KHitWireLine.cxx

Go to the documentation of this file.

#include <stdint.h>

#include "lardata/RecoObjects/KHitWireLine.h"
#include "lardata/RecoObjects/SurfWireLine.h"
#include "larcore/Geometry/Geometry.h"
#include "lardata/DetectorInfoServices/DetectorPropertiesService.h"
#include "cetlib_except/exception.h"

namespace trkf {

  KHitWireLine::KHitWireLine(const art::Ptr<recob::Hit>& hit,
                             const std::shared_ptr<const Surface>& psurf) :
    KHit(psurf),
    fHit(hit)
  {
    // Get services.
    const detinfo::DetectorProperties* detprop = art::ServiceHandle<detinfo::DetectorPropertiesService>()->provider();

    // Extract wire id.
    geo::WireID wireid = hit->WireID();

    // Extract time information from hit.

    double t = hit->PeakTime();
    double terr = hit->SigmaPeakTime();

    // Don't let the time error be less than 1./sqrt(12.) ticks.
    // This should be removed when hit errors are fixed.

    if(terr < 1./std::sqrt(12.))
      terr = 1./std::sqrt(12.);

    // Calculate position and error.

    double x = detprop->ConvertTicksToX(t, wireid.Plane, wireid.TPC, wireid.Cryostat);
    double xerr = terr * detprop->GetXTicksCoefficient();

    // Check the surface (determined by wire id + drift time).  If the
    // surface pointer is null, make a new SurfWireLine surface and
    // update the base class appropriately.  Otherwise, just check
    // that the specified surface agrees with the wire id + drift time.

    if(psurf.get() == 0) {
      std::shared_ptr<const Surface> new_psurf(new SurfWireLine(wireid, x));
      setMeasSurface(new_psurf);
    }
    else {
      SurfWireLine check_surf(wireid, x);
      if(!check_surf.isEqual(*psurf))
        throw cet::exception("KHitWireLine") << "Measurement surface doesn't match hit.\n";
    }

    setMeasPlane(wireid.Plane);

    // Update measurement vector and error matrix.

    trkf::KVector<1>::type mvec(1, 0.);
    setMeasVector(mvec);

    trkf::KSymMatrix<1>::type merr(1);
    merr(0,0) = xerr * xerr;
    setMeasError(merr);

    // Set the unique id from a combination of the channel number and the time.

    fID = (hit->Channel() % 200000) * 10000 + (int(std::abs(t)) % 10000);
  }

  KHitWireLine::KHitWireLine(const geo::WireID& wireid, double x, double xerr) :
    KHit(std::shared_ptr<const Surface>(new SurfWireLine(wireid, x)))
  {
    // Get services.

    art::ServiceHandle<geo::Geometry> geom;

    // Get plane number.

    setMeasPlane(wireid.Plane);

    // Update measurement vector and error matrix.
    // The measured value (aka impact parameter) is always zero.

    trkf::KVector<1>::type mvec(1, 0.);
    setMeasVector(mvec);

    trkf::KSymMatrix<1>::type merr(1);
    merr(0,0) = xerr * xerr;
    setMeasError(merr);
  }

  KHitWireLine::~KHitWireLine()
  {}

  bool KHitWireLine::subpredict(const KETrack& tre,
                                KVector<1>::type& pvec,
                                KSymMatrix<1>::type& perr,
                                KHMatrix<1>::type& hmatrix) const
  {
    // Make sure that the track surface and the measurement surface are the same.
    // Throw an exception if they are not.

    if(!getMeasSurface()->isEqual(*tre.getSurface()))
      throw cet::exception("KHitWireLine") << "Track surface not the same as measurement surface.\n";
 
    // Prediction is the signed impact parameter (parameter 0).

    int size = tre.getVector().size();
    pvec.resize(1, /* preserve */ false);
    pvec.clear();
    pvec(0) = tre.getVector()(0);

    perr.resize(1, /* preserve */ false);
    perr.clear();
    perr(0,0) = tre.getError()(0,0);

    // Update prediction error to include contribution from track slope.

    art::ServiceHandle<geo::Geometry> geom;
    double pitch = geom->WirePitch();
    double phi = tre.getVector()(2);
    double cosphi = std::cos(phi);
    double slopevar = pitch*pitch * cosphi*cosphi / 12.;
    perr(0,0) += slopevar;

    // Hmatrix - dr/dr = 1., all others are zero.

    hmatrix.resize(1, size, /* preserve */ false);
    hmatrix.clear();
    hmatrix(0,0) = 1.;

    return true;
  }
} // end namespace trkf