MultiHitGeneratorFromChi2.cc

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#include "RecoTracker/TkSeedGenerator/plugins/MultiHitGeneratorFromChi2.h"
#include "FWCore/ParameterSet/interface/ParameterSetDescription.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 "CommonTools/RecoAlgos/interface/KDTreeLinkerAlgo.h"
 
#include "RecoPixelVertexing/PixelTrackFitting/interface/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/BaseTrackerRecHit.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 "DataFormats/Math/interface/normalizedPhi.h"
 
#include "FWCore/Utilities/interface/isFinite.h"
#include "CommonTools/Utils/interface/DynArray.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;
  };
}  // namespace
 
MultiHitGeneratorFromChi2::MultiHitGeneratorFromChi2(const edm::ParameterSet& cfg)
    : MultiHitGeneratorFromPairAndLayers(cfg),
      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")),
      filterName_(cfg.getParameter<std::string>("ClusterShapeHitFilterName")),
      builderName_(cfg.existsAs<std::string>("TTRHBuilder") ? cfg.getParameter<std::string>("TTRHBuilder")
                                                            : std::string("WithTrackAngle")),
      useSimpleMF_(false),
      mfName_("") {
  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");
  }
#ifdef EDM_ML_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);
#endif
  // 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 = nullptr;
  bfield = nullptr;
  nomField = -1.;
}
 
MultiHitGeneratorFromChi2::~MultiHitGeneratorFromChi2() {}
 
void MultiHitGeneratorFromChi2::fillDescriptions(edm::ParameterSetDescription& desc) {
  MultiHitGeneratorFromPairAndLayers::fillDescriptions(desc);
 
  // fixed phi filtering
  desc.add<bool>("useFixedPreFiltering", false);
  desc.add<double>("phiPreFiltering", 0.3);
 
  // box properties
  desc.add<double>("extraHitRPhitolerance", 0);
  desc.add<double>("extraHitRZtolerance", 0);
  desc.add<double>("extraZKDBox", 0.2);
  desc.add<double>("extraRKDBox", 0.2);
  desc.add<double>("extraPhiKDBox", 0.005);
  desc.add<double>("fnSigmaRZ", 2.0);
 
  // refit&filter hits
  desc.add<bool>("refitHits", true);
  desc.add<std::string>("ClusterShapeHitFilterName", "ClusterShapeHitFilter");
  desc.add<std::string>("TTRHBuilder", "WithTrackAngle");
 
  // chi2 cuts
  desc.add<double>("maxChi2", 5.0);
  desc.add<bool>("chi2VsPtCut", true);
  desc.add<std::vector<double> >("pt_interv", std::vector<double>{{0.4, 0.7, 1.0, 2.0}});
  desc.add<std::vector<double> >("chi2_cuts", std::vector<double>{{3.0, 4.0, 5.0, 5.0}});
 
  // debugging
  desc.add<std::vector<int> >("detIdsToDebug", std::vector<int>{{0, 0, 0}});
}
 
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();
  ufield.set(nomField);  // more than enough (never actually used)
 
  if (refitHits) {
    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();
  }
}
 
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;
  }
}  // namespace
 
void MultiHitGeneratorFromChi2::hitSets(const TrackingRegion& region,
                                        OrderedMultiHits& result,
                                        const edm::Event& ev,
                                        const edm::EventSetup& es,
                                        SeedingLayerSetsHits::SeedingLayerSet pairLayers,
                                        std::vector<SeedingLayerSetsHits::SeedingLayer> thirdLayers) {
  LogDebug("MultiHitGeneratorFromChi2") << "pair: " << thePairGenerator->innerLayer(pairLayers).name() << "+"
                                        << thePairGenerator->outerLayer(pairLayers).name()
                                        << " 3rd lay size: " << thirdLayers.size();
 
  auto const& doublets = thePairGenerator->doublets(region, ev, es, pairLayers);
  LogTrace("MultiHitGeneratorFromChi2") << "";
  if (doublets.empty()) {
    //  LogDebug("MultiHitGeneratorFromChi2") << "empy pairs";
    return;
  }
 
  assert(theLayerCache);
  hitSets(region, result, ev, es, doublets, thirdLayers, *theLayerCache, cache);
}
 
