MultiHitGeneratorFromChi2.cc

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#include "RecoTracker/TkSeedGenerator/plugins/MultiHitGeneratorFromChi2.h"

#include "RecoPixelVertexing/PixelTriplets/interface/ThirdHitPredictionFromCircle.h"
#include "RecoPixelVertexing/PixelTriplets/plugins/ThirdHitRZPrediction.h"
#include "FWCore/Framework/interface/ESHandle.h"
#include <FWCore/Utilities/interface/ESInputTag.h>

#include "Geometry/TrackerGeometryBuilder/interface/TrackerGeometry.h"
#include "Geometry/Records/interface/TrackerDigiGeometryRecord.h"
#include "RecoPixelVertexing/PixelTriplets/plugins/ThirdHitCorrection.h"
#include "RecoTracker/TkHitPairs/interface/RecHitsSortedInPhi.h"

#include "RecoPixelVertexing/PixelTriplets/plugins/KDTreeLinkerAlgo.h" 
#include "RecoPixelVertexing/PixelTriplets/plugins/KDTreeLinkerTools.h"

#include "RecoPixelVertexing/PixelTrackFitting/src/RZLine.h"
#include "RecoTracker/TkSeedGenerator/interface/FastHelix.h"
#include "MagneticField/Records/interface/IdealMagneticFieldRecord.h"
#include "DataFormats/SiStripDetId/interface/StripSubdetector.h"
#include "DataFormats/SiPixelDetId/interface/PixelSubdetector.h"
#include "RecoTracker/TkHitPairs/interface/HitPairGeneratorFromLayerPair.h"

#include "DataFormats/TrackerRecHit2D/interface/SiStripRecHit2D.h"
#include "DataFormats/TrackerRecHit2D/interface/SiStripMatchedRecHit2D.h"
#include "DataFormats/TrackerRecHit2D/interface/ProjectedSiStripRecHit2D.h"
#include "DataFormats/SiStripDetId/interface/SiStripDetId.h"
#include "MagneticField/Engine/interface/MagneticField.h"

#include "TrackingTools/Records/interface/TransientRecHitRecord.h"

#include "FWCore/Utilities/interface/isFinite.h"

#include <algorithm>
#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <limits>

using namespace std;

typedef PixelRecoRange<float> Range;

namespace {
  struct LayerRZPredictions {
    ThirdHitRZPrediction<SimpleLineRZ> line;
  };
}

MultiHitGeneratorFromChi2::MultiHitGeneratorFromChi2(const edm::ParameterSet& cfg)
  : thePairGenerator(0),
    theLayerCache(0),
    useFixedPreFiltering(cfg.getParameter<bool>("useFixedPreFiltering")),
    extraHitRZtolerance(cfg.getParameter<double>("extraHitRZtolerance")),//extra window in ThirdHitRZPrediction range 
    extraHitRPhitolerance(cfg.getParameter<double>("extraHitRPhitolerance")),//extra window in ThirdHitPredictionFromCircle range (divide by R to get phi) 
    extraZKDBox(cfg.getParameter<double>("extraZKDBox")),//extra windown in Z when building the KDTree box (used in barrel)
    extraRKDBox(cfg.getParameter<double>("extraRKDBox")),//extra windown in R when building the KDTree box (used in endcap)
    extraPhiKDBox(cfg.getParameter<double>("extraPhiKDBox")),//extra windown in Phi when building the KDTree box
    fnSigmaRZ(cfg.getParameter<double>("fnSigmaRZ")),//this multiplies the max hit error on the layer when building the KDTree box
    chi2VsPtCut(cfg.getParameter<bool>("chi2VsPtCut")),
    maxChi2(cfg.getParameter<double>("maxChi2")),
    refitHits(cfg.getParameter<bool>("refitHits")),
    debug(cfg.getParameter<bool>("debug")),
    filterName_(cfg.getParameter<std::string>("ClusterShapeHitFilterName")),
    builderName_(cfg.existsAs<std::string>("TTRHBuilder") ? cfg.getParameter<std::string>("TTRHBuilder") : std::string("WithTrackAngle")),
    useSimpleMF_(false),
    mfName_("")
{    
  theMaxElement=cfg.getParameter<unsigned int>("maxElement");
  if (useFixedPreFiltering)
    dphi = cfg.getParameter<double>("phiPreFiltering");
  if (chi2VsPtCut) {
    pt_interv = cfg.getParameter<std::vector<double> >("pt_interv");
    chi2_cuts = cfg.getParameter<std::vector<double> >("chi2_cuts");    
  }  
  if (debug) {
    detIdsToDebug = cfg.getParameter<std::vector<int> >("detIdsToDebug");
    //if (detIdsToDebug.size()<3) //fixme
  } else {
    detIdsToDebug.push_back(0);
    detIdsToDebug.push_back(0);
    detIdsToDebug.push_back(0);
  }
  // 2014/02/11 mia:
  // we should get rid of the boolean parameter useSimpleMF,
  // and use only a string magneticField [instead of SimpleMagneticField]
  // or better an edm::ESInputTag (at the moment HLT does not handle ESInputTag)
  if (cfg.exists("SimpleMagneticField")) {
    useSimpleMF_ = true;
    mfName_ = cfg.getParameter<std::string>("SimpleMagneticField");
  }
  filter = 0;
  bfield = 0;
  nomField = -1.;
}

void MultiHitGeneratorFromChi2::init(const HitPairGenerator & pairs,
                     LayerCacheType *layerCache)
{
  thePairGenerator = pairs.clone();
  theLayerCache = layerCache;
}

