WireLine Class Reference

A three dimensional limited line represented by its closest approach to the z-axes (reference position ) and its skew parameter. More...

#include <WireLine.h>

Public Member Functions
	WireLine ()
	Default constructor initialising to all members to zero.
	WireLine (const Vector3D &forward, const Vector3D &backward, double sagCoeff)
	Constructor for a wire line between forward and backward point.
WireLine	movedBy (const Vector3D &offset) const
	Returns a copy of the wire line moved by a three dimensional offset.
WireLine	movedBy (const Vector2D &offset) const
	Returns a copy of the wire line moved by a two dimensional offset.
Vector3D	nominalPos3DAtZ (const double z) const
	Gives the three dimensional position without wire sag effect of the line at the given z value.
Vector2D	nominalPos2DAtZ (const double z) const
	Gives the two dimensional position without wire sag effect of the line at the given z value.
Vector3D	sagPos3DAtZ (const double z) const
	Gives the three dimensional position with wire sag effect of the line at the given z value.
Vector2D	sagPos2DAtZ (const double z) const
	Gives the two dimensional position with wire sag effect of the line at the given z value.
const Vector2D &	nominalMovePerZ () const
	Gives the positional move in the xy projection per unit z.
Vector2D	sagMovePerZ (const double z) const
	Gives the two dimensional position with wire sag effect of the line at the given z value.
double	nominalDistance (const Vector3D &pos3D) const
	Calculates the distance of the given point to the wire without wire sag effect.
double	sagDistance (const Vector3D &pos3D) const
	Calculates the distance of the given point to the wire with wire sag effect.
Vector3D	nominalClosest3D (const Vector3D &point) const
	Returns the closest approach on the wire without wire sag effect to the give point.
Vector3D	sagClosest3D (const Vector3D &point) const
	Returns the closest approach on the wire with wire sag effect to the give point.
Vector3D	forward3D () const
	Gives the position of the forward point.
Vector2D	forward2D () const
	Gives the xy position of the forward point.
Vector3D	backward3D () const
	Gives the position of the backward point.
Vector2D	backward2D () const
	Gives the xy position of the backward point.
Vector3D	wireVector () const
	Getter for the vector from backward to the forward position.
double	forwardZ () const
	Gives the forward z coordinate.
double	backwardZ () const
	Gives the backward z coordinate.
double	deltaZ () const
	Returns the difference between forward and backward z.
double	outOfZBoundsFactor (double z) const
	Returns the amount how much the given z position is outside the bounds in units of the wire length.
double	forwardPhi () const
	Gives the forward azimuth angle.
double	backwardPhi () const
	Gives the backward azimuth angle.
double	forwardCylindricalR () const
	Gives the cylindrical radius of the forward position.
double	backwardCylindricalR () const
	Gives the cylindrical radius of the backward position.
double	forwardPhiToRef () const
	Gives the azimuth angle of the forward position relative to the reference position.
double	backwardPhiToRef () const
	Gives the azimuth angle of the backward position relative to the reference position.
double	backwardToForwardAngle () const
	Gives the azimuth angle difference from backward to forward position.
double	tanLambda () const
	Returns the nominal tan lambda of the line. Also know as dz / ds.
double	lambda () const
	Returns the nominal lambda angle of the line.
double	tanTheta () const
	Returns the tangent of the opening angle between tangential vector and the z axes Also know as ds / dz.
double	theta () const
	Returns the nominal opening angle between tangential vector and the z axes.
double	nominalPerigeeZ () const
	Returns the z coordinate of the point of nominal closest approach to the z axes.
Vector3D	nominalPerigee3D () const
	Returns the point of nominal closest approach to the z axes.
Vector2D	nominalPerigee2D () const
	Returns the point of nominal closest approach to the z axes.
double	refX () const
	Returns the the x coordinate of the reference point.
double	refY () const
	Returns the the y coordinate of the reference point.
double	refZ () const
	Returns the the z coordinate of the reference point.
double	refCylindricalRSquared () const
	Returns the cylindrical radius of the reference position.
const Vector2D &	refPos2D () const
	Returns the xy vector of the reference position.
const Vector3D &	refPos3D () const
	Returns the reference position.
double	sagCoeff () const
	Returns the wire sag coefficient due to gravity.

Private Attributes
Vector3D	m_refPos3D
	Memory for the reference position.
Vector2D	m_nominalMovePerZ
	Memory for the nominal movement of the xy position per z unit off the reference.
double	m_forwardZ = 0.0
	Memory for the forward end z coordinate.
double	m_backwardZ = 0.0
	Memory for the backward end z coordinate.
double	m_sagCoeff = 0.0
	Memory for the wire sag coefficient.

