EIC code displayed by LXR master/​acts/​Tests/​UnitTests/​Core/​Vertexing/​ImpactPointEstimatorTests.cpp	Source navigation Diff markup Identifier search General search
	Version: master test Revert   Change

File indexing completed on 2026-09-15 08:21:46

 // This file is part of the ACTS project.
 //
 // Copyright (C) 2016 CERN for the benefit of the ACTS project
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
 #include <boost/test/data/test_case.hpp>
 #include <boost/test/unit_test.hpp>
 
 #include "Acts/Definitions/Algebra.hpp"
 #include "Acts/Definitions/Common.hpp"
 #include "Acts/Definitions/Direction.hpp"
 #include "Acts/Definitions/TrackParametrization.hpp"
 #include "Acts/Definitions/Units.hpp"
 #include "Acts/EventData/BoundTrackParameters.hpp"
 #include "Acts/Geometry/GeometryContext.hpp"
 #include "Acts/Geometry/GeometryIdentifier.hpp"
 #include "Acts/MagneticField/ConstantBField.hpp"
 #include "Acts/MagneticField/MagneticFieldContext.hpp"
 #include "Acts/MagneticField/MagneticFieldProvider.hpp"
 #include "Acts/MagneticField/NullBField.hpp"
 #include "Acts/Propagator/EigenStepper.hpp"
 #include "Acts/Propagator/Propagator.hpp"
 #include "Acts/Propagator/StraightLineStepper.hpp"
 #include "Acts/Propagator/VoidNavigator.hpp"
 #include "Acts/Surfaces/PerigeeSurface.hpp"
 #include "Acts/Surfaces/PlaneSurface.hpp"
 #include "Acts/Surfaces/Surface.hpp"
 #include "Acts/Utilities/Intersection.hpp"
 #include "Acts/Utilities/Logger.hpp"
 #include "Acts/Utilities/Result.hpp"
 #include "Acts/Vertexing/ImpactPointEstimator.hpp"
 #include "Acts/Vertexing/Vertex.hpp"
 #include "ActsTests/CommonHelpers/FloatComparisons.hpp"
 
 #include <cmath>
 #include <limits>
 #include <memory>
 #include <numbers>
 #include <optional>
 #include <utility>
 #include <vector>
 
 namespace ActsTests {
 
 namespace bd = boost::unit_test::data;
 
 using namespace Acts;
 using namespace Acts::UnitLiterals;
 using Acts::VectorHelpers::makeVector4;
 
 using MagneticField = ConstantBField;
 using StraightPropagator = Propagator<StraightLineStepper>;
 using Stepper = EigenStepper<>;
 using Propagator = Acts::Propagator<Stepper>;
 using Estimator = ImpactPointEstimator;
 using StraightLineEstimator = ImpactPointEstimator;
 
 const auto geoContext = GeometryContext::dangerouslyDefaultConstruct();
 const MagneticFieldContext magFieldContext;
 
 MagneticFieldProvider::Cache magFieldCache() {
   return NullBField{}.makeCache(magFieldContext);
 }
 
 // perigee track parameters dataset
 // only non-zero distances are tested
 auto d0s = bd::make({-25_um, 25_um});
 auto l0s = bd::make({-1_mm, 1_mm});
 auto t0s = bd::make({-2_ns, 2_ns});
 auto phis = bd::make({0_degree, -45_degree, 45_degree});
 auto thetas = bd::make({90_degree, 20_degree, 160_degree});
 auto ps = bd::make({0.4_GeV, 1_GeV, 10_GeV});
 auto qs = bd::make({-1_e, 1_e});
 // Cartesian products over all parameters
 auto tracksWithoutIPs = t0s * phis * thetas * ps * qs;
 auto IPs = d0s * l0s;
 auto tracks = IPs * tracksWithoutIPs;
 
 // vertex parameters dataset
 auto vx0s = bd::make({0_um, -10_um, 10_um});
 auto vy0s = bd::make({0_um, -10_um, 10_um});
 auto vz0s = bd::make({0_mm, -25_mm, 25_mm});
 auto vt0s = bd::make({0_ns, -2_ns, 2_ns});
 // Cartesian products over all parameters
 auto vertices = vx0s * vy0s * vz0s * vt0s;
 