void MultiHitGeneratorFromChi2::initES(const edm::EventSetup& es) 
{

  edm::ESHandle<MagneticField> bfield_h;
  if (useSimpleMF_) es.get<IdealMagneticFieldRecord>().get(mfName_, bfield_h);  
  else es.get<IdealMagneticFieldRecord>().get(bfield_h);
  bfield = bfield_h.product();
  nomField = bfield->nominalValue();

  edm::ESHandle<ClusterShapeHitFilter> filterHandle_;
  es.get<CkfComponentsRecord>().get(filterName_, filterHandle_);
  filter = filterHandle_.product();

  edm::ESHandle<TransientTrackingRecHitBuilder> builderH;
  es.get<TransientRecHitRecord>().get(builderName_, builderH);
  builder = (TkTransientTrackingRecHitBuilder const *)(builderH.product());
  cloner = (*builder).cloner();
}

void MultiHitGeneratorFromChi2::setSeedingLayers(SeedingLayerSetsHits::SeedingLayerSet pairLayers,
                                                 std::vector<SeedingLayerSetsHits::SeedingLayer> thirdLayers) {
  thePairGenerator->setSeedingLayers(pairLayers);
  theLayers = thirdLayers;
}

namespace {
  inline
  bool intersect(Range &range, const Range &second)
  {
    if (range.first > second.max() || range.second < second.min())
      return false;
    if (range.first < second.min())
      range.first = second.min();
    if (range.second > second.max())
      range.second = second.max();
    return range.first < range.second;
  }
}

void MultiHitGeneratorFromChi2::hitSets(const TrackingRegion& region, 
                    OrderedMultiHits & result,
                    const edm::Event & ev,
                    const edm::EventSetup& es)
{ 

  unsigned int debug_Id0 = detIdsToDebug[0];
  unsigned int debug_Id1 = detIdsToDebug[1];
  unsigned int debug_Id2 = detIdsToDebug[2];

  if (debug) cout << "pair: " << ((HitPairGeneratorFromLayerPair*) thePairGenerator)->innerLayer().name() << "+" <<  ((HitPairGeneratorFromLayerPair*) thePairGenerator)->outerLayer().name() << " 3rd lay size: " << theLayers.size() << endl;

  //gc: first get the pairs
  OrderedHitPairs pairs;
  pairs.reserve(30000);
  thePairGenerator->hitPairs(region,pairs,ev,es);
  if (debug) cout << endl;
  if (pairs.empty()) {
    //cout << "empy pairs" << endl;
    return;
  }
  
  //gc: these are all the layers compatible with the layer pairs (as defined in the config file)
  int size = theLayers.size();


  //gc: initialize a KDTree per each 3rd layer
  std::vector<KDTreeNodeInfo<RecHitsSortedInPhi::HitIter> > layerTree; // re-used throughout
  std::vector<RecHitsSortedInPhi::HitIter> foundNodes; // re-used thoughout
  foundNodes.reserve(100);
  #ifdef __clang__
  std::vector<KDTreeLinkerAlgo<RecHitsSortedInPhi::HitIter>> hitTree(size);
  #else
  KDTreeLinkerAlgo<RecHitsSortedInPhi::HitIter> hitTree[size];
  #endif
  float rzError[size]; //save maximum errors
  double maxphi = Geom::twoPi(), minphi = -maxphi; //increase to cater for any range

  map<std::string, LayerRZPredictions> mapPred;//need to use the name as map key since we may have more than one SeedingLayer per DetLayer (e.g. TID and MTID)
  const RecHitsSortedInPhi * thirdHitMap[size];//gc: this comes from theLayerCache

  //gc: loop over each layer
  for(int il = 0; il < size; il++) {
    thirdHitMap[il] = &(*theLayerCache)(theLayers[il], region, ev, es);
    if (debug) cout << "considering third layer: " << theLayers[il].name() << " with hits: " << thirdHitMap[il]->all().second-thirdHitMap[il]->all().first << endl;
    const DetLayer *layer = theLayers[il].detLayer();
    LayerRZPredictions &predRZ = mapPred[theLayers[il].name()];
    predRZ.line.initLayer(layer);
    predRZ.line.initTolerance(extraHitRZtolerance);

    //gc: now we take all hits in the layer and fill the KDTree    
    RecHitsSortedInPhi::Range hitRange = thirdHitMap[il]->all(); // Get iterators
    layerTree.clear();
    double minz=999999.0, maxz= -999999.0; // Initialise to extreme values in case no hits
    float maxErr=0.0f;
    bool barrelLayer = (theLayers[il].detLayer()->location() == GeomDetEnumerators::barrel);
    if (hitRange.first != hitRange.second)
      { minz = barrelLayer? hitRange.first->hit()->globalPosition().z() : hitRange.first->hit()->globalPosition().perp();
    maxz = minz; //In case there's only one hit on the layer
    for (RecHitsSortedInPhi::HitIter hi=hitRange.first; hi != hitRange.second; ++hi)
      { double angle = hi->phi();
        double myz = barrelLayer? hi->hit()->globalPosition().z() : hi->hit()->globalPosition().perp();

