recob::Trajectory Class Reference

A trajectory in space reconstructed from hits. More...

#include "Trajectory.h"

Inheritance diagram for recob::Trajectory:

Public Types
enum	Ends_t { kStart, kVertex = kStart, kEnd, NEnds }
	Mnemonics for the access to begin and end of trajectory. More...
using	Coord_t = tracking::Coord_t
	Type used for coordinates and values in general. More...
using	Point_t = tracking::Point_t
	Type for representation of position in physical 3D space. More...
using	Vector_t = tracking::Vector_t
	Type for representation of momenta in 3D space. More...
using	Positions_t = tracking::Positions_t
	Type of trajectory point list. More...
using	Momenta_t = tracking::Momenta_t
	Type of momentum list. More...
using	TrajectoryPoint_t = tracking::TrajectoryPoint_t
	A point in the trajectory, with position and momentum. More...
using	Rotation_t = tracking::Rotation_t
	Type for representation of space rotations. More...

Public Member Functions
	Trajectory ()=default
	Default constructor; do not use it! it's needed by ROOT I/O. More...
	Trajectory (Positions_t &&positions, Momenta_t &&momenta, bool hasMomenta)
	Constructor: specifies all the data for the trajectory. More...
	Trajectory (Positions_t const &positions, Momenta_t const &momenta, bool hasMomenta)
	Constructor: copies positions and momenta. More...
template<typename Stream >
void	Dump (Stream &&out, unsigned int verbosity, std::string indent, std::string indentFirst) const
	Prints trajectory content into a stream. More...
template<typename Stream >
void	Dump (Stream &&out, unsigned int verbosity=1, std::string indent={}) const
	Prints trajectory content into a stream. More...
template<typename Stream >
void	LowLevelDump (Stream &&out, std::string indent, std::string indentFirst) const
	Prints low-level trajectory content into a stream. More...
Access to trajectory information
size_t	NumberTrajectoryPoints () const
	Returns the number of stored trajectory points. More...
size_t	NPoints () const
	Returns the number of stored trajectory points. More...
size_t	FirstPoint () const
	Returns the index of the first point in the trajectory (yep, it's 0). More...
size_t	LastPoint () const
	Returns the index of the last point in the trajectory. More...
bool	HasPoint (size_t i) const
	Returns whether the specified trajectory point is available. More...
const Positions_t &	Positions () const
	Returns reference to stored vector of positions. More...
const Momenta_t &	Momenta () const
	Returns reference to stored vector of momenta. More...
TrajectoryPoint_t	TrajectoryPoint (size_t i) const
	Returns position and momentum at the specified trajectory point. More...
Point_t const &	Vertex () const
	Returns the position of the first point of the trajectory [cm]. More...
Point_t const &	Start () const
	Returns the position of the first point of the trajectory [cm]. More...
Point_t const &	End () const
	Returns the position of the last point of the trajectory [cm]. More...
Point_t const &	LocationAtPoint (size_t i) const
	Returns the position at the specified trajectory point. More...
template<typename T >
std::pair< T, T >	Extent () const
	Fills the first and last point in the trajectory. More...
std::pair< Point_t, Point_t >	Extent () const
	Returns a copy of the first and last point in the trajectory. More...
double	Length (size_t startAt=0) const
	Returns the approximate length of the trajectory. More...
Access to direction and momentum information
Vector_t	VertexDirection () const
	Returns the direction of the trajectory at the first point. More...
Vector_t	StartDirection () const
	Returns the direction of the trajectory at the first point. More...
Vector_t	EndDirection () const
	Returns the direction of the trajectory at the last point. More...
double	Theta (size_t p=0) const
	Trajectory angle at point, with respect to positive z direction. More...
double	Phi (size_t p=0) const
	Azimuthal angle at a point on the trajectory, with respect to z. More...
double	ZenithAngle (size_t p=0) const
	"Zenith" angle of trajectory, with respect to the vertical axis. More...
double	AzimuthAngle (size_t p=0) const
	"Azimuth" angle of trajectory, with respect to the sky. More...
Vector_t const &	VertexMomentumVector () const
	Returns the momentum of the trajectory at the first point [GeV/c]. More...
Vector_t const &	StartMomentumVector () const
	Returns the momentum of the trajectory at the first point [GeV/c]. More...
Vector_t const &	EndMomentumVector () const
	Returns the momentum of the trajectory at the last point [GeV/c]. More...
double	VertexMomentum () const
	Computes and returns the modulus of momentum at the first point [GeV/c]. More...
double	StartMomentum () const
	Computes and returns the modulus of momentum at the first point [GeV/c]. More...
double	EndMomentum () const
	Computes and returns the modulus of momentum at the last point [GeV/c]. More...
Vector_t	DirectionAtPoint (size_t i) const
	Computes and returns the direction of the trajectory at a point. More...
bool	HasMomentum () const
	Returns whether information about the momentum is available. More...
double	MomentumAtPoint (size_t i) const
	Computes and returns the modulus of the momentum at a point. More...
Vector_t const &	MomentumVectorAtPoint (size_t i) const
	Returns the momentum vector at a point. More...
template<typename T >
std::pair< T, T >	Direction () const
	Fills the starting and ending direction of the trajectory. More...
std::pair< Vector_t, Vector_t >	Direction () const
	Returns the trajectory directions at first and last point. More...
Rotation_t	GlobalToLocalRotationAtPoint (size_t p) const
	Returns a rotation matrix that brings trajectory direction along z. More...
Rotation_t	LocalToGlobalRotationAtPoint (size_t p) const
	Returns a rotation matrix bringing relative directions to global. More...
Templated version of homonymous functions to access to position, direction, and momentum information.
template<typename T >
T	Start () const
	Start position. Use e.g. as: More...
template<typename T >
T	Vertex () const
	Start position. Use e.g. as: More...
template<typename T >
T	End () const
	End position. Use e.g. as: More...
template<typename T >
T	LocationAtPoint (unsigned int p) const
	Position at point p. Use e.g. as: More...
template<typename T >
T	StartDirection () const
	Start direction. Use e.g. as: More...
template<typename T >
T	VertexDirection () const
	Start direction. Use e.g. as: More...
template<typename T >
T	EndDirection () const
	End direction. Use e.g. as: More...
template<typename T >
T	DirectionAtPoint (unsigned int p) const
	Direction at point p. Use e.g. as: More...
template<typename T >
T	StartMomentumVector () const
	Momentum vector at start point. Use e.g. as: More...
template<typename T >
T	VertexMomentumVector () const
	Momentum vector at start point. Use e.g. as: More...
template<typename T >
T	EndMomentumVector () const
	Momentum vector at end point. Use e.g. as: More...
template<typename T >
T	MomentumVectorAtPoint (unsigned int p) const
	Momentum vector at point p. Use e.g. as: More...
template<typename T >
T	GlobalToLocalRotationAtPoint (unsigned int p) const
	Returns a rotation matrix that brings trajectory direction along z. Use e.g. as: More...
template<typename T >
T	LocalToGlobalRotationAtPoint (unsigned int p) const
	Returns a rotation matrix bringing relative directions to global. Use e.g. as: More...

