Surface describing the point of closest approach (PCA) of a track to a single fixed 3D point (the surface center). More...

#include <Acts/Surfaces/PointSurface.hpp>

Inheritance diagram for Acts::PointSurface:

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Collaboration diagram for Acts::PointSurface:

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Public Member Functions
	PointSurface (const PointSurface &other) noexcept=default
	Copy constructor.
	~PointSurface () noexcept override=default
	Destructor.
AlignmentToPathMatrix	alignmentToPathDerivative (const GeometryContext &gctx, const Vector3 &position, const Vector3 &direction) const final
	Calculate the derivative of path length at the point-of-closest-approach w.r.t.
void	assignSurfaceBounds (std::shared_ptr< const PointBounds > newBounds)
	Overwrite the existing surface bounds with new ones.
const SurfaceBounds &	bounds () const final
	This method returns the bounds of the surface by reference.
const std::shared_ptr< const PointBounds > &	boundsPtr () const
	This method returns the shared_ptr to the PointBounds.
BoundToFreeMatrix	boundToFreeJacobian (const GeometryContext &gctx, const Vector3 &position, const Vector3 &direction) const final
	Calculate the jacobian from local to global.
FreeToBoundMatrix	freeToBoundJacobian (const GeometryContext &gctx, const Vector3 &position, const Vector3 &direction) const final
	Jacobian from free to bound parameters.
FreeToPathMatrix	freeToPathDerivative (const GeometryContext &gctx, const Vector3 &position, const Vector3 &direction) const final
	Calculate the derivative of path length at the point-of-closest-approach w.r.t.
Result< Vector2 >	globalToLocal (const GeometryContext &gctx, const Vector3 &position, const Vector3 &direction, double tolerance=s_onSurfaceTolerance) const final
	Global to local transformation.
MultiIntersection3D	intersect (const GeometryContext &gctx, const Vector3 &position, const Vector3 &direction, const BoundaryTolerance &boundaryTolerance=BoundaryTolerance::Infinite(), double tolerance=s_onSurfaceTolerance) const final
	Calculate the straight-line intersection with the point surface, i.e.
Matrix< 2, 3 >	localCartesianToBoundLocalDerivative (const GeometryContext &gctx, const Vector3 &position) const final
	Calculate the derivative of bound track parameters local position w.r.t.
Vector3	localToGlobal (const GeometryContext &gctx, const Vector2 &lposition, const Vector3 &direction) const final
	Local to global transformation.
std::string	name () const final
	Return properly formatted class name for screen output.
Vector3	normal (const GeometryContext &gctx, const Vector3 &pos, const Vector3 &direction) const final
	Return the surface normal, which for a point surface is the momentum direction (the measurement plane is perpendicular to the direction).
PointSurface &	operator= (const PointSurface &other) noexcept=default
	Assignment operator.
double	pathCorrection (const GeometryContext &gctx, const Vector3 &position, const Vector3 &direction) const final
	The pathCorrection is by definition 1 for point surfaces.
Polyhedron	polyhedronRepresentation (const GeometryContext &gctx, unsigned int quarterSegments) const final
	Return a Polyhedron for the surface (a non-physical marker at the center).
RotationMatrix3	referenceFrame (const GeometryContext &gctx, const Vector3 &position, const Vector3 &direction) const final
	Return the measurement frame, built from the momentum direction like a curvilinear surface.
Vector3	referencePosition (const GeometryContext &gctx, AxisDirection aDir) const final
	The binning position is the center of the point surface.
SurfaceType	type () const final
	Return the surface type.
Public Member Functions inherited from Acts::Surface
AlignmentToBoundMatrix	alignmentToBoundDerivative (const GeometryContext &gctx, const Vector3 &position, const Vector3 &direction, const FreeVector &pathDerivative) const
	The derivative of bound track parameters w.r.t.
void	assignIsSensitive (bool isSensitive)
	Assign whether the surface is sensitive.
virtual void	assignSurfaceMaterial (std::shared_ptr< const ISurfaceMaterial > material)
	Assign the surface material description.