        if (debug && hi->hit()->rawId()==debug_Id2) {
          cout << "filling KDTree with hit in id=" << debug_Id2 
           << " with pos: " << hi->hit()->globalPosition() 
           << " phi=" << hi->hit()->globalPosition().phi() 
           << " z=" << hi->hit()->globalPosition().z() 
           << " r=" << hi->hit()->globalPosition().perp() 
           << endl;
        }
        //use (phi,r) for endcaps rather than (phi,z)
        if (myz < minz) { minz = myz;} else { if (myz > maxz) {maxz = myz;}}
        float myerr = barrelLayer? hi->hit()->errorGlobalZ(): hi->hit()->errorGlobalR();
        if (myerr > maxErr) { maxErr = myerr;}
        layerTree.push_back(KDTreeNodeInfo<RecHitsSortedInPhi::HitIter>(hi, angle, myz)); // save it
        if (angle < 0)  // wrap all points in phi
          { layerTree.push_back(KDTreeNodeInfo<RecHitsSortedInPhi::HitIter>(hi, angle+Geom::twoPi(), myz));}
        else
          { layerTree.push_back(KDTreeNodeInfo<RecHitsSortedInPhi::HitIter>(hi, angle-Geom::twoPi(), myz));}
      }
      }
    KDTreeBox phiZ(minphi, maxphi, minz-0.01, maxz+0.01);  // declare our bounds
    //add fudge factors in case only one hit and also for floating-point inaccuracy
    hitTree[il].build(layerTree, phiZ); // make KDtree
    rzError[il] = maxErr; //save error
  }
  //gc: now we have initialized the KDTrees and we are out of the layer loop
  
  //gc: this sets the minPt of the triplet
  double curv = PixelRecoUtilities::curvature(1. / region.ptMin(), es);

  if (debug) std::cout << "pair size=" << pairs.size() << std::endl;

  //gc: now we loop over all pairs
  for (OrderedHitPairs::const_iterator ip = pairs.begin(); ip != pairs.end(); ++ip) {

    int foundTripletsFromPair = 0;
    bool usePair = false;
    cacheHitPointer bestH2;
    float minChi2 = std::numeric_limits<float>::max();

    SeedingHitSet::ConstRecHitPointer oriHit0 = ip->inner();
    SeedingHitSet::ConstRecHitPointer oriHit1 = ip->outer();

    HitOwnPtr hit0(*oriHit0);
    HitOwnPtr hit1(*oriHit1);
    GlobalPoint gp0 = hit0->globalPosition();
    GlobalPoint gp1 = hit1->globalPosition();

    bool debugPair = debug && ip->inner()->rawId()==debug_Id0 && ip->outer()->rawId()==debug_Id1;

    if (debugPair) {
      cout << endl << endl
       << "found new pair with ids "<<debug_Id0<<" "<<debug_Id1<<" with pos: " << gp0 << " " << gp1 
           << endl;
    }

    if (refitHits) {

      TrajectoryStateOnSurface tsos0, tsos1;
      assert(!hit0.isOwn()); assert(!hit1.isOwn());
      refit2Hits(hit0,hit1,tsos0,tsos1,region,nomField,debugPair);
      assert(hit0.isOwn()); assert(hit1.isOwn());

      //fixme add pixels
      bool passFilterHit0 = true;
      if (//hit0->geographicalId().subdetId() > 2
      hit0->geographicalId().subdetId()==SiStripDetId::TIB 
      || hit0->geographicalId().subdetId()==SiStripDetId::TID
      //|| hit0->geographicalId().subdetId()==SiStripDetId::TOB
      //|| hit0->geographicalId().subdetId()==SiStripDetId::TEC
      ) {   
    const std::type_info &tid = typeid(*hit0->hit());
    if (tid == typeid(SiStripMatchedRecHit2D)) {
      const SiStripMatchedRecHit2D* matchedHit = dynamic_cast<const SiStripMatchedRecHit2D *>(hit0->hit());
      if (filter->isCompatible(DetId(matchedHit->monoId()), matchedHit->monoCluster(), tsos0.localMomentum())==0 ||
          filter->isCompatible(DetId(matchedHit->stereoId()), matchedHit->stereoCluster(), tsos0.localMomentum())==0) passFilterHit0 = false;
    } else if (tid == typeid(SiStripRecHit2D)) {
      const SiStripRecHit2D* recHit = dynamic_cast<const SiStripRecHit2D *>(hit0->hit());
      if (filter->isCompatible(*recHit, tsos0.localMomentum())==0) passFilterHit0 = false;
    } else if (tid == typeid(ProjectedSiStripRecHit2D)) {
      const ProjectedSiStripRecHit2D* precHit = dynamic_cast<const ProjectedSiStripRecHit2D *>(hit0->hit());
      if (filter->isCompatible(precHit->originalHit(), tsos0.localMomentum())==0) passFilterHit0 = false;   //FIXME
    }
      }
      if (debugPair&&!passFilterHit0)  cout << "hit0 did not pass cluster shape filter" << endl;
      if (!passFilterHit0) continue;
      bool passFilterHit1 = true;
      if (//hit1->geographicalId().subdetId() > 2
      hit1->geographicalId().subdetId()==SiStripDetId::TIB 
      || hit1->geographicalId().subdetId()==SiStripDetId::TID
      //|| hit1->geographicalId().subdetId()==SiStripDetId::TOB
      //|| hit1->geographicalId().subdetId()==SiStripDetId::TEC
      ) {   
    const std::type_info &tid = typeid(*hit1->hit());
    if (tid == typeid(SiStripMatchedRecHit2D)) {
      const SiStripMatchedRecHit2D* matchedHit = dynamic_cast<const SiStripMatchedRecHit2D *>(hit1->hit());
      if (filter->isCompatible(DetId(matchedHit->monoId()), matchedHit->monoCluster(), tsos1.localMomentum())==0 ||
          filter->isCompatible(DetId(matchedHit->stereoId()), matchedHit->stereoCluster(), tsos1.localMomentum())==0) passFilterHit1 = false;
    } else if (tid == typeid(SiStripRecHit2D)) {
      const SiStripRecHit2D* recHit = dynamic_cast<const SiStripRecHit2D *>(hit1->hit());
      if (filter->isCompatible(*recHit, tsos1.localMomentum())==0) passFilterHit1 = false;
    } else if (tid == typeid(ProjectedSiStripRecHit2D)) {
      const ProjectedSiStripRecHit2D* precHit = dynamic_cast<const ProjectedSiStripRecHit2D *>(hit1->hit());
      if (filter->isCompatible(precHit->originalHit(), tsos1.localMomentum())==0) passFilterHit1 = false;  //FIXME
    }
      }
      if (debugPair&&!passFilterHit1)  cout << "hit1 did not pass cluster shape filter" << endl;
      if (!passFilterHit1) continue;