Static Public Attributes
static constexpr unsigned int	MaxDumpVerbosity = 6
	Largest verbosity level supported by Dump(). More...

Private Attributes
Positions_t	fPositions
	List of points the trajectory goes through. More...
Momenta_t	fMomenta
	Momentum of each of the points in trajectory. More...
bool	fHasMomentum = true
	Whether we have momentum modulus information. More...

Detailed Description

A trajectory in space reconstructed from hits.

---

See also

recob::Track, recob::trackutil::makeTrajectory()

The trajectory class contains a trajectory in 6D space representing the path walked by a particle. A trajectory point is made of a 3D position component (measured in centimeters) and a momentum component (measured in GeV/c); for a discussion on the object type for coordinates see: recob::tracking::Coord_t.

The object contains information about the trajectory, and no uncertainty, as that is considered a fit result (see recob::Track). By convention the first point is considered "start" (or "vertex") and the last point "end", although this assignment can be arbitrary and should not be relied upon for physics decisions.

The momentum content is in part optional: the trajectory creating algorithm may decide not to provide information about the modulus of the momentum. In that case, Trajectory::HasMomentum() will return false and every attempt to access the momentum vector will yield only the trajectory direction.

Invariants

• there must be at least two trajectory points;
• there must be one momentum per position; recob::trackutil::makeTrajectory() can make up a simple momentum vector from the trajectory, for algorithms reconstructing the trajectory which do not estimate momenta; Trajectory::HasMomentum() reports whether momentum modulus information is available;
• a list of hits associated with the trajectory is considered a mandatory part of the trajectory information; see recob::TrajectoryCollectionMaker.

Definition at line 66 of file Trajectory.h.

Member Typedef Documentation

using recob::Trajectory::Coord_t = tracking::Coord_t

Type used for coordinates and values in general.

Definition at line 69 of file Trajectory.h.

using recob::Trajectory::Momenta_t = tracking::Momenta_t

Type of momentum list.

Definition at line 81 of file Trajectory.h.

using recob::Trajectory::Point_t = tracking::Point_t

Type for representation of position in physical 3D space.

Definition at line 72 of file Trajectory.h.

using recob::Trajectory::Positions_t = tracking::Positions_t

Type of trajectory point list.

Definition at line 78 of file Trajectory.h.

using recob::Trajectory::Rotation_t = tracking::Rotation_t

Type for representation of space rotations.

Definition at line 95 of file Trajectory.h.

using recob::Trajectory::TrajectoryPoint_t = tracking::TrajectoryPoint_t

A point in the trajectory, with position and momentum.

Definition at line 92 of file Trajectory.h.

using recob::Trajectory::Vector_t = tracking::Vector_t

Type for representation of momenta in 3D space.

Definition at line 75 of file Trajectory.h.

Member Enumeration Documentation

enum recob::Trajectory::Ends_t

Mnemonics for the access to begin and end of trajectory.

Enumerator
kStart	Index representing the start of the trajectory.
kVertex	Index representing the start of the trajectory.
kEnd	Index representing the end of the trajectory.
NEnds	Number of ends.

Definition at line 84 of file Trajectory.h.

                {
      kStart,           
      kVertex = kStart, 
      kEnd,             
      NEnds             
    };                  // enum Ends_t

Constructor & Destructor Documentation

recob::Trajectory::Trajectory ( )

default

Default constructor; do not use it! it's needed by ROOT I/O.

recob::Trajectory::Trajectory	(	Positions_t &&	positions,
		Momenta_t &&	momenta,
		bool	hasMomenta
	)

Constructor: specifies all the data for the trajectory.

