#include <TrajectorySegmentBuilder.h>

Public Member Functions
TempTrajectoryContainer	segments (const TSOS startingState)
	new segments within layer More...

	TrajectorySegmentBuilder (const MeasurementTracker theInputMeasurementTracker, const LayerMeasurements theInputLayerMeasurements, const DetLayer &layer, const Propagator &propagator, const TrajectoryStateUpdator &updator, const MeasurementEstimator &estimator, bool lockHits, bool bestHitOnly)
	constructor from layer and helper objects More...

	~TrajectorySegmentBuilder ()
	destructor More...

Private Types
typedef TransientTrackingRecHit::ConstRecHitContainer	ConstRecHitContainer

typedef TransientTrackingRecHit::ConstRecHitPointer	ConstRecHitPointer

typedef FreeTrajectoryState	FTS

typedef std::vector < TempTrajectory >	TempTrajectoryContainer

typedef TrajectoryMeasurement	TM

typedef TrajectoryMeasurementGroup	TMG

typedef std::vector< Trajectory >	TrajectoryContainer

typedef TrajectoryStateOnSurface	TSOS

Private Member Functions
std::vector< TempTrajectory >	addGroup (TempTrajectory &traj, std::vector< TrajectoryMeasurementGroup >::const_iterator begin, std::vector< TrajectoryMeasurementGroup >::const_iterator end)

void	cleanCandidates (std::vector< TempTrajectory > &candidates) const
	clean a set of candidates More...

void	lockMeasurement (const TM &measurement)
	mark a hit as used More...

std::vector < TrajectoryMeasurement >	redoMeasurements (const TempTrajectory &traj, const DetGroup &detGroup) const
	retrieve compatible hits from a DetGroup More...

std::vector < TrajectoryMeasurement >	unlockedMeasurements (const std::vector< TM > &measurements) const
	get list of unused hits More...

void	updateCandidates (TempTrajectory &traj, const std::vector< TM > &measurements, TempTrajectoryContainer &candidates)
	creation of new candidates from a segment and a collection of hits More...

void	updateCandidatesWithBestHit (TempTrajectory &traj, const std::vector< TM > &measurements, TempTrajectoryContainer &candidates)
	creation of a new candidate from a segment and the best hit out of a collection More...

void	updateTrajectory (TempTrajectory &traj, const TM &tm) const
	update of a trajectory with a hit More...

void	updateWithInvalidHit (TempTrajectory &traj, const std::vector< TMG > &groups, TempTrajectoryContainer &candidates) const

Private Attributes
bool	theBestHitOnly

bool	theDbgFlg

const MeasurementEstimator &	theEstimator

const Propagator &	theFullPropagator

const Propagator &	theGeomPropagator

const DetLayer &	theLayer

const LayerMeasurements *	theLayerMeasurements

ConstRecHitContainer	theLockedHits

bool	theLockHits

const MeasurementTracker *	theMeasurementTracker

const TrajectoryStateUpdator &	theUpdator

Detailed Description

Definition at line 28 of file TrajectorySegmentBuilder.h.

Member Typedef Documentation

typedef TransientTrackingRecHit::ConstRecHitContainer TrajectorySegmentBuilder::ConstRecHitContainer

private

Definition at line 38 of file TrajectorySegmentBuilder.h.

typedef TransientTrackingRecHit::ConstRecHitPointer TrajectorySegmentBuilder::ConstRecHitPointer

private

Definition at line 39 of file TrajectorySegmentBuilder.h.

typedef FreeTrajectoryState TrajectorySegmentBuilder::FTS

private

Definition at line 32 of file TrajectorySegmentBuilder.h.

typedef std::vector<TempTrajectory> TrajectorySegmentBuilder::TempTrajectoryContainer

private

Definition at line 37 of file TrajectorySegmentBuilder.h.

typedef TrajectoryMeasurement TrajectorySegmentBuilder::TM

private

Definition at line 34 of file TrajectorySegmentBuilder.h.

typedef TrajectoryMeasurementGroup TrajectorySegmentBuilder::TMG

private

Definition at line 35 of file TrajectorySegmentBuilder.h.

typedef std::vector<Trajectory> TrajectorySegmentBuilder::TrajectoryContainer

private

Definition at line 36 of file TrajectorySegmentBuilder.h.

typedef TrajectoryStateOnSurface TrajectorySegmentBuilder::TSOS

private

Definition at line 33 of file TrajectorySegmentBuilder.h.