    } else {
      // not refit clone anyhow
      hit0.reset((BaseTrackerRecHit *)hit0->clone());
      hit1.reset((BaseTrackerRecHit *)hit1->clone());
    }

    //gc: create the RZ line for the pair
    SimpleLineRZ line(PixelRecoPointRZ(gp0.perp(),gp0.z()), PixelRecoPointRZ(gp1.perp(),gp1.z()));
    ThirdHitPredictionFromCircle predictionRPhi(gp0, gp1, extraHitRPhitolerance);

    //gc: this is the curvature of the two hits assuming the region
    Range pairCurvature = predictionRPhi.curvature(region.originRBound());
    //gc: intersect not only returns a bool but may change pairCurvature to intersection with curv
    if (!intersect(pairCurvature, Range(-curv, curv))) {
      if (debugPair) std::cout << "curvature cut: curv=" << curv 
                   << " gc=(" << pairCurvature.first << ", " << pairCurvature.second << ")" << std::endl;
      continue;
    }

    //gc: loop over all third layers compatible with the pair
    for(int il = 0; (il < size) & (!usePair); il++) {

      if (debugPair) 
    cout << "cosider layer: " << theLayers[il].name() << " for this pair. Location: " << theLayers[il].detLayer()->location() << endl;

      if (hitTree[il].empty()) {
    if (debugPair) {
      cout << "empty hitTree" << endl;
    }
    continue; // Don't bother if no hits
      }

      cacheHitPointer bestL2;
      float chi2FromThisLayer = std::numeric_limits<float>::max();

      const DetLayer *layer = theLayers[il].detLayer();
      bool barrelLayer = layer->location() == GeomDetEnumerators::barrel;

      LayerRZPredictions &predRZ = mapPred.find(theLayers[il].name())->second;
      predRZ.line.initPropagator(&line);
      
      //gc: this takes the z at R-thick/2 and R+thick/2 according to 
      //    the line from the two points and the adds the extra tolerance
      Range rzRange = predRZ.line();

      if (rzRange.first >= rzRange.second) {
    if (debugPair) {
      cout << "rzRange empty" << endl;
    }
        continue;
      }
      //gc: check that rzRange is compatible with detector bounds
      //    note that intersect may change rzRange to intersection with bounds
      if (!intersect(rzRange, predRZ.line.detSize())) {// theDetSize = Range(-maxZ, maxZ); 
    if (debugPair) {
      cout << "rzRange and detector do not intersect" << endl;
    }
    continue;
      }
      Range radius = barrelLayer ? predRZ.line.detRange() : rzRange;

      //gc: define the phi range of the hits
      Range phiRange;
      if (useFixedPreFiltering) { 
    //gc: in this case it takes as range the phi of the outer 
    //    hit +/- the phiPreFiltering value from cfg
        float phi0 = ip->outer()->globalPosition().phi();
        phiRange = Range(phi0 - dphi, phi0 + dphi);
      } else {  
    //gc: predictionRPhi uses the cosine rule to find the phi of the 3rd point at radius, assuming the pairCurvature range [-c,+c]
    if (pairCurvature.first<0. && pairCurvature.second<0.) {
      float phi12 = predictionRPhi.phi(pairCurvature.first,radius.second);
      float phi21 = predictionRPhi.phi(pairCurvature.second,radius.first);
      while(unlikely(phi12 <  phi21)) phi12 += float(2. * M_PI); 
      phiRange = Range(phi21,phi12);
    } else if (pairCurvature.first>=0. && pairCurvature.second>=0.) {
      float phi11 = predictionRPhi.phi(pairCurvature.first,radius.first);
      float phi22 = predictionRPhi.phi(pairCurvature.second,radius.second);
      while(unlikely(phi11 <  phi22)) phi11 += float(2. * M_PI); 
      phiRange = Range(phi22,phi11);
    } else {
      float phi12 = predictionRPhi.phi(pairCurvature.first,radius.second);
      float phi22 = predictionRPhi.phi(pairCurvature.second,radius.second);
      while(unlikely(phi12 <  phi22)) phi12 += float(2. * M_PI); 
      phiRange = Range(phi22,phi12);
    }
      }
      