Parameters

positions	(moved) trajectory as a sorted list of points
momenta	(moved) momentum along the trajectory, one per point
hasMomenta	whether the information on momentum modulus is provided

Exceptions

std::runtime_error

if the invariants are violated

See also

recob::trackutil::makeTrajectory()

The most convenient way to create a recob::Trajectory is to use recob::trackutil::makeTrajectory().

Requirements

• one momentum is required for each trajectory point
• at least two points must be provided

Definition at line 21 of file Trajectory.cxx.

References fMomenta, fPositions, and util::to_string().

  : fPositions(std::move(positions)), fMomenta(std::move(momenta)), fHasMomentum(hasMomenta)
{
  // invariant check
  if (fPositions.size() != fMomenta.size()) {
    throw std::runtime_error("recob::Trajectory constructed with " +
                             std::to_string(fPositions.size()) + " positions and " +
                             std::to_string(fMomenta.size()) +
                             " momenta! it requires the same number for both.");
  }
  if (fPositions.size() < 2) {
    throw std::runtime_error("recob::Trajectory constructed with " +
                             std::to_string(fPositions.size()) +
                             " trajectory points! it requires at least 2.");
  }
} // recob::Trajectory::Trajectory()

recob::Trajectory::Trajectory ( Positions_t const &  positions, Momenta_t const &  momenta, bool  hasMomenta  )

inline

Constructor: copies positions and momenta.

Parameters

positions	trajectory as a sorted list of points
momenta	momentum along the trajectory, one per point
hasMomenta	whether the information on momentum modulus is provided

Exceptions

std::runtime_error

if the invariants are violated

Definition at line 128 of file Trajectory.h.

      : Trajectory(Positions_t(positions), Momenta_t(momenta), hasMomenta)
    {}

Member Function Documentation

double recob::Trajectory::AzimuthAngle

(

size_t

p = 0

)

const

"Azimuth" angle of trajectory, with respect to the sky.

Parameters

p	the point index to extract the angle from (default: start)

Returns

the azimuth angle, in [radians]

See also

ZenithAngle()

The angle is defined on the plane orthogonal to the y direction. It describes the angle of the trajectory at the specified point. The angle is measured starting from the positive z direction, counterclockwise. Therefore, a trajectory start lying on the demiplane of y axis and positive z axis returns 0 radians, while one lying on the demiplane of y axis and positive x axis returns radians.

If the point number is invalid, the behaviour is undefined.

Definition at line 88 of file Trajectory.cxx.

References DirectionAtPoint().

Referenced by recob::TrackTrajectory::AzimuthAngle(), and Phi().

{
  //
  // std::atan2(y, x) returns the angle of a point (x,y) respect to x axis.
  // In our case, the definition of the angle (0 for z axis, pi/2 for x axis)
  // translates atan2's y into our x, and x into z.
  //
  decltype(auto) startDir = DirectionAtPoint(p);
  return std::atan2(startDir.X(), startDir.Z());
} // recob::Trajectory::AzimuthAngle()

template<typename T >

std::pair<T, T> recob::Trajectory::Direction ( ) const

inline

Fills the starting and ending direction of the trajectory.

Parameters

start	(output) direction at the beginning of the trajectory
end	(output) direction at the end of the trajectory

The two arguments are expected to point each one to an area with room for at least three double numbers. The two filled vectors have norm 1.

The labelling of start and end is consistent within the trajectory but is not guaranteed to be physically correct.

Definition at line 431 of file Trajectory.h.

    {
      return {VertexDirection<T>(), EndDirection<T>()};
    }

std::pair<Vector_t, Vector_t> recob::Trajectory::Direction ( ) const

inline

Returns the trajectory directions at first and last point.

Returns

a pair with the first and last direction

The two returned vectors have norm 1. The labelling of start and end is consistent within the trajectory but is not guaranteed to be physically correct.

Example:

recob::Trajectory::Vector_t startDir, endDir;

std::tie(startDir, endDir) = traj.Direction(); // assign start and end

Definition at line 453 of file Trajectory.h.

References EndDirection(), GlobalToLocalRotationAtPoint(), LocalToGlobalRotationAtPoint(), and StartDirection().

{ return {StartDirection(), EndDirection()}; }

recob::Trajectory::Vector_t recob::Trajectory::DirectionAtPoint

(

size_t

i

)

const

Computes and returns the direction of the trajectory at a point.

Parameters

i	index of the point in the trajectory

Returns

the direction at that point

The direction is computed as unit vector parallel to the momentum at that trajectory point. If the index is not contained in the trajectory, the result is undefined.

Definition at line 109 of file Trajectory.cxx.

References HasMomentum(), and MomentumVectorAtPoint().

Referenced by AzimuthAngle(), DirectionAtPoint(), EndDirection(), EndMomentum(), recob::TrackTrajectory::EndMomentum(), GlobalToLocalRotationAtPoint(), LocalToGlobalRotationAtPoint(), trkf::KalmanFilterFinalTrackFitter::restoreInputPoints(), StartDirection(), and ZenithAngle().

