PixelTrackBuilder.cc

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#include "RecoPixelVertexing/PixelTrackFitting/interface/PixelTrackBuilder.h"
 
#include "DataFormats/GeometrySurface/interface/LocalError.h"
#include "DataFormats/GeometrySurface/interface/BoundPlane.h"
#include "DataFormats/GeometryVector/interface/GlobalPoint.h"
 
#include "TrackingTools/TrajectoryParametrization/interface/LocalTrajectoryError.h"
#include "TrackingTools/TrajectoryParametrization/interface/LocalTrajectoryParameters.h"
#include "TrackingTools/TrajectoryState/interface/BasicTrajectoryStateOnSurface.h"
#include "TrackingTools/TrajectoryState/interface/TrajectoryStateOnSurface.h"
 
#include "TrackingTools/PatternTools/interface/TSCPBuilderNoMaterial.h"
#include "TrackingTools/PatternTools/interface/TransverseImpactPointExtrapolator.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "DataFormats/TrackReco/interface/TrackBase.h"
 
#include <sstream>
using namespace std;
using namespace reco;
 
template <class T>
T inline sqr(T t) {
  return t * t;
}
 
namespace {
  __attribute__((unused)) std::string print(const Measurement1D& pt,
                                            const Measurement1D& phi,
                                            const Measurement1D& cotTheta,
                                            const Measurement1D& tip,
                                            const Measurement1D& zip,
                                            float chi2,
                                            int charge) {
    ostringstream str;
    str << "\t pt: " << pt.value() << "+/-" << pt.error() << "\t phi: " << phi.value() << "+/-" << phi.error()
        << "\t cot: " << cotTheta.value() << "+/-" << cotTheta.error() << "\t tip: " << tip.value() << "+/-"
        << tip.error() << "\t zip: " << zip.value() << "+/-" << zip.error() << "\t chi2: " << chi2
        << "\t charge: " << charge;
    return str.str();
  }
 
  __attribute__((unused)) std::string print(const reco::Track& track, const GlobalPoint& origin) {
    math::XYZPoint bs(origin.x(), origin.y(), origin.z());
 
    Measurement1D phi(track.phi(), track.phiError());
 
    float theta = track.theta();
    float cosTheta = cos(theta);
    float sinTheta = sin(theta);
    float errLambda2 = sqr(track.lambdaError());
    Measurement1D cotTheta(cosTheta / sinTheta, sqrt(errLambda2) / sqr(sinTheta));
 
    float pt_v = track.pt();
    float errInvP2 = sqr(track.qoverpError());
    float covIPtTheta = track.covariance(TrackBase::i_qoverp, TrackBase::i_lambda);
    float errInvPt2 =
        (errInvP2 + sqr(cosTheta / pt_v) * errLambda2 + 2 * (cosTheta / pt_v) * covIPtTheta) / sqr(sinTheta);
    Measurement1D pt(pt_v, sqr(pt_v) * sqrt(errInvPt2));
 
    Measurement1D tip(track.dxy(bs), track.d0Error());
 
    Measurement1D zip(track.dz(bs), track.dzError());
 
    return print(pt, phi, cotTheta, tip, zip, track.chi2(), track.charge());
  }
 
  __attribute__((unused)) std::string print(const BasicTrajectoryStateOnSurface& state) {
    // TrajectoryStateOnSurface state(bstate);
    float pt_v = state.globalMomentum().perp();
    float phi_v = state.globalMomentum().phi();
    float theta_v = state.globalMomentum().theta();
 
    CurvilinearTrajectoryError curv = state.curvilinearError();
    float errPhi2 = curv.matrix()(3, 3);
    float errLambda2 = curv.matrix()(2, 2);
    float errInvP2 = curv.matrix()(1, 1);
    float covIPtTheta = curv.matrix()(1, 2);
    float cosTheta = cos(theta_v);
    float sinTheta = sin(theta_v);
    float errInvPt2 =
        (errInvP2 + sqr(cosTheta / pt_v) * errLambda2 + 2 * (cosTheta / pt_v) * covIPtTheta) / sqr(sinTheta);
    float errCotTheta = sqrt(errLambda2) / sqr(sinTheta);
    Measurement1D pt(pt_v, sqr(pt_v) * sqrt(errInvPt2));
    Measurement1D phi(phi_v, sqrt(errPhi2));
    Measurement1D cotTheta(cosTheta / sinTheta, errCotTheta);
 
    float zip_v = state.globalPosition().z();
    float zip_e = sqrt(state.localError().matrix()(4, 4));
    Measurement1D zip(zip_v, zip_e);
 
    float tip_v = state.localPosition().x();
    int tip_sign = (state.localMomentum().y() * cotTheta.value() > 0) ? -1 : 1;
    float tip_e = sqrt(state.localError().matrix()(3, 3));
    Measurement1D tip(tip_sign * tip_v, tip_e);
 
    return print(pt, phi, cotTheta, tip, zip, 0., state.charge());
  }
 
#ifdef DEBUG_STATE
  inline void checkState(const BasicTrajectoryStateOnSurface& bstate,
                         const MagneticField* mf,
                         const GlobalPoint& origin) {
    TrajectoryStateOnSurface state(bstate.clone());
 