void	assignSurfacePlacement (const SurfacePlacementBase &placement)
	Assign a placement object which may dynamically align the surface in space.
void	assignThickness (double thick)
	Assign the thickness of the surface in the orthogonal dimension.
const Layer *	associatedLayer () const
	Return method for the associated Layer in which the surface is embedded.
void	associateLayer (const Layer &lay)
	Set Associated Layer Many surfaces can be associated to a Layer, but it might not be known yet during construction of the layer, this can be set afterwards.
virtual Vector3	center (const GeometryContext &gctx) const
	Return method for the surface center.
virtual Vector2	closestPointOnBoundary (const Vector2 &lposition, const SquareMatrix2 &metric) const
	Calculates the closest point on the boundary of the surface to a given point in local coordinates.
virtual double	distanceToBoundary (const Vector2 &lposition) const
	Calculates the distance to the boundary of the surface from a given point in local coordinates.
std::shared_ptr< Surface >	getSharedPtr ()
	Retrieve a `std::shared_ptr` for this surface (non-const version).
std::shared_ptr< const Surface >	getSharedPtr () const
	Retrieve a `std::shared_ptr` for this surface (const version).
bool	hasMaterial () const
	Check if the surface has an associated material description.
virtual bool	insideBounds (const Vector2 &lposition, const BoundaryTolerance &boundaryTolerance=BoundaryTolerance::None()) const
	The insideBounds method for local positions.
bool	isAlignable () const
	Returns whether the Surface is alignable.
bool	isOnSurface (const GeometryContext &gctx, const Vector3 &position, const Vector3 &direction, const BoundaryTolerance &boundaryTolerance=BoundaryTolerance::None(), double tolerance=s_onSurfaceTolerance) const
	The geometric onSurface method.
bool	isSensitive () const
	Returns whether the Surface is sensitive.
const Transform3 &	localToGlobalTransform (const GeometryContext &gctx) const
	Return method for the surface Transform3 by reference In case a detector element is associated the surface transform is just forwarded to the detector element in order to keep the (mis-)alignment cache cetrally handled.
virtual const MaterialSlab &	materialSlab (const Vector2 &lp) const
	Return method for full material description of the Surface.
virtual MaterialSlab	materialSlab (const Vector2 &lp, Direction pDir, MaterialUpdateMode mode) const
	Return method for fully scaled material description of the Surface.
bool	operator== (const Surface &other) const
	Comparison (equality) operator The strategy for comparison is (a) first pointer comparison (b) then type comparison (c) then bounds comparison (d) then transform comparison.
const ISurfaceMaterial *	surfaceMaterial () const
	Return method for the associated Material to this surface.
const std::shared_ptr< const ISurfaceMaterial > &	surfaceMaterialSharedPtr () const
	Return method for the shared pointer to the associated Material.
const SurfacePlacementBase *	surfacePlacement () const
	Return the associated surface placement if there is any.
double	thickness () const
	Return the thickness of the surface in the normal direction.
GeometryContextOstreamWrapper< Surface >	toStream (const GeometryContext &gctx) const
	Helper method for printing: the returned object captures the surface and the geometry context and will print the surface.
std::string	toString (const GeometryContext &gctx) const
	Output into a std::string.
void	visualize (IVisualization3D &helper, const GeometryContext &gctx, const ViewConfig &viewConfig=s_viewSurface) const
	Visualize the surface for debugging and inspection.
Public Member Functions inherited from Acts::GeometryObject
	GeometryObject ()=default
	Defaulted constructor.
	GeometryObject (const GeometryIdentifier &geometryId)
	Constructor from a value.
	GeometryObject (const GeometryObject &)=default
	Defaulted copy constructor.
void	assignGeometryId (const GeometryIdentifier &geometryId)
	Set the value.
GeometryIdentifier	geometryId () const
virtual double	referencePositionValue (const GeometryContext &gctx, AxisDirection aDir) const
	Implement the binningValue.