{

  auto const& mom = MomentumVectorAtPoint(i);
  return HasMomentum() ? (mom / mom.R()) : mom;

} // recob::Trajectory::DirectionAtPoint()

template<typename T >

T recob::Trajectory::DirectionAtPoint ( unsigned int  p ) const

inline

Direction at point p. Use e.g. as:

TVector3 dir = traj.DirectionAtPoint<TVector3>(p); 

.

Definition at line 558 of file Trajectory.h.

References dir, and DirectionAtPoint().

    {
      auto dir = DirectionAtPoint(p);
      return T(dir.X(), dir.Y(), dir.Z());
    }

template<typename Stream >

void recob::Trajectory::Dump	(	Stream &&	out,
		unsigned int	verbosity,
		std::string	indent,
		std::string	indentFirst
	)		const

Prints trajectory content into a stream.

Template Parameters

Stream

type of the output stream

Parameters

out	stream to output the information into
verbosity	verbosity level (default: 1)
indent	indentation string (default: none)
indentFirst	indentation for first output line (default: as indent)

The amount of information dumped to screen is regulated by the Indentation string is prepended to each line, and the first line has its own special indentation string (indentFirst).

The output can be multi-line, it ends with no end-of-line and it does not inserts an end-of-line at its beginning (unless that is explicitly inside indentFirst). The lowest verbosity is guaranteed to be on a single line.

Information printed out (verbosity argument)

• level 0: start position, direction, momentum modulus and number of points
• level 1: also end position, direction and momentum modulus
• level 2: also trajectory length
• level 3: also angles at start
• level 4: also 9 intermediate trajectory points
• level 5: also 10 more intermediate trajectory points (19 total)
• level 6: all trajectory points

Referenced by lar::example::CheatTrack::dump(), Dump(), LocalToGlobalRotationAtPoint(), and recob::operator<<().

template<typename Stream >

void recob::Trajectory::Dump ( Stream &&  out, unsigned int  verbosity = 1, std::string  indent = {}  ) const

inline

Prints trajectory content into a stream.

Template Parameters

Stream

type of the output stream

Parameters

out	stream to output the information into
verbosity	verbosity level (default: 1)
indent	indentation string (default: none)

See also

Dump(Stream&&, unsigned int, std::string, std::string)

Implementation detail for Dump(Stream&&, unsigned int, std::string).

Definition at line 665 of file Trajectory.h.

References Dump(), and LowLevelDump().

                                                                           {}) const
    {
      Dump(std::forward<Stream>(out), verbosity, indent, indent);
    }

Point_t const& recob::Trajectory::End ( ) const

inline

Returns the position of the last point of the trajectory [cm].

Definition at line 207 of file Trajectory.h.

References LastPoint(), and LocationAtPoint().

Referenced by End(), Extent(), and Length().

{ return LocationAtPoint(LastPoint()); }

template<typename T >

T recob::Trajectory::End ( ) const

inline

End position. Use e.g. as:

TVector3 end = traj.End<TVector3>(); 

.

Definition at line 518 of file Trajectory.h.

References End().

    {
      auto& loc = End();
      return T(loc.X(), loc.Y(), loc.Z());
    }

Vector_t recob::Trajectory::EndDirection ( ) const

inline

Returns the direction of the trajectory at the last point.

Definition at line 280 of file Trajectory.h.

References DirectionAtPoint(), and LastPoint().

Referenced by Direction(), and EndDirection().

{ return DirectionAtPoint(LastPoint()); }

template<typename T >

T recob::Trajectory::EndDirection ( ) const

inline

End direction. Use e.g. as:

TVector3 enddir = traj.EndDirection<TVector3>(); 

.

Definition at line 550 of file Trajectory.h.

References dir, and EndDirection().

    {
      auto dir = EndDirection();
      return T(dir.X(), dir.Y(), dir.Z());
    }

double recob::Trajectory::EndMomentum ( ) const

inline

Computes and returns the modulus of momentum at the last point [GeV/c].

Definition at line 366 of file Trajectory.h.

References DirectionAtPoint(), and EndMomentumVector().

{ return EndMomentumVector().R(); }

Vector_t const& recob::Trajectory::EndMomentumVector ( ) const

inline

Returns the momentum of the trajectory at the last point [GeV/c].

Definition at line 357 of file Trajectory.h.

References LastPoint(), and MomentumVectorAtPoint().

Referenced by EndMomentum(), and EndMomentumVector().

{ return MomentumVectorAtPoint(LastPoint()); }

template<typename T >

T recob::Trajectory::EndMomentumVector ( ) const

inline

Momentum vector at end point. Use e.g. as:

TVector3 endmom = traj.EndMomentumVector<TVector3>(); 

.

Definition at line 582 of file Trajectory.h.

References EndMomentumVector().

    {
      auto mom = EndMomentumVector();
      return T(mom.X(), mom.Y(), mom.Z());
    }

template<typename T >

std::pair<T, T> recob::Trajectory::Extent ( ) const

inline

Fills the first and last point in the trajectory.

Parameters

start	(output) position of the beginning of the trajectory
end	(output) position of the end of the trajectory

The labelling of start and end is consistent within the trajectory but is not guaranteed to be physically correct.

Definition at line 227 of file Trajectory.h.

    {
      return {Vertex<T>(), End<T>()};
    }

std::pair<Point_t, Point_t> recob::Trajectory::Extent ( ) const

inline

Returns a copy of the first and last point in the trajectory.

Returns

a pair: the first and last point in the trajectory

The labelling of start and end is consistent within the trajectory but is not guaranteed to be physically correct.