      //gc: this is the place where hits in the compatible region are put in the foundNodes
      typedef RecHitsSortedInPhi::Hit Hit;
      foundNodes.clear(); // Now recover hits in bounding box...
      // This needs range -twoPi to +twoPi to work
      float prmin=phiRange.min(), prmax=phiRange.max(); //get contiguous range
      if ((prmax-prmin) > Geom::twoPi()) { 
    prmax=Geom::pi(); prmin = -Geom::pi();
      } else {
    while (prmax>maxphi) { prmin -= Geom::twoPi(); prmax -= Geom::twoPi();}
    while (prmin<minphi) { prmin += Geom::twoPi(); prmax += Geom::twoPi();}
      }
      
      if (debugPair) cout << "defining kd tree box" << endl;

      if (barrelLayer) {
    KDTreeBox phiZ(prmin-extraPhiKDBox, prmax+extraPhiKDBox,
               rzRange.min()-fnSigmaRZ*rzError[il]-extraZKDBox,
               rzRange.max()+fnSigmaRZ*rzError[il]+extraZKDBox);
    hitTree[il].search(phiZ, foundNodes);

    if (debugPair) cout << "kd tree box bounds, phi: " << prmin-extraPhiKDBox <<","<< prmax+extraPhiKDBox
                << " z: "<< rzRange.min()-fnSigmaRZ*rzError[il]-extraZKDBox <<","<<rzRange.max()+fnSigmaRZ*rzError[il]+extraZKDBox
                << " rzRange: " << rzRange.min() <<","<<rzRange.max()
                << endl;

      } else {
    KDTreeBox phiR(prmin-extraPhiKDBox, prmax+extraPhiKDBox,
               rzRange.min()-fnSigmaRZ*rzError[il]-extraRKDBox,
               rzRange.max()+fnSigmaRZ*rzError[il]+extraRKDBox);
    hitTree[il].search(phiR, foundNodes);

    if (debugPair) cout << "kd tree box bounds, phi: " << prmin-extraPhiKDBox <<","<< prmax+extraPhiKDBox
                << " r: "<< rzRange.min()-fnSigmaRZ*rzError[il]-extraRKDBox <<","<<rzRange.max()+fnSigmaRZ*rzError[il]+extraRKDBox
                << " rzRange: " << rzRange.min() <<","<<rzRange.max()
                << endl;
      }

      if (debugPair) cout << "kd tree box size: " << foundNodes.size() << endl;
      

      //gc: now we loop over the hits in the box for this layer
      for (std::vector<RecHitsSortedInPhi::HitIter>::iterator ih = foundNodes.begin();
       ih !=foundNodes.end() && !usePair; ++ih) {

    if (debugPair) std::cout << endl << "triplet candidate" << std::endl;

    const RecHitsSortedInPhi::HitIter KDdata = *ih;

    SeedingHitSet::ConstRecHitPointer oriHit2 = KDdata->hit();
    cacheHitPointer hit2;

    if (refitHits) {//fixme

      //fitting all 3 hits takes too much time... do it quickly only for 3rd hit
      GlobalVector initMomentum(oriHit2->globalPosition() - gp1);
      initMomentum *= (1./initMomentum.perp()); //set pT=1
      GlobalTrajectoryParameters kine = GlobalTrajectoryParameters(oriHit2->globalPosition(), initMomentum, 1, &*bfield);
      TrajectoryStateOnSurface state(kine,*oriHit2->surface());
      hit2.reset((SeedingHitSet::RecHitPointer)(cloner(*oriHit2,state)));

      //fixme add pixels
      bool passFilterHit2 = true;
      if (hit2->geographicalId().subdetId()==SiStripDetId::TIB 
          || hit2->geographicalId().subdetId()==SiStripDetId::TID
          // || hit2->geographicalId().subdetId()==SiStripDetId::TOB
          // || hit2->geographicalId().subdetId()==SiStripDetId::TEC
          ) {
        const std::type_info &tid = typeid(*hit2->hit());
        if (tid == typeid(SiStripMatchedRecHit2D)) {
          const SiStripMatchedRecHit2D* matchedHit = dynamic_cast<const SiStripMatchedRecHit2D *>(hit2->hit());
          if (filter->isCompatible(DetId(matchedHit->monoId()), matchedHit->monoCluster(), initMomentum)==0 ||
          filter->isCompatible(DetId(matchedHit->stereoId()), matchedHit->stereoCluster(), initMomentum)==0) passFilterHit2 = false;
        } else if (tid == typeid(SiStripRecHit2D)) {
          const SiStripRecHit2D* recHit = dynamic_cast<const SiStripRecHit2D *>(hit2->hit());
          if (filter->isCompatible(*recHit, initMomentum)==0) passFilterHit2 = false;
        } else if (tid == typeid(ProjectedSiStripRecHit2D)) {
          const ProjectedSiStripRecHit2D* precHit = dynamic_cast<const ProjectedSiStripRecHit2D *>(hit2->hit());
          if (filter->isCompatible(precHit->originalHit(), initMomentum)==0) passFilterHit2 = false;
        }
      }
      if (debugPair&&!passFilterHit2)  cout << "hit2 did not pass cluster shape filter" << endl;
      if (!passFilterHit2) continue;
      