 // Construct an impact point estimator for a constant bfield along z.
 Estimator makeEstimator(double bZ) {
   auto field = std::make_shared<MagneticField>(Vector3(0, 0, bZ));
   Stepper stepper(field);
   Estimator::Config cfg(field,
                         std::make_shared<Propagator>(
                             std::move(stepper), VoidNavigator(),
                             getDefaultLogger("Prop", Logging::Level::WARNING)));
   return Estimator(cfg);
 }
 
 // Construct a diagonal track covariance w/ reasonable values.
 BoundMatrix makeBoundParametersCovariance(double stdDevTime = 30_ps) {
   BoundVector stddev;
   stddev[eBoundLoc0] = 15_um;
   stddev[eBoundLoc1] = 100_um;
   stddev[eBoundTime] = stdDevTime;
   stddev[eBoundPhi] = 1_degree;
   stddev[eBoundTheta] = 1_degree;
   stddev[eBoundQOverP] = 1_e / 100_GeV;
   return stddev.cwiseProduct(stddev).asDiagonal();
 }
 
 // Construct a diagonal vertex covariance w/ reasonable values.
 SquareMatrix4 makeVertexCovariance() {
   Vector4 stddev;
   stddev[ePos0] = 10_um;
   stddev[ePos1] = 10_um;
   stddev[ePos2] = 75_um;
   stddev[eTime] = 1_ns;
   return stddev.cwiseProduct(stddev).asDiagonal();
 }
 
 // random value between 0 and 1
 std::uniform_real_distribution<double> uniformDist(0.0, 1.0);
 // random sign
 std::uniform_real_distribution<double> signDist(-1, 1);
 
 BOOST_AUTO_TEST_SUITE(VertexingSuite)
 
 // Check `calculateDistance`, `estimate3DImpactParameters`, and
 // `getVertexCompatibility`.
 BOOST_DATA_TEST_CASE(SingleTrackDistanceParametersCompatibility3D, tracks, d0,
                      l0, t0, phi, theta, p, q) {
   auto particleHypothesis = ParticleHypothesis::pion();
 
   BoundVector par;
   par[eBoundLoc0] = d0;
   par[eBoundLoc1] = l0;
   par[eBoundTime] = t0;
   par[eBoundPhi] = phi;
   par[eBoundTheta] = theta;
   par[eBoundQOverP] = particleHypothesis.qOverP(p, q);
 
   Estimator ipEstimator = makeEstimator(2_T);
   Estimator::State state{magFieldCache()};
   // reference position and corresponding perigee surface
   Vector3 refPosition(0., 0., 0.);
   auto perigeeSurface = Surface::makeShared<PerigeeSurface>(refPosition);
   // create the track
   BoundTrackParameters myTrack(
       perigeeSurface, par, makeBoundParametersCovariance(), particleHypothesis);
 
   // initial distance to the reference position in the perigee frame
   double distT = std::hypot(d0, l0);
   double dist3 =
       ipEstimator.calculateDistance(geoContext, myTrack, refPosition, state)
           .value();
   // estimated 3D distance should be less than the 2d distance in the perigee
   // frame. it should be equal if the track is a transverse track w/ theta =
   // 90deg. in that case there might be numerical deviations and we need to
   // check that it is less or equal within the numerical tolerance.
   BOOST_CHECK((dist3 < distT) ||
               (theta == 90_degree && std::abs(dist3 - distT) < 1_nm));
 
   // estimate parameters at the closest point in 3d
   auto res = ipEstimator.estimate3DImpactParameters(
       geoContext, magFieldContext, myTrack, refPosition, state);
   BoundTrackParameters trackAtIP3d = *res;
   const auto& atPerigee = myTrack.parameters();
   const auto& atIp3d = trackAtIP3d.parameters();
 