Protected Member Functions
	PointSurface (const GeometryContext &gctx, const PointSurface &other, const Transform3 &shift)
	Copy constructor - with shift.
	PointSurface (const Transform3 &transform, std::shared_ptr< const PointBounds > pbounds=nullptr)
	Constructor from a Transform3 and optional PointBounds.
	PointSurface (const Vector3 &center)
	Constructor from a global position (unbounded point surface).
	PointSurface (const Vector3 &center, double maxDistance)
	Constructor from a global position and a maximum distance.
std::array< AxisDirection, 2 >	localAxes () const final
	Local axes of the surface.
std::ostream &	toStreamImpl (const GeometryContext &gctx, std::ostream &sl) const final
	Output Method for std::ostream.
Protected Member Functions inherited from Acts::Surface
	Surface (const GeometryContext &gctx, const Surface &other, const Transform3 &shift) noexcept
	Copy constructor with optional shift.
	Surface (const Surface &other) noexcept=default
	Copy constructor.
	Surface (const SurfacePlacementBase &placement) noexcept
	Constructor from SurfacePlacement: Element proxy.
	Surface (const Transform3 &transform=Transform3::Identity())
	Constructor with Transform3 as a shared object.
Surface &	operator= (const Surface &other) noexcept=default
	Assignment operator.
virtual Vector2	transformSurfaceLocalToMaterialLocal (const Vector2 &surfaceLocal) const
	Transform surface local coordinates to material local coordinates.

Protected Attributes
std::shared_ptr< const PointBounds >	m_bounds
	bounds (shared, may be null)
Protected Attributes inherited from Acts::Surface
std::shared_ptr< const ISurfaceMaterial >	m_surfaceMaterial
	Possibility to attach a material description.
bool	m_swapMaterialAxes {false}
	Whether to swap the local coordinates for material lookup.
CloneablePtr< const Transform3 >	m_transform
	Transform3 definition that positions (translation, rotation) the surface in global space.
Protected Attributes inherited from Acts::GeometryObject
GeometryIdentifier	m_geometryId
	Unique geometry identifier for this object.

Additional Inherited Members
Public Types inherited from Acts::Surface
enum	SurfaceType { Cone = 0 , Cylinder = 1 , Disc = 2 , Perigee = 3 , Plane = 4 , Straw = 5 , Curvilinear = 6 , Point = 7 , Other = 8 }
	This enumerator simplifies the persistency & calculations, by saving a dynamic_cast, e.g. More...
Static Public Member Functions inherited from Acts::Surface
template<class T, typename... Args>
static std::shared_ptr< T >	makeShared (Args &&... args)
	Factory for producing memory managed instances of Surface.
Static Public Attributes inherited from Acts::Surface
static constexpr std::array< std::string_view, Surface::SurfaceType::Other+1 >	s_surfaceTypeNames
	Helper strings for screen output.

Detailed Description

Surface describing the point of closest approach (PCA) of a track to a single fixed 3D point (the surface center).

It is the point-analogue of the LineSurface (which represents the PCA to a line / Perigee).

Geometrically, a PointSurface behaves like a curvilinear plane anchored at the fixed center: a plane through the center whose normal always equals the track momentum direction. The track's crossing of that plane is therefore the PCA to the point. Consequently there is no parallel-line degeneracy: a unique intersection always exists.

The local coordinates are Cartesian (x, y) in the measurement plane perpendicular to the track direction. Cartesian (not polar r-phi) is used on purpose, because at the point itself (r = 0) the azimuth phi is degenerate.

The measurement frame is oriented from the track direction like the CurvilinearSurface: the third axis is the track direction, the first axis is built from global Z (with a fall-back to global X when the direction is (anti-)parallel to Z).

