This class defines the Albers Equal Area Conic projection. More...

#include <ilviews/maps/projection/alberseq.h>

Inheritance diagram for IlvAlbersEqualAreaProjection:

Public Member Functions
	IlvAlbersEqualAreaProjection (IlDouble lat1=IlvMaps::DegreeToRadian(29.5), IlDouble lat2=IlvMaps::DegreeToRadian(45.5))
	This constructor initializes an instance of the class `IlvAlbersEqualAreaProjection`. More...

virtual IlvMapsError	setEllipsoid (const IlvEllipsoid &ellipsoid)
	Sets the ellipsoid used for the projection. More...

virtual void	setLLCenter (IlDouble lon, IlDouble lat)
	Specifies the central meridian and the central parallel (in radian) associated with the projection. More...

virtual IlvMapsError	setSecantLatitudes (const IlvCoordinate &s)
	Sets the latitudes at which the cone of the projection intersects with the earth. More...

virtual void	write (IlvOutputFile &) const
	Saves the parameters of a projection to the specified output file. More...

Public Member Functions inherited from IlvConicProjection
virtual IlvProjectionClassInfo *	getClassInfo () const
	Returns the class information for the projection. More...

IlDouble	getSecantLatitude1 (void) const
	Gets the first secant latitude. More...

IlDouble	getSecantLatitude2 (void) const
	Gets the second secant latitude. More...

const IlvCoordinate &	getSecantLatitudes () const
	Returns the secant latitudes of the projection in an `IlvCoordinate`. More...

IlvMapsError	setSecantLatitude1 (IlDouble v)
	Sets the first secant latitude. More...

IlvMapsError	setSecantLatitude2 (IlDouble v)
	Sets the second secant latitude. More...

Public Member Functions inherited from IlvProjection
virtual IlvProjection *	copy () const =0
	Returns a copy of the projection. It must be overridden in each subclass. More...

IlvMapsError	forward (const IlvCoordinate &llIn, IlvCoordinate &xyOut) const
	Converts a latitude and a longitude to Cartesian coordinates (x,y). More...

IlvMapsError	forward (IlvCoordinate &x) const
	This member function converts a latitude and a longitude to Cartesian coordinates. More...

IlDouble	getCentralMeridian () const
	Returns the central meridian of the projection. More...

IlDouble	getCentralParallel () const
	Returns the central parallel of the projection. More...

const IlvHorizontalDatum *	getDatum (void) const
	Returns the horizontal datum used for the projection. More...

const IlvEllipsoid *	getEllipsoid (void) const
	Returns the ellipsoid used for the projection. More...

IlvMapsError	getError () const
	Returns the status of the projection. If the projection is valid, the function returns `IlvMapsError::NoError()`, otherwise, it returns an error code. See the `IlvMaps` class to know how to interpret the error codes. More...

IlDouble	getFalseEasting () const
	Returns the false easting of the projection. More...

IlDouble	getFalseNorthing () const
	Returns the false northing of the projection. More...

IlvProjectionInterface *	getInterface ()
	Returns the interface of the projection. More...

IlvCoordinate	getLLCenter (void) const
	Returns the central meridian and the central parallel associated with the projection (0-0 by default). More...

IlvProjectionGeometricProperty	getProperty () const
	Returns the geometric property of the projection. More...

const IlvUnitConverter *	getUnitConverter () const
	Returns the unit converter. More...

IlvCoordinate	getXYOffset (void) const
	Returns the false easting and the false northing of the projection. More...

IlvMapsError	inverse (const IlvCoordinate &xyIn, IlvCoordinate &llOut) const
	Converts the specified coordinate to a latitude and a longitude. More...

IlvMapsError	inverse (IlvCoordinate &x) const
	Converts the `IlvCoordinate` representing Cartesian coordinates to a latitude and a longitude. More...

IlBoolean	isBad () const
	Checks for an inconsistent state of the projection. More...

IlBoolean	isEllipsoidEnabled () const
	Returns `IlTrue` if non spherical ellipsoids can be used for the projection. More...

IlBoolean	isGeocentric () const
	Checks if the projection uses geocentric latitudes. More...

IlBoolean	isInverseEnabled () const
	Returns `IlTrue` if the inverse function is supported by the projection. More...

IlBoolean	isShared () const
	Returns `IlTrue` if the projection is shared. More...