   // all parameters except the helix invariants theta, q/p should be changed.
   // Exception: for a transverse track (theta = 90 deg) the 2D and 3D PCA
   // coincide and the point surface measurement frame aligns with the perigee
   // frame, so the local position is unchanged.
   if (theta != 90_degree) {
     BOOST_CHECK_NE(atPerigee[eBoundLoc0], atIp3d[eBoundLoc0]);
     BOOST_CHECK_NE(atPerigee[eBoundLoc1], atIp3d[eBoundLoc1]);
   }
   // BOOST_CHECK_NE(atPerigee[eBoundTime], atIp3d[eBoundTime]);
   // BOOST_CHECK_NE(atPerigee[eBoundPhi], atIp3d[eBoundPhi]);
   CHECK_CLOSE_ABS(atPerigee[eBoundTheta], atIp3d[eBoundTheta], 0.01_mrad);
   CHECK_CLOSE_REL(atPerigee[eBoundQOverP], atIp3d[eBoundQOverP],
                   std::numeric_limits<double>::epsilon());
 
   // check that we get sensible compatibility scores
   // this is a chi2-like value and should always be positive
   auto compatibility =
       ipEstimator.getVertexCompatibility(geoContext, &trackAtIP3d, refPosition)
           .value();
   BOOST_CHECK_GT(compatibility, 0);
 }
 
 BOOST_DATA_TEST_CASE(TimeAtPca, tracksWithoutIPs* vertices, t0, phi, theta, p,
                      q, vx0, vy0, vz0, vt0) {
   using Propagator = Acts::Propagator<Stepper>;
   using PropagatorOptions = Propagator::Options<>;
   using StraightPropagator = Acts::Propagator<StraightLineStepper>;
 
   // Set up quantities for constant B field
   auto field = std::make_shared<MagneticField>(Vector3(0, 0, 2_T));
   Stepper stepper(field);
   auto propagator = std::make_shared<Propagator>(std::move(stepper));
   Estimator::Config cfg(field, propagator);
   Estimator ipEstimator(cfg);
   Estimator::State ipState{magFieldCache()};
 
   // Set up quantities for B = 0
   auto zeroField = std::make_shared<MagneticField>(Vector3(0, 0, 0));
   StraightLineStepper straightLineStepper;
   auto straightLinePropagator =
       std::make_shared<StraightPropagator>(straightLineStepper);
   StraightLineEstimator::Config zeroFieldCfg(zeroField, straightLinePropagator);
   StraightLineEstimator zeroFieldIPEstimator(zeroFieldCfg);
   StraightLineEstimator::State zeroFieldIPState{magFieldCache()};
 
   // Vertex position and vertex object
   Vector4 vtxPos(vx0, vy0, vz0, vt0);
   Vertex vtx(vtxPos, makeVertexCovariance(), {});
 
   // Perigee surface at vertex position
   auto vtxPerigeeSurface =
       Surface::makeShared<PerigeeSurface>(vtxPos.head<3>());
 
   // Track parameter vector for a track that originates at the vertex.
   // Note that 2D and 3D PCA coincide since the track passes exactly through the
   // vertex.
   BoundVector paramVec;
   paramVec[eBoundLoc0] = 0.;
   paramVec[eBoundLoc1] = 0.;
   paramVec[eBoundTime] = t0;
   paramVec[eBoundPhi] = phi;
   paramVec[eBoundTheta] = theta;
   paramVec[eBoundQOverP] = q / p;
 
   BoundTrackParameters params(vtxPerigeeSurface, paramVec,
                               makeBoundParametersCovariance(),
                               ParticleHypothesis::pion());
 
   // Correct quantities for checking if IP estimation worked
   // Time of the track with respect to the vertex
   double corrTimeDiff = t0 - vt0;
 
   // Momentum direction at vertex (i.e., at 3D PCA)
   double cosPhi = std::cos(phi);
   double sinPhi = std::sin(phi);
   double sinTheta = std::sin(theta);
   Vector3 corrMomDir =
       Vector3(cosPhi * sinTheta, sinPhi * sinTheta, std::cos(theta));
 
   // Arbitrary reference point
   Vector3 refPoint(2_mm, -2_mm, -5_mm);
 
   // Perigee surface at vertex position
   auto refPerigeeSurface = Surface::makeShared<PerigeeSurface>(refPoint);
 
   // Set up the propagator options (they are the same with and without B field)
   PropagatorOptions pOptions(geoContext, magFieldContext);
   Intersection3D intersection =
       refPerigeeSurface
           ->intersect(geoContext, params.position(geoContext),
                       params.direction(), BoundaryTolerance::Infinite())
           .closest();
   pOptions.direction =
       Direction::fromScalarZeroAsPositive(intersection.pathLength());
 