Example:

recob::Trajectory::Point_t start, end;

std::tie(start, end) = traj.Extent(); // assign both start and end

Definition at line 248 of file Trajectory.h.

References End(), Length(), and Start().

{ return {Start(), End()}; }

size_t recob::Trajectory::FirstPoint ( ) const

inline

Returns the index of the first point in the trajectory (yep, it's 0).

Definition at line 156 of file Trajectory.h.

Referenced by recob::Track::FirstPoint(), Start(), StartDirection(), StartMomentumVector(), and recob::TrackTrajectory::Trajectory().

{ return 0U; }

recob::Trajectory::Rotation_t recob::Trajectory::GlobalToLocalRotationAtPoint

(

size_t

p

)

const

Returns a rotation matrix that brings trajectory direction along z.

Parameters

p	index of the trajectory point where to apply the rotation

Returns

a rotation matrix suitable to point the trajectory along z

The returned rotation matrix, applied to the direction vector of the trajectory at point p, will make that direction point toward the positive z axis direction, in a sort of "first person view" of the trajectory at that point. If p does not denote a valid trajectory point, the result is undefined.

The return value can be used on a Vector_t to rotate it. For example:

auto rot = traj.GlobalToLocalRotationAtPoint(0);
auto local = rot * traj.DirectionAtPoint(0);

local will be a Vector_t object (like the direction at the right side of the product) that points to (0, 0, 1).

While the transformation that yields the rotation matrix is continuous, the direction of the new "local" x and y axes is not defined.

Definition at line 118 of file Trajectory.cxx.

References DirectionAtPoint(), and recob::tracking::Plane::Global3DToLocal3DRotation().

Referenced by Direction(), recob::TrackTrajectory::Direction(), and GlobalToLocalRotationAtPoint().

{
  return recob::tracking::Plane::Global3DToLocal3DRotation(DirectionAtPoint(p));
} // recob::Trajectory::GlobalToLocalRotationAtPoint()

template<typename T >

T recob::Trajectory::GlobalToLocalRotationAtPoint ( unsigned int  p ) const

inline

Returns a rotation matrix that brings trajectory direction along z. Use e.g. as:

TMatrixD rot = traj.GlobalToLocalRotationAtPoint<TMatrixD>(p); 

.

Definition at line 598 of file Trajectory.h.

References GlobalToLocalRotationAtPoint().

    {
      T rot(3, 3);
      GlobalToLocalRotationAtPoint(p).GetRotationMatrix(rot);
      return rot;
    }

bool recob::Trajectory::HasMomentum ( ) const

inline

Returns whether information about the momentum is available.

Returns

whether information about the momentum is available

The trajectory may or may not store valid momentum information. If not, the methods returning momentum information will stick to a modulus 1 GeV/c and the momentum numerically matches the direction.

Definition at line 387 of file Trajectory.h.

References fHasMomentum.

Referenced by recob::Track::DirectionAtPoint(), DirectionAtPoint(), recob::TrackTrajectory::EndMomentum(), and trkmkr::KalmanFilterFitTrackMaker::restoreInputPoints().

{ return fHasMomentum; }

bool recob::Trajectory::HasPoint ( size_t  i ) const

inline

Returns whether the specified trajectory point is available.

Parameters

i	index of the trajectory point

Returns

whether the specified trajectory point is available.

Definition at line 166 of file Trajectory.h.

References NPoints().

Referenced by recob::Track::HasPoint(), recob::TrackTrajectory::HasValidPoint(), and recob::TrackTrajectory::Trajectory().

{ return i < NPoints(); }

size_t recob::Trajectory::LastPoint ( ) const

inline

Returns the index of the last point in the trajectory.

Definition at line 159 of file Trajectory.h.

References NPoints().

Referenced by End(), EndDirection(), EndMomentumVector(), recob::Track::LastPoint(), recob::TrackTrajectory::LastValidPoint(), Length(), recob::TrackTrajectory::Length(), and recob::TrackTrajectory::Trajectory().

{ return NPoints() - 1; }

double recob::Trajectory::Length

(

size_t

startAt = 0

)

const

Returns the approximate length of the trajectory.

Parameters

startAt

(default: 0, from beginning) point to start from

Returns

the approximate length of the trajectory [cm]

The residual length from the trajectory point startAt to the end of the trajectory is computed and returned. By default, the whole trajectory length is returned. If a non-existing point is specified, 0 is returned.

The length approximation is just the sum of Euclidean distances between all consecutive trajectory points (starting from the one with index startAt).

This operation is slow, and the result should be stored in a variable.

Definition at line 55 of file Trajectory.cxx.

References End(), LastPoint(), and LocationAtPoint().

Referenced by Extent().

{

  // sanity check
  if (startAt >= LastPoint()) return 0.;

  // just sum the distance between all locations in the trajectory
  Point_t const* curr = &(LocationAtPoint(startAt));
  Point_t const* next = curr;
  Point_t const* last = &(End());
  Coord_t length = 0.0;
  while (next++ != last) {
    length += (*next - *curr).R();
    curr = next;
  } // while
  return length;
} // recob::Trajectory::Length()

recob::Trajectory::Rotation_t recob::Trajectory::LocalToGlobalRotationAtPoint

(

size_t

p

)

const

Returns a rotation matrix bringing relative directions to global.