Constructor & Destructor Documentation

TrajectorySegmentBuilder::TrajectorySegmentBuilder	(	const MeasurementTracker *	theInputMeasurementTracker,
		const LayerMeasurements *	theInputLayerMeasurements,
		const DetLayer &	layer,
		const Propagator &	propagator,
		const TrajectoryStateUpdator &	updator,
		const MeasurementEstimator &	estimator,
		bool	lockHits,
		bool	bestHitOnly
	)

inline

constructor from layer and helper objects

Definition at line 44 of file TrajectorySegmentBuilder.h.

                                                  :
     theMeasurementTracker(theInputMeasurementTracker),
     theLayerMeasurements(theInputLayerMeasurements),
     theLayer(layer),
     theFullPropagator(propagator),
     theUpdator(updator),
     theEstimator(estimator),
     theGeomPropagator(propagator),
 //     theGeomPropagator(propagator.propagationDirection()),
     theLockHits(lockHits),theBestHitOnly(bestHitOnly)
   {}

TrajectorySegmentBuilder::~TrajectorySegmentBuilder ( )

inline

destructor

Definition at line 63 of file TrajectorySegmentBuilder.h.

63 {}

Member Function Documentation

TrajectorySegmentBuilder::TempTrajectoryContainer TrajectorySegmentBuilder::addGroup	(	TempTrajectory &	traj,
		std::vector< TrajectoryMeasurementGroup >::const_iterator	begin,
		std::vector< TrajectoryMeasurementGroup >::const_iterator	end
	)

private

Definition at line 143 of file TrajectorySegmentBuilder.cc.

References gather_cfg::cout, cmsutils::bqueue< T >::empty(), TempTrajectory::empty(), TempTrajectory::measurements(), runTheMatrix::ret, and cmsutils::bqueue< T >::size().

 {
   vector<TempTrajectory> ret;
   if ( begin==end ) {
     //std::cout << "TrajectorySegmentBuilder::addGroup" << " traj.empty()=" << traj.empty() << "EMPTY" << std::endl;
     if (theDbgFlg) cout << "TSB::addGroup : no groups left" << endl;
     if ( !traj.empty() )
       ret.push_back(traj);
     return ret;
   }
   
   if (theDbgFlg) cout << "TSB::addGroup : traj.size() = " << traj.measurements().size()
               << " first group at " << &(*begin)
            //        << " nr. of candidates = " << candidates.size() 
               << endl;
 
 
   TempTrajectoryContainer updatedTrajectories; updatedTrajectories.reserve(2);
   if ( traj.measurements().empty() ) {
     vector<TM> firstMeasurements = unlockedMeasurements(begin->measurements());
     if ( theBestHitOnly )
       updateCandidatesWithBestHit(traj,firstMeasurements,updatedTrajectories);
     else
       updateCandidates(traj,begin->measurements(),updatedTrajectories);
     if (theDbgFlg) cout << "TSB::addGroup : updating with first group - "
             << updatedTrajectories.size() << " trajectories" << endl;
   }
   else {
     if ( theBestHitOnly )
       updateCandidatesWithBestHit(traj,redoMeasurements(traj,begin->detGroup()),
                   updatedTrajectories);
     else
       updateCandidates(traj,redoMeasurements(traj,begin->detGroup()),
                updatedTrajectories);
     if (theDbgFlg) cout << "TSB::addGroup : updating"
             << updatedTrajectories.size() << " trajectories" << endl;
   }
 
   if (begin+1 != end) {
       ret.reserve(4); // a good upper bound
       for ( TempTrajectoryContainer::iterator it=updatedTrajectories.begin();
             it!=updatedTrajectories.end(); ++it ) {
         if (theDbgFlg) cout << "TSB::addGroup : trying to extend candidate at "
                             << &(*it) << " size " << it->measurements().size() << endl;
         vector<TempTrajectory> finalTrajectories = addGroup(*it,begin+1,end);
         if (theDbgFlg) cout << "TSB::addGroup : " << finalTrajectories.size()
                             << " finalised candidates before cleaning" << endl;
         //B.M. to be ported later
         cleanCandidates(finalTrajectories);
 