   StraightPropagator::Options<> straightPOptions(geoContext, magFieldContext);
   straightPOptions.direction = pOptions.direction;
 
   // Propagate to the 2D PCA of the reference point in a constant B field
   auto result = propagator->propagate(params, *refPerigeeSurface, pOptions);
   BOOST_CHECK(result.ok());
   const auto& refParams = *result->endParameters;
 
   // Propagate to the 2D PCA of the reference point when B = 0
   auto zeroFieldResult = straightLinePropagator->propagate(
       params, *refPerigeeSurface, straightPOptions);
   BOOST_CHECK(zeroFieldResult.ok());
   const auto& zeroFieldRefParams = *zeroFieldResult->endParameters;
 
   BOOST_TEST_CONTEXT(
       "Check time at 2D PCA (i.e., function getImpactParameters) for helical "
       "tracks") {
     // Calculate impact parameters
     auto ipParams = ipEstimator
                         .getImpactParameters(refParams, vtx, geoContext,
                                              magFieldContext, true)
                         .value();
     // Spatial impact parameters should be 0 because the track passes through
     // the vertex
     CHECK_CLOSE_ABS(ipParams.d0, 0., 30_nm);
     CHECK_CLOSE_ABS(ipParams.z0, 0., 100_nm);
     // Time impact parameter should correspond to the time where the track
     // passes through the vertex
     CHECK_CLOSE_OR_SMALL(ipParams.deltaT.value(), std::abs(corrTimeDiff), 1e-5,
                          1e-3);
   }
 
   auto checkGetDistanceAndMomentum = [&vtxPos, &corrMomDir, corrTimeDiff](
                                          const auto& ipe, const auto& rParams,
                                          auto& state) {
     // Find 4D distance and momentum of the track at the vertex starting from
     // the perigee representation at the reference position
     auto distAndMom = ipe.template getDistanceAndMomentum<4>(
                              geoContext, rParams, vtxPos, state)
                           .value();
 
     Vector4 distVec = distAndMom.first;
     Vector3 momDir = distAndMom.second;
 
     // Check quantities:
     // Spatial distance should be 0 as track passes through the vertex
     double dist = distVec.head<3>().norm();
     CHECK_CLOSE_ABS(dist, 0., 30_nm);
     // Distance in time should correspond to the time of the track in a
     // coordinate system with the vertex as the origin since the track passes
     // exactly through the vertex
     CHECK_CLOSE_OR_SMALL(distVec[3], corrTimeDiff, 1e-5, 1e-4);
     // Momentum direction should correspond to the momentum direction at the
     // vertex
     CHECK_CLOSE_OR_SMALL(momDir, corrMomDir, 1e-5, 1e-4);
   };
 
   BOOST_TEST_CONTEXT(
       "Check time at 3D PCA (i.e., function getDistanceAndMomentum) for "
       "straight tracks") {
     checkGetDistanceAndMomentum(zeroFieldIPEstimator, zeroFieldRefParams,
                                 zeroFieldIPState);
   }
   BOOST_TEST_CONTEXT(
       "Check time at 3D PCA (i.e., function getDistanceAndMomentum) for "
       "helical tracks") {
     checkGetDistanceAndMomentum(ipEstimator, refParams, ipState);
   }
 }
 
 BOOST_DATA_TEST_CASE(VertexCompatibility4D, IPs* vertices, d0, l0, vx0, vy0,
                      vz0, vt0) {
   // Set up RNG
   int seed = 31415;
   std::mt19937 gen(seed);
 
   // Impact point estimator
   Estimator ipEstimator = makeEstimator(2_T);
 
   // Vertex position
   Vector4 vtxPos(vx0, vy0, vz0, vt0);
 
   // Dummy coordinate system with origin at vertex
   Transform3 coordinateSystem;
   // First three columns correspond to coordinate system axes
   coordinateSystem.matrix().block<3, 3>(0, 0) = SquareMatrix<3>::Identity();
   // Fourth column corresponds to origin of the coordinate system
   coordinateSystem.matrix().block<3, 1>(0, 3) = vtxPos.head<3>();
 
   // Dummy plane surface
   std::shared_ptr<PlaneSurface> planeSurface =
       Surface::makeShared<PlaneSurface>(coordinateSystem);
 
