/data/refman/pasoursint/CMSSW_4_1_8_patch9/src/Alignment/ReferenceTrajectories/src/DualKalmanTrajectory.cc

Go to the documentation of this file.

 
#include "Alignment/ReferenceTrajectories/interface/DualKalmanTrajectory.h"

#include "TrackingTools/TrajectoryState/interface/TrajectoryStateOnSurface.h"
#include "TrackingTools/PatternTools/interface/Trajectory.h"
#include "TrackingTools/PatternTools/interface/TrajectoryMeasurement.h"

#include "TrackingTools/TrackFitters/interface/TrajectoryStateCombiner.h"
#include "TrackingTools/TransientTrackingRecHit/interface/HelpertRecHit2DLocalPos.h"

#include "DataFormats/CLHEP/interface/AlgebraicObjects.h" 
#include "DataFormats/TrajectoryState/interface/LocalTrajectoryParameters.h"
#include "DataFormats/GeometrySurface/interface/LocalError.h"
#include "DataFormats/GeometryVector/interface/LocalPoint.h"

#include "Alignment/ReferenceTrajectories/interface/ReferenceTrajectory.h"

#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "FWCore/Utilities/interface/Exception.h"

typedef TransientTrackingRecHit::ConstRecHitContainer ConstRecHitContainer;
typedef TransientTrackingRecHit::ConstRecHitPointer ConstRecHitPointer;

//-----------------------------------------------------------------------------------------------
DualKalmanTrajectory::DualKalmanTrajectory(const Trajectory::DataContainer &trajMeasurements,
                                           const TrajectoryStateOnSurface &referenceTsos,
                                           const std::vector<unsigned int> &forwardRecHitNums,
                                           const std::vector<unsigned int> &backwardRecHitNums,
                                           const MagneticField *magField,
                                           MaterialEffects materialEffects,
                                           PropagationDirection propDir,
                                           double mass, 
                                           bool useBeamSpot, const reco::BeamSpot &beamSpot,
                                           int residualMethod)
  : ReferenceTrajectoryBase(referenceTsos.localParameters().mixedFormatVector().kSize,
                            forwardRecHitNums.size() + backwardRecHitNums.size() - 1, 0, 0)
{
  theValidityFlag = this->construct(trajMeasurements, referenceTsos,
                                    forwardRecHitNums, backwardRecHitNums,
                                    mass, materialEffects, propDir, magField,
                                    useBeamSpot, beamSpot, residualMethod);
}



//-----------------------------------------------------------------------------------------------
DualKalmanTrajectory::DualKalmanTrajectory(unsigned int nPar, unsigned int nHits)
  : ReferenceTrajectoryBase(nPar, nHits, 0, 0)
{}


//-----------------------------------------------------------------------------------------------
bool DualKalmanTrajectory::construct(const Trajectory::DataContainer &trajMeasurements,
                                     const TrajectoryStateOnSurface &refTsos, 
                                     const std::vector<unsigned int> &forwardRecHitNums,
                                     const std::vector<unsigned int> &backwardRecHitNums,
                                     double mass, MaterialEffects materialEffects,
                                     const PropagationDirection propDir,
                                     const MagneticField *magField, 
                                     bool useBeamSpot, const reco::BeamSpot &beamSpot,
                                     int residualMethod)
{

  ReferenceTrajectoryPtr fwdTraj = this->construct(trajMeasurements, refTsos, forwardRecHitNums,
                                                   mass, materialEffects,
                                                   propDir, magField, useBeamSpot, beamSpot);
  
  ReferenceTrajectoryPtr bwdTraj = this->construct(trajMeasurements, refTsos, backwardRecHitNums,
                                                   mass, materialEffects,
                                                   this->oppositeDirection(propDir), magField,
                                                   useBeamSpot, beamSpot);

  //   edm::LogError("Alignment") << "@SUB=DualKalmanTrajectory::construct"
  //                         << "valid fwd/bwd " << fwdTraj->isValid() 
  //                         << "/" << bwdTraj->isValid();
  
  if (!fwdTraj->isValid() || !bwdTraj->isValid()) {
    return false;
  }

  //
  // Combine both reference trajactories to a dual reference trajectory
  //

//   const std::vector<TrajectoryStateOnSurface>& fwdTsosVec = fwdTraj->trajectoryStates();
//   const std::vector<TrajectoryStateOnSurface>& bwdTsosVec = bwdTraj->trajectoryStates();
//   theTsosVec.insert( theTsosVec.end(), fwdTsosVec.begin(), fwdTsosVec.end() );
//   theTsosVec.insert( theTsosVec.end(), ++bwdTsosVec.begin(), bwdTsosVec.end() );