Note: A point has no intrinsic orientation, so only translation (center) alignment is supported; rotational alignment derivatives are zero.

Constructor & Destructor Documentation

◆ PointSurface() [1/5]

Acts::PointSurface::PointSurface ( const Vector3 & center )

explicitprotected

Constructor from a global position (unbounded point surface).

Parameters

center position of the point in the global frame

◆ PointSurface() [2/5]

Acts::PointSurface::PointSurface	(	const Vector3 &	center,
		double	maxDistance )

protected

Constructor from a global position and a maximum distance.

Parameters

center	position of the point in the global frame
maxDistance	maximum distance from the point (radius of the PointBounds disc in the measurement plane)

◆ PointSurface() [3/5]

Acts::PointSurface::PointSurface	(	const Transform3 &	transform,
		std::shared_ptr< const PointBounds >	pbounds = nullptr )

explicitprotected

Constructor from a Transform3 and optional PointBounds.

Parameters

transform	the transform whose translation positions the point
pbounds	the bounds describing the maximum distance, may be nullptr for an unbounded point surface

◆ PointSurface() [4/5]

Acts::PointSurface::PointSurface	(	const GeometryContext &	gctx,
		const PointSurface &	other,
		const Transform3 &	shift )

protected

Copy constructor - with shift.

Parameters

gctx	The current geometry context object, e.g. alignment
other	is the source surface
shift	is the additional transform applied after copying

◆ PointSurface() [5/5]

Acts::PointSurface::PointSurface ( const PointSurface & other )

defaultnoexcept

Copy constructor.

Parameters

other The source surface for copying

Member Function Documentation

◆ alignmentToPathDerivative()

AlignmentToPathMatrix Acts::PointSurface::alignmentToPathDerivative	(	const GeometryContext &	gctx,
		const Vector3 &	position,
		const Vector3 &	direction ) const

finalvirtual

Calculate the derivative of path length at the point-of-closest-approach w.r.t.

alignment parameters of the surface. Only the center (translation) contributes; a point has no orientation so the rotation block is zero.

Parameters

gctx	The current geometry context object, e.g. alignment
position	global 3D position
direction	global 3D momentum direction

Returns: Derivative of path length w.r.t. the alignment parameters

Reimplemented from Acts::Surface.

◆ assignSurfaceBounds()

void Acts::PointSurface::assignSurfaceBounds ( std::shared_ptr< const PointBounds > newBounds )

Overwrite the existing surface bounds with new ones.

Parameters

newBounds Pointer to the new bounds

◆ bounds()

const SurfaceBounds & Acts::PointSurface::bounds ( ) const

finalvirtual

This method returns the bounds of the surface by reference.

Returns: Reference to the surface bounds

Implements Acts::Surface.

◆ boundsPtr()

const std::shared_ptr< const PointBounds > & Acts::PointSurface::boundsPtr ( ) const

This method returns the shared_ptr to the PointBounds.

Returns: Shared pointer to the point bounds (may be nullptr)

◆ boundToFreeJacobian()

BoundToFreeMatrix Acts::PointSurface::boundToFreeJacobian	(	const GeometryContext &	gctx,
		const Vector3 &	position,
		const Vector3 &	direction ) const

finalvirtual

Calculate the jacobian from local to global.

Parameters

gctx	The current geometry context object, e.g. alignment
position	global 3D position
direction	global 3D momentum direction

Returns: Jacobian from local to global

Reimplemented from Acts::Surface.

◆ freeToBoundJacobian()

FreeToBoundMatrix Acts::PointSurface::freeToBoundJacobian	(	const GeometryContext &	gctx,
		const Vector3 &	position,
		const Vector3 &	direction ) const

finalvirtual

Jacobian from free to bound parameters.

The measurement frame rotates with the track direction, so the loc rows have a direction block as well as the position block.