IlBoolean	isUsingLongitudeReduction () const
	Returns `IlTrue` if the projection uses range reduction for longitudes. More...

void	lock ()
	Locks the projection.

virtual IL_STDPREF ostream &	printPROJ4Descriptor (IL_STDPREF ostream &ostr, IlvMapsError *status=0) const
	This virtual member function converts the projection to a string in the PROJ4 format. More...

void	save (IlvOutputFile &outputFile) const
	Saves an instance of a subclass of `IlvProjection` to the specified output file. More...

void	setCentralMeridian (IlDouble lon)
	Sets the central meridian of the projection. More...

void	setCentralParallel (IlDouble lat)
	Sets the central parallel of the projection. More...

virtual IlvMapsError	setDatum (const IlvHorizontalDatum *datum)
	Sets the datum used for the projection. More...

void	setFalseEasting (IlDouble falseEasting)
	Sets the false easting of the projection. More...

void	setFalseNorthing (IlDouble falseNorthing)
	Sets the false northing of the projection. More...

void	setGeocentric (IlBoolean geoc)
	Specifies whether the projection uses geocentric or geodetic latitudes. More...

void	setShared ()
	Specifies that the projection will be shared. More...

void	setUnitConverter (const IlvUnitConverter &converter)
	Sets the unit converter of the projection. The default unit is meters. More...

void	setUsingLongitudeReduction (IlBoolean use)
	Specifies whether the projection uses longitude reduction. More...

void	setXYOffset (IlDouble x0, IlDouble y0)
	Specifies the false easting and the false northing. More...

void	unLock ()
	Unlocks the object. More...

Protected Member Functions
virtual IlvMapsError	eForward (IlvCoordinate &ll) const
	Must be redefined in subclasses to implement the projection for a non spherical ellipsoid. More...

virtual IlvMapsError	eInverse (IlvCoordinate &xy) const
	Implements the inverse projection for a non spherical ellipsoid. More...

virtual IlvMapsError	sForward (IlvCoordinate &ll) const
	Must be redefined in subclasses to implement the projection for a sphere. More...

virtual IlvMapsError	sInverse (IlvCoordinate &xy) const
	Must be redefined in subclasses to implement the inverse projection for a sphere. More...

Protected Member Functions inherited from IlvConicProjection
	IlvConicProjection (IlBoolean ellipsoidEnabled, IlBoolean inverseEnabled, IlvProjectionGeometricProperty property)
	Initializes a new instance of the class `IlvConicProjection`. More...

Protected Member Functions inherited from IlvProjection
	IlvProjection (IlBoolean ellipsoidEnabled, IlBoolean inverseEnabled, IlvProjectionGeometricProperty property)
	This constructor initializes a new instance of the class. More...

void	addError (IlvMapsError error)
	Used by the constructors of subclasses if an error occurs during an object initialization. More...

void	setError (IlvMapsError error)
	Sets the status of this projection. More...

Additional Inherited Members
Static Public Member Functions inherited from IlvProjection
static IlvProjectionClassInfo *	ClassInfo ()
	Returns the class information of the class. More...

static IlvClassInfo **	ClassInfoRef ()
	Returns the address of the class information of the class. More...

static IlvMapsError	InputError ()
	Returned if the coordinates passed to the forward function are not in a valid range for radian angles.

static IlvMapsError	InvalidEllipsoidError ()
	Returned if you attempt to set a non spherical ellipsoid to a projection that does not support non spherical ellipsoids.

static IlvProjection *	Load (IlvInputFile &inputFile)
	Loads a projection from the specified file. More...

static IlvProjection *	PROJ4ToIlvProjection (const char PROJ4descriptor, IlvMapsError status=0)
	Creates the projection specified by proj4Descriptor. More...

static IlvMapsError	ToleranceConditionError ()
	Returned when an internal projection computation fails. Some projections, however, can return more specific error codes in this case.

static IlvMapsError	UnsupportedFeatureError ()
	Returned if an unsupported projection feature is requested, like inverse projection for a projection that does not support inverse projection.

Detailed Description

This class defines the Albers Equal Area Conic projection.

This conic projection transfers the image of the globe to a cone either secant or tangent to the surface of the earth.

When used to display maps of the conterminous United States, this projection is often used with the first secant latitude set to 29.5DN and the second secant latitude set to 45.5DN.

This projection applies both to spherical and non-spherical ellipsoids and implements an inverse function.

This projection is Equal Area.

