Acts::Experimental::CompositeSpacePointLineSeeder Class Reference

Initial line parameters from a pattern recognition like the Hough transform are often not suitable for a line fit as the resolution of the hough bins usually exceeds the size of the straws. More...

#include <Acts/Seeding/CompositeSpacePointLineSeeder.hpp>

Classes
struct	Config
	Configuration of the cuts to sort out generated seeds with poor quality. More...
struct	SeedingState
	Central auxiliary struct to steer the seeding process. More...
struct	SegmentSeed
	Helper struct to pack the parameters and the associated measurements into a common object. More...
struct	TwoCircleTangentPars
	Helper struct describing the line parameters that are tangential to a pair of straw measurements. More...

Public Types
using	CovIdx = detail::CompSpacePointAuxiliaries::ResidualIdx
	Use the assignment of the parameter indices from the CompSpacePointAuxiliaries.
using	Line_t = std::pair<Vector, Vector>
	Abrivation of the straight line.
using	ParIdx = detail::CompSpacePointAuxiliaries::FitParIndex
	Use the assignment of the parameter indices from the CompSpacePointAuxiliaries.
using	SeedParam_t = std::array<double, toUnderlying(ParIdx::nPars)>
	Vector containing the 5 straight segment line parameters.
enum class	TangentAmbi : std::uint8_t { RR = 0 , RL = 1 , LR = 2 , LL = 3 }
	Enumeration to pick one of the four tangent lines to the straw circle pair. More...
using	Vector = detail::CompSpacePointAuxiliaries::Vector
	Use the vector from the CompSpacePointAuxiliaires.

Public Member Functions
	CompositeSpacePointLineSeeder (const Config &cfg, std::unique_ptr< const Logger > logger=getDefaultLogger("CompositeSpacePointLineSeeder", Logging::Level::INFO))
	Class constructor.
const Config &	config () const
	Return the configuration object of the seeder.
template<CompositeSpacePointContainer UncalibCont_t, CompositeSpacePointContainer CalibCont_t, detail::CompSpacePointSeederDelegate< UncalibCont_t, CalibCont_t > Delegate_t>
std::optional< SegmentSeed< CalibCont_t > >	nextSeed (const CalibrationContext &cctx, SeedingState< UncalibCont_t, CalibCont_t, Delegate_t > &state) const
	Main interface method provided by the SeederClass.

Static Public Member Functions
template<CompositeSpacePoint Sp_t>
static TwoCircleTangentPars	constructTangentLine (const Sp_t &topHit, const Sp_t &bottomHit, const TangentAmbi ambi)
	Construct the line that is tangential to a pair of two straw circle measurements.
static TangentAmbi	encodeAmbiguity (const int signTop, const int signBottom)
	Translate the combination of two drift signs into the proper tangent ambiguity enum value.
template<CompositeSpacePoint Spt_t>
static Vector	makeDirection (const Spt_t &refHit, const double tanAngle)
	Creates the direction vector from the reference hit used to construct the tangent seed and the result on theta.
static std::string	toString (const TangentAmbi ambi)
	Converts the line tangent ambiguity into a string.

Detailed Description

Initial line parameters from a pattern recognition like the Hough transform are often not suitable for a line fit as the resolution of the hough bins usually exceeds the size of the straws.

The CompositeSpacePointLineSeeder refines the parameters and the selected measurements such that both become candidates for a stright line fit. The user needs to split the straw measurements per logical straw layer. Further, the interface needs to provide some auxiliary methods to interact with an empty space point container & to calculate a calbrated candidate pull. From these ingredients, the CompositeSpacePointLineSeeder iterates from the outermost layers at both ends and tries to construct new candidates. Tangent lines are constructed to a pair of circles from each seeding layer and then straw measurements from the other layers are tried to be added onto the line. If the number of straws exceed the threshold, compatible strip measurements from each strip layer are added.

Member Typedef Documentation

CovIdx

using Acts::Experimental::CompositeSpacePointLineSeeder::CovIdx = detail::CompSpacePointAuxiliaries::ResidualIdx

Use the assignment of the parameter indices from the CompSpacePointAuxiliaries.

