WireCell::Pimpos Class Reference

Pitch-Impact-Position. More...

#include <Pimpos.h>

Public Member Functions
	Pimpos (int nwires, double minwirepitch, double maxwirepitch, const Vector &wire=Vector(0, 1, 0), const Vector &pitch=Vector(0, 0, 1), const Point &origin=Point(0, 0, 0), int nimpact_bins_per_wire_region=10)
int	nimpbins_per_wire () const
	Trivial accessor. More...
const Point &	origin () const
	Return given 3-point origin for plane pitch. More...
const Vector &	axis (int i) const
Vector	relative (const Point &pt) const
	Return the vector from the origin to the given point. More...
double	distance (const Point &pt, int axis=2) const
Point	transform (const Point &pt) const
const Binning &	region_binning () const
const Binning &	impact_binning () const
std::pair< int, int >	closest (double pitch) const
int	wire_impact (int wireind) const
	Return the impact position index coincident with the wire index. More...
std::pair< int, int >	wire_impacts (int wireind) const
int	reflect (int wireind, int impind) const

Private Attributes
int	m_nimpbins_per_wire
Point	m_origin
Vector	m_axis [3]
Binning	m_regionbins
Binning	m_impactbins

Detailed Description

Pitch-Impact-Position.

A Pimpos object encapsulates information and methods related to geometry and binning of a plane of parallel and equidistant wires and a further uniform sub division along their pitch directions.

A wire region or wire bin is the locus centered on a wire and which extends +/- 1/2 pitch from the wire position.

An impact region or impact bin is the smaller locus of pitch formed by uniformly splitting a wire region. It is bound by two (not centered on one) impact positions.

Impact positions are "in phase" with wires" such that there is one impact position coincident with a wire position.

For 3D "lab" to "plane" coordinate transformations there is a plane coordinate system which has these three orthogonal axes:

axis0) anti nominal drift direction (normal to the wire plane) and axis1) along the wire direction such that, axis2) the pitch direction is the cross product of axis0 X axis1.

Definition at line 36 of file Pimpos.h.

Constructor & Destructor Documentation

Pimpos::Pimpos	(	int	nwires,
		double	minwirepitch,
		double	maxwirepitch,
		const Vector &	wire = Vector(0,1,0),
		const Vector &	pitch = Vector(0,0,1),
		const Point &	origin = Point(0,0,0),
		int	nimpact_bins_per_wire_region = 10
	)

Create a Pimpos object for a particular plane.

Parameters

nwires	is the number of wires in the plane.
minwirepitch	is the location in the pitch coordinate of the first (zero index) wire.
maxwirepitch	is the location in the pitch coordinate of the last wire (ie, index=nwires-1).
wire	is a Vector which sets the direction of the wires in the plane. If the underlying wires are not exactly parallel, this should be some representative average wire direction.
pitch	is a Vector which sets the direction and of the pitch of the wires in the plane. The pitch should be such that the cross product, wire (x) pitch, points in the anti-drift direction for the region this plane services. If the underlying wires are not exactly parallel, this pitcvector should be some representative average pitch direction.
origin	is a Point which sets an origin for all transforms. In particular, the projection of this origin point along the drift direction to the plane of wires sets the origin for the pitch coordinate.
nbins	gives the number of of impact bins covering one wire region.

The pitch extents and the origin vector must be expressed in the WCT system of (length) units.

Definition at line 5 of file Pimpos.cxx.

    : m_nimpbins_per_wire(nbins)
    , m_origin(origin)
    , m_axis{Vector(0,0,0), wire.norm(), pitch.norm()}
{
    // drift = X = wire (x) pitch = Y cross Z
    m_axis[0] = m_axis[1].cross(m_axis[2]);

    // total number of impact bins:
    const int nimpstot = nwires*nbins;

    // total pitch span from first to last wire
    const double regionsize = (maxwirepitch-minwirepitch)/(nwires-1);

    // expand by 1/2 pitch on either end to get total sensitive span in pitch direction
    const double pmin = minwirepitch - 0.5*regionsize;
    const double pmax = maxwirepitch + 0.5*regionsize;

    // Wire binning.  Wires are at bin center.
    m_regionbins.set(nwires, pmin, pmax);

    // Impact binning.  Impact *positions* are bin-edges.
    m_impactbins.set(nimpstot, pmin, pmax);
}

Member Function Documentation

const Vector& WireCell::Pimpos::axis ( int  i ) const

inline

Return an axis of the plan. 0=normal to plane (aka anti-drift), 1=wire direction, 2=pitch direction.

