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IlvAlbersEqualAreaProjection Class Reference

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

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

Inheritance diagram for IlvAlbersEqualAreaProjection:
IlvConicProjection IlvProjection IlvLambertEqualAreaConicProjection

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 IlvProjectionClassInfogetClassInfo () 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 IlvCoordinategetSecantLatitudes () 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 IlvProjectioncopy () const =0
 Returns a copy of the projection. 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 IlvHorizontalDatumgetDatum (void) const
 Returns the horizontal datum used for the projection. More...
 
const IlvEllipsoidgetEllipsoid () const
 Returns the ellipsoid used for the projection. More...
 
IlvMapsError getError () const
 Returns the status of the projection. More...
 
IlDouble getFalseEasting () const
 Returns the false easting of the projection. More...
 
IlDouble getFalseNorthing () const
 Returns the false northing of the projection. More...
 
IlvProjectionInterfacegetInterface ()
 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 IlvUnitConvertergetUnitConverter () const
 Returns the unit converter. More...
 
IlvCoordinate getXYOffset () 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
 Indicates 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
 Indicates if the inverse function is supported by the projection. More...
 
IlBoolean isShared () const
 Indicates that 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 std::ostream & printPROJ4Descriptor (std::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. 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)
 Initializes a new IlvProjection object. 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 IlvProjectionClassInfoClassInfo ()
 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 ()
 Indicates that the coordinates passed to the forward function are not in a valid range for radian angles.
 
static IlvMapsError InvalidEllipsoidError ()
 Indicates that you attempt to set a non spherical ellipsoid to a projection that does not support non spherical ellipsoids.
 
static IlvProjectionLoad (IlvInputFile &inputFile)
 Loads a projection from the specified file. More...
 
static IlvProjectionPROJ4ToIlvProjection (const char *proj4Descriptor, IlvMapsError *status=0)
 Creates the projection from a PROJ4 descriptor. More...
 
static IlvMapsError ToleranceConditionError ()
 Indicates that an internal projection computation failed. More...
 
static IlvMapsError UnsupportedFeatureError ()
 Indicates that 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::IlvAlbersEqualAreaProjection ( IlDouble  lat1 = IlvMaps::DegreeToRadian(29.5),
IlDouble  lat2 = IlvMaps::DegreeToRadian(45.5) 
)

This constructor initializes an instance of the class IlvAlbersEqualAreaProjection.

Parameters
lat1The first secant latitude, in radian. If omitted, the first secant latitude is set to 29.5 degrees.
lat2The second secant latitude, in radian. If omitted, the second secant latitude is set to 45.5 degrees.

Member Function Documentation

§ eForward()

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
llContains the longitude and latitude coordinates in radian (x = longitude, y = latitude).
Returns
An error code.

Reimplemented from IlvProjection.

§ eInverse()

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

Implements the inverse projection for a non spherical ellipsoid.

The default implementation returns IlvProjection::UnsupportedFeatureError().

Parameters
xyContains the Cartesian coordinates to inverse.
Returns
An error code.

Reimplemented from IlvProjection.

§ setEllipsoid()

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
ellipsoidThe ellipsoid used for the projection.
Returns
IlvMapsError if the ellipsoid does not match the projection.

Reimplemented from IlvProjection.

§ setLLCenter()

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
lonThe central meridian in radian.
latThe central parallel in radian.

Reimplemented from IlvProjection.

§ setSecantLatitudes()

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

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

Parameters
secantA 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.

§ sForward()

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

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

Parameters
llContains the longitude and latitude coordinates in radian (x = longitude, y = latitude).
Returns
An error code.

Implements IlvProjection.

§ sInverse()

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
xyContains the Cartesian coordinates to inverse.
Returns
An error code.

Reimplemented from IlvProjection.

§ write()

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
outputFileThe file to write the projection parameters to.

Reimplemented from IlvConicProjection.

Reimplemented in IlvLambertEqualAreaConicProjection.


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