         if (theDbgFlg) cout << "TSB::addGroup : got " << finalTrajectories.size()
                             << " finalised candidates" << endl;
         ret.insert(ret.end(),finalTrajectories.begin(),
                       finalTrajectories.end());
       }
   } else {
       ret.reserve(updatedTrajectories.size());
       for (TempTrajectoryContainer::iterator it=updatedTrajectories.begin(); 
               it!=updatedTrajectories.end(); ++it ) { 
         if (!it->empty()) ret.push_back(*it);
       }
   }
 
   //std::cout << "TrajectorySegmentBuilder::addGroup" << 
   //             " traj.empty()=" << traj.empty() << 
   //             " end-begin=" << (end-begin)  <<
   //             " #updated=" << updatedTrajectories.size() << 
   //             " #result=" << ret.size() << std::endl;
   return ret;
 }

void TrajectorySegmentBuilder::cleanCandidates ( std::vector< TempTrajectory > & candidates ) const

private

clean a set of candidates

Definition at line 479 of file TrajectorySegmentBuilder.cc.

References TrackingRecHit::all, gather_cfg::cout, newFWLiteAna::found, TempTrajectory::isValid(), cmsutils::bqueue< T >::rbegin(), cmsutils::bqueue< T >::rend(), and python.multivaluedict::sort().

 {
   //
   // remove candidates which are subsets of others
   // assumptions: no invalid hits and no duplicates
   //
   if ( candidates.size()<=1 )  return;
   //RecHitEqualByChannels recHitEqual(false,true);
   //
   vector<TempTrajectory> sortedCandidates(candidates);
   sort(sortedCandidates.begin(),sortedCandidates.end(),TrajectoryLessByFoundHits());
 //   cout << "SortedCandidates.foundHits";
 //   for ( vector<Trajectory>::iterator i1=sortedCandidates.begin();
 //  i1!=sortedCandidates.end(); i1++ ) 
 //     cout << " " << i1->foundHits();
 //   cout << endl;
   //
   for ( vector<TempTrajectory>::iterator i1=sortedCandidates.begin();
     i1!=sortedCandidates.end()-1; ++i1 ) {
     // get measurements of candidate to be checked
     const TempTrajectory::DataContainer & measurements1 = i1->measurements();
     for ( vector<TempTrajectory>::iterator i2=i1+1;
       i2!=sortedCandidates.end(); ++i2 ) {
       // no duplicates: two candidates of same size are different
       if ( i2->foundHits()==i1->foundHits() )  continue;
       // get measurements of "reference"
       const TempTrajectory::DataContainer & measurements2 = i2->measurements();
       //
       // use the fact that TMs are ordered:
       // start search in trajectory#1 from last hit match found
       //
       bool allFound(true);
       TempTrajectory::DataContainer::const_iterator from2 = measurements2.rbegin(), im2end = measurements2.rend();
       for ( TempTrajectory::DataContainer::const_iterator im1=measurements1.rbegin(),im1end = measurements1.rend();
         im1!=im1end; --im1 ) {
     // redundant protection - segments should not contain invalid RecHits
     if ( !im1->recHit()->isValid() )  continue;
     bool found(false);
     for ( TempTrajectory::DataContainer::const_iterator im2=from2;
           im2!=im2end; --im2 ) {
       // redundant protection - segments should not contain invalid RecHits
       if ( !im2->recHit()->isValid() )  continue;
       if ( im1->recHit()->hit()->sharesInput(im2->recHit()->hit(), TrackingRecHit::all) ) {
         found = true;
         from2 = im2; --from2;
         break;
       }
     }
     if ( !found ) {
       allFound = false;
       break;
     }
       }
       if ( allFound )  i1->invalidate();
     }
   }
 /*
   candidates.clear();
   for ( vector<Trajectory>::const_iterator i=sortedCandidates.begin();
     i!=sortedCandidates.end(); i++ ) {
     if ( i->isValid() )  candidates.push_back(*i);
   }
 */
   candidates.erase(std::remove_if( candidates.begin(),candidates.end(),
                                    std::not1(std::mem_fun_ref(&TempTrajectory::isValid))),
  //                                boost::bind(&TempTrajectory::isValid,_1)), 
                                    candidates.end()); 
 #ifdef DBG_TSB
   cout << "TSB: cleanCandidates: reduced from " << sortedCandidates.size()
        << " to " << candidates.size() << " candidates" << endl;
 #endif
   return;
 }

