algorithms/tracking/CKFTracking.cc

0001 // SPDX-License-Identifier: LGPL-3.0-or-later
0002 // Copyright (C) 2022 - 2025 Whitney Armstrong, Wouter Deconinck, Dmitry Romanov, Shujie Li, Dmitry Kalinkin
0003
0004 #include "CKFTracking.h"
0005
0006 #include <Acts/Definitions/Algebra.hpp>
0007 #include <Acts/Definitions/TrackParametrization.hpp>
0008 #include <Acts/Definitions/Units.hpp>
0009 #include <Acts/Utilities/MathHelpers.hpp>
0010 #if Acts_VERSION_MAJOR >= 46
0011 #else
0012 #include <Acts/EventData/GenericBoundTrackParameters.hpp>
0013 #endif
0014 #include <Acts/EventData/MeasurementHelpers.hpp>
0015 #include <Acts/EventData/ParticleHypothesis.hpp>
0016 #include <Acts/EventData/ProxyAccessor.hpp>
0017 #include <Acts/EventData/SourceLink.hpp>
0018 #include <Acts/EventData/TrackContainer.hpp>
0019 #include <Acts/EventData/TrackProxy.hpp>
0020 #include <Acts/EventData/TrackStatePropMask.hpp>
0021 #include <Acts/EventData/VectorMultiTrajectory.hpp>
0022 #include <Acts/EventData/VectorTrackContainer.hpp>
0023 #include <Acts/Geometry/GeometryContext.hpp>
0024 #include <Acts/Geometry/GeometryHierarchyMap.hpp>
0025 #include <Acts/Geometry/GeometryIdentifier.hpp>
0026 #include <Acts/Propagator/ActorList.hpp>
0027 #include <Acts/Propagator/EigenStepper.hpp>
0028 #include <Acts/Propagator/MaterialInteractor.hpp>
0029 #include <Acts/Propagator/Navigator.hpp>
0030 #include <Acts/Propagator/Propagator.hpp>
0031 #include <Acts/Propagator/PropagatorOptions.hpp>
0032 #include <Acts/Propagator/StandardAborters.hpp>
0033 #include <Acts/Surfaces/PerigeeSurface.hpp>
0034 #include <Acts/Surfaces/Surface.hpp>
0035 #include <Acts/TrackFinding/CombinatorialKalmanFilterExtensions.hpp>
0036 #include <Acts/TrackFinding/TrackStateCreator.hpp>
0037 #include <Acts/TrackFitting/GainMatrixUpdater.hpp>
0038 #include <Acts/Utilities/CalibrationContext.hpp>
0039 #include <Acts/Utilities/Logger.hpp>
0040 #include <Acts/Utilities/TrackHelpers.hpp>
0041 #include <ActsExamples/EventData/GeometryContainers.hpp>
0042 #include <ActsExamples/EventData/IndexSourceLink.hpp>
0043 #include <ActsExamples/EventData/Track.hpp>
0044 #include <boost/container/vector.hpp>
0045 #include <edm4eic/Cov3f.h>
0046 #include <edm4eic/Cov6f.h>
0047 #include <edm4eic/Measurement2DCollection.h>
0048 #include <edm4eic/TrackParametersCollection.h>
0049 #include <edm4eic/TrackSeedCollection.h>
0050 #include <edm4eic/unit_system.h>
0051 #include <edm4hep/Vector2f.h>
0052 #include <spdlog/common.h>
0053 #include <Eigen/Core>
0054 #include <Eigen/Geometry>
0055 #include <Eigen/LU> // IWYU pragma: keep
0056 #include <algorithm>
0057 #include <any>
0058 #include <array>
0059 #include <cmath>
0060 #include <cstddef>
0061 #include <cstdint>
0062 #include <format>
0063 #include <functional>
0064 #include <string>
0065 #include <system_error>
0066 #include <tuple>
0067 #include <utility>
0068 // IWYU pragma: no_include <Acts/Utilities/detail/ContextType.hpp>
0069 // IWYU pragma: no_include <Acts/Utilities/detail/ContainerIterator.hpp>
0070
0071 #include "ActsGeometryProvider.h"
0072 #include "extensions/edm4eic/EDM4eicToActs.h"
0073 #include "extensions/spdlog/SpdlogFormatters.h" // IWYU pragma: keep
0074 #include "extensions/spdlog/SpdlogToActs.h"
0075
0076 namespace {
0077
0078 /// Calibrator that reads directly from edm4eic::Measurement2DCollection.
