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refactor(gx2f): analyse temporary track in an extra function (acts-pr…
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…oject#3799)

As a step to make the gx2f easier to read, I pulled out the step, where we check out all trackstates and fill all variables of the gx2f-system.

Maybe we manage in the future to remove the template using a internal track-type and put this into a separate compile unit.
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@AJPfleger @Rosie-Hasan
AJPfleger authored and Rosie-Hasan committed Nov 13, 2024
1 parent 151a9c1 commit 0fe1db4
Showing 1 changed file with 101 additions and 73 deletions.
174 changes: 101 additions & 73 deletions Core/include/Acts/TrackFitting/GlobalChiSquareFitter.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
#include "Acts/EventData/SourceLink.hpp"
#include "Acts/EventData/TrackContainerFrontendConcept.hpp"
#include "Acts/EventData/TrackParameters.hpp"
#include "Acts/EventData/TrackProxyConcept.hpp"
#include "Acts/EventData/VectorMultiTrajectory.hpp"
#include "Acts/EventData/VectorTrackContainer.hpp"
#include "Acts/Geometry/GeometryContext.hpp"
Expand Down Expand Up @@ -485,6 +486,103 @@ void addMaterialToGx2fSums(
return;
}

/// @brief Fill the GX2F system with data from a track
///
/// This function processes a track proxy and updates the aMatrix, bVector, and
/// chi2 values for the GX2F fitting system. It considers material only if
/// multiple scattering is enabled.
///
/// @tparam track_proxy_t The type of the track proxy
///
/// @param track A mutable track proxy to operate on
/// @param aMatrixExtended The aMatrix, summing over second derivatives for the fitting system
/// @param bVectorExtended The bVector, summing over first derivatives for the fitting system
/// @param chi2sum Accumulated chi2 value of the system
/// @param countNdf The number of degrees of freedom counted so far
/// @param multipleScattering Flag to consider multiple scattering in the calculation
/// @param scatteringMap Map of geometry identifiers to scattering properties, containing all scattering angles and covariances
/// @param geoIdVector A vector to store geometry identifiers for tracking processed elements
/// @param logger A logger instance
template <TrackProxyConcept track_proxy_t>
void fillGx2fSystem(
const track_proxy_t track, Eigen::MatrixXd& aMatrixExtended,
Eigen::VectorXd& bVectorExtended, double& chi2sum, std::size_t& countNdf,
const bool multipleScattering,
const std::unordered_map<GeometryIdentifier, ScatteringProperties>&
scatteringMap,
std::vector<GeometryIdentifier>& geoIdVector, const Logger& logger) {
std::vector<BoundMatrix> jacobianFromStart;
jacobianFromStart.emplace_back(BoundMatrix::Identity());

for (const auto& trackState : track.trackStates()) {
// Get and store geoId for the current surface
const GeometryIdentifier geoId = trackState.referenceSurface().geometryId();
ACTS_DEBUG("Start to investigate trackState on surface " << geoId);
const auto typeFlags = trackState.typeFlags();
const bool stateHasMeasurement =
typeFlags.test(TrackStateFlag::MeasurementFlag);
const bool stateHasMaterial = typeFlags.test(TrackStateFlag::MaterialFlag);

// First we figure out, if we would need to look into material
// surfaces at all. Later, we also check, if the material slab is
// valid, otherwise we modify this flag to ignore the material
// completely.
bool doMaterial = multipleScattering && stateHasMaterial;
if (doMaterial) {
const auto scatteringMapId = scatteringMap.find(geoId);
assert(scatteringMapId != scatteringMap.end() &&
"No scattering angles found for material surface.");
doMaterial = doMaterial && scatteringMapId->second.materialIsValid();
}

// We only consider states with a measurement (and/or material)
if (!stateHasMeasurement && !doMaterial) {
ACTS_DEBUG(" Skip state.");
continue;
}

// update all Jacobians from start
for (auto& jac : jacobianFromStart) {
jac = trackState.jacobian() * jac;
}

