Utility class implementing the Kalmanesk combination of to two dimensional trajectories to one three dimensional trajectory. More...

#include <CDCAxialStereoFusion.h>

Public Member Functions
	CDCAxialStereoFusion (bool reestimateDriftLength=true)
	Constructor setting up the options of the fit.

void	reconstructFuseTrajectories (const CDCSegmentPair &segmentPair)
	Combine the two trajectories of the segments in the pair and assign the resulting three dimensional trajectory to the segment pair.

void	fusePreliminary (const CDCSegmentPair &segmentPair)
	Fit the given segment pair using the preliminary helix fit without proper covariance matrix.

CDCTrajectory3D	reconstructFuseTrajectories (const CDCSegment2D &fromSegment2D, const CDCSegment2D &toSegment2D)
	Combine the trajectories of the two given segments to a full helix trajectory.

CDCTrajectory3D	fusePreliminary (const CDCSegment2D &fromSegment2D, const CDCSegment2D &toSegment2D)
	Fit the two given segments together using the preliminary helix fit without proper covariance matrix.

CDCTrajectory3D	reconstructFuseTrajectories (const CDCSegment2D &fromSegment2D, const CDCSegment2D &toSegment2D, const CDCTrajectory3D &preliminaryTrajectory3D)
	Combine the two segments given a prelimiary reference trajectory to which a creation is applied.

PerigeeHelixAmbiguity	calcAmbiguity (const CDCSegment3D &segment3D, const CDCTrajectory2D &trajectory2D)
	Calculate the ambiguity of the helix parameters relative to the three circle parameters given the hit content of the segment and their stereo displacement.

Private Attributes
bool	m_reestimateDriftLength
	Swtich to reestimate the drift length.

DriftLengthEstimator	m_driftLengthEstimator
	Helper object to carry out the drift length estimation.

Detailed Description

Utility class implementing the Kalmanesk combination of to two dimensional trajectories to one three dimensional trajectory.

Definition at line 30 of file CDCAxialStereoFusion.h.

Constructor & Destructor Documentation

◆ CDCAxialStereoFusion()

CDCAxialStereoFusion ( bool reestimateDriftLength = true )

inlineexplicit

Constructor setting up the options of the fit.

Definition at line 34 of file CDCAxialStereoFusion.h.

        : m_reestimateDriftLength(reestimateDriftLength)
      {
      }

Member Function Documentation

◆ calcAmbiguity()

PerigeeHelixAmbiguity calcAmbiguity	(	const CDCSegment3D &	segment3D,
		const CDCTrajectory2D &	trajectory2D
	)

Calculate the ambiguity of the helix parameters relative to the three circle parameters given the hit content of the segment and their stereo displacement.

Definition at line 170 of file CDCAxialStereoFusion.cc.

{
  size_t nHits = segment3D.size();
 
  const Vector2D& localOrigin2D = trajectory2D.getLocalOrigin();
  const UncertainPerigeeCircle& localCircle = trajectory2D.getLocalCircle();
 
  double zeta = 0;
  for (const CDCRecoHit3D& recoHit3D : segment3D) {
    const Vector2D& recoPos2D = recoHit3D.getRecoPos2D();
    const Vector2D localRecoPos2D = recoPos2D - localOrigin2D;
    const Vector2D normal = localCircle->normal(localRecoPos2D);
    const CDCWire& wire = recoHit3D.getWire();
    zeta += wire.getWireLine().sagMovePerZ(recoHit3D.getRecoZ()).dot(normal);
  }
  zeta /= nHits;
 
  PerigeeHelixAmbiguity result = HelixUtil::defaultPerigeeAmbiguity();
 
  using namespace NHelixParameterIndices;
  result(c_Curv, c_Curv) = 1.0;
  result(c_Phi0, c_Phi0) = 1.0;
  result(c_I, c_I)       = 1.0;
 
  result(c_Phi0, c_TanL) =   zeta;
  result(c_I, c_Z0)      = - zeta;
 
  return result;
}

◆ fusePreliminary() [1/2]

CDCTrajectory3D fusePreliminary	(	const CDCSegment2D &	fromSegment2D,
		const CDCSegment2D &	toSegment2D
	)

Fit the two given segments together using the preliminary helix fit without proper covariance matrix.

The fit is used as the expansion point for the least square fuse fit with proper covariance.

Definition at line 92 of file CDCAxialStereoFusion.cc.

{
  if (fromSegment2D.empty()) {
    B2WARNING("From segment is empty.");
    return CDCTrajectory3D();
  }
 
  if (toSegment2D.empty()) {
    B2WARNING("To segment is empty.");
    return CDCTrajectory3D();
  }
 
  bool fromIsAxial = fromSegment2D.isAxial();
  const CDCSegment2D& axialSegment2D = fromIsAxial ? fromSegment2D : toSegment2D;
  const CDCSegment2D& stereoSegment2D = not fromIsAxial ? fromSegment2D : toSegment2D;
 
  CDCTrajectory2D axialTrajectory2D = axialSegment2D.getTrajectory2D();
 
  Vector2D localOrigin2D = (fromIsAxial ? fromSegment2D.back() : toSegment2D.front()).getRecoPos2D();
  axialTrajectory2D.setLocalOrigin(localOrigin2D);
 
  CDCSegment3D stereoSegment3D = CDCSegment3D::reconstruct(stereoSegment2D, axialTrajectory2D);
 
  CDCTrajectorySZ trajectorySZ;
 
  CDCSZFitter szFitter = CDCSZFitter::getFitter();
  trajectorySZ = szFitter.fit(stereoSegment3D);
  if (not trajectorySZ.isFitted()) {
    CDCTrajectory3D result;
    result.setChi2(NAN);
    return result;
  }
 
  CDCTrajectory3D preliminaryTrajectory3D(axialTrajectory2D, trajectorySZ);
  Vector3D localOrigin3D(localOrigin2D, 0.0);
  preliminaryTrajectory3D.setLocalOrigin(localOrigin3D);
  return preliminaryTrajectory3D;
}

◆ fusePreliminary() [2/2]

void fusePreliminary ( const CDCSegmentPair & segmentPair )

Fit the given segment pair using the preliminary helix fit without proper covariance matrix.