  // Take hits as they come from the Kalman fit.
  const ConstRecHitContainer &fwdRecHits = fwdTraj->recHits(); 
  const ConstRecHitContainer &bwdRecHits = bwdTraj->recHits();
  theRecHits.insert(theRecHits.end(), fwdRecHits.begin(), fwdRecHits.end());
  theRecHits.insert(theRecHits.end(), ++bwdRecHits.begin(), bwdRecHits.end());

  theParameters = this->extractParameters(refTsos);

  unsigned int nParam   = theParameters.num_row();
  unsigned int nFwdMeas = nMeasPerHit * fwdTraj->numberOfHits();
  unsigned int nBwdMeas = nMeasPerHit * bwdTraj->numberOfHits();

//   theMeasurements.sub( 1, fwdTraj->measurements() );
//   theMeasurements.sub( nFwdMeas+1, bwdTraj->measurements().sub( nMeasPerHit+1, nBwdMeas ) );

//   theMeasurementsCov.sub( 1, fwdTraj->measurementErrors() );
//   theMeasurementsCov.sub( nFwdMeas+1, bwdTraj->measurementErrors().sub( nMeasPerHit+1, nBwdMeas ) );

//   theTrajectoryPositions.sub( 1, fwdTraj->trajectoryPositions() );
//   theTrajectoryPositions.sub( nFwdMeas+1, bwdTraj->trajectoryPositions().sub( nMeasPerHit+1, nBwdMeas ) );

//   theTrajectoryPositionCov.sub( 1, fwdTraj->trajectoryPositionErrors() );
//   theTrajectoryPositionCov.sub( nFwdMeas+1, bwdTraj->trajectoryPositionErrors().sub( nMeasPerHit+1, nBwdMeas ) );

  theDerivatives.sub(1, 1, fwdTraj->derivatives());
  theDerivatives.sub(nFwdMeas+1, 1,
                     bwdTraj->derivatives().sub(nMeasPerHit+1, nBwdMeas, 1, nParam));

  // FIXME: next lines stolen from ReferenceTrajectory, no idea whether OK or not...
  if (refTsos.hasError()) {
    AlgebraicSymMatrix parameterCov = asHepMatrix<5>(refTsos.localError().matrix());
    theTrajectoryPositionCov = parameterCov.similarity(theDerivatives);
  } else {
    theTrajectoryPositionCov = AlgebraicSymMatrix(theDerivatives.num_row(), 1);
  }

  // Fill Kalman part, first for forward, then for backward part.
  return this->fillKalmanPart(trajMeasurements, forwardRecHitNums, true, 0, residualMethod) 
    && this->fillKalmanPart(trajMeasurements, backwardRecHitNums, false,
                            forwardRecHitNums.size(), residualMethod);
}


//-----------------------------------------------------------------------------------------------
ReferenceTrajectory*
DualKalmanTrajectory::construct(const Trajectory::DataContainer &trajMeasurements,
                                const TrajectoryStateOnSurface &referenceTsos, 
                                const std::vector<unsigned int> &recHitNums,
                                double mass, MaterialEffects materialEffects,
                                const PropagationDirection propDir,
                                const MagneticField *magField,
                                bool useBeamSpot, const reco::BeamSpot &beamSpot) const
{

  ConstRecHitContainer recHits;
  recHits.reserve(recHitNums.size());
  for (unsigned int i = 0; i < recHitNums.size(); ++i) {
    recHits.push_back(trajMeasurements[recHitNums[i]].recHit());
  }

  return new ReferenceTrajectory(referenceTsos, recHits, false, // hits are already ordered
                                 magField, materialEffects, propDir, mass,
                                 useBeamSpot, beamSpot);
}