Parameters

gctx	The current geometry context object, e.g. alignment
position	global 3D position
direction	global 3D momentum direction

Returns: Jacobian from global to local

Reimplemented from Acts::Surface.

◆ freeToPathDerivative()

FreeToPathMatrix Acts::PointSurface::freeToPathDerivative	(	const GeometryContext &	gctx,
		const Vector3 &	position,
		const Vector3 &	direction ) const

finalvirtual

Calculate the derivative of path length at the point-of-closest-approach w.r.t.

free parameters.

Parameters

gctx	The current geometry context object, e.g. alignment
position	global 3D position
direction	global 3D momentum direction

Returns: Derivative of path length w.r.t. free parameters

Reimplemented from Acts::Surface.

◆ globalToLocal()

Result< Vector2 > Acts::PointSurface::globalToLocal	(	const GeometryContext &	gctx,
		const Vector3 &	position,
		const Vector3 &	direction,
		double	tolerance = s_onSurfaceTolerance ) const

finalvirtual

Global to local transformation.

Parameters

gctx	The current geometry context object, e.g. alignment
position	global 3D position - considered to be on surface but not inside bounds (check is done)
direction	global 3D momentum direction
tolerance	the tolerance for the on-surface check

Returns: A Result<Vector2> which is !ok() if position is not the point of closest approach to the point surface.

Implements Acts::Surface.

◆ intersect()

MultiIntersection3D Acts::PointSurface::intersect	(	const GeometryContext &	gctx,
		const Vector3 &	position,
		const Vector3 &	direction,
		const BoundaryTolerance &	boundaryTolerance = BoundaryTolerance::Infinite(),
		double	tolerance = s_onSurfaceTolerance ) const

finalvirtual

Calculate the straight-line intersection with the point surface, i.e.

the point of closest approach of the track to the point.

Given the track (position \( \vec m \), direction \( \vec e \), normalized), the PCA path length is \( u = (\vec c - \vec m) \cdot \vec e \) where \( \vec c \) is the point, and the intersection point is \(\vec m + u \vec e \). Unlike the LineSurface there is no parallel degeneracy.

Parameters

gctx	The current geometry context object, e.g. alignment
position	The global position as a starting point
direction	The global direction at the starting point

Note: expected to be normalized

Parameters

boundaryTolerance	The boundary check directive for the estimate
tolerance	the tolerance used for the intersection

Returns: is the intersection object

Implements Acts::Surface.

◆ localAxes()

std::array< AxisDirection, 2 > Acts::PointSurface::localAxes ( ) const

finalprotectedvirtual

Local axes of the surface.

Returns: An array of local axes directions

Implements Acts::Surface.

◆ localCartesianToBoundLocalDerivative()

Matrix< 2, 3 > Acts::PointSurface::localCartesianToBoundLocalDerivative	(	const GeometryContext &	gctx,
		const Vector3 &	position ) const

finalvirtual

Calculate the derivative of bound track parameters local position w.r.t.

position in local 3D Cartesian coordinates

Parameters

gctx	The current geometry context object, e.g. alignment
position	The position of the parameters in global

Returns: Derivative of bound local position w.r.t. position in local 3D cartesian coordinates

Implements Acts::Surface.

◆ localToGlobal()

Vector3 Acts::PointSurface::localToGlobal	(	const GeometryContext &	gctx,
		const Vector2 &	lposition,
		const Vector3 &	direction ) const

finalvirtual

Local to global transformation.

Note: for point surfaces the momentum direction is used in order to build the measurement plane

Parameters

gctx	The current geometry context object, e.g. alignment
lposition	is the local (x, y) position to be transformed
direction	is the global momentum direction

Returns: global position by value

Implements Acts::Surface.

◆ name()

std::string Acts::PointSurface::name ( ) const

finalvirtual

Return properly formatted class name for screen output.

Returns: String representation of the class name

Implements Acts::Surface.