    LogTrace("") << " *** PixelTrackBuilder::checkState: ";
    LogTrace("") << "INPUT,  ROTATION" << '\n' << state.surface().rotation();
    LogTrace("") << "INPUT,  TSOS:" << '\n' << state;
 
    TransverseImpactPointExtrapolator tipe(mf);
    TrajectoryStateOnSurface test = tipe.extrapolate(state, origin);
    LogTrace("") << "CHECK-1 ROTATION" << '\n' << test.surface().rotation();
    LogTrace("") << "CHECK-1 TSOS" << '\n' << test;
 
    TSCPBuilderNoMaterial tscpBuilder;
    TrajectoryStateClosestToPoint tscp = tscpBuilder(*(state.freeState()), origin);
    const FreeTrajectoryState& fs = tscp.theState();
    LogTrace("") << "CHECK-2 FTS: " << fs;
  }
#endif
 
}  // namespace
 
reco::Track* PixelTrackBuilder::build(const Measurement1D& pt,
                                      const Measurement1D& phi,
                                      const Measurement1D& cotTheta,
                                      const Measurement1D& tip,
                                      const Measurement1D& zip,
                                      float chi2,
                                      int charge,
                                      const std::vector<const TrackingRecHit*>& hits,
                                      const MagneticField* mf,
                                      const GlobalPoint& origin) const {
  LogDebug("PixelTrackBuilder::build");
  LogTrace("") << "Reconstructed triplet kinematics: " << print(pt, phi, cotTheta, tip, zip, chi2, charge);
 
  double sinTheta = 1 / std::sqrt(1 + sqr(cotTheta.value()));
  double cosTheta = cotTheta.value() * sinTheta;
  int tipSign = tip.value() > 0 ? 1 : -1;
 
  AlgebraicSymMatrix55 m;
  double invPtErr = 1. / sqr(pt.value()) * pt.error();
  m(0, 0) = sqr(sinTheta) * (sqr(invPtErr) + sqr(cotTheta.error() / pt.value() * cosTheta * sinTheta));
  m(0, 2) = sqr(cotTheta.error()) * cosTheta * sqr(sinTheta) / pt.value();
  m(1, 1) = sqr(phi.error());
  m(2, 2) = sqr(cotTheta.error());
  m(3, 3) = sqr(tip.error());
  m(4, 4) = sqr(zip.error());
  LocalTrajectoryError error(m);
 
  LocalTrajectoryParameters lpar(LocalPoint(tipSign * tip.value(), -tipSign * zip.value(), 0),
                                 LocalVector(0., -tipSign * pt.value() * cotTheta.value(), pt.value()),
                                 charge);
 
  float sp = std::sin(phi.value());
  float cp = std::cos(phi.value());
  Surface::RotationType rot(sp * tipSign, -cp * tipSign, 0, 0, 0, -tipSign, cp, sp, 0);
 
  // BTSOS hold Surface in a shared pointer and  will be autodeleted when BTSOS goes out of scope...
  // to avoid memory churn we allocate it locally and just avoid it be deleted by refcount...
  Plane impPointPlane(origin, rot);
  // (twice just to be sure!)
  impPointPlane.addReference();
  impPointPlane.addReference();
  // use Base (to avoid a useless new)
  BasicTrajectoryStateOnSurface impactPointState(lpar, error, impPointPlane, mf);
 
#ifdef DEBUG_STATE
  checkState(impactPointState, mf);
#endif
  LogTrace("") << "constructed TSOS:\n" << print(impactPointState);
 
  int ndof = 2 * hits.size() - 5;
  GlobalPoint vv = impactPointState.globalPosition();
  math::XYZPoint pos(vv.x(), vv.y(), vv.z());
  GlobalVector pp = impactPointState.globalMomentum();
  math::XYZVector mom(pp.x(), pp.y(), pp.z());
 
  reco::Track* track =
      new reco::Track(chi2, ndof, pos, mom, impactPointState.charge(), impactPointState.curvilinearError());
 
  return track;
}