//-----------------------------------------------------------------------------------------------
bool DualKalmanTrajectory::fillKalmanPart(const Trajectory::DataContainer &trajMeasurements,
                                          const std::vector<unsigned int> &recHitNums,
                                          bool startFirst, unsigned int iNextHit,
                                          int residualMethod)
{
  // startFirst==false: skip first hit of recHitNums
  // iNextHit: first hit number to fill data members with
  //
  // Three approaches, choosen by 'residualMethod':
  // 0: Just take hit error and the updated state as millepede needs it to redo the last fit step.
  // 1: Use the unbiased residuals as for residual monitoring.
  // 2: Use the _updated_ state and calculate the sigma that is part of
  //    the pull as sqrt(sigma_hit^2 - sigma_tsos^2).
  //    This should lead to the pull as defined on p. 236 of Blobel's book.
  //    Not sure whether this is 100% applicable/correct here, at least it might lead to 
  //    numerical instabilities, cf.:
  //    https://hypernews.cern.ch/HyperNews/CMS/get/recoTracking/517/1/1/1/1/1.html

  for (unsigned int iMeas = (startFirst ? 0 : 1); iMeas < recHitNums.size(); ++iMeas, ++iNextHit) {
    const TrajectoryMeasurement &trajMeasurement = trajMeasurements[recHitNums[iMeas]];

    TrajectoryStateOnSurface tsos; // depends on method
    switch (residualMethod) {
    case 0:
      tsos = this->fillMeasurementAndError2(trajMeasurement.recHit(), iNextHit, trajMeasurement,
                                            false); // plain hit error, not pull
      break;
    case 1:
      tsos = this->fillMeasurementAndError1(trajMeasurement.recHit(), iNextHit, trajMeasurement);
      break;
    case 2:
      tsos = this->fillMeasurementAndError2(trajMeasurement.recHit(), iNextHit, trajMeasurement,
                                            true); // error of pull
      break;
    default:
      throw cms::Exception("BadConfig")
        << "[DualKalmanTrajectory::fillKalmanPart] expect residualMethod == 0, 1 or 2, not "
        << residualMethod << ".";
    }

    if (!tsos.isValid()) return false;
    theTsosVec.push_back(tsos);
    
    this->fillTrajectoryPositions(trajMeasurement.recHit()->projectionMatrix(),
                                  tsos, iNextHit);
  }

  return true;
} 

//-----------------------------------------------------------------------------------------------
TrajectoryStateOnSurface 
DualKalmanTrajectory::fillMeasurementAndError1(const ConstRecHitPointer &hitPtr,
                                               unsigned int iHit,
                                               const TrajectoryMeasurement &trajMeasurement)
{
  // Get the measurements and their errors.
  // We have to add error from hit and that tsos that is combination of fwd and bwd state.

  TrajectoryStateCombiner tsosComb;
  const TrajectoryStateOnSurface tsos = tsosComb(trajMeasurement.forwardPredictedState(),
                                                 trajMeasurement.backwardPredictedState());
  if (tsos.isValid()) {
    // No update of hit with tsos: it comes already from fwd+bwd tsos combination.
    // See also https://hypernews.cern.ch/HyperNews/CMS/get/recoTracking/517/1.html .
    // ConstRecHitPointer newHitPtr(hitPtr->canImproveWithTrack() ? hitPtr->clone(tsos) : hitPtr);
    
    const LocalPoint localMeasurement(hitPtr->localPosition());
    const LocalError hitErr(this->hitErrorWithAPE(hitPtr));
    // tsos prediction includes APE of other hits:
    const LocalError tsosErr(tsos.localError().positionError());
    const LocalError localMeasurementCov(hitErr.xx() + tsosErr.xx(),
                                         hitErr.xy() + tsosErr.xy(),
                                         hitErr.yy() + tsosErr.yy());
    
    theMeasurements[nMeasPerHit*iHit]   = localMeasurement.x();
    theMeasurements[nMeasPerHit*iHit+1] = localMeasurement.y();
    theMeasurementsCov[nMeasPerHit*iHit]  [nMeasPerHit*iHit]   = localMeasurementCov.xx();
    theMeasurementsCov[nMeasPerHit*iHit]  [nMeasPerHit*iHit+1] = localMeasurementCov.xy();
    theMeasurementsCov[nMeasPerHit*iHit+1][nMeasPerHit*iHit+1] = localMeasurementCov.yy();
  }

  return tsos;
}

//-----------------------------------------------------------------------------------------------
TrajectoryStateOnSurface
DualKalmanTrajectory::fillMeasurementAndError2(const ConstRecHitPointer &hitPtr,
                                               unsigned int iHit,
                                               const TrajectoryMeasurement &trajMeasurement,
                                               bool doPull)
{
  // Get the measurements and their errors.
  // We have to subtract error of updated tsos from hit.