0079 /// Also owns the geometry-ordered IndexSourceLink multiset built from the same collection.
0080 class EDM4eicMeasurementSourceLinkCalibrator {
0081 public:
0082   EDM4eicMeasurementSourceLinkCalibrator(const edm4eic::Measurement2DCollection* meas2Ds,
0083                                          bool useTime)
0084       : m_meas2Ds(meas2Ds), m_useTime(useTime) {
0085     for (std::size_t index = 0; index < meas2Ds->size(); ++index) {
0086       m_orderedSourceLinks.emplace(Acts::GeometryIdentifier{(*meas2Ds)[index].getSurface()}, index);
0087     }
0088   }
0089
0090   const ActsExamples::GeometryIdMultiset<ActsExamples::IndexSourceLink>&
0091   orderedSourceLinks() const {
0092     return m_orderedSourceLinks;
0093   }
0094
0095   void calibrate(const Acts::GeometryContext& /*gctx*/, const Acts::CalibrationContext& /*cctx*/,
0096                  const Acts::SourceLink& sourceLink,
0097                  Acts::VectorMultiTrajectory::TrackStateProxy trackState) const {
0098     trackState.setUncalibratedSourceLink(Acts::SourceLink{sourceLink});
0099     const auto& idxSourceLink = sourceLink.get<ActsExamples::IndexSourceLink>();
0100     const auto& meas2D        = (*m_meas2Ds)[idxSourceLink.index()];
0101
0102     if (m_useTime) {
0103       calibrateImpl<3>(meas2D, trackState);
0104     } else {
0105       calibrateImpl<2>(meas2D, trackState);
0106     }
0107   }
0108
0109 private:
0110   /// Fill the calibrated measurement with loc0, loc1 (N = 2) and additionally time (N = 3)
0111   template <std::size_t N>
0112   static void calibrateImpl(const edm4eic::Measurement2D& meas2D,
0113                             Acts::VectorMultiTrajectory::TrackStateProxy& trackState) {
0114 #if Acts_VERSION_MAJOR > 45 || (Acts_VERSION_MAJOR == 45 && Acts_VERSION_MINOR >= 2)
0115     Acts::Vector<N> loc       = Acts::Vector<N>::Zero();
0116     Acts::SquareMatrix<N> cov = Acts::SquareMatrix<N>::Zero();
0117 #else
0118     Acts::ActsVector<N> loc       = Acts::ActsVector<N>::Zero();
0119     Acts::ActsSquareMatrix<N> cov = Acts::ActsSquareMatrix<N>::Zero();
0120 #endif
0121     // Bound parameters that make up the calibrated measurement, in storage order
0122     constexpr auto indices = []() {
0123       std::array<uint8_t, N> idx{static_cast<uint8_t>(Acts::eBoundLoc0),
0124                                  static_cast<uint8_t>(Acts::eBoundLoc1)};
0125       if constexpr (N == 3) {
0126         idx[2] = static_cast<uint8_t>(Acts::eBoundTime);
0127       }
0128       return idx;
0129     }();
0130     // Position of a bound parameter within the compact calibrated vector
0131     constexpr auto position = [indices](Acts::BoundIndices bound) {
0132       return static_cast<std::size_t>(std::find(indices.begin(), indices.end(), bound) -
0133                                       indices.begin());
0134     };
0135     constexpr std::size_t iLoc0 = position(Acts::eBoundLoc0);
0136     constexpr std::size_t iLoc1 = position(Acts::eBoundLoc1);
0137
0138     constexpr auto mm  = Acts::UnitConstants::mm / edm4eic::unit::mm;
0139     constexpr auto mm2 = mm * mm;
0140     loc[iLoc0]         = meas2D.getLoc().a * mm;
0141     loc[iLoc1]         = meas2D.getLoc().b * mm;
0142     cov(iLoc0, iLoc0)  = meas2D.getCovariance().xx * mm2;
0143     cov(iLoc1, iLoc1)  = meas2D.getCovariance().yy * mm2;
