IlvPolyconicProjection Class Reference

This class defines the Polyconic projection. More...

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

Inheritance diagram for IlvPolyconicProjection:

List of all members.

Public Member Functions
	IlvPolyconicProjection ()
	Constructor.
virtual IlvProjection *	copy () const
	Returns a copy of the projection. It must be overridden in each subclass.
virtual IlvProjectionClassInfo *	getClassInfo () const
	Returns the class information for the projection.
virtual IlvMapsError	setEllipsoid (const IlvEllipsoid &ellipsoid)
	Sets the ellipsoid used for the projection.
virtual void	setLLCenter (IlDouble lon, IlDouble lat)
	Specifies the central meridian and the central parallel (in radian) associated with the projection.
virtual void	write (IlvOutputFile &) const
	Saves the parameters of a projection to the specified output file.
Static Public Member Functions
static IlvProjectionClassInfo *	ClassInfo ()
	Returns the class information of the class.
static IlvClassInfo **	ClassInfoRef ()
	Returns the address of the class information of the class.
Protected Member Functions
virtual IlvMapsError	eForward (IlvCoordinate &ll) const
	Must be redefined in subclasses to implement the projection for a non spherical ellipsoid.
virtual IlvMapsError	eInverse (IlvCoordinate &xy) const
	Implements the inverse projection for a non spherical ellipsoid.
virtual IlvMapsError	sForward (IlvCoordinate &ll) const
	Must be redefined in subclasses to implement the projection for a sphere.
virtual IlvMapsError	sInverse (IlvCoordinate &xy) const
	Must be redefined in subclasses to implement the inverse projection for a sphere.

---

Detailed Description

This class defines the Polyconic projection.

The polyconic projection offers a good compromise between shape distortion and area distortion. This projection was selected in 1819 by the first U.S. survey organization for large-scale mapping in the United States. This projection was used until the mid-1950s for standard topographic maps of the United States.

This projection applies to both spherical and non-spherical ellipsoids and implements an inverse function. However, it is impossible to inverse Cartesian coordinates representing a longitude further than 75 degrees from the center of the projection.

This projection is neither conformal nor equal area.

Polyconic Projection

Library: ilvmaps

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Constructor & Destructor Documentation

IlvPolyconicProjection::IlvPolyconicProjection

(

)

Constructor.

Initialize a new instance of the class IlvPolyconicProjection.

---

Member Function Documentation

static IlvProjectionClassInfo* IlvPolyconicProjection::ClassInfo

(

)

[static]

Returns the class information of the class.

This static function is also available for the subclasses of IlvProjection.

Returns:

The IlvProjectionClassInfo of the class.

Reimplemented from IlvProjection.

static IlvClassInfo** IlvPolyconicProjection::ClassInfoRef

(

)

[static]

Returns the address of the class information of the class.

This static function is also available for the subclasses of IlvProjection.

Returns:

The address of the IlvProjectionClassInfo of the class.

Reimplemented from IlvProjection.

virtual IlvProjection* IlvPolyconicProjection::copy

(

)

const [virtual]

Returns a copy of the projection. It must be overridden in each subclass.

Returns:

The copy of the object.

Implements IlvProjection.

virtual IlvMapsError IlvPolyconicProjection::eForward

(

IlvCoordinate &

ll

)

const [protected, virtual]

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 IlvPolyconicProjection::eInverse

(

IlvCoordinate &

xy

)

const [protected, virtual]

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 IlvProjectionClassInfo* IlvPolyconicProjection::getClassInfo

(

)

const [virtual]

Returns the class information for the projection.

Returns:

The class information for the projection.

Reimplemented from IlvProjection.

virtual IlvMapsError IlvPolyconicProjection::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 IlvPolyconicProjection::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 IlvPolyconicProjection::sForward

(

IlvCoordinate &

ll

)

const [protected, virtual]

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 IlvPolyconicProjection::sInverse

(

IlvCoordinate &

xy

)

const [protected, virtual]

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 IlvPolyconicProjection::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 IlvProjection.