A class for computing the closest points on a surface defined by a level set function. More...

#include <deal.II/non_matching/closest_surface_point.h>

Detailed Description

template<int dim, class Number>
class NonMatching::ClosestSurfacePoint< dim, Number >

A class for computing the closest points on a surface defined by a level set function.

This class implements algorithms to find the closest points on a surface (zero level set) to a given set of query points. The surface is implicitly defined by a level set function discretized on a finite element mesh. The class uses Newton's method to iteratively find the closest surface points by minimizing the distance function subject to the constraint that the point lies on the zero level set.

Level set functions discretized on DoFHandler with cartesian grid.
Configurable Newton iteration parameters (tolerance, maximum iterations)
Supports active cells and MG cells

Template Parameters

dim	The spatial dimension of the problem
Number	The scalar type of vector used to store the level set function values

Note: The level set function should be negative inside the domain, positive outside, and zero on the surface boundary.

Warning: The Newton iteration may not converge for points that are too far from the surface or in regions where the level set function has poor conditioning.

Definition at line 55 of file closest_surface_point.h.

Inheritance diagram for NonMatching::ClosestSurfacePoint< dim, Number >:

[legend]

Classes
struct	AdditionalData

Public Member Functions
	ClosestSurfacePoint (const ReadVector< Number > &level_set, const DoFHandler< dim > &dof_handler, Mapping< dim > &mapping, const AdditionalData &data=AdditionalData())

std::pair< std::vector< Point< dim > >, std::vector< Point< dim > > >	compute_closest_surface_points (const typename Triangulation< dim >::cell_iterator &search_cell, const typename Triangulation< dim >::cell_iterator &reference_cell, const std::vector< Point< dim > > &quadrature_points) const

template<class Archive >
void	serialize (Archive &ar, const unsigned int version)

Querying the observer pointers an object has.
unsigned int	n_subscriptions () const

template<typename StreamType >
void	list_subscribers (StreamType &stream) const

void	list_subscribers () const

Static Public Member Functions
static ::ExceptionBase &	ExcInUse (int arg1, std::string arg2, std::string arg3)

static ::ExceptionBase &	ExcNoSubscriber (std::string arg1, std::string arg2)

Private Member Functions
void	newton_monolithic (const Point< dim > &point, const FiniteElement< dim > &fe, const std::vector< Number > &dof_values, Point< dim > &closest_point) const

EnableObserverPointer functionality
Classes derived from EnableObserverPointer provide a facility to subscribe to this object. This is mostly used by the ObserverPointer class.
void	subscribe (std::atomic< bool > *const validity, const std::string &identifier="") const

void	unsubscribe (std::atomic< bool > *const validity, const std::string &identifier="") const

void	check_no_subscribers () const noexcept

Private Attributes
AdditionalData	data

ObserverPointer< const DoFHandler< dim > >	dof_handler

ObserverPointer< const ReadVector< Number > >	level_set

ObserverPointer< Mapping< dim > >	mapping

std::atomic< unsigned int >	counter

std::map< std::string, unsigned int >	counter_map

std::vector< std::atomic< bool > * >	validity_pointers

const std::type_info *	object_info

Static Private Attributes
static std::mutex	mutex

Constructor & Destructor Documentation

◆ ClosestSurfacePoint()

template<int dim, class Number >

NonMatching::ClosestSurfacePoint< dim, Number >::ClosestSurfacePoint	(	const ReadVector< Number > &	level_set,
		const DoFHandler< dim > &	dof_handler,
		Mapping< dim > &	mapping,
		const AdditionalData &	data = `AdditionalData()`
	)

Constructor for the ClosestSurfacePoint class.

Definition at line 21 of file closest_surface_point.cc.

Member Function Documentation

◆ compute_closest_surface_points()

template<int dim, class Number >

std::pair< std::vector< Point< dim > >, std::vector< Point< dim > > > NonMatching::ClosestSurfacePoint< dim, Number >::compute_closest_surface_points	(	const typename Triangulation< dim >::cell_iterator &	search_cell,
		const typename Triangulation< dim >::cell_iterator &	reference_cell,
		const std::vector< Point< dim > > &	quadrature_points
	)		const

Compute closest points to given set of points.