void TrajectorySegmentBuilder::lockMeasurement ( const TM & measurement )

private

mark a hit as used

Definition at line 470 of file TrajectorySegmentBuilder.cc.

References TrajectoryMeasurement::recHit().

 {
   theLockedHits.push_back(measurement.recHit());
 }

vector< TrajectoryMeasurement > TrajectorySegmentBuilder::redoMeasurements	(	const TempTrajectory &	traj,
		const DetGroup &	detGroup
	)		const

private

retrieve compatible hits from a DetGroup

Definition at line 279 of file TrajectorySegmentBuilder.cc.

References gather_cfg::cout, end, MeasurementDet::fastMeasurements(), GeomDetCompatibilityChecker::isCompatible(), TempTrajectory::lastMeasurement(), TrackingRecHit::missing, query::result, tmp, and TrajectoryMeasurement::updatedState().

 {
   vector<TM> result;
   vector<TM> tmpResult;
   //
   // loop over all dets
   //
   if (theDbgFlg) cout << "TSB::redoMeasurements : nr. of measurements / group =";
 
   for (DetGroup::const_iterator idet=detGroup.begin(); 
        idet!=detGroup.end(); ++idet) {
     //
     // ======== ask for measurements ==============       
     //B.M vector<TM> tmp = idet->det()->measurements(traj.lastMeasurement().updatedState(),
     //                         theGeomPropagator,theEstimator);
     
     pair<bool, TrajectoryStateOnSurface> compat = 
       GeomDetCompatibilityChecker().isCompatible(idet->det(),
                          traj.lastMeasurement().updatedState(),
                          theGeomPropagator,theEstimator);
     
     vector<TM> tmp; 
     if(compat.first){
       const MeasurementDet* mdet = theMeasurementTracker->idToDet(idet->det()->geographicalId());
       tmp = mdet->fastMeasurements( compat.second, idet->trajectoryState(), theGeomPropagator, theEstimator);
     }
 
     //perhaps could be enough just:
     //vector<TM> tmp = mdet->fastMeasurements( idet->trajectoryState(),
     //                       traj.lastMeasurement().updatedState(),
     //                           theGeomPropagator, theEstimator);
     // ==================================================
 
     if ( tmp.empty() )  continue;
     //
     // only collect valid RecHits
     //
     vector<TM>::iterator end = (tmp.back().recHit()->getType() != TrackingRecHit::missing ? tmp.end() : tmp.end()-1);
     if (theDbgFlg) cout << " " << tmp.size();
     tmpResult.insert(tmpResult.end(),tmp.begin(),end);
   }
   if (theDbgFlg) cout << endl;
   //
   // set layer in TM, because the Det cannot do it
   //
   for(vector<TM>::const_iterator tmpIt=tmpResult.begin();tmpIt!=tmpResult.end();++tmpIt){
     if ( tmpIt->recHit()->isValid() )
       result.push_back(  TrajectoryMeasurement(tmpIt->predictedState(),tmpIt->recHit(),tmpIt->estimate(),&theLayer)  );
   }
   
   return result;
 }

TrajectorySegmentBuilder::TempTrajectoryContainer TrajectorySegmentBuilder::segments ( const TSOS startingState )

new segments within layer

Definition at line 27 of file TrajectorySegmentBuilder.cc.

References gather_cfg::cout, TrajectoryStateOnSurface::localError(), LocalTrajectoryError::matrix(), and AlCaRecoCosmics_cfg::name.

Referenced by GroupedCkfTrajectoryBuilder::advanceOneLayer().