// Handle measurement
if (stateHasMeasurement) {
ACTS_DEBUG(" Handle measurement.");

const auto measDim = trackState.calibratedSize();

if (measDim < 1 || 6 < measDim) {
ACTS_ERROR("Can not process state with measurement with "
<< measDim << " dimensions.");
throw std::domain_error(
"Found measurement with less than 1 or more than 6 dimension(s).");
}

countNdf += measDim;

visit_measurement(measDim, [&](auto N) {
addMeasurementToGx2fSums<N>(aMatrixExtended, bVectorExtended, chi2sum,
jacobianFromStart, trackState, logger);
});
}

// Handle material
if (doMaterial) {
ACTS_DEBUG(" Handle material");
// Add for this material a new Jacobian, starting from this surface.
jacobianFromStart.emplace_back(BoundMatrix::Identity());

// Add the material contribution to the system
addMaterialToGx2fSums(aMatrixExtended, bVectorExtended, chi2sum,
geoIdVector.size(), scatteringMap, trackState,
logger);

geoIdVector.emplace_back(geoId);
}
}
}

/// @brief Calculate and update the covariance of the fitted parameters
///
/// This function calculates the covariance of the fitted parameters using
Expand Down Expand Up @@ -1185,85 +1283,15 @@ class Gx2Fitter {
Eigen::VectorXd bVectorExtended =
Eigen::VectorXd::Zero(dimsExtendedParams);

std::vector<BoundMatrix> jacobianFromStart;
jacobianFromStart.emplace_back(BoundMatrix::Identity());

// This vector stores the IDs for each visited material in order. We use
// it later for updating the scattering angles. We cannot use
// scatteringMap directly, since we cannot guarantee, that we will visit
// all stored material in each propagation.
std::vector<GeometryIdentifier> geoIdVector;

for (const auto& trackState : track.trackStates()) {
// Get and store geoId for the current surface
const GeometryIdentifier geoId =
trackState.referenceSurface().geometryId();
ACTS_DEBUG("Start to investigate trackState on surface " << geoId);
const auto typeFlags = trackState.typeFlags();
const bool stateHasMeasurement =
typeFlags.test(TrackStateFlag::MeasurementFlag);
const bool stateHasMaterial =
typeFlags.test(TrackStateFlag::MaterialFlag);

// First we figure out, if we would need to look into material surfaces
// at all. Later, we also check, if the material slab is valid,
// otherwise we modify this flag to ignore the material completely.
bool doMaterial = multipleScattering && stateHasMaterial;
if (doMaterial) {
const auto scatteringMapId = scatteringMap.find(geoId);
assert(scatteringMapId != scatteringMap.end() &&
"No scattering angles found for material surface.");
doMaterial = doMaterial && scatteringMapId->second.materialIsValid();
}

// We only consider states with a measurement (and/or material)
if (!stateHasMeasurement && !doMaterial) {
ACTS_DEBUG(" Skip state.");
continue;
}

// update all Jacobians from start
for (auto& jac : jacobianFromStart) {
jac = trackState.jacobian() * jac;
}

// Handle measurement
if (stateHasMeasurement) {
ACTS_DEBUG(" Handle measurement.");

const auto measDim = trackState.calibratedSize();

if (measDim < 1 || 6 < measDim) {
ACTS_ERROR("Can not process state with measurement with "
<< measDim << " dimensions.");
throw std::domain_error(
"Found measurement with less than 1 or more than 6 "
"dimension(s).");
}

countNdf += measDim;

visit_measurement(measDim, [&](auto N) {
addMeasurementToGx2fSums<N>(aMatrixExtended, bVectorExtended,
chi2sum, jacobianFromStart, trackState,
*m_addToSumLogger);
});
}

// Handle material
if (doMaterial) {
ACTS_DEBUG(" Handle material");
// Add for this material a new Jacobian, starting from this surface.
jacobianFromStart.emplace_back(BoundMatrix::Identity());

// Add the material contribution to the system
addMaterialToGx2fSums(aMatrixExtended, bVectorExtended, chi2sum,
geoIdVector.size(), scatteringMap, trackState,
*m_addToSumLogger);

geoIdVector.emplace_back(geoId);
}
}
fillGx2fSystem(track, aMatrixExtended, bVectorExtended, chi2sum, countNdf,
multipleScattering, scatteringMap, geoIdVector,
*m_addToSumLogger);

// Get required number of degrees of freedom ndfSystem.
// We have only 3 cases, because we always have l0, l1, phi, theta
Expand Down

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