◆ normal()

Vector3 Acts::PointSurface::normal	(	const GeometryContext &	gctx,
		const Vector3 &	pos,
		const Vector3 &	direction ) const

finalvirtual

Return the surface normal, which for a point surface is the momentum direction (the measurement plane is perpendicular to the direction).

Parameters

gctx	The current geometry context object, e.g. alignment
pos	is the global position (ignored)
direction	is the global momentum direction

Returns: the normal vector (equal to direction)

Implements Acts::Surface.

◆ operator=()

PointSurface & Acts::PointSurface::operator= ( const PointSurface & other )

defaultnoexcept

Assignment operator.

Parameters

other is the source surface for copying

Returns: Reference to this PointSurface after assignment

◆ pathCorrection()

double Acts::PointSurface::pathCorrection	(	const GeometryContext &	gctx,
		const Vector3 &	position,
		const Vector3 &	direction ) const

finalvirtual

The pathCorrection is by definition 1 for point surfaces.

Parameters

gctx	Geometry context (ignored)
position	Position parameter (ignored)
direction	Direction parameter (ignored)

Returns: Always returns 1.0 for point surfaces

Implements Acts::Surface.

◆ polyhedronRepresentation()

Polyhedron Acts::PointSurface::polyhedronRepresentation	(	const GeometryContext &	gctx,
		unsigned int	quarterSegments ) const

finalvirtual

Return a Polyhedron for the surface (a non-physical marker at the center).

Parameters

gctx	The current geometry context object, e.g. alignment
quarterSegments	is an ignored parameter

Returns: A list of vertices and a face/facet description of it

Implements Acts::Surface.

◆ referenceFrame()

RotationMatrix3 Acts::PointSurface::referenceFrame	(	const GeometryContext &	gctx,
		const Vector3 &	position,
		const Vector3 &	direction ) const

finalvirtual

Return the measurement frame, built from the momentum direction like a curvilinear surface.

Columns are (U, V, T) with T the direction.

Parameters

gctx	The current geometry context object, e.g. alignment
position	is the global position (ignored)
direction	is the momentum direction used to build the frame

Returns: a rotation matrix that indicates the measurement frame

Reimplemented from Acts::Surface.

◆ referencePosition()

Vector3 Acts::PointSurface::referencePosition	(	const GeometryContext &	gctx,
		AxisDirection	aDir ) const

finalvirtual

The binning position is the center of the point surface.

Parameters

gctx	The current geometry context object, e.g. alignment
aDir	is the axis direction for the reference position request

Returns: the center position

Implements Acts::GeometryObject.

◆ toStreamImpl()

std::ostream & Acts::PointSurface::toStreamImpl	(	const GeometryContext &	gctx,
		std::ostream &	sl ) const

finalprotectedvirtual

Output Method for std::ostream.

Parameters

gctx	The current geometry context object, e.g. alignment
sl	is the ostream to be dumped into

Returns: ostream object which was streamed into

Reimplemented from Acts::Surface.

◆ type()

SurfaceType Acts::PointSurface::type ( ) const

finalvirtual

Return the surface type.

Returns: Surface type identifier for point surfaces

Implements Acts::Surface.

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ PointSurface() [1/5]

◆ PointSurface() [2/5]

◆ PointSurface() [3/5]

◆ PointSurface() [4/5]

◆ PointSurface() [5/5]

Member Function Documentation

◆ alignmentToPathDerivative()

◆ assignSurfaceBounds()

◆ bounds()

◆ boundsPtr()

◆ boundToFreeJacobian()

◆ freeToBoundJacobian()

◆ freeToPathDerivative()

◆ globalToLocal()

◆ intersect()

◆ localAxes()

◆ localCartesianToBoundLocalDerivative()

◆ localToGlobal()

◆ name()

◆ normal()

◆ operator=()

◆ pathCorrection()

◆ polyhedronRepresentation()

◆ referenceFrame()

◆ referencePosition()

◆ toStreamImpl()

◆ type()