Parameters

p	index of the trajectory point where to apply the rotation

Returns

a rotation matrix suitable to convert directions to global

The returned rotation matrix, applied to the unit vector (0, 0, 1) (local z axis direction), will turn it into the trajectory direction at point p. If p does not denote a valid trajectory point, the result is undefined.

While the transformation that yields the rotation matrix is continuous, the conversion of the directions orthogonal to the local z is not defined.

Definition at line 124 of file Trajectory.cxx.

References DirectionAtPoint(), and recob::tracking::Plane::Local3DToGlobal3DRotation().

Referenced by Direction(), recob::TrackTrajectory::Direction(), and LocalToGlobalRotationAtPoint().

{
  return recob::tracking::Plane::Local3DToGlobal3DRotation(DirectionAtPoint(p));
} // recob::Trajectory::GlobalToLocalRotationAtPoint()

template<typename T >

T recob::Trajectory::LocalToGlobalRotationAtPoint ( unsigned int  p ) const

inline

Returns a rotation matrix bringing relative directions to global. Use e.g. as:

TMatrixD rot = traj.LocalToGlobalRotationAtPoint<TMatrixD>(p); 

.

Definition at line 607 of file Trajectory.h.

References Dump(), art::detail::indent(), and LocalToGlobalRotationAtPoint().

    {
      T rot(3, 3);
      LocalToGlobalRotationAtPoint(p).GetRotationMatrix(rot);
      return rot;
    }

Point_t const& recob::Trajectory::LocationAtPoint ( size_t  i ) const

inline

Returns the position at the specified trajectory point.

Parameters

i	index of the point in the trajectory

Returns

position at the specified trajectory point [cm]

If the point index is invalid, the result is undefined.

Definition at line 216 of file Trajectory.h.

References fPositions.

Referenced by End(), recob::TrackTrajectory::End(), Length(), LocationAtPoint(), trkf::KalmanFilterFinalTrackFitter::restoreInputPoints(), Start(), and TrajectoryPoint().

{ return fPositions[i]; }

template<typename T >

T recob::Trajectory::LocationAtPoint ( unsigned int  p ) const

inline

Position at point p. Use e.g. as:

TVector3 pos = traj.LocationAtPoint<TVector3>(p); 

.

Definition at line 526 of file Trajectory.h.

References LocationAtPoint().

    {
      auto& loc = LocationAtPoint(p);
      return T(loc.X(), loc.Y(), loc.Z());
    }

template<typename Stream >

void recob::Trajectory::LowLevelDump	(	Stream &&	out,
		std::string	indent,
		std::string	indentFirst
	)		const

Prints low-level trajectory content into a stream.

Template Parameters

Stream

type of the output stream

Parameters

out	stream to output the information into
indent	indentation string (default: none)
indentFirst	indentation for first output line (default: as indent)

Referenced by Dump().

const Momenta_t& recob::Trajectory::Momenta ( ) const

inline

Returns reference to stored vector of momenta.

Returns

reference to stored vector of momenta

Definition at line 178 of file Trajectory.h.

References fMomenta.

{ return fMomenta; }

double recob::Trajectory::MomentumAtPoint ( size_t  i ) const

inline

Computes and returns the modulus of the momentum at a point.

Parameters

i	index of the point in the trajectory

Returns

modulus of the momentum at that point [GeV/c]

See also

HasMomentum()

The modulus of the momentum at the specified trajectory point is computed and returned. If the trajectory does not have momentum information, the value 1 GeV/c is always returned. This can be tested trajectory by trajectory by HasMomentum(). If the index is not valid in the trajectory, the result is undefined.

Definition at line 402 of file Trajectory.h.

References MomentumVectorAtPoint().

Referenced by recob::TrackTrajectory::EndMomentum(), and recob::Track::MomentumAtPoint().

{ return MomentumVectorAtPoint(i).R(); }

Vector_t const& recob::Trajectory::MomentumVectorAtPoint ( size_t  i ) const

inline

Returns the momentum vector at a point.

Parameters

i	index of the point in the trajectory

Returns

the momentum at that point [GeV/c]

See also

HasMomentum(), MomentumAtPoint(), DirectionAtPoint()

The momentum at the specified trajectory point is returned. If the trajectory does not have momentum information, the returned value will represent the direction, that is a momentum with modulus 1 GeV/c. This can be tested trajectory by trajectory by HasMomentum(). If the index is not valid in the trajectory, the result is undefined.

Definition at line 416 of file Trajectory.h.

References fMomenta.

Referenced by DirectionAtPoint(), recob::TrackTrajectory::EndMomentum(), EndMomentumVector(), MomentumAtPoint(), MomentumVectorAtPoint(), Phi(), StartMomentumVector(), Theta(), and TrajectoryPoint().

{ return fMomenta[i]; }

template<typename T >

T recob::Trajectory::MomentumVectorAtPoint ( unsigned int  p ) const

inline

Momentum vector at point p. Use e.g. as:

TVector3 mom = traj.MomentumVectorAtPoint<TVector3>(p); 

.

Definition at line 590 of file Trajectory.h.

References MomentumVectorAtPoint().

    {
      auto mom = MomentumVectorAtPoint(p);
      return T(mom.X(), mom.Y(), mom.Z());
    }

size_t recob::Trajectory::NPoints ( ) const

inline

Returns the number of stored trajectory points.

