C# Class SharpMap.CoordinateSystems.Projections.Mercator

Implements the Mercator projection.

This map projection introduced in 1569 by Gerardus Mercator. It is often described as a cylindrical projection, but it must be derived mathematically. The meridians are equally spaced, parallel vertical lines, and the parallels of latitude are parallel, horizontal straight lines, spaced farther and farther apart as their distance from the Equator increases. This projection is widely used for navigation charts, because any straight line on a Mercator-projection map is a line of constant true bearing that enables a navigator to plot a straight-line course. It is less practical for world maps because the scale is distorted; areas farther away from the equator appear disproportionately large. On a Mercator projection, for example, the landmass of Greenland appears to be greater than that of the continent of South America; in actual area, Greenland is smaller than the Arabian Peninsula.

Inheritance: MapProjection

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Public Methods

Method	Description
DegreesToMeters ( SharpMap lonlat ) : SharpMap.Geometries.Point	Converts coordinates in decimal degrees to projected meters. The parameters this projection expects are listed below. ItemsDescriptions longitude_of_natural_originThe longitude of the point from which the values of both the geographical coordinates on the ellipsoid and the grid coordinates on the projection are deemed to increment or decrement for computational purposes. Alternatively it may be considered as the longitude of the point which in the absence of application of false coordinates has grid coordinates of (0,0). Sometimes known as ""central meridian""." latitude_of_natural_originThe latitude of the point from which the values of both the geographical coordinates on the ellipsoid and the grid coordinates on the projection are deemed to increment or decrement for computational purposes. Alternatively it may be considered as the latitude of the point which in the absence of application of false coordinates has grid coordinates of (0,0). scale_factor_at_natural_originThe factor by which the map grid is reduced or enlarged during the projection process, defined by its value at the natural origin. false_eastingSince the natural origin may be at or near the centre of the projection and under normal coordinate circumstances would thus give rise to negative coordinates over parts of the mapped area, this origin is usually given false coordinates which are large enough to avoid this inconvenience. The False Easting, FE, is the easting value assigned to the abscissa (east). false_northingSince the natural origin may be at or near the centre of the projection and under normal coordinate circumstances would thus give rise to negative coordinates over parts of the mapped area, this origin is usually given false coordinates which are large enough to avoid this inconvenience. The False Northing, FN, is the northing value assigned to the ordinate .
Inverse ( ) : IMathTransform	Returns the inverse of this projection.
Mercator ( List parameters ) : System	Initializes the MercatorProjection object with the specified parameters to project points.
Mercator ( List parameters, bool isInverse ) : System	Initializes the MercatorProjection object with the specified parameters. The parameters this projection expects are listed below. ItemsDescriptions central_meridianThe longitude of the point from which the values of both the geographical coordinates on the ellipsoid and the grid coordinates on the projection are deemed to increment or decrement for computational purposes. Alternatively it may be considered as the longitude of the point which in the absence of application of false coordinates has grid coordinates of (0,0). latitude_of_originThe latitude of the point from which the values of both the geographical coordinates on the ellipsoid and the grid coordinates on the projection are deemed to increment or decrement for computational purposes. Alternatively it may be considered as the latitude of the point which in the absence of application of false coordinates has grid coordinates of (0,0). scale_factorThe factor by which the map grid is reduced or enlarged during the projection process, defined by its value at the natural origin. false_eastingSince the natural origin may be at or near the centre of the projection and under normal coordinate circumstances would thus give rise to negative coordinates over parts of the mapped area, this origin is usually given false coordinates which are large enough to avoid this inconvenience. The False Easting, FE, is the easting value assigned to the abscissa (east). false_northingSince the natural origin may be at or near the centre of the projection and under normal coordinate circumstances would thus give rise to negative coordinates over parts of the mapped area, this origin is usually given false coordinates which are large enough to avoid this inconvenience. The False Northing, FN, is the northing value assigned to the ordinate.
MetersToDegrees ( SharpMap p ) : SharpMap.Geometries.Point	Converts coordinates in projected meters to decimal degrees.

