superclass::ParametersType                 ParametersType;

  typedef  typename Superclass::JacobianType                   JacobianType;

  typedef Vector<TScalarType,
                itkGetStaticConstMacro(InputSpaceDimension)>  InputVectorType;
  typedef Vector<TScalarType,
                itkGetStaticConstMacro(OutputSpaceDimension)> OutputVectorType;

  typedef CovariantVector<TScalarType,
                          itkGetStaticConstMacro(InputSpaceDimension)>  InputCovariantVectorType;
  typedef CovariantVector<TScalarType,
                          itkGetStaticConstMacro(OutputSpaceDimension)> OutputCovariantVectorType;

  typedef vnl_vector_fixed<TScalarType,
                           itkGetStaticConstMacro(InputSpaceDimension)>  InputVnlVectorType;
  typedef vnl_vector_fixed<TScalarType,
                           itkGetStaticConstMacro(OutputSpaceDimension)> OutputVnlVectorType;

  typedef Point<TScalarType,
                itkGetStaticConstMacro(InputSpaceDimension)> InputPointType;
  typedef Point<TScalarType,
                itkGetStaticConstMacro(OutputSpaceDimension)> OutputPointType;

  typedef typename Superclass::InverseTransformBaseType InverseTransformBaseType;
  typedef typename InverseTransformBaseType::Pointer    InverseTransformBasePointer;

  virtual OutputPointType TransformPoint(const InputPointType  &point ) const
    { return point; }

  virtual OutputVectorType TransformVector(const InputVectorType &vector) const
    { return vector; }

  virtual OutputVnlVectorType TransformVector(const InputVnlVectorType &vector) const
    { return vector; }

  virtual OutputCovariantVectorType TransformCovariantVector(
    const InputCovariantVectorType &vector) const
    { return vector; }

  void SetIdentity( void ) { }


  virtual void SetParameters(const ParametersType &) {};

  virtual const JacobianType & GetJacobian(const InputPointType  & ) const
    { 
    return this->m_Jacobian;
    }

  virtual InverseTransformBasePointer GetInverseTransform() const
    {
    return this->New().GetPointer();
    }

  virtual bool IsLinear() const { return true; }

protected:
  IdentityTransform():Transform<TScalarType,NDimensions,NDimensions>(NDimensions,1) 
    {
    // The Jacobian is constant, therefore it can be initialized in the constructor.
    this->m_Jacobian = JacobianType(NDimensions,1); 
    this->m_Jacobian.Fill(0.0); 
    } 
  virtual ~IdentityTransform() {}

private:
  IdentityTransform(const Self&); //purposely not implemented
  void operator=(const Self&); //purposely not implemented
};

} // end namespace itk

#endif

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