void MultiHitGeneratorFromChi2::hitSets(const TrackingRegion& region,
                                        OrderedMultiHits& result,
                                        const edm::Event& ev,
                                        const edm::EventSetup& es,
                                        const HitDoublets& doublets,
                                        const std::vector<SeedingLayerSetsHits::SeedingLayer>& thirdLayers,
                                        LayerCacheType& layerCache,
                                        cacheHits& refittedHitStorage) {
  int size = thirdLayers.size();
  const RecHitsSortedInPhi* thirdHitMap[size];
  vector<const DetLayer*> thirdLayerDetLayer(size, nullptr);
  for (int il = 0; il < size; ++il) {
    thirdHitMap[il] = &layerCache(thirdLayers[il], region, es);
 
    thirdLayerDetLayer[il] = thirdLayers[il].detLayer();
  }
  hitSets(region, result, es, doublets, thirdHitMap, thirdLayerDetLayer, size, refittedHitStorage);
}
 
void MultiHitGeneratorFromChi2::hitTriplets(const TrackingRegion& region,
                                            OrderedMultiHits& result,
                                            const edm::EventSetup& es,
                                            const HitDoublets& doublets,
                                            const RecHitsSortedInPhi** thirdHitMap,
                                            const std::vector<const DetLayer*>& thirdLayerDetLayer,
                                            const int nThirdLayers) {
  hitSets(region, result, es, doublets, thirdHitMap, thirdLayerDetLayer, nThirdLayers, cache);
}
 
void MultiHitGeneratorFromChi2::hitSets(const TrackingRegion& region,
                                        OrderedMultiHits& result,
                                        const edm::EventSetup& es,
                                        const HitDoublets& doublets,
                                        const RecHitsSortedInPhi** thirdHitMap,
                                        const std::vector<const DetLayer*>& thirdLayerDetLayer,
                                        const int nThirdLayers,
                                        cacheHits& refittedHitStorage) {
#ifdef EDM_ML_DEBUG
  unsigned int debug_Id0 = detIdsToDebug[0];
  unsigned int debug_Id1 = detIdsToDebug[1];
  unsigned int debug_Id2 = detIdsToDebug[2];
#endif
 
  std::array<bool, 3> bl;
  bl[0] = doublets.innerLayer().isBarrel;
  bl[1] = doublets.outerLayer().isBarrel;
 
  //gc: these are all the layers compatible with the layer pairs (as defined in the config file)
 
  //gc: initialize a KDTree per each 3rd layer
  std::vector<KDTreeNodeInfo<RecHitsSortedInPhi::HitIter, 2> > layerTree;  // re-used throughout
  std::vector<RecHitsSortedInPhi::HitIter> foundNodes;                     // re-used thoughout
  foundNodes.reserve(100);
  declareDynArray(KDTreeLinkerAlgo<RecHitsSortedInPhi::HitIter>, nThirdLayers, hitTree);
  declareDynArray(LayerRZPredictions, nThirdLayers, mapPred);
  float rzError[nThirdLayers];  //save maximum errors
 
  const float maxDelphi = region.ptMin() < 0.3f ? float(M_PI) / 4.f : float(M_PI) / 8.f;  // FIXME move to config??
  const float maxphi = M_PI + maxDelphi, minphi = -maxphi;  // increase to cater for any range
  const float safePhi = M_PI - maxDelphi;                   // sideband
 
  //gc: loop over each layer
  for (int il = 0; il < nThirdLayers; il++) {
    LogTrace("MultiHitGeneratorFromChi2")
        << "considering third layer: with hits: " << thirdHitMap[il]->all().second - thirdHitMap[il]->all().first;
    const DetLayer* layer = thirdLayerDetLayer[il];
    LayerRZPredictions& predRZ = mapPred[il];
    predRZ.line.initLayer(layer);
    predRZ.line.initTolerance(extraHitRZtolerance);
 