      // fitting all 3 hits takes too much time :-(
      // TrajectoryStateOnSurface tsos0, tsos1, tsos2;
      // refit3Hits(hit0,hit1,hit2,tsos0,tsos1,tsos2,nomField,debugPair);
      // if (hit2->geographicalId().subdetId()==SiStripDetId::TIB 
      //     // || hit2->geographicalId().subdetId()==SiStripDetId::TOB
      //     // || hit2->geographicalId().subdetId()==SiStripDetId::TID
      //     // || hit2->geographicalId().subdetId()==SiStripDetId::TEC
      //     ) {
      //   const std::type_info &tid = typeid(*hit2->hit());
      //   if (tid == typeid(SiStripMatchedRecHit2D)) {
      //     const SiStripMatchedRecHit2D* matchedHit = dynamic_cast<const SiStripMatchedRecHit2D *>(hit2->hit());
      //     if (filter->isCompatible(DetId(matchedHit->monoId()), matchedHit->monoCluster(), tsos2.localMomentum())==0 ||
      //          filter->isCompatible(DetId(matchedHit->stereoId()), matchedHit->stereoCluster(), tsos2.localMomentum())==0) continue;
      //   } else if (tid == typeid(SiStripRecHit2D)) {
      //     const SiStripRecHit2D* recHit = dynamic_cast<const SiStripRecHit2D *>(hit2->hit());
      //     if (filter->isCompatible(*recHit, tsos2.localMomentum())==0) continue;
      //   } else if (tid == typeid(ProjectedSiStripRecHit2D)) {
      //     const ProjectedSiStripRecHit2D* precHit = dynamic_cast<const ProjectedSiStripRecHit2D *>(hit2->hit());
      //     if (filter->isCompatible(precHit->originalHit(), tsos2.localMomentum())==0) continue;;
      //   }
      // }

    } else {
      // not refit clone anyhow
      hit2.reset((BaseTrackerRecHit*)oriHit2->clone());
    }

    //gc: add the chi2 cut
    vector<GlobalPoint> gp(3);
    vector<GlobalError> ge(3);
    vector<bool> bl(3);
    gp[0] = hit0->globalPosition();
    ge[0] = hit0->globalPositionError();
    int subid0 = hit0->geographicalId().subdetId();
    bl[0] = (subid0 == StripSubdetector::TIB || subid0 == StripSubdetector::TOB || subid0 == (int) PixelSubdetector::PixelBarrel);
    gp[1] = hit1->globalPosition();
    ge[1] = hit1->globalPositionError();
    int subid1 = hit1->geographicalId().subdetId();
    bl[1] = (subid1 == StripSubdetector::TIB || subid1 == StripSubdetector::TOB || subid1 == (int) PixelSubdetector::PixelBarrel);
    gp[2] = hit2->globalPosition();
    ge[2] = hit2->globalPositionError();
    int subid2 = hit2->geographicalId().subdetId();
    bl[2] = (subid2 == StripSubdetector::TIB || subid2 == StripSubdetector::TOB || subid2 == (int) PixelSubdetector::PixelBarrel);
    RZLine rzLine(gp,ge,bl);
    float  cottheta, intercept, covss, covii, covsi;
    rzLine.fit(cottheta, intercept, covss, covii, covsi);
    float chi2 = rzLine.chi2(cottheta, intercept);

    bool debugTriplet = debugPair && hit2->rawId()==debug_Id2;
    if (debugTriplet) {
      std::cout << endl << "triplet candidate in debug id" << std::endl;
      cout << "hit in id="<<hit2->rawId()<<" (from KDTree) with pos: " << KDdata->hit()->globalPosition()
           << " refitted: " << hit2->globalPosition() 
           << " chi2: " << chi2
           << endl;
      //cout << state << endl;
    }
    // should fix nan
    if ( (chi2 > maxChi2) | edm::isNotFinite(chi2) ) continue; 

    if (chi2VsPtCut) {

      FastCircle theCircle(hit2->globalPosition(),hit1->globalPosition(),hit0->globalPosition());
      float tesla0 = 0.1*nomField;
      float rho = theCircle.rho();
      float cm2GeV = 0.01 * 0.3*tesla0;
      float pt = cm2GeV * rho;
      if (debugTriplet) {
        std::cout << "triplet pT=" << pt << std::endl;
      }
      if (pt<region.ptMin()) continue;
      
      if (chi2_cuts.size()==4) {
        if ( ( pt>pt_interv[0] && pt<=pt_interv[1] && chi2 > chi2_cuts[0] ) ||
         ( pt>pt_interv[1] && pt<=pt_interv[2] && chi2 > chi2_cuts[1] ) ||
         ( pt>pt_interv[2] && pt<=pt_interv[3] && chi2 > chi2_cuts[2] ) ||
         ( pt>pt_interv[3] && chi2 > chi2_cuts[3] ) ) continue;     
      }
      
      // apparently this takes too much time...
      //      if (chi2_cuts.size()>1) {     
      //        int ncuts = chi2_cuts.size();
      //        if ( pt<=pt_interv[0] && chi2 > chi2_cuts[0] ) continue; 
      //        bool pass = true;
      //        for (int icut=1; icut<ncuts-1; icut++){
      //          if ( pt>pt_interv[icut-1] && pt<=pt_interv[icut] && chi2 > chi2_cuts[icut] ) pass=false;
      //        }
      //        if (!pass) continue;
      //        if ( pt>pt_interv[ncuts-2] && chi2 > chi2_cuts[ncuts-1] ) continue;         
      //        if (debug && hit0->rawId()==debug_Id0 && hit1->rawId()==debug_Id1 && hit2->rawId()==debug_Id2) {
      //          std::cout << "triplet passed chi2 vs pt cut" << std::endl;
      //        }
      //      } 
      