Returns: A pair of vectors, where the first vector contains the shifted quadrature points in absolute coordinates, and the second vector contains the corresponding shifted points in coordinates of the reference cell.

Parameters

search_cell	The cell in the triangulation where the search for closest surface points is performed.
reference_cell	The reference cell in which local coordinates unit points are outputted.
quadrature_points	The original quadrature points to be shifted.

Definition at line 49 of file closest_surface_point.cc.

◆ newton_monolithic()

template<int dim, class Number >

void NonMatching::ClosestSurfacePoint< dim, Number >::newton_monolithic	(	const Point< dim > &	point,
		const FiniteElement< dim > &	fe,
		const std::vector< Number > &	dof_values,
		Point< dim > &	closest_point
	)		const

private

Find the closest point on a surface using Newton's method with a monolithic approach.

This function implements Newton's method to find the point on the surface defined by the finite element and DOF values that is closest to the given input point. The monolithic approach solves the constrained optimization problem:

\[ \min_{x} \frac{1}{2} \|x - x_0 \|^2 \quad \text{subject to} \quad \phi(x) = 0 \]

where \(\phi(x)\) is the level set function. Using Lagrange multipliers, this becomes the unconstrained problem:

\[ \min_{x, \lambda} L(x, \lambda) = \frac{1}{2} \|x - x_0\|^2 + \lambda \phi(x) \]

Newton's method iteratively solves this system using the Hessian.

Parameters

[in]	point	The reference point for which to find the closest surface point
[in]	fe	The finite element used to define the surface geometry
[in]	dof_values	The degrees of freedom values that define the surface
[out]	closest_point	The computed closest point on the surface

Definition at line 106 of file closest_surface_point.cc.

◆ n_subscriptions()

unsigned int EnableObserverPointer::n_subscriptions ( ) const

inlineinherited

Return the present number of subscriptions to this object. This allows to use this class for reference counted lifetime determination where the last one to unsubscribe also deletes the object.

Definition at line 318 of file enable_observer_pointer.h.

◆ list_subscribers() [1/2]

template<typename StreamType >

void EnableObserverPointer::list_subscribers ( StreamType & stream ) const

inlineinherited

List the subscribers to the input stream.

Definition at line 335 of file enable_observer_pointer.h.

◆ list_subscribers() [2/2]

void EnableObserverPointer::list_subscribers ( ) const

inherited

List the subscribers to deallog.

Definition at line 200 of file enable_observer_pointer.cc.

◆ serialize()

template<class Archive >

void EnableObserverPointer::serialize	(	Archive &	ar,
		const unsigned int	version
	)

inlineinherited

Read or write the data of this object to or from a stream for the purpose of serialization using the BOOST serialization library.

This function does not actually serialize any of the member variables of this class. The reason is that what this class stores is only who subscribes to this object, but who does so at the time of storing the contents of this object does not necessarily have anything to do with who subscribes to the object when it is restored. Consequently, we do not want to overwrite the subscribers at the time of restoring, and then there is no reason to write the subscribers out in the first place.

Definition at line 327 of file enable_observer_pointer.h.

◆ subscribe()

void EnableObserverPointer::subscribe	(	std::atomic< bool > *const	validity,
		const std::string &	identifier = `""`
	)		const

privateinherited

Subscribes a user of the object by storing the pointer validity. The subscriber may be identified by text supplied as identifier.

Definition at line 136 of file enable_observer_pointer.cc.

◆ unsubscribe()

void EnableObserverPointer::unsubscribe	(	std::atomic< bool > *const	validity,
		const std::string &	identifier = `""`
	)		const

privateinherited

Unsubscribes a user from the object.

Note: The identifier and the validity pointer must be the same as the one supplied to subscribe().