Returns

the number of stored trajectory points

See also

PositionAtPoint(), MomentumVectorAtPoint(), DirectionAtPoint()

For each point, both position and momentum are available.

Definition at line 153 of file Trajectory.h.

References fPositions.

Referenced by recob::TrackTrajectory::AtLeastValidTrajectoryPoints(), recob::TrackTrajectory::CountValidPoints(), trkf::TrajectoryMCSFitter::fitMcs(), HasPoint(), LastPoint(), recob::Track::NPoints(), NumberTrajectoryPoints(), recob::TrackTrajectory::TrackTrajectory(), and recob::TrackTrajectory::Trajectory().

{ return fPositions.size(); }

size_t recob::Trajectory::NumberTrajectoryPoints ( ) const

inline

Returns the number of stored trajectory points.

Returns

the number of stored trajectory points

See also

PositionAtPoint(), MomentumVectorAtPoint(), DirectionAtPoint()

For each point, both position and momentum are available.

Definition at line 143 of file Trajectory.h.

References NPoints().

Referenced by recob::Track::Trajectory(), and recob::TrackTrajectory::Trajectory().

{ return NPoints(); }

double recob::Trajectory::Phi ( size_t  p = 0 ) const

inline

Azimuthal angle at a point on the trajectory, with respect to z.

Parameters

p	the point index to extract the angle from (default: start)

Returns

the azimuthal angle, in [radians]

See also

Theta(), ZenithAngle()

The angle is measured on the plane orthogonal to the z axis, in the same reference where Theta() is measured. The angle is measured counterclockwise from the x axis. Skyward direction is expected to be radians in this system, provided that the standard reference frame with the y axis pointing skyward is chosen.

If the point number is invalid, the behaviour is undefined.

Definition at line 311 of file Trajectory.h.

References AzimuthAngle(), MomentumVectorAtPoint(), and ZenithAngle().

Referenced by recob::TrackTrajectory::Phi().

{ return MomentumVectorAtPoint(p).Phi(); }

const Positions_t& recob::Trajectory::Positions ( ) const

inline

Returns reference to stored vector of positions.

Returns

reference to stored vector of positions

Definition at line 172 of file Trajectory.h.

References fPositions.

{ return fPositions; }

Point_t const& recob::Trajectory::Start ( ) const

inline

Returns the position of the first point of the trajectory [cm].

Definition at line 204 of file Trajectory.h.

References FirstPoint(), and LocationAtPoint().

Referenced by Extent(), Start(), and Vertex().

{ return LocationAtPoint(FirstPoint()); }

template<typename T >

T recob::Trajectory::Start ( ) const

inline

Start position. Use e.g. as:

TVector3 start = traj.Start<TVector3>(); 

.

Definition at line 502 of file Trajectory.h.

References Start().

    {
      auto& loc = Start();
      return T(loc.X(), loc.Y(), loc.Z());
    }

Vector_t recob::Trajectory::StartDirection ( ) const

inline

Returns the direction of the trajectory at the first point.

Definition at line 277 of file Trajectory.h.

References DirectionAtPoint(), and FirstPoint().

Referenced by Direction(), StartDirection(), and VertexDirection().

{ return DirectionAtPoint(FirstPoint()); }

template<typename T >

T recob::Trajectory::StartDirection ( ) const

inline

Start direction. Use e.g. as:

TVector3 startdir = traj.StartDirection<TVector3>(); 

.

Definition at line 534 of file Trajectory.h.

References dir, and StartDirection().

    {
      auto dir = StartDirection();
      return T(dir.X(), dir.Y(), dir.Z());
    }

double recob::Trajectory::StartMomentum ( ) const

inline

Computes and returns the modulus of momentum at the first point [GeV/c].

Definition at line 363 of file Trajectory.h.

References StartMomentumVector().

Referenced by lar::example::CheatTrack::momentum(), and VertexMomentum().

{ return StartMomentumVector().R(); }

Vector_t const& recob::Trajectory::StartMomentumVector ( ) const

inline

Returns the momentum of the trajectory at the first point [GeV/c].

Definition at line 354 of file Trajectory.h.

References FirstPoint(), and MomentumVectorAtPoint().

Referenced by StartMomentum(), StartMomentumVector(), and VertexMomentumVector().

{ return MomentumVectorAtPoint(FirstPoint()); }

template<typename T >

T recob::Trajectory::StartMomentumVector ( ) const

inline

Momentum vector at start point. Use e.g. as:

TVector3 startmom = traj.StartMomentumVector<TVector3>(); 

.

Definition at line 566 of file Trajectory.h.

References StartMomentumVector().

    {
      auto mom = StartMomentumVector();
      return T(mom.X(), mom.Y(), mom.Z());
    }

double recob::Trajectory::Theta ( size_t  p = 0 ) const

inline

Trajectory angle at point, with respect to positive z direction.

Parameters

p	the index point to extract the angle from (default: start)

Returns

angle with respect to positive z, in [radians]

The reference direction is the positive z axis. Although this usually matches the beam direction, this is not guaranteed and if the explicit angle from beam direction is needed, the scalar product of the beam direction and the direction from StartDirection() should be used instead.

If the point number is invalid, the behaviour is undefined.

Definition at line 295 of file Trajectory.h.

References MomentumVectorAtPoint().