    //gc: now we take all hits in the layer and fill the KDTree
    auto const& layer3 = *thirdHitMap[il];  // Get iterators
    layerTree.clear();
    float minz = 999999.0f, maxz = -minz;  // Initialise to extreme values in case no hits
    float maxErr = 0.0f;
    if (!layer3.empty()) {
      minz = layer3.v[0];
      maxz = minz;  //In case there's only one hit on the layer
      for (auto i = 0U; i < layer3.size(); ++i) {
        auto hi = layer3.theHits.begin() + i;
        auto angle = layer3.phi(i);
        auto myz = layer3.v[i];
#ifdef EDM_ML_DEBUG
        IfLogTrace(hi->hit()->rawId() == debug_Id2, "MultiHitGeneratorFromChi2")
            << "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();
#endif
        //use (phi,r) for endcaps rather than (phi,z)
        if (myz < minz) {
          minz = myz;
        } else {
          if (myz > maxz) {
            maxz = myz;
          }
        }
        auto myerr = layer3.dv[i];
        if (myerr > maxErr) {
          maxErr = myerr;
        }
        layerTree.push_back(KDTreeNodeInfo<RecHitsSortedInPhi::HitIter, 2>(hi, angle, myz));  // save it
        // populate side-bands
        if (angle > safePhi)
          layerTree.push_back(
              KDTreeNodeInfo<RecHitsSortedInPhi::HitIter, 2>(hi, float(angle - Geom::twoPi()), float(myz)));
        else if (angle < -safePhi)
          layerTree.push_back(
              KDTreeNodeInfo<RecHitsSortedInPhi::HitIter, 2>(hi, float(angle + Geom::twoPi()), float(myz)));
      }
    }
    KDTreeBox phiZ(minphi, maxphi, minz - 0.01f, maxz + 0.01f);  // 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
  auto curv = PixelRecoUtilities::curvature(1. / region.ptMin(), es);
 
  LogTrace("MultiHitGeneratorFromChi2") << "doublet size=" << doublets.size() << std::endl;
 
  //fixme add pixels
  auto filterHit = [&](TrackingRecHit const* hit, GlobalVector const& dir) -> bool {
    auto hh = reinterpret_cast<BaseTrackerRecHit const*>(hit);
    if (  //hh->geographicalId().subdetId() > 2
        hh->geographicalId().subdetId() == SiStripDetId::TIB || hh->geographicalId().subdetId() == SiStripDetId::TID
        //|| hh->geographicalId().subdetId()==SiStripDetId::TOB
        //|| hh->geographicalId().subdetId()==SiStripDetId::TEC
    ) {
      // carefull " for matched and projected local of tsos != local for individual clusters...
      if (hh->isMatched()) {
        const SiStripMatchedRecHit2D* matchedHit = reinterpret_cast<const SiStripMatchedRecHit2D*>(hh);
        if (filter->isCompatible(DetId(matchedHit->monoId()), matchedHit->monoCluster(), dir) == 0 ||
            filter->isCompatible(DetId(matchedHit->stereoId()), matchedHit->stereoCluster(), dir) == 0)
          return false;
      } else if (hh->isProjected()) {
        const ProjectedSiStripRecHit2D* precHit = reinterpret_cast<const ProjectedSiStripRecHit2D*>(hh);
        if (filter->isCompatible(precHit->originalHit(), dir) == 0)
          return false;  //FIXME??
      } else if (hh->isSingle()) {
        const SiStripRecHit2D* recHit = reinterpret_cast<const SiStripRecHit2D*>(hh);
        if (filter->isCompatible(*recHit, dir) == 0)
          return false;
      }
    }
    return true;
  };
 
  //gc: now we loop over all pairs
  for (std::size_t ip = 0; ip != doublets.size(); ip++) {
    int foundTripletsFromPair = 0;
    bool usePair = false;
    cacheHitPointer bestH2;
    float minChi2 = std::numeric_limits<float>::max();
 
    SeedingHitSet::ConstRecHitPointer oriHit0 = doublets.hit(ip, HitDoublets::inner);
    SeedingHitSet::ConstRecHitPointer oriHit1 = doublets.hit(ip, HitDoublets::outer);
 
    HitOwnPtr hit0(*oriHit0);
    HitOwnPtr hit1(*oriHit1);
    GlobalPoint gp0 = doublets.gp(ip, HitDoublets::inner);
    GlobalPoint gp1 = doublets.gp(ip, HitDoublets::outer);
 
#ifdef EDM_ML_DEBUG
    bool debugPair = oriHit0->rawId() == debug_Id0 && oriHit1->rawId() == debug_Id1;
#endif
    IfLogTrace(debugPair, "MultiHitGeneratorFromChi2") << endl
                                                       << endl
                                                       << "found new pair with ids " << oriHit0->rawId() << " "
                                                       << oriHit1->rawId() << " with pos: " << gp0 << " " << gp1;
 
    if (refitHits) {
      TrajectoryStateOnSurface tsos0, tsos1;
      assert(!hit0.isOwn());
      assert(!hit1.isOwn());
#ifdef EDM_ML_DEBUG
      refit2Hits(hit0, hit1, tsos0, tsos1, region, nomField, debugPair);
#else
      refit2Hits(hit0, hit1, tsos0, tsos1, region, nomField, false);
#endif
 