 {
   //
   // create empty trajectory
   //
   theLockedHits.clear();
   TempTrajectory startingTrajectory(theFullPropagator.propagationDirection());
   //
   // get measurement groups
   //
   vector<TMG> measGroups = 
     theLayerMeasurements->groupedMeasurements(theLayer,startingState,theFullPropagator,theEstimator);
     //B.M. theLayer.groupedMeasurements(startingState,theFullPropagator,theEstimator);
 
 #ifdef DBG_TSB
   cout << "TSB: number of measurement groups = " << measGroups.size() << endl;
   //  theDbgFlg = measGroups.size()>1;
   theDbgFlg = true;
 #else
   theDbgFlg = false;
 #endif
 
   if ( theDbgFlg ) {
     int ntot(1);
     for (vector<TMG>::const_iterator ig=measGroups.begin();
      ig!=measGroups.end(); ++ig) {
       int ngrp(0);
       const vector<TM>& measurements = ig->measurements();
       for ( vector<TM>::const_iterator im=measurements.begin();
         im!=measurements.end(); ++im ) {
     if ( im->recHit()->isValid() )  ngrp++;
       }
       cout << " " << ngrp;
       if ( ngrp>0 )  ntot *= ngrp;
     }  
     cout << endl;
     cout << "TrajectorySegmentBuilder::partialTrajectories:: det ids & hit types / group" << endl;
     for (vector<TMG>::const_iterator ig=measGroups.begin();
      ig!=measGroups.end(); ++ig) {
       const vector<TM>& measurements = ig->measurements();
       for ( vector<TM>::const_iterator im=measurements.begin();
         im!=measurements.end(); ++im ) {
     if ( im!=measurements.begin() )  cout << " / ";
     if ( im->recHit()->det() )
       cout << im->recHit()->det()->geographicalId().rawId() << " "
            << im->recHit()->getType();
     else
       cout << "no det";
       }
       cout << endl;
     }  
   }
 
 #ifdef DBG_TSB
 //   if ( measGroups.size()>4 ) {
     cout << typeid(theLayer).name() << endl;
     cout << startingState.localError().matrix() << endl;
 //     for (vector<TMG>::const_iterator ig=measGroups.begin();
 //   ig!=measGroups.end(); ig++) {
 //       cout << "Nr. of measurements = " << ig->measurements().size() << endl;
 //       const DetGroup& dg = ig->detGroup();
 //       for ( DetGroup::const_iterator id=dg.begin();
 //      id!=dg.end(); id++ ) {
 //  GlobalPoint p(id->det()->position());
 //  GlobalVector v(id->det()->toGlobal(LocalVector(0.,0.,1.)));
 //  cout << p.perp() << " " << p.phi() << " " << p.z() << " ; "
 //       << v.phi() << " " << v.z() << endl;
 //       }
 //     }
 //   }
 #endif
 
   TempTrajectoryContainer candidates = 
     addGroup(startingTrajectory,measGroups.begin(),measGroups.end());
 
   if (theDbgFlg) cout << "TSB: back with " << candidates.size() << " candidates" << endl;
   // clean
   //
   //
   // add invalid hit - try to get first detector hit by the extrapolation
   //
 
   updateWithInvalidHit(startingTrajectory,measGroups,candidates);
   if (theDbgFlg) cout << "TSB: " << candidates.size() << " candidates after invalid hit" << endl;
   return candidates;
 }

vector< TrajectoryMeasurement > TrajectorySegmentBuilder::unlockedMeasurements ( const std::vector< TM > & measurements ) const

private

get list of unused hits

Definition at line 438 of file TrajectorySegmentBuilder.cc.

References TrackingRecHit::all, newFWLiteAna::found, and query::result.

 {
 //   if ( !theLockHits )  return measurements;
 
   //========== B.M. to be ported later ===============
   vector<TM> result;
   result.reserve(measurements.size());
 
   //RecHitEqualByChannels recHitEqual(false,true);
 
   for ( vector<TM>::const_iterator im=measurements.begin();
     im!=measurements.end(); ++im ) {
     ConstRecHitPointer testHit = im->recHit();
     if ( !testHit->isValid() )  continue;
     bool found(false);
     if ( theLockHits ) {
       for ( ConstRecHitContainer::const_iterator ih=theLockedHits.begin();
         ih!=theLockedHits.end(); ++ih ) {
     if ( (*ih)->hit()->sharesInput(testHit->hit(), TrackingRecHit::all) ) {
       found = true;
       break;
     }
       }
     }
     if ( !found )  result.push_back(*im);
   }
   return result;
   //================================= 
   //return measurements; // temporary solution before RecHitEqualByChannels is ported
 }

void TrajectorySegmentBuilder::updateCandidates	(	TempTrajectory &	traj,
		const std::vector< TM > &	measurements,
		TempTrajectoryContainer &	candidates
	)

private

creation of new candidates from a segment and a collection of hits

Definition at line 217 of file TrajectorySegmentBuilder.cc.

