#include <DeformableSurfaceModel.h>

Inheritance diagram for mirtk::DeformableSurfaceModel:

Collaboration diagram for mirtk::DeformableSurfaceModel:

Public Member Functions
void	Add (class ExternalForce *, bool=true)
	Add external force term and take over ownership of the object.

void	Add (class InternalForce *, bool=true)
	Add internal force term and take over ownership of the object.

void	Add (TransformationConstraint *, bool=true)
	Add transformation regularization term and take over ownership of the object.

void	Clear ()
	Delete previously added energy terms.

	DeformableSurfaceModel ()
	Constructor.

bool	Empty () const
	Whether energy function has no terms.

virtual double	Evaluate (double dx=NULL, double step=.0, bool sgn_chg=NULL)

class ExternalForce *	ExternalForce (int)
	Get the n-th external force term.

const class ExternalForce *	ExternalForce (int) const
	Get the n-th external force term.

virtual void	Get (double *x) const

virtual double	Get (int) const

void	Gradient (double dx, double step=.0, bool sgn_chg=NULL)

double	GradientNorm (const double *) const

void	GradientStep (const double *dx, double &min, double &max) const

virtual void	Initialize ()
	Initialize energy terms once input and parameters have been set.

double	InitialValue ()
	Query/evaluate initial value of energy function.

double	InitialValue (int)
	Get initial value of n-th energy term.

class InternalForce *	InternalForce (int)
	Get the n-th internal force term.

const class InternalForce *	InternalForce (int) const
	Get the n-th internal force term.

bool	IsExternalForce (int) const
	Determine whether n-th energy term is an external force.

bool	IsImplicitSurfaceForce (int) const
	Determine whether n-th energy term is an external implicit surface force.

bool	IsInternalForce (int) const
	Determine whether n-th energy term is an internal force.

virtual int	NumberOfDOFs () const
	Get number of deformable surface parameters.

int	NumberOfExternalForces () const
	Number of external force terms.

int	NumberOfForces () const
	Number of energy terms.

int	NumberOfInternalForces () const
	Number of internal force terms.

int	NumberOfPoints () const
	Get number of deformable surface points.

vtkSmartPointer< vtkPointSet >	Output () const
	Output surface mesh.

virtual ParameterList	Parameter () const
	Get parameter as key/value as string map.

virtual void	Put (const double *x)

double	RawValue (int)

virtual bool	Remesh ()

virtual bool	Set (const char , const char )
	Set parameter value from string.

virtual double	Step (double *dx)

void	Sub (class ExternalForce *)
	Remove external force term and revoke ownership of the object.

void	Sub (class InternalForce *)
	Remove internal force term and revoke ownership of the object.

void	Sub (TransformationConstraint *)
	Remove transformation regularization term and revoke ownership of the object.

EnergyTerm *	Term (int)
	Get the n-th energy term.

const EnergyTerm *	Term (int) const
	Get the n-th energy term.

virtual void	Update (bool=true)
	Update internal state after change of parameters.

virtual bool	Upgrade ()

double	Value ()
	Evaluate energy function.

double	Value (int)
	Get value of n-th energy term computed upon last evaluation.

virtual void	WriteDataSets (const char , const char , bool=true) const
	Write input of data force terms.

virtual void	WriteGradient (const char , const char ) const
	Write gradient of force terms.

virtual	~DeformableSurfaceModel ()
	Destructor.

Public Member Functions inherited from mirtk::ObjectiveFunction
virtual void	AddConstraintGradient (double dx, double step=.0, bool sgn_chg=nullptr)

virtual void	DataFidelityGradient (double dx, double step=.0, bool sgn_chg=nullptr)

virtual	~ObjectiveFunction ()=0
	Destructor.

Public Member Functions inherited from mirtk::Observable
void	AddObserver (Observer &)
	Add observer.

void	Broadcast (Event, const void *=NULL)
	Broadcast event to observers.

void	ClearObservers ()
	Delete all observers.

void	DeleteObserver (Observer &)
	Delete observer.

void	NotifyObservers (Event, const void *=NULL)
	Notify all observers about given event if this object has changed.

int	NumberOfObservers () const
	Number of current observers.

virtual	~Observable ()
	Destructor.