0144     cov(iLoc0, iLoc1)  = meas2D.getCovariance().xy * mm2;
0145     cov(iLoc1, iLoc0)  = meas2D.getCovariance().xy * mm2;
0146
0147     if constexpr (N == 3) {
0148       constexpr std::size_t iTime = position(Acts::eBoundTime);
0149       constexpr auto ns           = Acts::UnitConstants::ns / edm4eic::unit::ns;
0150       constexpr auto ns2          = ns * ns;
0151       // The time variance is stored in the zz component of the measurement covariance
0152       loc[iTime]        = meas2D.getTime() * ns;
0153       cov(iTime, iTime) = meas2D.getCovariance().zz * ns2;
0154       cov(iLoc0, iTime) = meas2D.getCovariance().xz * mm * ns;
0155       cov(iTime, iLoc0) = cov(iLoc0, iTime);
0156       cov(iLoc1, iTime) = meas2D.getCovariance().yz * mm * ns;
0157       cov(iTime, iLoc1) = cov(iLoc1, iTime);
0158     }
0159
0160     trackState.allocateCalibrated(loc, cov);
0161     trackState.setProjectorSubspaceIndices(indices);
0162   }
0163
0164   const edm4eic::Measurement2DCollection* m_meas2Ds;
0165   bool m_useTime;
0166   ActsExamples::GeometryIdMultiset<ActsExamples::IndexSourceLink> m_orderedSourceLinks;
0167 };
0168
0169 /// Per-branch stopper for the CombinatorialKalmanFilter.
0170 ///
0171 /// ACTS's default branch stopper never stops a branch, so a diverging branch is
0172 /// never abandoned. Once a fit goes bad the covariance inflates, the Kalman
0173 /// gain on q/p becomes ill-conditioned, and each further update throws q/p
0174 /// further off. The covariance eventually overflows double precision and the
0175 /// chi2 becomes NaN, which crashes the MeasurementSelector (seen in the
0176 /// far-forward B0 tracker).
0177 ///
0178 /// The divergence is visible in the filtered variance of q/p long before it
0179 /// becomes fatal: a well-behaved fit never exceeds the variance asserted by the
0180 /// seed, while a diverging one exceeds it by many orders of magnitude, and
0181 /// ultimately turns negative or non-finite as positive-definiteness is lost.
0182 /// Testing that variance therefore catches the divergence at the first bad
0183 /// update, while the chi2 still looks harmless, and costs a single matrix
0184 /// element with no history to inspect.
0185 class CKFBranchStopper {
0186 public:
0187   using TrackProxy      = ActsExamples::TrackContainer::TrackProxy;
0188   using TrackStateProxy = ActsExamples::TrackContainer::TrackStateProxy;
0189   using Result          = Acts::CombinatorialKalmanFilterBranchStopperResult;
0190   using LogFunc         = std::function<void(const std::string&)>;
0191
0192   CKFBranchStopper(const eicrecon::CKFTrackingConfig& cfg, LogFunc log)
0193       : m_cfg(cfg), m_log(std::move(log)) {}
0194
0195   Result operator()(const TrackProxy& track, const TrackStateProxy& trackState) const {
0196 #if Acts_VERSION_MAJOR >= 45
0197     if (!trackState.typeFlags().hasMeasurement() || !trackState.hasFiltered()) {
0198 #else
0199     if (!trackState.typeFlags().test(Acts::TrackStateFlag::MeasurementFlag) ||
0200         !trackState.hasFiltered()) {
0201 #endif
0202       return Result::Continue;
0203     }
0204
0205     const double varQOverP =
0206         trackState.filteredCovariance()(Acts::eBoundQOverP, Acts::eBoundQOverP);
0207     // Catches an inflated variance, and also a negative or NaN one, which mean
0208     // the covariance has lost positive-definiteness altogether.