      bool passFilterHit0 = filterHit(hit0->hit(), tsos0.globalMomentum());
      IfLogTrace(debugPair && !passFilterHit0, "MultiHitGeneratorFromChi2") << "hit0 did not pass cluster shape filter";
      if (!passFilterHit0)
        continue;
      bool passFilterHit1 = filterHit(hit1->hit(), tsos1.globalMomentum());
      IfLogTrace(debugPair && !passFilterHit1, "MultiHitGeneratorFromChi2") << "hit1 did not pass cluster shape filter";
      if (!passFilterHit1)
        continue;
      // refit hits
      hit0.reset((SeedingHitSet::RecHitPointer)(cloner(*hit0, tsos0)));
      hit1.reset((SeedingHitSet::RecHitPointer)(cloner(*hit1, tsos1)));
 
#ifdef EDM_ML_DEBUG
      IfLogTrace(debugPair, "MultiHitGeneratorFromChi2")
          << "charge=" << tsos0.charge() << std::endl
          << "state1 pt=" << tsos0.globalMomentum().perp() << " eta=" << tsos0.globalMomentum().eta()
          << " phi=" << tsos0.globalMomentum().phi() << std::endl
          << "state2 pt=" << tsos1.globalMomentum().perp() << " eta=" << tsos1.globalMomentum().eta()
          << " phi=" << tsos1.globalMomentum().phi() << std::endl
          << "positions after refitting: " << hit0->globalPosition() << " " << hit1->globalPosition();
#endif
    } else {
      // not refit clone anyhow
      hit0.reset((BaseTrackerRecHit*)hit0->clone());
      hit1.reset((BaseTrackerRecHit*)hit1->clone());
    }
 
    assert(hit0.isOwn());
    assert(hit1.isOwn());
 
    //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);
 
    auto toPos = std::signbit(gp1.z() - gp0.z());
 
    //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))) {
      IfLogTrace(debugPair, "MultiHitGeneratorFromChi2")
          << "curvature cut: curv=" << curv << " gc=(" << pairCurvature.first << ", " << pairCurvature.second << ")";
      continue;
    }
 
    std::array<GlobalPoint, 3> gp;
    std::array<GlobalError, 3> ge;
    gp[0] = hit0->globalPosition();
    ge[0] = hit0->globalPositionError();
    gp[1] = hit1->globalPosition();
    ge[1] = hit1->globalPositionError();
 
    //gc: loop over all third layers compatible with the pair
    for (int il = 0; (il < nThirdLayers) & (!usePair); il++) {
      IfLogTrace(debugPair, "MultiHitGeneratorFromChi2")
          << "cosider layer:"
          << " for this pair. Location: " << thirdLayerDetLayer[il]->location();
 
      if (hitTree[il].empty()) {
        IfLogTrace(debugPair, "MultiHitGeneratorFromChi2") << "empty hitTree";
        continue;  // Don't bother if no hits
      }
 
      cacheHitPointer bestL2;
      float chi2FromThisLayer = std::numeric_limits<float>::max();
 
      const DetLayer* layer = thirdLayerDetLayer[il];
      // bool barrelLayer = layer->location() == GeomDetEnumerators::barrel;
      auto const& layer3 = *thirdHitMap[il];
      bool barrelLayer = layer3.isBarrel;
      bl[2] = layer3.isBarrel;
 
      if ((!barrelLayer) & (toPos != std::signbit(layer->position().z())))
        continue;
 
      LayerRZPredictions& predRZ = mapPred[il];
      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) {
        IfLogTrace(debugPair, "MultiHitGeneratorFromChi2") << "rzRange empty";
        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);
        IfLogTrace(debugPair, "MultiHitGeneratorFromChi2") << "rzRange and detector do not intersect";
        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 = oriHit0->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.) {
          radius.swap();
        } else if (pairCurvature.first >= 0. && pairCurvature.second >= 0.) {
          ;
        } else {
          radius.first = radius.second;
        }
        auto phi12 = predictionRPhi.phi(pairCurvature.first, radius.first);
        auto phi22 = predictionRPhi.phi(pairCurvature.second, radius.second);
        phi12 = normalizedPhi(phi12);
        phi22 = proxim(phi22, phi12);
        phiRange = Range(phi12, phi22);
        phiRange.sort();
      }
 
      float prmin = phiRange.min(), prmax = phiRange.max();
 
      if (prmax - prmin > maxDelphi) {
        auto prm = phiRange.mean();
        prmin = prm - 0.5f * maxDelphi;
        prmax = prm + 0.5f * maxDelphi;
      }
 
      //gc: this is the place where hits in the compatible region are put in the foundNodes
      using Hit = RecHitsSortedInPhi::Hit;
      foundNodes.clear();  // Now recover hits in bounding box...
 