Referenced by recob::TrackTrajectory::Theta().

{ return MomentumVectorAtPoint(p).Theta(); }

TrajectoryPoint_t recob::Trajectory::TrajectoryPoint ( size_t  i ) const

inline

Returns position and momentum at the specified trajectory point.

Parameters

i	index of the trajectory point

Returns

the information at the specified trajectory point

Note that this method returns the momentum, not the direction.

auto trajPoint = traj.TrajectoryPoint(0);
std::cout << "Start of trajectory at " << trajPoint.position
  << " cm, with momentum " << trajPoint.momentum << " GeV/c"
  << std::endl;

If the specified index is not valid, result is undefined.

Definition at line 195 of file Trajectory.h.

References LocationAtPoint(), and MomentumVectorAtPoint().

Referenced by recob::Track::CountValidPoints(), and recob::TrackTrajectory::LastValidPoint().

    {
      return {LocationAtPoint(i), MomentumVectorAtPoint(i)};
    }

Point_t const& recob::Trajectory::Vertex ( ) const

inline

Returns the position of the first point of the trajectory [cm].

Definition at line 201 of file Trajectory.h.

References Start().

Referenced by Vertex().

{ return Start(); }

template<typename T >

T recob::Trajectory::Vertex ( ) const

inline

Start position. Use e.g. as:

TVector3 vertex = traj.Vertex<TVector3>(); 

.

Definition at line 510 of file Trajectory.h.

References Vertex().

    {
      auto& loc = Vertex();
      return T(loc.X(), loc.Y(), loc.Z());
    }

Vector_t recob::Trajectory::VertexDirection ( ) const

inline

Returns the direction of the trajectory at the first point.

Definition at line 274 of file Trajectory.h.

References StartDirection().

Referenced by VertexDirection().

{ return StartDirection(); }

template<typename T >

T recob::Trajectory::VertexDirection ( ) const

inline

Start direction. Use e.g. as:

TVector3 vertexdir = traj.VertexDirection<TVector3>(); 

.

Definition at line 542 of file Trajectory.h.

References dir, and VertexDirection().

    {
      auto dir = VertexDirection();
      return T(dir.X(), dir.Y(), dir.Z());
    }

double recob::Trajectory::VertexMomentum ( ) const

inline

Computes and returns the modulus of momentum at the first point [GeV/c].

Definition at line 360 of file Trajectory.h.

References StartMomentum().

{ return StartMomentum(); }

Vector_t const& recob::Trajectory::VertexMomentumVector ( ) const

inline

Returns the momentum of the trajectory at the first point [GeV/c].

Definition at line 351 of file Trajectory.h.

References StartMomentumVector().

Referenced by VertexMomentumVector().

{ return StartMomentumVector(); }

template<typename T >

T recob::Trajectory::VertexMomentumVector ( ) const

inline

Momentum vector at start point. Use e.g. as:

TVector3 vertexmom = traj.VertexMomentumVector<TVector3>(); 

.

Definition at line 574 of file Trajectory.h.

References VertexMomentumVector().

    {
      auto mom = VertexMomentumVector();
      return T(mom.X(), mom.Y(), mom.Z());
    }

double recob::Trajectory::ZenithAngle

(

size_t

p = 0

)

const

"Zenith" angle of trajectory, with respect to the vertical axis.

Parameters

p	the point index to extract the angle from (default: start)

Returns

opposite of the actual zenith angle, in [radians]

See also

AzimuthAngle()

The angle is defined with respect to the negative y direction. It describes the angle at the specified point on the trajectory. Therefore, a trajectory starting along the positive y direction returns radians, while a trajectory going downward along the negative y direction returns 0.

This is designed so that vertical cosmic rays produce trajectories with angle 0 radians.

If the point number is invalid, the behaviour is undefined.

Definition at line 74 of file Trajectory.cxx.

References DirectionAtPoint().

Referenced by Phi(), and recob::TrackTrajectory::ZenithAngle().

{

  // The zenith angle is defined by the angle between the track starting
  // direction and the y axis.
  // The y component of the starting direction is in fact the cosine of that
  // angle (and std::acos() conveniently returns a value in [0;pi]).
  // Our convention has the zenith angle the supplemental of the standard one.

  return util::pi<Coord_t>() - std::acos(DirectionAtPoint(p).Y());

} // recob::Trajectory::ZenithAngle()

Member Data Documentation

bool recob::Trajectory::fHasMomentum = true

private

Whether we have momentum modulus information.

Definition at line 688 of file Trajectory.h.

Referenced by HasMomentum().

Momenta_t recob::Trajectory::fMomenta

private

Momentum of each of the points in trajectory.

Definition at line 686 of file Trajectory.h.

Referenced by Momenta(), MomentumVectorAtPoint(), and Trajectory().

Positions_t recob::Trajectory::fPositions

private

List of points the trajectory goes through.

Definition at line 685 of file Trajectory.h.

Referenced by LocationAtPoint(), NPoints(), Positions(), and Trajectory().

constexpr unsigned int recob::Trajectory::MaxDumpVerbosity = 6

static

Largest verbosity level supported by Dump().

Definition at line 681 of file Trajectory.h.

---

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

• lardataobj/v09_18_03/source/lardataobj/RecoBase/Trajectory.h
• lardataobj/v09_18_03/source/lardataobj/RecoBase/Trajectory.cxx