ResidualSVDStateFilter.cc

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
#include <tracking/ckf/svd/filters/states/ResidualSVDStateFilter.h>
 
#include <tracking/spacePointCreation/SpacePoint.h>
#include <framework/core/ModuleParamList.h>
#include <tracking/trackingUtilities/utilities/StringManipulation.h>
 
#include <Math/Vector3D.h>
 
using namespace Belle2;
using namespace TrackingUtilities;
 
void ResidualSVDStateFilter::exposeParameters(ModuleParamList* moduleParamList, const std::string& prefix)
{
  moduleParamList->addParameter(TrackingUtilities::prefixed(prefix, "maximalResidual"), m_param_maximalResidual,
                                "Maximum residual between extrapolated and measured position based on Kalman step.",
                                m_param_maximalResidual);
}
 
Weight ResidualSVDStateFilter::operator()(const BaseSVDStateFilter::Object& pair)
{
  const std::vector<TrackingUtilities::WithWeight<const CKFToSVDState*>>& previousStates = pair.first;
  CKFToSVDState* currentState = pair.second;
 
  const auto* spacePoint = currentState->getHit();
 
  genfit::MeasuredStateOnPlane firstMeasurement;
  if (currentState->mSoPSet()) {
    firstMeasurement = currentState->getMeasuredStateOnPlane();
  } else {
    firstMeasurement = previousStates.back()->getMeasuredStateOnPlane();
  }
 
  ROOT::Math::XYZVector position = ROOT::Math::XYZVector(firstMeasurement.getPos());
  const ROOT::Math::XYZVector hitPosition = spacePoint->getPosition();
 
  const bool sameHemisphere = fabs(position.Phi() - hitPosition.Phi()) < TMath::PiOver2();
  if (not sameHemisphere) {
    return NAN;
  }
 
  const double residual = m_kalmanStepper.calculateResidual(firstMeasurement, *currentState);
  if (residual > m_param_maximalResidual) {
    return NAN;
  }
 
  // add 1e-6 to prevent divisin with 0.
  return 1 / (residual + 1e-6);
}