larcfm::Projection Class Reference

#include <Projection.h>

Static Public Member Functions
static EuclideanProjection	createProjection (double lat, double lon, double alt)
static EuclideanProjection	createProjection (const LatLonAlt &lla)
static EuclideanProjection	createProjection (const Position &pos)
static double	projectionConflictRange (double lat, double accuracy)
static double	projectionMaxRange ()
static void	setProjectionType (ProjectionType t)
static ProjectionType	getProjectionTypeFromString (std::string s)
static ProjectionType	getProjectionType ()

Static Private Attributes
static EuclideanProjection	projection = EuclideanProjection()
static ProjectionType	ptype = projection_type_value__

Detailed Description

A static holding class for universal projection (Spherical Earth to Euclidean plane) information.
All projection objects should be retrieved from this class.

Remember that the given projection point becomes the origin of the Euclidean space, so to preserve absolute altitude (above sea level) information in the Euclidean space, it may be necessary to make the projection point's altitude zero.

Member Function Documentation

createProjection() [1/3]

EuclideanProjection larcfm::Projection::createProjection ( const LatLonAlt &  lla )

static

Returns a new projection for the current type with the given reference point.

Note that in the projected Euclidean frame, if two points are made using the same projection, their relative altitudes will be consistent, but their absolute altitudes may have changed (the reference point is subtracted). If you need to have the same absolute altitude values in the geodetic and Euclidean frames, the reference point should have a zero altitude.

For example, if you call p2 = Projection.createProjection(p1).project(p1), p2 will have an altitude of zero. If you instead call p2 = Projection.createProjection(p1.zeroAlt(0)).project(p1), p2 will have the same altitude as p1.

Parameters

lla	reference point

Returns

new projection

createProjection() [2/3]

EuclideanProjection larcfm::Projection::createProjection ( const Position &  pos )

static

Returns a new projection for the current type with the given reference point. This will return an altitude-preserving projection against the given Position if it is lat/lon. If it is Euclidean, the projection will be against the LatLonAlt.ZERO point.

Note that in the projected Euclidean frame, if two points are made using the same projection, their relative altitudes will be consistent, but their absolute altitudes may have changed (the reference point is subtracted). If you need to have the same absolute altitude values in the geodetic and Euclidean frames, the reference point should have a zero altitude.

For example, if you call p2 = Projection.createProjection(p1).project(p1), p2 will have an altitude of zero. If you instead call p2 = Projection.createProjection(p1.zeroAlt(0)).project(p1), p2 will have the same altitude as p1.

Parameters

pos	reference point

Returns

new projection

createProjection() [3/3]

EuclideanProjection larcfm::Projection::createProjection ( double  lat, double  lon, double  alt  )

static

Returns a new projection for the current type with the given reference point.

Note that in the projected Euclidean frame, if two points are made using the same projection, their relative altitudes will be consistent, but their absolute altitudes may have changed (the reference point is subtracted). If you need to have the same absolute altitude values in the geodetic and Euclidean frames, the reference point should have a zero altitude.

Parameters

lat	latitude of reference point
lon	longitude of reference point
alt	altitude of reference point

Returns

new projection

getProjectionType()

ProjectionType larcfm::Projection::getProjectionType ( )

static

Return the current ProjectionType

Returns

type of projection

getProjectionTypeFromString()

ProjectionType larcfm::Projection::getProjectionTypeFromString ( std::string  s )

static

Given a string representation of a ProjectionType, return the ProjectionType

Parameters

s	name of projection type

Returns

projection type

projectionConflictRange()

double larcfm::Projection::projectionConflictRange ( double  lat, double  accuracy  )

static

Geodetic projections into the Euclidean frame, for various reasons, tend to lose accuracy over long distances or when close to the poles. This can be countered by examining trajectories as shorter segments at a time.
This is already done in Detector and Stratway, but not in any other tools. For CDII, it is best to break up the ownship's plan in this way. For CDSI and IntentBands, it is better to break up the traffic in this way.

This return an estimate on the suggested maximum segment size, depending on the current projection.

Parameters

lat	- latitude [rad]
accuracy	- desired accuracy (allowable error) [m]

Returns

the maximum length of a trajectory segment at the given latitude that preserves the desired accuracy.

projectionMaxRange()

double larcfm::Projection::projectionMaxRange ( )

static

This is a range about which the projection will completely break down and start producing nonsensical answers. Attempting to use the projection at ranges greater than this is an error state (at ranges less than this but greater than the conflictRange, it may still be unacceptably inaccurate, however).

Returns

maximum range for the projection (in meters).

setProjectionType()

void larcfm::Projection::setProjectionType ( ProjectionType  t )

static

Set the projection to a new type. This is a global change.

Parameters

t	type of projection

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

• Modules/ACCoRD/inc/Projection.h
• Modules/ACCoRD/src/Projection.cpp