Line_t

using Acts::Experimental::CompositeSpacePointLineSeeder::Line_t = std::pair<Vector, Vector>

Abrivation of the straight line.

The first element is the reference position and the second element is the direction

ParIdx

using Acts::Experimental::CompositeSpacePointLineSeeder::ParIdx = detail::CompSpacePointAuxiliaries::FitParIndex

Use the assignment of the parameter indices from the CompSpacePointAuxiliaries.

SeedParam_t

using Acts::Experimental::CompositeSpacePointLineSeeder::SeedParam_t = std::array<double, toUnderlying(ParIdx::nPars)>

Vector containing the 5 straight segment line parameters.

Vector

using Acts::Experimental::CompositeSpacePointLineSeeder::Vector = detail::CompSpacePointAuxiliaries::Vector

Use the vector from the CompSpacePointAuxiliaires.

Member Enumeration Documentation

TangentAmbi

enum class Acts::Experimental::CompositeSpacePointLineSeeder::TangentAmbi : std::uint8_t

strong

Enumeration to pick one of the four tangent lines to the straw circle pair.

Enumerator
RR
RL
LR
LL

Constructor & Destructor Documentation

CompositeSpacePointLineSeeder()

Acts::Experimental::CompositeSpacePointLineSeeder::CompositeSpacePointLineSeeder ( const Config & cfg, std::unique_ptr< const Logger > logger = getDefaultLogger("CompositeSpacePointLineSeeder", Logging::Level::INFO) )

explicit

Class constructor.

Parameters

cfg	Reference to the seeder configuration object
logger	Logger object used for debug print out

Member Function Documentation

config()

const Config & Acts::Experimental::CompositeSpacePointLineSeeder::config

(

)

const

Return the configuration object of the seeder.

constructTangentLine()

template<CompositeSpacePoint Sp_t>

TwoCircleTangentPars Acts::Experimental::CompositeSpacePointLineSeeder::constructTangentLine ( const Sp_t & topHit, const Sp_t & bottomHit, const TangentAmbi ambi )

static

Construct the line that is tangential to a pair of two straw circle measurements.

Parameters

topHit	First straw hit
bottomHit	Second straw hit
ambi	Left right ambiguity of the bottom & top hit

encodeAmbiguity()

TangentAmbi Acts::Experimental::CompositeSpacePointLineSeeder::encodeAmbiguity ( const int signTop, const int signBottom )

static

Translate the combination of two drift signs into the proper tangent ambiguity enum value.

Parameters

signTop	Left/right sign of the top straw tube
signBottom	Left/right sign of the bottom straw tube

makeDirection()

template<CompositeSpacePoint Spt_t>

Vector Acts::Experimental::CompositeSpacePointLineSeeder::makeDirection ( const Spt_t & refHit, const double tanAngle )

static

Creates the direction vector from the reference hit used to construct the tangent seed and the result on theta.

Parameters

refHit	Reference hit to define the local axes (Bottom hit)
tanAngle	Theta value from the TwoCircleTangentPars

nextSeed()

template<CompositeSpacePointContainer UncalibCont_t, CompositeSpacePointContainer CalibCont_t, detail::CompSpacePointSeederDelegate< UncalibCont_t, CalibCont_t > Delegate_t>

std::optional< SegmentSeed< CalibCont_t > > Acts::Experimental::CompositeSpacePointLineSeeder::nextSeed	(	const CalibrationContext &	cctx,
		SeedingState< UncalibCont_t, CalibCont_t, Delegate_t > &	state ) const

Main interface method provided by the SeederClass.

The user instantiates a SeedingState object containing all the straw hit candidates from which the seed shall be constructed. Then, the nextSeed() returns the next best seed candidate which can then be fitted. The user continues to call the method until a nullopt is returned.

Parameters

cctx	Experiment specific calibration context to be piped back to the caller such that the space points may be calibrated during the seeding process.
state	Mutable reference to the SeedingState object from which all the segment seeds are constructed.

toString()

std::string Acts::Experimental::CompositeSpacePointLineSeeder::toString ( const TangentAmbi ambi )

static

Converts the line tangent ambiguity into a string.