Definition at line 89 of file Pimpos.h.

{ return m_axis[i]; }

std::pair< int, int > Pimpos::closest

(

double

pitch

)

const

Return a pair of indices. The first is the index of the wire closest to the given pitch. The second is the relative index of the impact closest impact position (index=0 means the impact position coincident with the wire).

Definition at line 34 of file Pimpos.cxx.

{
    const int iwire = m_regionbins.bin(pitch);
    const double wire_pitch = m_regionbins.center(iwire);
    const double remainder = pitch - wire_pitch;
    const int irelimp = int(round(remainder/m_impactbins.binsize()));
    return std::make_pair(iwire, irelimp);
}

double Pimpos::distance	(	const Point &	pt,
		int	axis = 2
	)		const

Return the distance from origin to point along the given axis. Default is pitch distance.

Definition at line 71 of file Pimpos.cxx.

{
    return m_axis[axis].dot(relative(pt));
}

const Binning& WireCell::Pimpos::impact_binning ( ) const

inline

Return impact position binning. Bin edges are at impact positions and are in-phase with wire centers.

Definition at line 113 of file Pimpos.h.

{ return m_impactbins; }

int WireCell::Pimpos::nimpbins_per_wire ( ) const

inline

Trivial accessor.

Definition at line 79 of file Pimpos.h.

{ return m_nimpbins_per_wire; }

const Point& WireCell::Pimpos::origin ( ) const

inline

Return given 3-point origin for plane pitch.

Definition at line 85 of file Pimpos.h.

{ return m_origin; }

int Pimpos::reflect	(	int	wireind,
		int	impind
	)		const

Return the impact position index which is the reflection of the given impact position index through the given wire index.

Definition at line 56 of file Pimpos.cxx.

{
    const int wireimpind = wire_impact(wireind);
    const int delta = impind - wireimpind;
    return wireimpind - delta;
}

const Binning& WireCell::Pimpos::region_binning ( ) const

inline

Return wire region binning. Each bin is centered on the wire. Bin edges extend a distance of 1/2 pitch between neighboring wires.

Definition at line 109 of file Pimpos.h.

{ return m_regionbins; }

Vector Pimpos::relative

(

const Point &

pt

)

const

Return the vector from the origin to the given point.

Definition at line 66 of file Pimpos.cxx.

{
    return pt - m_origin;
}

Point Pimpos::transform

(

const Point &

pt

)

const

Transform the given point into the Pimpos coordinate system.

Definition at line 76 of file Pimpos.cxx.

{
    const Vector v = relative(pt);
    Point ret;
    for (int axis=0; axis<3; ++axis) {
        ret[axis] = m_axis[axis].dot(v);
    }
    return ret;
}

int Pimpos::wire_impact

(

int

wireind

)

const

Return the impact position index coincident with the wire index.

Definition at line 43 of file Pimpos.cxx.

{
    return (0.5 + wireind)*m_nimpbins_per_wire;
}

std::pair< int, int > Pimpos::wire_impacts

(

int

wireind

)

const

Return the impact position indices (bin edges) at either extreme of the wire region. The smaller index for this wire is the larger index of wireind-1's values and vice versa.

Definition at line 48 of file Pimpos.cxx.

{
    const int wi = wire_impact(wireind);
    return std::make_pair(wi - m_nimpbins_per_wire/2,
                          wi + m_nimpbins_per_wire/2);
}

Member Data Documentation

Vector WireCell::Pimpos::m_axis[3]

private

Definition at line 141 of file Pimpos.h.

Binning WireCell::Pimpos::m_impactbins

private

Definition at line 142 of file Pimpos.h.

int WireCell::Pimpos::m_nimpbins_per_wire

private

Definition at line 139 of file Pimpos.h.

Point WireCell::Pimpos::m_origin

private

Definition at line 140 of file Pimpos.h.

Binning WireCell::Pimpos::m_regionbins

private

Definition at line 142 of file Pimpos.h.

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

• wire-cell-build/util/inc/WireCellUtil/Pimpos.h
• wire-cell-build/util/src/Pimpos.cxx