   // Create two track parameter vectors that are alike except that one is closer
   // to the vertex in time. Note that momenta don't play a role in the
   // computation and we set the angles and q/p to 0.
   // Time offsets
   double timeDiffFactor = uniformDist(gen);
   double timeDiffClose = timeDiffFactor * 0.1_ps;
   double timeDiffFar = timeDiffFactor * 0.11_ps;
 
   // Different random signs for the time offsets
   double sgnClose = std::copysign(1., signDist(gen));
   double sgnFar = std::copysign(1., signDist(gen));
 
   BoundVector paramVecClose = BoundVector::Zero();
   paramVecClose[eBoundLoc0] = d0;
   paramVecClose[eBoundLoc1] = l0;
   paramVecClose[eBoundPhi] = 0;
   paramVecClose[eBoundTheta] = std::numbers::pi / 2;
   paramVecClose[eBoundQOverP] = 0;
   paramVecClose[eBoundTime] = vt0 + sgnClose * timeDiffClose;
 
   BoundVector paramVecFar = paramVecClose;
   paramVecFar[eBoundTime] = vt0 + sgnFar * timeDiffFar;
 
   // Track whose time is similar to the vertex time
   BoundTrackParameters paramsClose(planeSurface, paramVecClose,
                                    makeBoundParametersCovariance(30_ns),
                                    ParticleHypothesis::pion());
 
   // Track whose time is similar to the vertex time but with a larger time
   // variance
   BoundTrackParameters paramsCloseLargerCov(
       planeSurface, paramVecClose, makeBoundParametersCovariance(31_ns),
       ParticleHypothesis::pion());
 
   // Track whose time differs slightly more from the vertex time
   BoundTrackParameters paramsFar(planeSurface, paramVecFar,
                                  makeBoundParametersCovariance(30_ns),
                                  ParticleHypothesis::pion());
 
   // Calculate the 4D vertex compatibilities of the three tracks
   double compatibilityClose =
       ipEstimator.getVertexCompatibility(geoContext, &paramsClose, vtxPos)
           .value();
   double compatibilityCloseLargerCov =
       ipEstimator
           .getVertexCompatibility(geoContext, &paramsCloseLargerCov, vtxPos)
           .value();
   double compatibilityFar =
       ipEstimator.getVertexCompatibility(geoContext, &paramsFar, vtxPos)
           .value();
 
   // The track who is closer in time must have a better (i.e., smaller)
   // compatibility
   BOOST_CHECK_LT(compatibilityClose, compatibilityFar);
   // The track with the larger covariance must be the most compatible
   BOOST_CHECK_LT(compatibilityCloseLargerCov, compatibilityClose);
 }
 
 // Compare calculations w/ known good values from Athena.
 //
 // Checks the results for a single track with the same test values as in Athena
 // unit test algorithm
 //
 //   Tracking/TrkVertexFitter/TrkVertexFitterUtils/test/ImpactPointEstimator_test
 //
 BOOST_AUTO_TEST_CASE(SingleTrackDistanceParametersAthenaRegression) {
   Estimator ipEstimator = makeEstimator(1.9971546939_T);
   Estimator::State state{magFieldCache()};
 
   // Use same values as in Athena unit test
   Vector4 pos1(2_mm, 1_mm, -10_mm, 0_ns);
   Vector3 mom1(400_MeV, 600_MeV, 200_MeV);
   Vector3 vtxPos(1.2_mm, 0.8_mm, -7_mm);
 
   // Start creating some track parameters
   auto perigeeSurface =
       Surface::makeShared<PerigeeSurface>(pos1.segment<3>(ePos0));
   // Some fixed track parameter values
   auto params1 = BoundTrackParameters::create(
                      geoContext, perigeeSurface, pos1, mom1, 1_e / mom1.norm(),
                      BoundMatrix::Identity(), ParticleHypothesis::pion())
                      .value();
 
   // Compare w/ desired result from Athena unit test
   auto distance =
       ipEstimator.calculateDistance(geoContext, params1, vtxPos, state).value();
   CHECK_CLOSE_ABS(distance, 3.10391_mm, 10_nm);
 
   auto res2 = ipEstimator.estimate3DImpactParameters(
       geoContext, magFieldContext, params1, vtxPos, state);
   BOOST_CHECK(res2.ok());
   BoundTrackParameters endParams = *res2;
   Vector3 surfaceCenter = endParams.referenceSurface().center(geoContext);
 
   BOOST_CHECK_EQUAL(surfaceCenter, vtxPos);
 }
 
 // Test the Impact3d Point estimator 2d and 3d lifetimes sign
 // on a single track.
 