Detailed Description

A three dimensional limited line represented by its closest approach to the z-axes (reference position ) and its skew parameter.

The representation is only suitable for lines out of the xy plane. The endpoints are stored encoded by their z position. The end point with the higher z value is called forward, the one with the smaller is called backward. This class is mainly used to describe the cdc wires with as few parameters as possible and simplifies the retrieval of the two dimensional track reference position, which is taken at the closest approach to the beam z-axes.

A three dimensional limited line

Definition at line 31 of file WireLine.h.

Constructor & Destructor Documentation

WireLine() [1/2]

WireLine ( )

inline

Default constructor initialising to all members to zero.

Definition at line 35 of file WireLine.h.

      {}

WireLine() [2/2]

WireLine	(	const Vector3D &	forward,
		const Vector3D &	backward,
		double	sagCoeff
	)

Constructor for a wire line between forward and backward point.

Definition at line 15 of file WireLine.cc.

  : m_refPos3D{(backward * forward.z() - forward * backward.z()) / (forward.z() - backward.z()) }
  , m_nominalMovePerZ{(forward.xy() - backward.xy()) / (forward.z() - backward.z())}
  , m_forwardZ{forward.z()}
  , m_backwardZ{backward.z()}
  , m_sagCoeff(sagCoeff)
{
  B2ASSERT("Wire reference position is not at 0", m_refPos3D.z() == 0);
}

Member Function Documentation

backward2D()

Vector2D backward2D ( ) const

inline

Gives the xy position of the backward point.

Definition at line 122 of file WireLine.h.

      { return nominalPos2DAtZ(backwardZ()); }

backward3D()

Vector3D backward3D ( ) const

inline

Gives the position of the backward point.

Definition at line 118 of file WireLine.h.

      { return nominalPos3DAtZ(backwardZ()); }

backwardCylindricalR()

double backwardCylindricalR ( ) const

inline

Gives the cylindrical radius of the backward position.

Definition at line 158 of file WireLine.h.

      { return backward2D().cylindricalR(); }

backwardPhi()

double backwardPhi ( ) const

inline

Gives the backward azimuth angle.

Definition at line 150 of file WireLine.h.

      { return backward2D().phi(); }

backwardPhiToRef()

double backwardPhiToRef ( ) const

inline

Gives the azimuth angle of the backward position relative to the reference position.

Definition at line 166 of file WireLine.h.

      { return backward2D().angleWith(refPos2D()); }

backwardToForwardAngle()

double backwardToForwardAngle ( ) const

inline

Gives the azimuth angle difference from backward to forward position.

Definition at line 172 of file WireLine.h.

      { return backward2D().angleWith(forward2D()) ; }

backwardZ()

double backwardZ ( ) const

inline

Gives the backward z coordinate.

Definition at line 134 of file WireLine.h.

      { return m_backwardZ; }

deltaZ()

double deltaZ ( ) const

inline

Returns the difference between forward and backward z.

Definition at line 138 of file WireLine.h.

      { return forwardZ() - backwardZ(); }

forward2D()

Vector2D forward2D ( ) const

inline

Gives the xy position of the forward point.

Definition at line 114 of file WireLine.h.

      { return nominalPos2DAtZ(forwardZ()); }

forward3D()

Vector3D forward3D ( ) const

inline

Gives the position of the forward point.

Definition at line 110 of file WireLine.h.

      { return nominalPos3DAtZ(forwardZ()); }

forwardCylindricalR()

double forwardCylindricalR ( ) const

inline

Gives the cylindrical radius of the forward position.

Definition at line 154 of file WireLine.h.

      { return forward2D().cylindricalR(); }

forwardPhi()

double forwardPhi ( ) const

inline

Gives the forward azimuth angle.

Definition at line 146 of file WireLine.h.

      { return forward2D().phi(); }

forwardPhiToRef()

double forwardPhiToRef ( ) const

inline

Gives the azimuth angle of the forward position relative to the reference position.

Definition at line 162 of file WireLine.h.

      { return forward2D().angleWith(refPos2D()); }

forwardZ()

double forwardZ ( ) const

inline

Gives the forward z coordinate.

Definition at line 130 of file WireLine.h.

      { return m_forwardZ; }

lambda()

double lambda ( ) const

inline

Returns the nominal lambda angle of the line.

