#include <itkLandmarkBasedTransformInitializer.h>

Detailed Description

template<typename TTransform, typename TFixedImage = itk::ImageBase<TTransform::InputSpaceDimension>, typename TMovingImage = itk::ImageBase<TTransform::OutputSpaceDimension>>
class itk::LandmarkBasedTransformInitializer< TTransform, TFixedImage, TMovingImage >

This class computes the transform that aligns the fixed and moving images given a set of pair landmarks. The class is templated over the Transform type as well as fixed image and moving image types. The transform computed gives the best fit transform that maps the fixed and moving images in a least squares sense. The indices are taken to correspond, so point 1 in the first set will get mapped close to point 1 in the second set, etc.

Currently, the following transforms are supported by the class: VersorRigid3DTransform Similarity3DTransform Rigid2DTransform AffineTransform BSplineTransform

An equal number of fixed and moving landmarks need to be specified using SetFixedLandmarks() and SetMovingLandmarks(). Any number of landmarks may be specified. In the case of the Affine transformation the number of landmarks must be greater than the landmark dimensionality. If this is not the case an exception is thrown. In the case of the VersorRigid3DTransform and Rigid2DTransform the number of landmarks must be equal or greater than the landmark dimensionality. If this is not the case, only the translational component of the transformation is computed and the rotation is the identity. In the case of using Affine or BSpline transforms, each landmark pair can contribute in the final transform based on its defined weight. Number of weights should be equal to the number of landmarks and can be specified using SetLandmarkWeight(). By defaults are weights are set to one. Call InitializeTransform() to initialize the transform.

The class is based in part on Hybrid/vtkLandmarkTransform originally implemented in python by David G. Gobbi.

The solution is based on Berthold K. P. Horn (1987), "Closed-form solution of absolute orientation using unit quaternions," https://people.csail.mit.edu/bkph/papers/Absolute_Orientation.pdf

The Affine Transform initializer is based on an algorithm by H Spaeth, and is described in the Insight Journal Article "Affine Transformation for Landmark Based Registration Initializer in ITK" by Kim E.Y., Johnson H., Williams N. available at https://midasjournal.org/browse/publication/825

ITK Sphinx Examples:

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Definition at line 90 of file itkLandmarkBasedTransformInitializer.h.

Inheritance diagram for itk::LandmarkBasedTransformInitializer< TTransform, TFixedImage, TMovingImage >:

Collaboration diagram for itk::LandmarkBasedTransformInitializer< TTransform, TFixedImage, TMovingImage >:

Public Types
using	AffineTransformType = AffineTransform< ParametersValueType, FixedImageType::ImageDimension >

using	BSplineTransformType = BSplineTransform< ParametersValueType, FixedImageType::ImageDimension, SplineOrder >

using	ConstPointer = SmartPointer< const Self >

using	FixedImagePointer = typename FixedImageType::ConstPointer

using	FixedImageType = TFixedImage

using	InputPointType = typename TransformType::InputPointType

using	LandmarkPointContainer = std::vector< LandmarkPointType >

using	LandmarkPointType = Point< double, ImageDimension >

using	LandmarkWeightConstIterator = LandmarkWeightType::const_iterator

using	LandmarkWeightType = std::vector< double >

using	MovingImagePointer = typename MovingImageType::ConstPointer

using	MovingImageType = TMovingImage

using	OutputVectorType = typename TransformType::OutputVectorType

using	ParametersType = typename TransformType::ParametersType

using	ParametersValueType = typename ParametersType::ValueType

using	Pointer = SmartPointer< Self >

using	PointsContainerConstIterator = typename LandmarkPointContainer::const_iterator

using	PointType3D = Point< double, 3 >

using	Rigid2DTransformType = Rigid2DTransform< ParametersValueType >

using	Self = LandmarkBasedTransformInitializer

using	Similarity3DTransformType = Similarity3DTransform< ParametersValueType >

using	Superclass = Object

using	TransformPointer = typename TransformType::Pointer

using	TransformType = TTransform

using	VersorRigid3DTransformType = VersorRigid3DTransform< ParametersValueType >

Public Types inherited from itk::Object
using	ConstPointer = SmartPointer< const Self >

using	Pointer = SmartPointer< Self >

using	Self = Object

using	Superclass = LightObject

Public Types inherited from itk::LightObject
using	ConstPointer = SmartPointer< const Self >

using	Pointer = SmartPointer< Self >

using	Self = LightObject

Public Member Functions
const char *	GetNameOfClass () const override

virtual void	InitializeTransform ()

virtual void	SetBSplineNumberOfControlPoints (unsigned int _arg)

void	SetFixedLandmarks (const LandmarkPointContainer &fixedLandmarks)

void	SetLandmarkWeight (LandmarkWeightType &landmarkWeight)

void	SetMovingLandmarks (const LandmarkPointContainer &movingLandmarks)

virtual void	SetReferenceImage (const FixedImageType *_arg)

virtual void	SetTransform (TransformType *_arg)