 {
   //
   // generate updated candidates with all valid hits
   //
   for ( vector<TM>::const_iterator im=measurements.begin();
     im!=measurements.end(); ++im ) {
     if ( im->recHit()->isValid() ) {
       candidates.push_back(traj);
       updateTrajectory(candidates.back(),*im);
       if ( theLockHits )  lockMeasurement(*im);
     }
   }
   //
   // keep old trajectory
   //
   candidates.push_back(traj);
 }

void TrajectorySegmentBuilder::updateCandidatesWithBestHit	(	TempTrajectory &	traj,
		const std::vector< TM > &	measurements,
		TempTrajectoryContainer &	candidates
	)

private

creation of a new candidate from a segment and the best hit out of a collection

Definition at line 239 of file TrajectorySegmentBuilder.cc.

References gather_cfg::cout.

 {
   vector<TM>::const_iterator ibest = measurements.end();
   bool bestIsValid = false;
   for ( vector<TM>::const_iterator im=measurements.begin();
     im!=measurements.end(); ++im ) {
     if ( im->recHit()->isValid() ) {
         if (!bestIsValid || (ibest==measurements.end()) || (im->estimate()<ibest->estimate()) )  {
             ibest = im;
             bestIsValid = true;
         }
     } 
 //     else if (!bestIsValid && (im->recHit()->getType() != TrackingRecHit::missing)) {
 //         if (ibest==measurements.end()) ibest = im;
 //     }
   }
   if ( ibest!=measurements.end() ) {
     if ( theLockHits )  lockMeasurement(*ibest);
     candidates.push_back(traj);
     updateTrajectory(candidates.back(),*ibest);
     if ( theDbgFlg ) {
       if (bestIsValid) {
           cout << "TSB: found best measurement at " 
                << ibest->recHit()->globalPosition().perp() << " "
                << ibest->recHit()->globalPosition().phi() << " "
                << ibest->recHit()->globalPosition().z() << endl;
       } else {
     cout << "TSB: found best measurement at invalid hit on det " << ibest->recHit()->geographicalId().rawId() << endl;
       }
     }
   }
   //
   // keep old trajectorTempy
   //
   candidates.push_back(traj);
 }

void TrajectorySegmentBuilder::updateTrajectory	(	TempTrajectory &	traj,
		const TM &	tm
	)		const

private

update of a trajectory with a hit

Definition at line 114 of file TrajectorySegmentBuilder.cc.

References TrajectoryMeasurement::estimate(), TrajectoryMeasurement::layer(), TrajectoryMeasurement::predictedState(), TempTrajectory::push(), TrajectoryMeasurement::recHit(), and TrajectoryStateOnSurface::update().

 {
   TSOS predictedState = tm.predictedState();
   ConstRecHitPointer hit = tm.recHit();
  
   if ( hit->isValid()) {
     traj.push( TM( predictedState, theUpdator.update( predictedState, *hit),
            hit, tm.estimate(), tm.layer()));
 //     TrajectoryMeasurement tm(traj.lastMeasurement());
 //     if ( tm.updatedState().isValid() ) {
 //       if ( !hit.det().surface().bounds().inside(tm.updatedState().localPosition(),
 //                      tm.updatedState().localError().positionError(),3.) ) {
 //  cout << "Incompatibility after update for det at " << hit.det().position() << ":" << endl;
 //  cout << tm.predictedState().localPosition() << " " 
 //       << tm.predictedState().localError().positionError() << endl;
 //  cout << hit.localPosition() << " " << hit.localPositionError() << endl;
 //  cout << tm.updatedState().localPosition() << " "
 //       << tm.updatedState().localError().positionError() << endl;
 //       }
 //     }
   }
   else {
     traj.push( TM( predictedState, hit,0, tm.layer()));
   }
 }

void TrajectorySegmentBuilder::updateWithInvalidHit	(	TempTrajectory &	traj,
		const std::vector< TMG > &	groups,
		TempTrajectoryContainer &	candidates
	)		const

private

Definition at line 334 of file TrajectorySegmentBuilder.cc.