Definition at line 180 of file WireLine.h.

      { return std::atan(tanLambda()); }

movedBy() [1/2]

WireLine movedBy

(

const Vector2D &

offset

)

const

Returns a copy of the wire line moved by a two dimensional offset.

Definition at line 36 of file WireLine.cc.

{
  WireLine moved = *this;
  moved.m_refPos3D += offset;
  return moved;
}

movedBy() [2/2]

WireLine movedBy

(

const Vector3D &

offset

)

const

Returns a copy of the wire line moved by a three dimensional offset.

Definition at line 27 of file WireLine.cc.

{
  WireLine moved = *this;
  moved.m_refPos3D += offset.xy() + nominalMovePerZ() * offset.z();
  moved.m_forwardZ += offset.z();
  moved.m_backwardZ += offset.z();
  return moved;
}

nominalClosest3D()

Vector3D nominalClosest3D ( const Vector3D &  point ) const

inline

Returns the closest approach on the wire without wire sag effect to the give point.

Definition at line 98 of file WireLine.h.

      { return  refPos3D() - (point - refPos3D()).parallelVector(Vector3D(nominalMovePerZ(), 1)); }

nominalDistance()

double nominalDistance ( const Vector3D &  pos3D ) const

inline

Calculates the distance of the given point to the wire without wire sag effect.

Definition at line 86 of file WireLine.h.

      { return (pos3D - refPos3D()).orthogonalComp(Vector3D(nominalMovePerZ(), 1)); }

nominalMovePerZ()

const Vector2D & nominalMovePerZ ( ) const

inline

Gives the positional move in the xy projection per unit z.

Definition at line 71 of file WireLine.h.

      { return m_nominalMovePerZ; }

nominalPerigee2D()

Vector2D nominalPerigee2D ( ) const

inline

Returns the point of nominal closest approach to the z axes.

Definition at line 203 of file WireLine.h.

      { return refPos2D().orthogonalVector(nominalMovePerZ()); }

nominalPerigee3D()

Vector3D nominalPerigee3D ( ) const

inline

Returns the point of nominal closest approach to the z axes.

Definition at line 199 of file WireLine.h.

      { return nominalPos3DAtZ(nominalPerigeeZ()); }

nominalPerigeeZ()

double nominalPerigeeZ ( ) const

inline

Returns the z coordinate of the point of nominal closest approach to the z axes.

Definition at line 195 of file WireLine.h.

      { return -refPos2D().dot(nominalMovePerZ()) / nominalMovePerZ().normSquared(); }

nominalPos2DAtZ()

Vector2D nominalPos2DAtZ ( const double  z ) const

inline

Gives the two dimensional position without wire sag effect of the line at the given z value.

Definition at line 52 of file WireLine.h.

      { return refPos2D() + nominalMovePerZ() * z; }

nominalPos3DAtZ()

Vector3D nominalPos3DAtZ ( const double  z ) const

inline

Gives the three dimensional position without wire sag effect of the line at the given z value.

Definition at line 48 of file WireLine.h.

      { return Vector3D(nominalPos2DAtZ(z), z); }

outOfZBoundsFactor()

double outOfZBoundsFactor ( double  z ) const

inline

Returns the amount how much the given z position is outside the bounds in units of the wire length.

Definition at line 142 of file WireLine.h.

      { return std::fmax(backwardZ() - z, z - forwardZ()) / deltaZ(); }

refCylindricalRSquared()

double refCylindricalRSquared ( ) const

inline

Returns the cylindrical radius of the reference position.

Definition at line 219 of file WireLine.h.

      { return m_refPos3D.cylindricalRSquared(); }

refPos2D()

const Vector2D & refPos2D ( ) const

inline

Returns the xy vector of the reference position.

Definition at line 223 of file WireLine.h.

      { return m_refPos3D.xy(); }

refPos3D()

const Vector3D & refPos3D ( ) const

inline

Returns the reference position.

Definition at line 227 of file WireLine.h.

      { return m_refPos3D; }

refX()

double refX ( ) const

inline

Returns the the x coordinate of the reference point.

Definition at line 207 of file WireLine.h.

      { return m_refPos3D.x(); }

refY()

double refY ( ) const

inline

Returns the the y coordinate of the reference point.

Definition at line 211 of file WireLine.h.

      { return m_refPos3D.y(); }

refZ()

double refZ ( ) const

inline

Returns the the z coordinate of the reference point.

Definition at line 215 of file WireLine.h.