Public Member Functions inherited from itk::Object
unsigned long	AddObserver (const EventObject &event, Command *cmd) const

unsigned long	AddObserver (const EventObject &event, std::function< void(const EventObject &)> function) const

LightObject::Pointer	CreateAnother () const override

virtual void	DebugOff () const

virtual void	DebugOn () const

Command *	GetCommand (unsigned long tag)

bool	GetDebug () const

MetaDataDictionary &	GetMetaDataDictionary ()

const MetaDataDictionary &	GetMetaDataDictionary () const

virtual ModifiedTimeType	GetMTime () const

const char *	GetNameOfClass () const override

virtual const TimeStamp &	GetTimeStamp () const

bool	HasObserver (const EventObject &event) const

void	InvokeEvent (const EventObject &)

void	InvokeEvent (const EventObject &) const

virtual void	Modified () const

void	Register () const override

void	RemoveAllObservers ()

void	RemoveObserver (unsigned long tag) const

void	SetDebug (bool debugFlag) const

void	SetReferenceCount (int) override

void	UnRegister () const noexcept override

void	SetMetaDataDictionary (const MetaDataDictionary &rhs)

void	SetMetaDataDictionary (MetaDataDictionary &&rrhs)

virtual void	SetObjectName (std::string _arg)

virtual const std::string &	GetObjectName () const

Public Member Functions inherited from itk::LightObject
Pointer	Clone () const

virtual Pointer	CreateAnother () const

virtual void	Delete ()

virtual const char *	GetNameOfClass () const

virtual int	GetReferenceCount () const

void	Print (std::ostream &os, Indent indent=0) const

virtual void	Register () const

virtual void	SetReferenceCount (int)

virtual void	UnRegister () const noexcept

Static Public Member Functions
static Pointer	New ()

Static Public Member Functions inherited from itk::Object
static bool	GetGlobalWarningDisplay ()

static void	GlobalWarningDisplayOff ()

static void	GlobalWarningDisplayOn ()

static Pointer	New ()

static void	SetGlobalWarningDisplay (bool val)

Static Public Member Functions inherited from itk::LightObject
static void	BreakOnError ()

static Pointer	New ()

Static Public Attributes
static constexpr unsigned int	ImageDimension = FixedImageType::ImageDimension

static constexpr unsigned int	InputSpaceDimension = TransformType::InputSpaceDimension

static constexpr unsigned int	OutputSpaceDimension = TransformType::OutputSpaceDimension

static constexpr unsigned int	SplineOrder = 3

Protected Member Functions
	LandmarkBasedTransformInitializer ()=default

void	PrintSelf (std::ostream &os, Indent indent) const override

	~LandmarkBasedTransformInitializer () override=default

Protected Member Functions inherited from itk::Object
	Object ()

bool	PrintObservers (std::ostream &os, Indent indent) const

void	PrintSelf (std::ostream &os, Indent indent) const override

virtual void	SetTimeStamp (const TimeStamp &timeStamp)

	~Object () override

Protected Member Functions inherited from itk::LightObject
virtual LightObject::Pointer	InternalClone () const

	LightObject ()

virtual void	PrintHeader (std::ostream &os, Indent indent) const

virtual void	PrintSelf (std::ostream &os, Indent indent) const

virtual void	PrintTrailer (std::ostream &os, Indent indent) const

virtual	~LightObject ()

Private Member Functions
PointType3D	ComputeCentroid (const LandmarkPointContainer)

void	CreateMatrix (itk::Matrix< ParametersValueType, 4, 4 > &, const itk::Matrix< ParametersValueType, ImageDimension, ImageDimension >)

void	InternalInitializeTransform (AffineTransformType *)

void	InternalInitializeTransform (BSplineTransformType *)

void	InternalInitializeTransform (Rigid2DTransformType *)

void	InternalInitializeTransform (Similarity3DTransformType *)

template<typename TTransform2 >
void	InternalInitializeTransform (TTransform2 *)

void	InternalInitializeTransform (VersorRigid3DTransformType *)

Private Attributes
unsigned int	m_BSplineNumberOfControlPoints { 4 }

LandmarkPointContainer	m_FixedLandmarks {}

LandmarkWeightType	m_LandmarkWeight {}

LandmarkPointContainer	m_MovingLandmarks {}

FixedImagePointer	m_ReferenceImage {}

TransformPointer	m_Transform {}

Additional Inherited Members
Protected Attributes inherited from itk::LightObject
std::atomic< int >	m_ReferenceCount {}