Definition at line 154 of file enable_observer_pointer.cc.

◆ check_no_subscribers()

void EnableObserverPointer::check_no_subscribers ( ) const

privatenoexceptinherited

Check that there are no objects subscribing to this object. If this check passes then it is safe to destroy the current object. It this check fails then this function will either abort or print an error message to deallog (by using the AssertNothrow mechanism), but will not throw an exception.

Note: Since this function is just a consistency check it does nothing in release mode.; If this function is called when there is an uncaught exception then, rather than aborting, this function prints an error message to the standard error stream and returns.

Definition at line 58 of file enable_observer_pointer.cc.

Member Data Documentation

◆ data

template<int dim, class Number >

AdditionalData NonMatching::ClosestSurfacePoint< dim, Number >::data

private

Definition at line 105 of file closest_surface_point.h.

◆ dof_handler

template<int dim, class Number >

ObserverPointer<const DoFHandler<dim> > NonMatching::ClosestSurfacePoint< dim, Number >::dof_handler

private

Definition at line 106 of file closest_surface_point.h.

◆ level_set

template<int dim, class Number >

ObserverPointer<const ReadVector<Number> > NonMatching::ClosestSurfacePoint< dim, Number >::level_set

private

Definition at line 107 of file closest_surface_point.h.

◆ mapping

template<int dim, class Number >

ObserverPointer<Mapping<dim> > NonMatching::ClosestSurfacePoint< dim, Number >::mapping

private

Definition at line 108 of file closest_surface_point.h.

◆ counter

std::atomic<unsigned int> EnableObserverPointer::counter

mutableprivateinherited

Store the number of objects which subscribed to this object. Initially, this number is zero, and upon destruction it shall be zero again (i.e. all objects which subscribed should have unsubscribed again).

The creator (and owner) of an object is counted in the map below if HE manages to supply identification.

We use the mutable keyword in order to allow subscription to constant objects also.

This counter may be read from and written to concurrently in multithreaded code: hence we use the std::atomic class template.

Definition at line 212 of file enable_observer_pointer.h.

◆ counter_map

std::map<std::string, unsigned int> EnableObserverPointer::counter_map

mutableprivateinherited

In this map, we count subscriptions for each different identification string supplied to subscribe().

Definition at line 218 of file enable_observer_pointer.h.

◆ validity_pointers

std::vector<std::atomic<bool> *> EnableObserverPointer::validity_pointers

mutableprivateinherited

In this vector, we store pointers to the validity bool in the ObserverPointer objects that subscribe to this class.

Definition at line 224 of file enable_observer_pointer.h.

◆ object_info

const std::type_info* EnableObserverPointer::object_info

mutableprivateinherited

Pointer to the typeinfo object of this object, from which we can later deduce the class name. Since this information on the derived class is neither available in the destructor, nor in the constructor, we obtain it in between and store it here.

Definition at line 232 of file enable_observer_pointer.h.

◆ mutex

std::mutex EnableObserverPointer::mutex

staticprivateinherited

A mutex used to ensure data consistency when accessing the mutable members of this class. This lock is used in the subscribe() and unsubscribe() functions, as well as in list_subscribers().

Definition at line 239 of file enable_observer_pointer.h.

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

include/deal.II/non_matching/closest_surface_point.h
source/non_matching/closest_surface_point.cc

Detailed Description

Classes

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Static Private Attributes

Constructor & Destructor Documentation

◆ ClosestSurfacePoint()

Member Function Documentation

◆ compute_closest_surface_points()

◆ newton_monolithic()

◆ n_subscriptions()

◆ list_subscribers() [1/2]

◆ list_subscribers() [2/2]

◆ serialize()

◆ subscribe()

◆ unsubscribe()

◆ check_no_subscribers()

Member Data Documentation

◆ data

◆ dof_handler

◆ level_set

◆ mapping

◆ counter

◆ counter_map

◆ validity_pointers

◆ object_info

◆ mutex