0209     if (!(varQOverP > 0.) || varQOverP > m_cfg.maxQOverPVariance) {
0210       if (m_log) {
0211         m_log(std::format("Dropping diverged CKF branch with {} measurement(s): "
0212                           "filtered var(q/p) = {:g}, limit {:g}",
0213                           track.nMeasurements(), varQOverP, m_cfg.maxQOverPVariance));
0214       }
0215       return Result::StopAndDrop;
0216     }
0217     return Result::Continue;
0218   }
0219
0220 private:
0221   const eicrecon::CKFTrackingConfig& m_cfg;
0222   LogFunc m_log;
0223 };
0224
0225 } // anonymous namespace
0226
0227 namespace eicrecon {
0228
0229 using namespace Acts::UnitLiterals;
0230
0231 void CKFTracking::init() {
0232   m_acts_logger = Acts::getDefaultLogger(
0233       "CKF", eicrecon::SpdlogToActsLevel(static_cast<spdlog::level::level_enum>(this->level())));
0234
0235   // eta bins, chi2 and #sourclinks per surface cutoffs
0236   m_sourcelinkSelectorCfg = {
0237       {Acts::GeometryIdentifier(),
0238        {.etaBins               = m_cfg.etaBins,
0239         .chi2CutOff            = m_cfg.chi2CutOff,
0240         .numMeasurementsCutOff = {m_cfg.numMeasurementsCutOff.begin(),
0241                                   m_cfg.numMeasurementsCutOff.end()}}},
0242   };
0243   m_trackFinderFunc = CKFTracking::makeCKFTrackingFunction(
0244       m_geoSvc->trackingGeometry(), m_geoSvc->getFieldProvider(), acts_logger());
0245 }
0246
0247 void CKFTracking::process(const Input& input, const Output& output) const {
0248   const auto [init_trk_seeds, meas2Ds]      = input;
0249   auto [output_track_states, output_tracks] = output;
0250
0251   // If measurements or initial track parameters are empty, create empty output containers
0252   if (meas2Ds->empty() || init_trk_seeds->empty()) {
0253     debug("No seeds or measurements, creating empty output containers");
0254     *output_track_states = new Acts::ConstVectorMultiTrajectory();
0255     *output_tracks       = new Acts::ConstVectorTrackContainer();
0256     return;
0257   }
0258
0259   // Time-enabled calibration requires a valid time uncertainty on every measurement
0260   if (m_cfg.useTime) {
0261     bool invalid = false;
0262     for (const auto& meas2D : *meas2Ds) {
0263       const float var_t = meas2D.getCovariance().zz;
0264       if (!std::isfinite(var_t) || var_t <= 0) {
0265         error("UseTime is enabled but measurement on surface {} has invalid time variance {}; "
0266               "skipping tracking for this event",
0267               meas2D.getSurface(), var_t);
0268         invalid = true;
0269         break;
0270       }
0271     }
0272     if (invalid) {
0273       *output_track_states = new Acts::ConstVectorMultiTrajectory();
0274       *output_tracks       = new Acts::ConstVectorTrackContainer();
0275       return;
0276     }
0277   }
0278
0279   ActsExamples::TrackParametersContainer acts_init_trk_params;
0280   for (const auto& track_seed : *init_trk_seeds) {
0281
0282     const auto& track_parameter = track_seed.getParams();
0283
0284     Acts::BoundVector params;
0285     params(Acts::eBoundLoc0) =
0286         track_parameter.getLoc().a * Acts::UnitConstants::mm; // cylinder radius
0287     params(Acts::eBoundLoc1) =
0288         track_parameter.getLoc().b * Acts::UnitConstants::mm; // cylinder length
0289     params(Acts::eBoundPhi)    = track_parameter.getPhi();