Public Member Functions inherited from mirtk::Object
virtual const char *	NameOfClass () const =0
	Get name of class, which this object is an instance of.

bool	Parameter (const ParameterList &)
	Set parameters from name/value pairs.

virtual	~Object ()
	Destructor.

Static Public Member Functions
static bool	IsExternalForce (const EnergyTerm *)
	Determine whether a given force term is an external force.

static bool	IsImplicitSurfaceForce (const EnergyTerm *)
	Determine whether a given force term is an external implicit surface force.

static bool	IsInternalForce (const EnergyTerm *)
	Determine whether a given force term is an internal force.

Static Public Member Functions inherited from mirtk::Object
static const char *	NameOfType ()
	Get name of this class type.

Protected Member Functions
virtual void	EnforceHardConstraints (double *dx) const

void	ResolveSurfaceCollisions (double *dx, bool nsi, double mind, double minw) const

virtual void	SmoothGradient (double *dx) const
	Smooth gradient such that neighboring points move coherently.

Protected Member Functions inherited from mirtk::ObjectiveFunction
	mirtkAttributeMacro (double, StepLength)
	Default step length used for gradient approximation.

Protected Member Functions inherited from mirtk::Observable
	Observable ()
	Default constructor.

	Observable (const Observable &)
	Copy constructor.

Observable &	operator= (const Observable &)
	Assignment operator.

Protected Member Functions inherited from mirtk::Object
template<typename... Args>
void	Throw (ErrorType err, const char *func, Args... args) const

Protected Attributes
Array< vtkSmartPointer< vtkPolyData > >	_BoundaryConstraint
	Input surface meshes which the deformed surface mesh may not intersect.

Array< TransformationConstraint * >	_Constraint
	Energy terms which regularize the parametric transformation.

Array< class ExternalForce * >	_ExternalForce
	Energy terms corresponding to external forces.

Array< class InternalForce * >	_InternalForce
	Energy terms corresponding to internal forces.

int	_LowPassCounter
	Number of iterations since last low-pass filtering.

Additional Inherited Members
Static Protected Member Functions inherited from mirtk::Object
template<typename... Args>
static void	ThrowStatic (ErrorType err, const char cls, const char func, Args... args)

Detailed Description

Energy function describing a deformable surface model

Definition at line 48 of file DeformableSurfaceModel.h.

Member Function Documentation

§ EnforceHardConstraints()

virtual void mirtk::DeformableSurfaceModel::EnforceHardConstraints ( double * dx ) const

protectedvirtual

Enforce hard constraints on surface model deformation

This function clamps a nodes' displacement vector (velocity times \(\delta t\)), if otherwise the hard constraints of the deformable surface model would be violated. Common hard constraints are non-self-intersection and a maximum total node displacement. If the surface model is deformed by a parametric transformation, this function does nothing as hard constraints can only be enforced during the optimization when the parameters of the deformable surface model are the positions of the individual surface nodes.

Parameters

[in,out] dx (Scaled) gradient of objective function.

§ Evaluate()

virtual double mirtk::DeformableSurfaceModel::Evaluate	(	double *	dx = `NULL`,
		double	step = `.0`,
		bool *	sgn_chg = `NULL`
	)

virtual

Evaluate energy function

This function first updates the internal state of the function object if required due to a previous change of the function parameters and then evaluates the current energy function value.

Parameters

[in]	step	Step length for finite differences.
[out]	dx	Gradient of objective function. If `NULL`, only the function value is computed.
[out]	sgn_chg	Whether function parameter value is allowed to change sign when stepping along the computed gradient. Ignord if `dx` is `NULL`.

Reimplemented from mirtk::ObjectiveFunction.

§ Get() [1/2]

virtual void mirtk::DeformableSurfaceModel::Get ( double * x ) const

virtual

Get deformable surface parameters

This function can be used to store a backup of the current deformable surface parameters before an update such that these can be restored using the Put member function if the update did not result in the desired change of the overall energy.

Parameters

[in] x Current values of deformable surface parameters (DoFs).

Implements mirtk::ObjectiveFunction.

§ Get() [2/2]

virtual double mirtk::DeformableSurfaceModel::Get ( int ) const

virtual

Get function parameter value

Returns: Value of specified function parameter (DoF).

Implements mirtk::ObjectiveFunction.

§ Gradient()

void mirtk::DeformableSurfaceModel::Gradient	(	double *	dx,
		double	step = `.0`,
		bool *	sgn_chg = `NULL`
	)

virtual

Evaluate gradient of energy function

This gradient corresponds to the weighted sum of external and internal forces of the deformable surface model.

Parameters

[in]	dx	Gradient of energy function.
[in]	step	Step length for finite differences.
[out]	sgn_chg	Whether function parameter value is allowed to change sign when stepping along the computed gradient.

Implements mirtk::ObjectiveFunction.

§ GradientNorm()

double mirtk::DeformableSurfaceModel::GradientNorm ( const double * ) const

virtual

Compute norm of gradient of energy function

This norm can, for example, be the maximum absolute parameter change, the maximum control point displacement if a FFD transformation is used to deform the initial surface mesh, or the maximum vertex displacement.

Implements mirtk::ObjectiveFunction.

§ GradientStep()

void mirtk::DeformableSurfaceModel::GradientStep	(	const double *	dx,
		double &	min,
		double &	max
	)		const

virtual

Adjust step length range

Parameters

[in]	dx	Gradient of objective function.
[in,out]	min	Minimum step length.
[in,out]	max	Maximum step length.

Reimplemented from mirtk::ObjectiveFunction.

§ Put()

virtual void mirtk::DeformableSurfaceModel::Put ( const double * x )

virtual

Set deformable surface parameters

This function can be used to restore the deformable surface parameters after a failed update which did not result in the desired improvement.

Parameters

[in] x Value of deformable surface parameters (DoFs).

Implements mirtk::ObjectiveFunction.

§ RawValue()

double mirtk::DeformableSurfaceModel::RawValue ( int )

Get unweighted and unnormalized value of n-th energy term

Remarks: Use for progress reporting only.

§ Remesh()

virtual bool mirtk::DeformableSurfaceModel::Remesh ( )

virtual

Perform local adaptive remeshing

Returns: Whether the surface model has been remeshed. The Update function must be called after such remeshing operation before evaluating the energy and/or gradient of the deformable surface model.

§ ResolveSurfaceCollisions()

void mirtk::DeformableSurfaceModel::ResolveSurfaceCollisions	(	double *	dx,
		bool	nsi,
		double	mind,
		double	minw
	)		const

protected

Adjust node displacements to avoid self-intersections and collisions

Parameters

[in,out]	dx	(Scaled) gradient of objective function.
[in]	nsi	Enforce non-self-intersection.
[in]	mind	Minimum front-facing distance.
[in]	minw	Minimum back-facing distance.

§ Step()

virtual double mirtk::DeformableSurfaceModel::Step ( double * dx )

virtual

Add change (i.e., scaled gradient) to each deformable surface parameter

This function updates each parameter of the deformable surface model given a vector of desired changes, i.e., the computed gradient of the energy function.

Parameters

[in,out] dx Change of each function parameter (DoF) as computed by the Gradient member function and scaled by a chosen step length. The change of a parameter may be modified by this function in order to satisfy the hard constraints (if any).

Returns: Maximum change of transformation parameter.

Implements mirtk::ObjectiveFunction.

§ Upgrade()

virtual bool mirtk::DeformableSurfaceModel::Upgrade ( )

virtual

Update energy function after convergence

For example, fiducial registration error (FRE) terms may update the point correspondences before another gradient-based optimization of the new FRE term.

Returns: Whether the energy function has changed.

Reimplemented from mirtk::ObjectiveFunction.

The documentation for this class was generated from the following file:

DeformableSurfaceModel.h

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Member Function Documentation

§ EnforceHardConstraints()

§ Evaluate()

§ Get() [1/2]

§ Get() [2/2]

§ Gradient()

§ GradientNorm()

§ GradientStep()

§ Put()

§ RawValue()

§ Remesh()

§ ResolveSurfaceCollisions()

§ Step()

§ Upgrade()