Albers Equal Area conic Projection

Library: ilvmaps

Constructor & Destructor Documentation

IlvAlbersEqualAreaProjection::IlvAlbersEqualAreaProjection	(	IlDouble	lat1 = `IlvMaps::DegreeToRadian(29.5)`,
		IlDouble	lat2 = `IlvMaps::DegreeToRadian(45.5)`
	)

This constructor initializes an instance of the class IlvAlbersEqualAreaProjection.

Parameters

lat1	The first secant latitude, in radian. If omitted, the first secant latitude is set to 29.5 degrees.
lat2	The second secant latitude, in radian. If omitted, the second secant latitude is set to 45.5 degrees.

Member Function Documentation

virtual IlvMapsError IlvAlbersEqualAreaProjection::eForward ( IlvCoordinate & ll ) const

protectedvirtual

Must be redefined in subclasses to implement the projection for a non spherical ellipsoid.

The default implementation returns IlvProjection::UnsupportedFeatureError().

Parameters

ll	Contains the longitude and latitude coordinates in radian (x = longitude, y = latitude).

Returns: An error code.

Reimplemented from IlvProjection.

virtual IlvMapsError IlvAlbersEqualAreaProjection::eInverse ( IlvCoordinate & xy ) const

protectedvirtual

Implements the inverse projection for a non spherical ellipsoid.

The default implementation returns IlvProjection::UnsupportedFeatureError().

Parameters

xy	Contains the Cartesian coordinates to inverse.

Returns: An error code.

Reimplemented from IlvProjection.

virtual IlvMapsError IlvAlbersEqualAreaProjection::setEllipsoid ( const IlvEllipsoid & ellipsoid )

virtual

Sets the ellipsoid used for the projection.

This virtual member function sets the ellipsoid used for the projection. Most of the projections are initialized with a spherical ellipsoid with a radius of 6,370,997 meters.
This function returns IlvMaps::NoError() if the operation is successful or an error status if you specify a non spherical ellipsoid and your type does not support non spherical.

Parameters

ellipsoid The ellipsoid used for the projection.

Returns: IlvMapsError if the ellipsoid does not match the projection.

Reimplemented from IlvProjection.

virtual void IlvAlbersEqualAreaProjection::setLLCenter	(	IlDouble	lon,
		IlDouble	lat
	)

virtual

Specifies the central meridian and the central parallel (in radian) associated with the projection.

By default, theses values are set to 0. This function is virtual because it can be overridden by subclasses of IlvProjection to update the internal parameters when the center is changed.

Parameters

lon	The central meridian in radian.
lat	The central parallel in radian.

Reimplemented from IlvProjection.

virtual IlvMapsError IlvAlbersEqualAreaProjection::setSecantLatitudes ( const IlvCoordinate & secant )

virtual

Sets the latitudes at which the cone of the projection intersects with the earth.

Parameters

secant A vector that contains two values: secant.x represents the first latitude at which the cone intersects with the earth. secant.y represents the second latitude at which the cone intersects with the earth.
Both values are expressed in radian.

Returns: An error status if the latitudes specify a limiting form, that is, if secant.x = -secant.y or secant.x = secant.y = PI/2.

Reimplemented from IlvConicProjection.

Reimplemented in IlvLambertEqualAreaConicProjection.

virtual IlvMapsError IlvAlbersEqualAreaProjection::sForward ( IlvCoordinate & ll ) const

protectedvirtual

Must be redefined in subclasses to implement the projection for a sphere.

Parameters

ll	Contains the longitude and latitude coordinates in radian (x = longitude, y = latitude).

Implements IlvProjection.

virtual IlvMapsError IlvAlbersEqualAreaProjection::sInverse ( IlvCoordinate & xy ) const

protectedvirtual

Must be redefined in subclasses to implement the inverse projection for a sphere.

The default implementation returns IlvProjection::UnsupportedFeatureError().

Parameters

xy	Contains the Cartesian coordinates to inverse.

Returns: An error code.

Reimplemented from IlvProjection.

virtual void IlvAlbersEqualAreaProjection::write ( IlvOutputFile & outputFile ) const

virtual

Saves the parameters of a projection to the specified output file.

It must be overridden by subclasses of IlvProjection that need to save additional parameters. This function should not be directly called; use the save function instead.

Parameters

outputFile The file to write the projection parameters to.

Reimplemented from IlvConicProjection.

Reimplemented in IlvLambertEqualAreaConicProjection.

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation