File GlobalChiSquareFitter.hpp

namespace Acts

Note

This file is foreseen for the Geometry module to replace Extent

namespace Experimental

Functions

template<size_t measDim, typename traj_t>
void collector(typename traj_t::TrackStateProxy &trackStateProxy, Gx2FitterResult<traj_t> &result, const Logger &logger)

Collector for the GX2F Actor The collector prepares each measurement for the actual fitting process.

Each n-dimensional measurement is split into n 1-dimensional linearly independent measurements. Then the collector saves the following information:

  • Residual: Calculated from measurement and prediction

  • Covariance: The covariance of the measurement

  • Projected Jacobian: This implicitly contains the measurement type It also checks if the covariance is above a threshold, to detect and avoid too small covariances for a stable fit.

Template Parameters

  • measDim – Number of dimensions of the measurement

  • traj_t – The trajectory type

Parameters

  • trackStateProxy – is the current track state

  • result – is the mutable result/cache object

  • logger – a logger instance

template<typename propagator_t, typename traj_t>
class Gx2Fitter
#include <Acts/TrackFitting/GlobalChiSquareFitter.hpp>

Global Chi Square fitter (GX2F) implementation.

TODO Write description

Template Parameters

propagator_t – Type of the propagation class

Public Functions

inline Gx2Fitter(propagator_t pPropagator, std::unique_ptr<const Logger> _logger = getDefaultLogger("Gx2Fitter", Logging::INFO))
template<typename source_link_iterator_t, typename start_parameters_t, typename parameters_t = BoundTrackParameters, typename track_container_t, template<typename> class holder_t, bool _isdn = isDirectNavigator>
inline auto fit(source_link_iterator_t it, source_link_iterator_t end, const start_parameters_t &sParameters, const Gx2FitterOptions<traj_t> &gx2fOptions, TrackContainer<track_container_t, traj_t, holder_t> &trackContainer) const -> std::enable_if_t<!_isdn, Result<typename TrackContainer<track_container_t, traj_t, holder_t>::TrackProxy>>

Fit implementation.

Note

The input measurements are given in the form of SourceLink s. It’s the calibrators job to turn them into calibrated measurements used in the fit.

Template Parameters

  • source_link_iterator_t – Iterator type used to pass source links

  • start_parameters_t – Type of the initial parameters

  • parameters_t – Type of parameters used for local parameters

  • track_container_t – Type of the track container backend

  • holder_t – Type defining track container backend ownership

Parameters

  • it – Begin iterator for the fittable uncalibrated measurements

  • end – End iterator for the fittable uncalibrated measurements

  • sParameters – The initial track parameters

  • gx2fOptions – Gx2FitterOptions steering the fit

  • trackContainer – Input track container storage to append into

Returns

the output as an output track

Private Types

using Gx2fNavigator = typename propagator_t::Navigator

The navigator type.

Private Functions

inline const Logger &logger() const

Private Members

std::unique_ptr<const Logger> m_actorLogger
std::unique_ptr<const Logger> m_logger

The logger instance.

propagator_t m_propagator

The propagator for the transport and material update.

Private Static Attributes

static constexpr bool isDirectNavigator = std::is_same<Gx2fNavigator, DirectNavigator>::value

The navigator has DirectNavigator type or not.

template<typename parameters_t>
class Aborter

Aborter can stay like this probably.

Public Types

using action_type = Actor<parameters_t>

Broadcast the result_type.

Public Functions

template<typename propagator_state_t, typename stepper_t, typename navigator_t, typename result_t>
inline bool operator()(propagator_state_t&, const stepper_t&, const navigator_t&, const result_t &result, const Logger&) const
template<typename parameters_t>
class Actor

Propagator Actor plugin for the GX2F.

The GX2FnActor does not rely on the measurements to be sorted along the track. /// TODO is this true?

Template Parameters

  • parameters_t – The type of parameters used for “local” parameters.

  • calibrator_t – The type of calibrator

  • outlier_finder_t – Type of the outlier finder class

Public Types

using result_type = Gx2FitterResult<traj_t>

Broadcast the result_type.

Public Functions

inline const Logger &logger() const

Logger helper.

template<typename propagator_state_t, typename stepper_t, typename navigator_t>
inline void operator()(propagator_state_t &state, const stepper_t &stepper, const navigator_t &navigator, result_type &result, const Logger&) const

Gx2f actor operation.

Template Parameters

  • propagator_state_t – is the type of Propagator state

  • stepper_t – Type of the stepper

  • navigator_t – Type of the navigator

Parameters

  • state – is the mutable propagator state object

  • stepper – The stepper in use

  • navigator – The navigator in use

  • result – is the mutable result state object

Public Members

const Logger *actorLogger = {nullptr}

The logger instance.

const CalibrationContext *calibrationContext = {nullptr}

Calibration context for the fit.

bool energyLoss = false

TODO implement later.

Whether to consider energy loss.

Gx2FitterExtensions<traj_t> extensions
FreeToBoundCorrection freeToBoundCorrection

TODO implement later.

Whether to include non-linear correction during global to local transformation

const std::map<GeometryIdentifier, SourceLink> *inputMeasurements = nullptr

Allows retrieving measurements for a surface.

bool multipleScattering = false

Whether to consider multiple scattering.

size_t nUpdate = Acts::MultiTrajectoryTraits::kInvalid

The current iteration of the fitter.

The variable is updated in fit(). The actor needs to know the current iteration for adding new trackStates. During the first iteration, each measurement surfaces will be added to the track.

std::shared_ptr<MultiTrajectory<traj_t>> outputStates

Input MultiTrajectory.

SurfaceReached targetReached

The Surface being.

const Surface *targetSurface = nullptr

The target surface.

template<typename traj_t>
struct Gx2FitterExtensions
#include <Acts/TrackFitting/GlobalChiSquareFitter.hpp>

Extension struct which holds delegates to customize the KF behavior.

Public Types

using Calibrator = Delegate<void(const GeometryContext&, const CalibrationContext&, const SourceLink&, TrackStateProxy)>
using ConstTrackStateProxy = typename MultiTrajectory<traj_t>::ConstTrackStateProxy
using OutlierFinder = Delegate<bool(ConstTrackStateProxy)>
using Parameters = typename TrackStateProxy::Parameters
using TrackStateProxy = typename MultiTrajectory<traj_t>::TrackStateProxy
using Updater = Delegate<Result<void>(const GeometryContext&, TrackStateProxy, Direction, const Logger&)>

Public Functions

inline Gx2FitterExtensions()

Default constructor which connects the default void components.

Public Members

Calibrator calibrator

The Calibrator is a dedicated calibration algorithm that allows to calibrate measurements using track information, this could be e.g.

sagging for wires, module deformations, etc.

OutlierFinder outlierFinder

Determines whether a measurement is supposed to be considered as an outlier.

SourceLinkSurfaceAccessor surfaceAccessor

Retrieves the associated surface from a source link.

Updater updater

The updater incorporates measurement information into the track parameters.

template<typename traj_t>
struct Gx2FitterOptions
#include <Acts/TrackFitting/GlobalChiSquareFitter.hpp>

Combined options for the Global-Chi-Square fitter.

Template Parameters

traj_t – The trajectory type

Public Functions

Gx2FitterOptions() = delete

Contexts are required and the options must not be default-constructible.

inline Gx2FitterOptions(const GeometryContext &gctx, const MagneticFieldContext &mctx, std::reference_wrapper<const CalibrationContext> cctx, Gx2FitterExtensions<traj_t> extensions_, const PropagatorPlainOptions &pOptions, const Surface *rSurface = nullptr, bool mScattering = false, bool eLoss = false, const FreeToBoundCorrection &freeToBoundCorrection_ = FreeToBoundCorrection(false), const size_t nUpdateMax_ = 5)

PropagatorOptions with context.

Parameters

  • gctx – The geometry context for this fit

  • mctx – The magnetic context for this fit

  • cctx – The calibration context for this fit

  • extensions_ – The KF extensions

  • pOptions – The plain propagator options

  • rSurface – The reference surface for the fit to be expressed at

  • mScattering – Whether to include multiple scattering

  • eLoss – Whether to include energy loss

  • freeToBoundCorrection_ – Correction for non-linearity effect during transform from free to bound

  • nUpdateMax_ – Max number of iterations for updating the parameters

Public Members

std::reference_wrapper<const CalibrationContext> calibrationContext

context object for the calibration

bool energyLoss = false

Whether to consider energy loss.

Gx2FitterExtensions<traj_t> extensions
FreeToBoundCorrection freeToBoundCorrection

Whether to include non-linear correction during global to local transformation.

std::reference_wrapper<const GeometryContext> geoContext

Context object for the geometry.

std::reference_wrapper<const MagneticFieldContext> magFieldContext

Context object for the magnetic field.

bool multipleScattering = false

Whether to consider multiple scattering.

size_t nUpdateMax = 5

Max number of iterations during the fit.

PropagatorPlainOptions propagatorPlainOptions

The trivial propagator options.

const Surface *referenceSurface = nullptr

The reference Surface.

template<typename traj_t>
struct Gx2FitterResult
#include <Acts/TrackFitting/GlobalChiSquareFitter.hpp>

Public Members

std::vector<ActsScalar> collectorCovariances
std::vector<BoundVector> collectorProjectedJacobians
std::vector<ActsScalar> collectorResiduals
bool finished = false
std::optional<BoundTrackParameters> fittedParameters
traj_t *fittedStates = {nullptr}
BoundMatrix jacobianFromStart = BoundMatrix::Identity()
size_t lastMeasurementIndex = Acts::MultiTrajectoryTraits::kInvalid
size_t lastTrackIndex = Acts::MultiTrajectoryTraits::kInvalid
size_t measurementHoles = 0
size_t measurementStates = 0
std::vector<const Surface*> missedActiveSurfaces
std::vector<const Surface*> passedAgainSurfaces
size_t processedStates = 0
Result<void> result = {Result<void>::success()}
size_t surfaceCount = 0