0290     params(Acts::eBoundTheta)  = track_parameter.getTheta();
0291     params(Acts::eBoundQOverP) = track_parameter.getQOverP() / Acts::UnitConstants::GeV;
0292     params(Acts::eBoundTime)   = track_parameter.getTime() * Acts::UnitConstants::ns;
0293
0294 #if Acts_VERSION_MAJOR > 45 || (Acts_VERSION_MAJOR == 45 && Acts_VERSION_MINOR >= 1)
0295     Acts::BoundMatrix cov = Acts::BoundMatrix::Zero();
0296 #else
0297     Acts::BoundSquareMatrix cov = Acts::BoundSquareMatrix::Zero();
0298 #endif
0299     for (std::size_t i = 0; const auto& [a, x] : edm4eic_indexed_units) {
0300       for (std::size_t j = 0; const auto& [b, y] : edm4eic_indexed_units) {
0301         cov(a, b) = track_parameter.getCovariance()(i, j) * x * y;
0302         ++j;
0303       }
0304       ++i;
0305     }
0306
0307     // Construct a perigee surface as the target surface
0308     auto pSurface = Acts::Surface::makeShared<const Acts::PerigeeSurface>(Acts::Vector3(0, 0, 0));
0309
0310     // Create parameters
0311     acts_init_trk_params.emplace_back(pSurface, params, cov, Acts::ParticleHypothesis::pion());
0312   }
0313
0314   //// Construct a perigee surface as the target surface
0315   auto pSurface = Acts::Surface::makeShared<Acts::PerigeeSurface>(Acts::Vector3{0., 0., 0.});
0316
0317   // Convert algorithm log level to Acts log level for local logger
0318   const auto spdlog_level = static_cast<spdlog::level::level_enum>(this->level());
0319   const auto acts_level   = eicrecon::SpdlogToActsLevel(spdlog_level);
0320   ACTS_LOCAL_LOGGER(Acts::getDefaultLogger("CKF", acts_level));
0321
0322   // Get run-scoped contexts from service
0323   const auto& gctx = m_geoSvc->getActsGeometryContext();
0324   const auto& mctx = m_geoSvc->getActsMagneticFieldContext();
0325   const auto& cctx = m_geoSvc->getActsCalibrationContext();
0326
0327   Acts::PropagatorPlainOptions pOptions(gctx, mctx);
0328   pOptions.maxSteps = 10000;
0329
0330   EDM4eicMeasurementSourceLinkCalibrator calibratorImpl{meas2Ds, m_cfg.useTime};
0331   Acts::GainMatrixUpdater kfUpdater;
0332   Acts::MeasurementSelector measSel{m_sourcelinkSelectorCfg};
0333
0334   Acts::CombinatorialKalmanFilterExtensions<ActsExamples::TrackContainer> extensions;
0335   extensions.updater.connect<&Acts::GainMatrixUpdater::operator()<
0336       typename ActsExamples::TrackContainer::TrackStateContainerBackend>>(&kfUpdater);
0337
0338   ActsExamples::IndexSourceLinkAccessor slAccessor;
0339   slAccessor.container = &calibratorImpl.orderedSourceLinks();
0340   using TrackStateCreatorType =
0341       Acts::TrackStateCreator<ActsExamples::IndexSourceLinkAccessor::Iterator,
0342                               ActsExamples::TrackContainer>;
0343   TrackStateCreatorType trackStateCreator;
0344   trackStateCreator.sourceLinkAccessor
0345       .template connect<&ActsExamples::IndexSourceLinkAccessor::range>(&slAccessor);
0346   trackStateCreator.calibrator.template connect<&EDM4eicMeasurementSourceLinkCalibrator::calibrate>(
0347       &calibratorImpl);
0348   trackStateCreator.measurementSelector
0349       .template connect<&Acts::MeasurementSelector::select<Acts::VectorMultiTrajectory>>(&measSel);
0350
0351   extensions.createTrackStates.template connect<&TrackStateCreatorType::createTrackStates>(
0352       &trackStateCreator);
0353
0354   // Per-branch stopping (ACTS default never stops a branch).