Updates the contained trajectory.

Definition at line 63 of file CDCAxialStereoFusion.cc.

{
  const CDCSegment2D* ptrFromSegment = segmentPair.getFromSegment();
  const CDCSegment2D* ptrToSegment = segmentPair.getToSegment();
 
  if (not ptrFromSegment) {
    B2WARNING("From segment unset.");
    return;
  }
 
  if (not ptrToSegment) {
    B2WARNING("To segment unset.");
    return;
  }
  const CDCSegment2D& fromSegment = *ptrFromSegment;
  const CDCSegment2D& toSegment = *ptrToSegment;
 
  CDCTrajectory3D trajectory3D = fusePreliminary(fromSegment, toSegment);
  segmentPair.setTrajectory3D(trajectory3D);
}

◆ reconstructFuseTrajectories() [1/3]

CDCTrajectory3D reconstructFuseTrajectories	(	const CDCSegment2D &	fromSegment2D,
		const CDCSegment2D &	toSegment2D
	)

Combine the trajectories of the two given segments to a full helix trajectory.

Definition at line 85 of file CDCAxialStereoFusion.cc.

{
  CDCTrajectory3D preliminaryTrajectory3D = fusePreliminary(fromSegment2D, toSegment2D);
  return reconstructFuseTrajectories(fromSegment2D, toSegment2D, preliminaryTrajectory3D);
}

◆ reconstructFuseTrajectories() [2/3]

CDCTrajectory3D reconstructFuseTrajectories	(	const CDCSegment2D &	fromSegment2D,
		const CDCSegment2D &	toSegment2D,
		const CDCTrajectory3D &	preliminaryTrajectory3D
	)

Combine the two segments given a prelimiary reference trajectory to which a creation is applied.

Definition at line 132 of file CDCAxialStereoFusion.cc.

{
  Vector3D localOrigin3D = preliminaryTrajectory3D.getLocalOrigin();
  Vector2D localOrigin2D = localOrigin3D.xy();
 
  CDCRiemannFitter riemannFitter;
  //riemannFitter.useOnlyOrientation();
  riemannFitter.useOnlyPosition();
 
  CDCSegment3D fromSegment3D = reconstruct(fromSegment2D, preliminaryTrajectory3D);
  CDCSegment3D toSegment3D   = reconstruct(toSegment2D, preliminaryTrajectory3D);
 
  if (m_reestimateDriftLength) {
    double tanLambda = preliminaryTrajectory3D.getTanLambda();
    m_driftLengthEstimator.updateDriftLength(fromSegment3D, tanLambda);
    m_driftLengthEstimator.updateDriftLength(toSegment3D, tanLambda);
  }
 
  CDCTrajectory2D fromTrajectory2D = riemannFitter.fit(fromSegment3D);
  CDCTrajectory2D toTrajectory2D   = riemannFitter.fit(toSegment3D);
 
  fromTrajectory2D.setLocalOrigin(localOrigin2D);
  toTrajectory2D.setLocalOrigin(localOrigin2D);
 
  SZParameters refSZ = preliminaryTrajectory3D.getLocalSZLine().szParameters();
 
  const UncertainPerigeeCircle& fromCircle = fromTrajectory2D.getLocalCircle();
  const UncertainPerigeeCircle& toCircle   = toTrajectory2D.getLocalCircle();
 
  JacobianMatrix<3, 5> fromH = calcAmbiguity(fromSegment3D, fromTrajectory2D);
  JacobianMatrix<3, 5> toH   = calcAmbiguity(toSegment3D,   toTrajectory2D);
 
  UncertainHelix resultHelix = UncertainHelix::average(fromCircle, fromH, toCircle, toH, refSZ);
  return CDCTrajectory3D(localOrigin3D, resultHelix);
}

◆ reconstructFuseTrajectories() [3/3]

void reconstructFuseTrajectories ( const CDCSegmentPair & segmentPair )

Combine the two trajectories of the segments in the pair and assign the resulting three dimensional trajectory to the segment pair.

Definition at line 41 of file CDCAxialStereoFusion.cc.

{
  const CDCSegment2D* ptrFromSegment = segmentPair.getFromSegment();
  const CDCSegment2D* ptrToSegment = segmentPair.getToSegment();
 
  if (not ptrFromSegment) {
    B2WARNING("From segment unset.");
    return;
  }
 
  if (not ptrToSegment) {
    B2WARNING("To segment unset.");
    return;
  }
 
  const CDCSegment2D& fromSegment = *ptrFromSegment;
  const CDCSegment2D& toSegment = *ptrToSegment;
 
  CDCTrajectory3D trajectory3D = reconstructFuseTrajectories(fromSegment, toSegment);
  segmentPair.setTrajectory3D(trajectory3D);
}

Member Data Documentation

◆ m_driftLengthEstimator

DriftLengthEstimator m_driftLengthEstimator

private

Helper object to carry out the drift length estimation.

Definition at line 86 of file CDCAxialStereoFusion.h.

◆ m_reestimateDriftLength

bool m_reestimateDriftLength