      IfLogTrace(debugPair, "MultiHitGeneratorFromChi2") << "defining kd tree box";
 
      if (barrelLayer) {
        KDTreeBox phiZ(prmin - extraPhiKDBox,
                       prmax + extraPhiKDBox,
                       float(rzRange.min() - fnSigmaRZ * rzError[il] - extraZKDBox),
                       float(rzRange.max() + fnSigmaRZ * rzError[il] + extraZKDBox));
        hitTree[il].search(phiZ, foundNodes);
 
        IfLogTrace(debugPair, "MultiHitGeneratorFromChi2")
            << "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();
 
      } else {
        KDTreeBox phiR(prmin - extraPhiKDBox,
                       prmax + extraPhiKDBox,
                       float(rzRange.min() - fnSigmaRZ * rzError[il] - extraRKDBox),
                       float(rzRange.max() + fnSigmaRZ * rzError[il] + extraRKDBox));
        hitTree[il].search(phiR, foundNodes);
 
        IfLogTrace(debugPair, "MultiHitGeneratorFromChi2")
            << "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();
      }
 
      IfLogTrace(debugPair, "MultiHitGeneratorFromChi2") << "kd tree box size: " << foundNodes.size();
 
      //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) {
        IfLogTrace(debugPair, "MultiHitGeneratorFromChi2") << endl << "triplet candidate";
 
        const RecHitsSortedInPhi::HitIter KDdata = *ih;
 
        auto oriHit2 = KDdata->hit();
        auto kk = KDdata - layer3.theHits.begin();
        cacheHitPointer hit2;
        auto gp2 = layer3.gp(kk);
        if (refitHits) {  //fixme
 
          //fitting all 3 hits takes too much time... do it quickly only for 3rd hit
          GlobalVector initMomentum(gp2 - gp1);
          initMomentum /= initMomentum.perp();  //set pT=1
 
          //fixme add pixels
          bool passFilterHit2 = filterHit(oriHit2->hit(), initMomentum);
          if (!passFilterHit2)
            continue;
          TrajectoryStateOnSurface state(GlobalTrajectoryParameters(gp2, initMomentum, 1, &ufield),
                                         *oriHit2->surface());
          hit2.reset((SeedingHitSet::RecHitPointer)(cloner(*oriHit2, state)));
 
        } else {
          // not refit clone anyhow
          hit2.reset((BaseTrackerRecHit*)oriHit2->clone());
        }
 
        //gc: add the chi2 cut
        gp[2] = hit2->globalPosition();
        ge[2] = hit2->globalPositionError();
        RZLine rzLine(gp, ge, bl);
        float chi2 = rzLine.chi2();
 
#ifdef EDM_ML_DEBUG
        bool debugTriplet = debugPair && hit2->rawId() == debug_Id2;
#endif
        IfLogTrace(debugTriplet, "MultiHitGeneratorFromChi2")
            << endl
            << "triplet candidate in debug id" << std::endl
            << "hit in id=" << hit2->rawId() << " (from KDTree) with pos: " << KDdata->hit()->globalPosition()
            << " refitted: " << hit2->globalPosition() << " chi2: " << chi2;
        // should fix nan
        if ((chi2 > maxChi2) | edm::isNotFinite(chi2))
          continue;
 
        if (chi2VsPtCut) {
          FastCircle theCircle(gp[2], gp[1], gp[0]);
          float tesla0 = 0.1f * nomField;
          float rho = theCircle.rho();
          float cm2GeV = 0.01f * 0.3f * tesla0;
          float pt = cm2GeV * rho;
          IfLogTrace(debugTriplet, "MultiHitGeneratorFromChi2") << "triplet pT=" << pt;
          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 (hit0->rawId()==debug_Id0 && hit1->rawId()==debug_Id1 && hit2->rawId()==debug_Id2) {
          //          LogTrace("MultiHitGeneratorFromChi2") << "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;
        }
        IfLogTrace(debugPair, "MultiHitGeneratorFromChi2") << "triplet made";
        //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;
          IfLogTrace(debugPair, "MultiHitGeneratorFromChi2") << "using pair";
          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)
        LogTrace("MultiHitGeneratorFromChi2") << "what?? " <<  minChi2 << ' '  << chi2FromThisLayer;
    }
    */
      }
 