    }
    
    if (theMaxElement!=0 && result.size() >= theMaxElement) {
      result.clear();
      edm::LogError("TooManyTriplets")<<" number of triples exceed maximum. no triplets produced.";
      return;
    }
    if (debugPair) std::cout << "triplet made" << std::endl;
    //result.push_back(SeedingHitSet(hit0, hit1, hit2));
    /* no refit so keep only hit2
    assert(tripletFromThisLayer.empty());
    assert(hit0.isOwn()); assert(hit1.isOwn());assert(hit2.isOwn());
    tripletFromThisLayer.emplace_back(std::move(hit0));
    tripletFromThisLayer.emplace_back(std::move(hit1));
    tripletFromThisLayer.emplace_back(std::move(hit2));
    assert(hit0.isEmpty()); assert(hit1.isEmpty());assert(hit2.isEmpty());
    */
    bestL2 = std::move(hit2);
    chi2FromThisLayer = chi2;
    foundTripletsFromPair++;
    if (foundTripletsFromPair>=2) {
      usePair=true;
      if (debugPair) 
           std::cout << "using pair" << std::endl;
      break;
    }
      }//loop over hits in KDTree

      if (usePair) break;
      else {
    //if there is one triplet in more than one layer, try picking the one with best chi2
    if (chi2FromThisLayer<minChi2) {
      bestH2 = std::move(bestL2);
      minChi2 = chi2FromThisLayer;
    }
    /*
    else {
      if (!bestH2 && foundTripletsFromPair>0)
        std::cout << "what?? " <<  minChi2 << ' '  << chi2FromThisLayer << std::endl;
    }
    */
      }

    }//loop over layers

    if (foundTripletsFromPair==0) continue;

    //push back only (max) once per pair
    if (debugPair) std::cout << "Done seed #" << result.size() << std::endl;
    if (usePair) result.push_back(SeedingHitSet(ip->inner(), ip->outer())); 
    else { 
      assert(1==foundTripletsFromPair);
      assert(bestH2);
      result.emplace_back(&*hit0,&*hit1,&*bestH2); 
      assert(hit0.isOwn()); assert(hit1.isOwn());
      cache.emplace_back(const_cast<BaseTrackerRecHit*>(hit0.release()));
      cache.emplace_back(const_cast<BaseTrackerRecHit*>(hit1.release()));
      cache.emplace_back(std::move(bestH2));
      assert(hit0.empty()); assert(hit1.empty());assert(!bestH2);
    }
    // std::cout << (usePair ? "pair " : "triplet ") << minChi2 <<' ' << cache.size() << std::endl;  


  }//loop over pairs
  if (debug) {
    std::cout << "triplet size=" << result.size() << std::endl;
  }
}

bool MultiHitGeneratorFromChi2::checkPhiInRange(float phi, float phi1, float phi2) const
{ while (phi > phi2) phi -= 2. * M_PI;
  while (phi < phi1) phi += 2. * M_PI;
  return phi <= phi2;
}  

std::pair<float, float>
MultiHitGeneratorFromChi2::mergePhiRanges(const std::pair<float, float> &r1,
                          const std::pair<float, float> &r2) const
{ float r2Min = r2.first;
  float r2Max = r2.second;
  while (r1.first - r2Min > +M_PI) r2Min += 2. * M_PI, r2Max += 2. * M_PI;
  while (r1.first - r2Min < -M_PI) r2Min -= 2. * M_PI, r2Max -= 2. * M_PI;
  //std::cout << "mergePhiRanges " << fabs(r1.first-r2Min) << " " <<  fabs(r1.second-r2Max) << endl;
  return std::make_pair(min(r1.first, r2Min), max(r1.second, r2Max));
}

void MultiHitGeneratorFromChi2::refit2Hits(HitOwnPtr & hit1,
                       HitOwnPtr & hit2,
                       TrajectoryStateOnSurface& state1,
                       TrajectoryStateOnSurface& state2,
                       const TrackingRegion& region, float nomField, bool isDebug) {

  //these need to be sorted in R
  GlobalPoint gp0 = region.origin();
  GlobalPoint gp1 = hit1->globalPosition();
  GlobalPoint gp2 = hit2->globalPosition();

  if (isDebug) {
    cout << "positions before refitting: " << hit1->globalPosition() << " " << hit2->globalPosition() <<endl;
  }

  FastCircle theCircle(gp2,gp1,gp0);
  GlobalPoint cc(theCircle.x0(),theCircle.y0(),0);
  float tesla0 = 0.1*nomField;
  float rho = theCircle.rho();
  float cm2GeV = 0.01 * 0.3*tesla0;
  float pt = cm2GeV * rho;

  GlobalVector vec20 = gp2-gp0;
  //if (isDebug) { cout << "vec20.eta=" << vec20.eta() << endl; }

  GlobalVector p0( gp0.y()-cc.y(), -gp0.x()+cc.x(), 0. );
  p0 = p0*pt/p0.perp();
  GlobalVector p1( gp1.y()-cc.y(), -gp1.x()+cc.x(), 0. );
  p1 = p1*pt/p1.perp();
  GlobalVector p2( gp2.y()-cc.y(), -gp2.x()+cc.x(), 0. );
  p2 = p2*pt/p2.perp();

  //check sign according to scalar product
  if ( (p0.x()*(gp1.x()-gp0.x())+p0.y()*(gp1.y()-gp0.y()) ) < 0 ) {
    p0*=-1.;
    p1*=-1.;
    p2*=-1.;
  }