      { return m_refPos3D.z(); }

sagClosest3D()

Vector3D sagClosest3D ( const Vector3D &  point ) const

inline

Returns the closest approach on the wire with wire sag effect to the give point.

Definition at line 102 of file WireLine.h.

      {
        Vector3D wirePos3D = sagPos3DAtZ(point.z());
        Vector3D movePerZ(sagMovePerZ(point.z()), 1);
        return  wirePos3D - (point - wirePos3D).parallelVector(movePerZ);
      }

sagCoeff()

double sagCoeff ( ) const

inline

Returns the wire sag coefficient due to gravity.

Definition at line 231 of file WireLine.h.

      { return m_sagCoeff; }

sagDistance()

double sagDistance ( const Vector3D &  pos3D ) const

inline

Calculates the distance of the given point to the wire with wire sag effect.

Definition at line 90 of file WireLine.h.

      {
        Vector3D wirePos3D = sagPos3DAtZ(pos3D.z());
        Vector3D movePerZ(sagMovePerZ(pos3D.z()), 1);
        return (pos3D - wirePos3D).orthogonalComp(movePerZ);
      }

sagMovePerZ()

Vector2D sagMovePerZ ( const double  z ) const

inline

Gives the two dimensional position with wire sag effect of the line at the given z value.

Efficient version without divisions

Definition at line 75 of file WireLine.h.

      {
        Vector2D movePerZ = nominalMovePerZ();
        double xzFactorSquared = 1 + nominalMovePerZ().x() * nominalMovePerZ().x();
        double sagDYDZ = - sagCoeff() * xzFactorSquared * (forwardZ() + backwardZ() - 2 * z);
        movePerZ.setY(movePerZ.y() + sagDYDZ);
        return movePerZ;
      }

sagPos2DAtZ()

Vector2D sagPos2DAtZ ( const double  z ) const

inline

Gives the two dimensional position with wire sag effect of the line at the given z value.

Efficient version without divisions

Definition at line 60 of file WireLine.h.

      {
        Vector2D pos2D = nominalPos2DAtZ(z);
        double xzFactorSquared = 1 + nominalMovePerZ().x() * nominalMovePerZ().x();
        double sagY = - sagCoeff() * xzFactorSquared * (forwardZ() - z) * (z - backwardZ());
        pos2D.setY(pos2D.y() + sagY);
        return pos2D;
      }

sagPos3DAtZ()

Vector3D sagPos3DAtZ ( const double  z ) const

inline

Gives the three dimensional position with wire sag effect of the line at the given z value.

Definition at line 56 of file WireLine.h.

      { return Vector3D(sagPos2DAtZ(z), z); }

tanLambda()

double tanLambda ( ) const

inline

Returns the nominal tan lambda of the line. Also know as dz / ds.

Definition at line 176 of file WireLine.h.

      { return 1 / nominalMovePerZ().norm(); }

tanTheta()

double tanTheta ( ) const

inline

Returns the tangent of the opening angle between tangential vector and the z axes Also know as ds / dz.

Definition at line 187 of file WireLine.h.

      { return std::atan(nominalMovePerZ().norm()); }

theta()

double theta ( ) const

inline

Returns the nominal opening angle between tangential vector and the z axes.

Definition at line 191 of file WireLine.h.

      { return std::atan(nominalMovePerZ().norm()); }

wireVector()

Vector3D wireVector ( ) const

inline

Getter for the vector from backward to the forward position.

Definition at line 126 of file WireLine.h.

      { return Vector3D(nominalMovePerZ() * deltaZ(), deltaZ()); }

Member Data Documentation

m_backwardZ

double m_backwardZ = 0.0

private

Memory for the backward end z coordinate.

Definition at line 245 of file WireLine.h.

m_forwardZ

double m_forwardZ = 0.0

private

Memory for the forward end z coordinate.

Definition at line 242 of file WireLine.h.

m_nominalMovePerZ

Vector2D m_nominalMovePerZ

private

Memory for the nominal movement of the xy position per z unit off the reference.

Definition at line 239 of file WireLine.h.

m_refPos3D

Vector3D m_refPos3D

private

Memory for the reference position.

Definition at line 236 of file WireLine.h.

m_sagCoeff

double m_sagCoeff = 0.0

private

Memory for the wire sag coefficient.

Definition at line 248 of file WireLine.h.

---

The documentation for this class was generated from the following files:

• tracking/trackFindingCDC/topology/include/WireLine.h
• tracking/trackFindingCDC/topology/src/WireLine.cc