References gather_cfg::cout, newFWLiteAna::found, align_cfg::iteration, TrackingRecHit::missing, and TrackingRecHit::valid.

 {
   //
   // first try to find an inactive hit with dets crossed by the prediction,
   //   then take any inactive hit
   //
   // loop over groups
   for ( int iteration=0; iteration<2; iteration++ ) {
     for ( vector<TMG>::const_iterator ig=groups.begin(); ig!=groups.end(); ++ig) {
       // loop over measurements
       const vector<TM>& measurements = ig->measurements();
       for ( vector<TM>::const_reverse_iterator im=measurements.rbegin();
         im!=measurements.rend(); ++im ) {
     ConstRecHitPointer hit = im->recHit();
     if ( hit->getType()==TrackingRecHit::valid ||
          hit->getType()==TrackingRecHit::missing )  continue;
     //
     // check, if the extrapolation traverses the Det or
     // if 2nd iteration
     //
     if ( hit->det() ) {
       TSOS predState(im->predictedState());
       if ( iteration>0 || 
            (predState.isValid() &&
         hit->det()->surface().bounds().inside(predState.localPosition())) ) {
         // add the hit
         /*TempTrajectory newTraj(traj);
         updateTrajectory(newTraj,*im);
         candidates.push_back(newTraj);  // FIXME: avoid useless copy */
             candidates.push_back(traj); 
             updateTrajectory(candidates.back(), *im);
         if ( theDbgFlg ) cout << "TrajectorySegmentBuilder::updateWithInvalidHit "
                   << "added inactive hit" << endl;
         return;
       }
     }
       }
     }
   }
   //
   // No suitable inactive hit: add a missing one
   //
   bool found(false);
   for ( int iteration=0; iteration<2; iteration++ ) {
     //
     // loop over groups
     //
     for ( vector<TMG>::const_iterator ig=groups.begin();
       ig!=groups.end(); ++ig) {
       const vector<TM>& measurements = ig->measurements();
       for ( vector<TM>::const_reverse_iterator im=measurements.rbegin();
         im!=measurements.rend(); ++im ) {
     //
     // only use invalid hits
     //
     ConstRecHitPointer hit = im->recHit();
     if ( hit->isValid() )  continue;
 
     //
     // check, if the extrapolation traverses the Det
     //
     TSOS predState(im->predictedState());
     if(hit->det()){ 
       if ( iteration>0 || (predState.isValid() &&
                    hit->det()->surface().bounds().inside(predState.localPosition())) ) {
         // add invalid hit
         /*TempTrajectory newTraj(traj);
         updateTrajectory(newTraj,*im);
         candidates.push_back(newTraj);  // FIXME: avoid useless copy */
             candidates.push_back(traj); 
             updateTrajectory(candidates.back(), *im);
         found = true;
         break;
       }
 
     }else{
       if ( iteration>0 || (predState.isValid() &&
                    im->layer()->surface().bounds().inside(predState.localPosition())) ){
         // add invalid hit
         /*TempTrajectory newTraj(traj);
         updateTrajectory(newTraj,*im);
         candidates.push_back(newTraj);  // FIXME: avoid useless copy */
             candidates.push_back(traj); 
             updateTrajectory(candidates.back(), *im);
         found = true;
         break;      
       }
     }
       }
       if ( found )  break;
     }
     if ( theDbgFlg && !found ) cout << "TrajectorySegmentBuilder::updateWithInvalidHit: "
                     << " did not find invalid hit on 1st iteration" << endl;
     if ( found )  break;
   }
   if ( !found ) {
     if (theDbgFlg) cout << "TrajectorySegmentBuilder::updateWithInvalidHit: "
             << " did not find invalid hit" << endl;
   }
 }