Method Details

DegreesToMeters() public method

Converts coordinates in decimal degrees to projected meters.

The parameters this projection expects are listed below.

ItemsDescriptions longitude_of_natural_originThe longitude of the point from which the values of both the geographical coordinates on the ellipsoid and the grid coordinates on the projection are deemed to increment or decrement for computational purposes. Alternatively it may be considered as the longitude of the point which in the absence of application of false coordinates has grid coordinates of (0,0). Sometimes known as ""central meridian""." latitude_of_natural_originThe latitude of the point from which the values of both the geographical coordinates on the ellipsoid and the grid coordinates on the projection are deemed to increment or decrement for computational purposes. Alternatively it may be considered as the latitude of the point which in the absence of application of false coordinates has grid coordinates of (0,0). scale_factor_at_natural_originThe factor by which the map grid is reduced or enlarged during the projection process, defined by its value at the natural origin. false_eastingSince the natural origin may be at or near the centre of the projection and under normal coordinate circumstances would thus give rise to negative coordinates over parts of the mapped area, this origin is usually given false coordinates which are large enough to avoid this inconvenience. The False Easting, FE, is the easting value assigned to the abscissa (east). false_northingSince the natural origin may be at or near the centre of the projection and under normal coordinate circumstances would thus give rise to negative coordinates over parts of the mapped area, this origin is usually given false coordinates which are large enough to avoid this inconvenience. The False Northing, FN, is the northing value assigned to the ordinate .

public DegreesToMeters ( SharpMap lonlat ) : SharpMap.Geometries.Point
lonlat	SharpMap	The point in decimal degrees.
return	SharpMap.Geometries.Point

Inverse() public method

Returns the inverse of this projection.

public Inverse ( ) : IMathTransform
return	IMathTransform

Mercator() public method

Initializes the MercatorProjection object with the specified parameters to project points.

public Mercator ( List parameters ) : System
parameters	List	ParameterList with the required parameters.
return	System

Mercator() public method

Initializes the MercatorProjection object with the specified parameters.

The parameters this projection expects are listed below.

ItemsDescriptions central_meridianThe longitude of the point from which the values of both the geographical coordinates on the ellipsoid and the grid coordinates on the projection are deemed to increment or decrement for computational purposes. Alternatively it may be considered as the longitude of the point which in the absence of application of false coordinates has grid coordinates of (0,0). latitude_of_originThe latitude of the point from which the values of both the geographical coordinates on the ellipsoid and the grid coordinates on the projection are deemed to increment or decrement for computational purposes. Alternatively it may be considered as the latitude of the point which in the absence of application of false coordinates has grid coordinates of (0,0). scale_factorThe factor by which the map grid is reduced or enlarged during the projection process, defined by its value at the natural origin. false_eastingSince the natural origin may be at or near the centre of the projection and under normal coordinate circumstances would thus give rise to negative coordinates over parts of the mapped area, this origin is usually given false coordinates which are large enough to avoid this inconvenience. The False Easting, FE, is the easting value assigned to the abscissa (east). false_northingSince the natural origin may be at or near the centre of the projection and under normal coordinate circumstances would thus give rise to negative coordinates over parts of the mapped area, this origin is usually given false coordinates which are large enough to avoid this inconvenience. The False Northing, FN, is the northing value assigned to the ordinate.

public Mercator ( List parameters, bool isInverse ) : System
parameters	List	List of parameters to initialize the projection.
isInverse	bool	Indicates whether the projection forward (meters to degrees or degrees to meters).
return	System

MetersToDegrees() public method

Converts coordinates in projected meters to decimal degrees.

public MetersToDegrees ( SharpMap p ) : SharpMap.Geometries.Point
p	SharpMap	Point in meters
return	SharpMap.Geometries.Point