0355   CKFBranchStopper branchStopper{m_cfg, [this](const std::string& msg) { debug("{}", msg); }};
0356   extensions.branchStopper.connect<&CKFBranchStopper::operator()>(&branchStopper);
0357
0358   // Set the CombinatorialKalmanFilter options
0359   CKFTracking::TrackFinderOptions options(gctx, mctx, cctx, extensions, pOptions);
0360
0361   using Extrapolator        = Acts::Propagator<Acts::EigenStepper<>, Acts::Navigator>;
0362   using ExtrapolatorOptions = Extrapolator::template Options<
0363       Acts::ActorList<Acts::MaterialInteractor, Acts::EndOfWorldReached>>;
0364   Extrapolator extrapolator(Acts::EigenStepper<>(m_BField),
0365                             Acts::Navigator({.trackingGeometry = m_geoSvc->trackingGeometry()},
0366                                             acts_logger().cloneWithSuffix("Navigator")),
0367                             acts_logger().cloneWithSuffix("Propagator"));
0368   ExtrapolatorOptions extrapolationOptions(gctx, mctx);
0369
0370   // Create track container
0371   auto trackContainer      = std::make_shared<Acts::VectorTrackContainer>();
0372   auto trackStateContainer = std::make_shared<Acts::VectorMultiTrajectory>();
0373   ActsExamples::TrackContainer acts_tracks(trackContainer, trackStateContainer);
0374
0375   // Create temporary track container
0376   auto trackContainerTemp      = std::make_shared<Acts::VectorTrackContainer>();
0377   auto trackStateContainerTemp = std::make_shared<Acts::VectorMultiTrajectory>();
0378   ActsExamples::TrackContainer acts_tracks_temp(trackContainerTemp, trackStateContainerTemp);
0379
0380   // Add seed number column
0381   acts_tracks.addColumn<unsigned int>("seed");
0382   acts_tracks_temp.addColumn<unsigned int>("seed");
0383   Acts::ProxyAccessor<unsigned int> seedNumber("seed");
0384
0385   // Loop over seeds
0386   for (std::size_t iseed = 0; iseed < acts_init_trk_params.size(); ++iseed) {
0387
0388     // Clear trackContainerTemp and trackStateContainerTemp
0389     acts_tracks_temp.clear();
0390
0391     // Run track finding for this seed
0392     auto result = (*m_trackFinderFunc)(acts_init_trk_params.at(iseed), options, acts_tracks_temp);
0393
0394     if (!result.ok()) {
0395       debug("Track finding failed for seed {} with error {}", iseed, result.error().message());
0396       continue;
0397     }
0398
0399     // Set seed number for all found tracks
0400     auto& tracksForSeed = result.value();
0401     for (auto& track : tracksForSeed) {
0402       // Check if track has at least one valid (non-outlier) measurement
0403       // (this check avoids errors inside smoothing and extrapolation)
0404       auto lastMeasurement = Acts::findLastMeasurementState(track);
0405       if (!lastMeasurement.ok()) {
0406         debug("Track {} for seed {} has no valid measurements, skipping", track.index(), iseed);
0407         continue;
0408       }
0409
0410       if (track.nMeasurements() < m_cfg.numMeasurementsMin) {
0411         trace("Track {} for seed {} has fewer measurements than minimum of {}, skipping",
0412               track.index(), iseed, m_cfg.numMeasurementsMin);
0413         continue;
0414       }
0415
0416       auto smoothingResult = Acts::smoothTrack(gctx, track, acts_logger());
0417       if (!smoothingResult.ok()) {
0418         debug("Smoothing for seed {} and track {} failed with error {}", iseed, track.index(),
0419               smoothingResult.error().message());
0420         continue;
0421       }
0422
0423       auto extrapolationResult = Acts::extrapolateTrackToReferenceSurface(
0424           track, *pSurface, extrapolator, extrapolationOptions,
0425           Acts::TrackExtrapolationStrategy::firstOrLast, acts_logger());
0426
0427       if (!extrapolationResult.ok()) {
0428         debug("Extrapolation for seed {} and track {} failed with error {}", iseed, track.index(),
0429               extrapolationResult.error().message());
0430         continue;
0431       }
0432
0433       seedNumber(track) = iseed;
0434
0435       // Copy accepted track into main track container
0436       auto acts_tracks_proxy = acts_tracks.makeTrack();
0437       acts_tracks_proxy.copyFrom(track);
0438     }
0439   }
0440
0441   // Allocate new const containers and assign pointers to outputs
0442   *output_track_states = new Acts::ConstVectorMultiTrajectory(std::move(*trackStateContainer));
0443   *output_tracks       = new Acts::ConstVectorTrackContainer(std::move(*trackContainer));
0444 }
0445
0446 } // namespace eicrecon