 BOOST_AUTO_TEST_CASE(Lifetimes2d3d) {
   Estimator ipEstimator = makeEstimator(2_T);
 
   // Create a track from a decay
   BoundVector trk_par;
   trk_par[eBoundLoc0] = 200_um;
   trk_par[eBoundLoc1] = 300_um;
   trk_par[eBoundTime] = 1_ns;
   trk_par[eBoundPhi] = 45_degree;
   trk_par[eBoundTheta] = 45_degree;
   trk_par[eBoundQOverP] = 1_e / 10_GeV;
 
   Vector4 ip_pos{0., 0., 0., 0.};
   Vertex ip_vtx(ip_pos, makeVertexCovariance(), {});
 
   // Form the bound track parameters at the ip
   auto perigeeSurface = Surface::makeShared<PerigeeSurface>(ip_pos.head<3>());
   BoundTrackParameters track(perigeeSurface, trk_par,
                              makeBoundParametersCovariance(),
                              ParticleHypothesis::pion());
 
   Vector3 direction{0., 1., 0.};
   auto lifetimes_signs = ipEstimator.getLifetimeSignOfTrack(
       track, ip_vtx, direction, geoContext, magFieldContext);
 
   // Check if the result is OK
   BOOST_CHECK(lifetimes_signs.ok());
 
   // Check that d0 sign is positive
   BOOST_CHECK_GT((*lifetimes_signs).first, 0.);
 
   // Check that z0 sign is negative
   BOOST_CHECK_LT((*lifetimes_signs).second, 0.);
 
   // Check the 3d sign
 
   auto sign3d = ipEstimator.get3DLifetimeSignOfTrack(
       track, ip_vtx, direction, geoContext, magFieldContext);
 
   // Check result is OK
   BOOST_CHECK(sign3d.ok());
 
   // Check 3D sign (should be positive)
   BOOST_CHECK_GT((*sign3d), 0.);
 }
 
 // Check `.getImpactParameters`.
 BOOST_DATA_TEST_CASE(SingeTrackImpactParameters, tracks* vertices, d0, l0, t0,
                      phi, theta, p, q, vx0, vy0, vz0, vt0) {
   BoundVector par;
   par[eBoundLoc0] = d0;
   par[eBoundLoc1] = l0;
   par[eBoundTime] = t0;
   par[eBoundPhi] = phi;
   par[eBoundTheta] = theta;
   par[eBoundQOverP] = q / p;
   Vector4 vtxPos;
   vtxPos[ePos0] = vx0;
   vtxPos[ePos1] = vy0;
   vtxPos[ePos2] = vz0;
   vtxPos[eTime] = vt0;
 
   Estimator ipEstimator = makeEstimator(1_T);
   Estimator::State state{magFieldCache()};
 
   // reference position and corresponding perigee surface
   Vector3 refPosition(0., 0., 0.);
   auto perigeeSurface = Surface::makeShared<PerigeeSurface>(refPosition);
   // create track and vertex
   BoundTrackParameters track(perigeeSurface, par,
                              makeBoundParametersCovariance(),
                              ParticleHypothesis::pionLike(std::abs(q)));
   Vertex myConstraint(vtxPos, makeVertexCovariance(), {});
 
   // check that computed impact parameters are meaningful
   ImpactParametersAndSigma output =
       ipEstimator
           .getImpactParameters(track, myConstraint, geoContext, magFieldContext)
           .value();
   BOOST_CHECK_NE(output.d0, 0.);
   BOOST_CHECK_NE(output.z0, 0.);
   // TODO what about the other struct members? can the parameter space be
   // restricted further?
 }
 
 BOOST_AUTO_TEST_SUITE_END()
 
 }  // namespace ActsTests

This page was automatically generated by the 2.3.7 LXR engine. The LXR team