  const TrajectoryStateOnSurface tsos = trajMeasurement.updatedState();
  if (tsos.isValid()) {
    // No further update of hit: 
    // - The Kalman fit used hitPtr as it comes here (besides APE, see below).
    // - If the hit errors improve, we might get (rare) problems of negative diagonal elements, see below.
    // ConstRecHitPointer newHitPtr(hitPtr->canImproveWithTrack() ? hitPtr->clone(tsos) : hitPtr);

    const LocalPoint localMeasurement(hitPtr->localPosition());
    // Add APE manually to avoid that the hit error might be smaller than tsos error:
    // - hit local errors are always without APE,
    // - the tsos errors include APE since they come from track fit.
    const LocalError hitErr(this->hitErrorWithAPE(hitPtr));

    LocalError localMeasurementCov(hitErr.xx(), hitErr.xy(), hitErr.yy());
    if (doPull) {
      const LocalError tsosErr(tsos.localError().positionError());
      // Should not be possible to become negative if all is correct - see above.
      if (hitErr.xx() < tsosErr.xx() || hitErr.yy() < tsosErr.yy()) {
        edm::LogError("Alignment") << "@SUB=DualKalmanTrajectory::fillMeasurementAndError2"
                                   << "not OK in subdet " << hitPtr->geographicalId().subdetId()
                                   << "\ns_x " << sqrt(hitErr.xx()) << " " << sqrt(tsosErr.xx())
                                   << "\ns_xy " << hitErr.xy() << " " << tsosErr.xy()
                                   << "\ns_y " << sqrt(hitErr.yy()) << " " << sqrt(tsosErr.yy());
        return TrajectoryStateOnSurface(); // is invalid state
      }
      // cf. Blobel/Lohrmann, p. 236:
      // But numerical stability? Should we return false if difference very small compared to values?
      localMeasurementCov = LocalError(hitErr.xx() - tsosErr.xx(), // tsos puts correlation in,   
                                       hitErr.xy() - tsosErr.xy(), // even for 1D strip!            
                                       hitErr.yy() - tsosErr.yy());
    }

    theMeasurements[nMeasPerHit*iHit]   = localMeasurement.x();
    theMeasurements[nMeasPerHit*iHit+1] = localMeasurement.y();
    theMeasurementsCov[nMeasPerHit*iHit]  [nMeasPerHit*iHit]   = localMeasurementCov.xx();
    theMeasurementsCov[nMeasPerHit*iHit]  [nMeasPerHit*iHit+1] = localMeasurementCov.xy();
    theMeasurementsCov[nMeasPerHit*iHit+1][nMeasPerHit*iHit+1] = localMeasurementCov.yy();
  }

  return tsos;
}

//-----------------------------------------------------------------------------------------------
void DualKalmanTrajectory::fillTrajectoryPositions(const AlgebraicMatrix &projection, 
                                                   const TrajectoryStateOnSurface &tsos, 
                                                   unsigned int iHit)
{
  // get the local coordinates of the reference trajectory
  // (~copied from ReferenceTrajectory::fillTrajectoryPositions)
  AlgebraicVector mixedLocalParams = asHepVector<5>(tsos.localParameters().mixedFormatVector());
  const AlgebraicVector localPosition(projection * mixedLocalParams);

  theTrajectoryPositions[nMeasPerHit*iHit]   = localPosition[0];
  theTrajectoryPositions[nMeasPerHit*iHit+1] = localPosition[1];
}

//-----------------------------------------------------------------------------------------------
LocalError DualKalmanTrajectory::hitErrorWithAPE(const ConstRecHitPointer &hitPtr) const
{
  if (hitPtr->det() && hitPtr->det()->alignmentPositionError()) {
    HelpertRecHit2DLocalPos help;
    const AlgebraicSymMatrix errMat(help.parError(hitPtr->localPositionError(), *(hitPtr->det())));
    return LocalError(errMat[0][0], errMat[0][1], errMat[1][1]);
  } else {
    return hitPtr->localPositionError();
  }
}

//-----------------------------------------------------------------------------------------------
AlgebraicVector
DualKalmanTrajectory::extractParameters(const TrajectoryStateOnSurface &referenceTsos) const
{
  return asHepVector<5>( referenceTsos.localParameters().mixedFormatVector() );
}