  //now set z component
  p0 = GlobalVector(p0.x(),p0.y(),p0.perp()/tan(vec20.theta()));
  p1 = GlobalVector(p1.x(),p1.y(),p1.perp()/tan(vec20.theta()));
  p2 = GlobalVector(p2.x(),p2.y(),p2.perp()/tan(vec20.theta()));

  //get charge from vectorial product
  TrackCharge q = 1;
  if ((gp1-cc).x()*p1.y() - (gp1-cc).y()*p1.x() > 0) q =-q;

  GlobalTrajectoryParameters kine1 = GlobalTrajectoryParameters(gp1, p1, q, &*bfield);
  state1 = TrajectoryStateOnSurface(kine1,*hit1->surface());
  hit1.reset((SeedingHitSet::RecHitPointer)(cloner(*hit1,state1)));

  GlobalTrajectoryParameters kine2 = GlobalTrajectoryParameters(gp2, p2, q, &*bfield);
  state2 = TrajectoryStateOnSurface(kine2,*hit2->surface());
  hit2.reset((SeedingHitSet::RecHitPointer)(cloner(*hit2,state2)));

  if (isDebug) {
    cout << "charge=" << q << endl;
    cout << "state1 pt=" << state1.globalMomentum().perp() << " eta=" << state1.globalMomentum().eta()  << " phi=" << state1.globalMomentum().phi() << endl;
    cout << "state2 pt=" << state2.globalMomentum().perp() << " eta=" << state2.globalMomentum().eta()  << " phi=" << state2.globalMomentum().phi() << endl;
    cout << "positions after refitting: " << hit1->globalPosition() << " " << hit2->globalPosition() <<endl;
  }

}

/*
void MultiHitGeneratorFromChi2::refit3Hits(HitOwnPtr & hit0,
                       HitOwnPtr & hit1,
                       HitOwnPtr & hit2,
                       TrajectoryStateOnSurface& state0,
                       TrajectoryStateOnSurface& state1,
                       TrajectoryStateOnSurface& state2,
                       float nomField, bool isDebug) {

  //these need to be sorted in R
  GlobalPoint gp0 = hit0->globalPosition();
  GlobalPoint gp1 = hit1->globalPosition();
  GlobalPoint gp2 = hit2->globalPosition();

  if (isDebug) {
    cout << "positions before refitting: " << hit0->globalPosition() << " " << hit1->globalPosition() << " " << hit2->globalPosition() <<endl;
  }

  FastCircle theCircle(gp2,gp1,gp0);
  GlobalPoint cc(theCircle.x0(),theCircle.y0(),0);
  float tesla0 = 0.1*nomField;
  float rho = theCircle.rho();
  float cm2GeV = 0.01 * 0.3*tesla0;
  float pt = cm2GeV * rho;

  GlobalVector vec20 = gp2-gp0;
  //if (isDebug) { cout << "vec20.eta=" << vec20.eta() << endl; }

  GlobalVector p0( gp0.y()-cc.y(), -gp0.x()+cc.x(), 0. );
  p0 = p0*pt/p0.perp();
  GlobalVector p1( gp1.y()-cc.y(), -gp1.x()+cc.x(), 0. );
  p1 = p1*pt/p1.perp();
  GlobalVector p2( gp2.y()-cc.y(), -gp2.x()+cc.x(), 0. );
  p2 = p2*pt/p2.perp();

  //check sign according to scalar product
  if ( (p0.x()*(gp1.x()-gp0.x())+p0.y()*(gp1.y()-gp0.y()) ) < 0 ) {
    p0*=-1.;
    p1*=-1.;
    p2*=-1.;
  }

  //now set z component
  p0 = GlobalVector(p0.x(),p0.y(),p0.perp()/tan(vec20.theta()));
  p1 = GlobalVector(p1.x(),p1.y(),p1.perp()/tan(vec20.theta()));
  p2 = GlobalVector(p2.x(),p2.y(),p2.perp()/tan(vec20.theta()));

  //get charge from vectorial product
  TrackCharge q = 1;
  if ((gp1-cc).x()*p1.y() - (gp1-cc).y()*p1.x() > 0) q =-q;

  GlobalTrajectoryParameters kine0 = GlobalTrajectoryParameters(gp0, p0, q, &*bfield);
  state0 = TrajectoryStateOnSurface(kine0,*hit0->surface());
  hit0 = hit0->clone(state0);

  GlobalTrajectoryParameters kine1 = GlobalTrajectoryParameters(gp1, p1, q, &*bfield);
  state1 = TrajectoryStateOnSurface(kine1,*hit1->surface());
  hit1 = hit1->clone(state1);

  GlobalTrajectoryParameters kine2 = GlobalTrajectoryParameters(gp2, p2, q, &*bfield);
  state2 = TrajectoryStateOnSurface(kine2,*hit2->surface());
  hit2 = hit2->clone(state2);

  if (isDebug) {
    cout << "charge=" << q << endl;
    cout << "state0 pt=" << state0.globalMomentum().perp() << " eta=" << state0.globalMomentum().eta()  << " phi=" << state0.globalMomentum().phi() << endl;
    cout << "state1 pt=" << state1.globalMomentum().perp() << " eta=" << state1.globalMomentum().eta()  << " phi=" << state1.globalMomentum().phi() << endl;
    cout << "state2 pt=" << state2.globalMomentum().perp() << " eta=" << state2.globalMomentum().eta()  << " phi=" << state2.globalMomentum().phi() << endl;
    cout << "positions after refitting: " << hit0->globalPosition() << " " << hit1->globalPosition() << " " << hit2->globalPosition() <<endl;
  }

}
*/