    }  //loop over layers
 
    if (foundTripletsFromPair == 0)
      continue;
 
    //push back only (max) once per pair
    IfLogTrace(debugPair, "MultiHitGeneratorFromChi2") << "Done seed #" << result.size();
    if (usePair)
      result.push_back(SeedingHitSet(oriHit0, oriHit1));
    else {
      assert(1 == foundTripletsFromPair);
      assert(bestH2);
      result.emplace_back(&*hit0, &*hit1, &*bestH2);
      assert(hit0.isOwn());
      assert(hit1.isOwn());
      refittedHitStorage.emplace_back(const_cast<BaseTrackerRecHit*>(hit0.release()));
      refittedHitStorage.emplace_back(const_cast<BaseTrackerRecHit*>(hit1.release()));
      refittedHitStorage.emplace_back(std::move(bestH2));
      assert(hit0.empty());
      assert(hit1.empty());
      assert(!bestH2);
    }
    // LogTrace("MultiHitGeneratorFromChi2") << (usePair ? "pair " : "triplet ") << minChi2 <<' ' << refittedHitStorage.size();
 
  }  //loop over pairs
  LogTrace("MultiHitGeneratorFromChi2") << "triplet size=" << result.size();
  // std::cout << "MultiHitGeneratorFromChi2 " << "triplet size=" << result.size() << std::endl;
}
 
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
  const GlobalPoint& gp0 = region.origin();
  GlobalPoint gp1 = hit1->globalPosition();
  GlobalPoint gp2 = hit2->globalPosition();
 
  IfLogTrace(isDebug, "MultiHitGeneratorFromChi2")
      << "positions before refitting: " << hit1->globalPosition() << " " << hit2->globalPosition();
 
  FastCircle theCircle(gp2, gp1, gp0);
  GlobalPoint cc(theCircle.x0(), theCircle.y0(), 0);
  float tesla0 = 0.1f * nomField;
  float rho = theCircle.rho();
  float cm2GeV = 0.01f * 0.3f * 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
  auto zv = vec20.z() / vec20.perp();
  p0 = GlobalVector(p0.x(), p0.y(), p0.perp() * zv);
  p1 = GlobalVector(p1.x(), p1.y(), p1.perp() * zv);
  p2 = GlobalVector(p2.x(), p2.y(), p2.perp() * zv);
 
  //get charge from vectorial product
  TrackCharge q = 1;
  if ((gp1 - cc).x() * p1.y() - (gp1 - cc).y() * p1.x() > 0)
    q = -q;
 
  TrajectoryStateOnSurface(GlobalTrajectoryParameters(gp1, p1, q, &ufield), *hit1->surface()).swap(state1);
  // hit1.reset((SeedingHitSet::RecHitPointer)(cloner(*hit1,state1)));
 
  TrajectoryStateOnSurface(GlobalTrajectoryParameters(gp2, p2, q, &ufield), *hit2->surface()).swap(state2);
  // hit2.reset((SeedingHitSet::RecHitPointer)(cloner(*hit2,state2)));
}
 
/*
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();
 
  IfLogTrace(isDebug, "MultiHitGeneratorFromChi2") << "positions before refitting: " << hit0->globalPosition() << " " << hit1->globalPosition() << " " << hit2->globalPosition();
  }
 
  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;
  //IfLogTrace(isDebug, "MultiHitGeneratorFromChi2") << "vec20.eta=" << vec20.eta();
 
  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);
 
  IfLogTrace(isDebug, "MultiHitGeneratorFromChi2") << "charge=" << q << std::endl
                                                   << "state0 pt=" << state0.globalMomentum().perp() << " eta=" << state0.globalMomentum().eta()  << " phi=" << state0.globalMomentum().phi() << std::endl
                                                   << "state1 pt=" << state1.globalMomentum().perp() << " eta=" << state1.globalMomentum().eta()  << " phi=" << state1.globalMomentum().phi() << std::endl
                                                   << "state2 pt=" << state2.globalMomentum().perp() << " eta=" << state2.globalMomentum().eta()  << " phi=" << state2.globalMomentum().phi() << std::endl
                                                   << "positions after refitting: " << hit0->globalPosition() << " " << hit1->globalPosition() << " " << hit2->globalPosition();
}
*/