org.openstreetmap.josm.data.projection.proj

Class TransverseMercator

java.lang.Object

org.openstreetmap.josm.data.projection.proj.TransverseMercator

All Implemented Interfaces:

Proj

public class TransverseMercator
extends java.lang.Object
implements Proj

Transverse Mercator projection.

Field Summary

Fields

Modifier and Type	Field and Description
protected double	a
protected double	b

Constructor Summary

Constructors

Constructor and Description
TransverseMercator()

Method Summary

Modifier and Type	Method and Description
private double	ArcLengthOfMeridian(double phi) ArcLengthOfMeridian Computes the ellipsoidal distance from the equator to a point at a given latitude.
private double	footpointLatitude(double y) FootpointLatitude Computes the footpoint latitude for use in converting transverse Mercator coordinates to ellipsoidal coordinates.
java.lang.String	getName() Replies a human readable name of this projection.
java.lang.String	getProj4Id() Replies the Proj.4 identifier.
void	initialize(ProjParameters params) Initialize the projection using the provided parameters.
double[]	invproject(double x, double y) Converts x and y coordinates in the Transverse Mercator projection to a latitude/longitude pair.
double[]	project(double phi, double lambda) Converts a latitude/longitude pair to x and y coordinates in the Transverse Mercator projection.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

a

protected double a

b

protected double b

Constructor Detail

TransverseMercator

public TransverseMercator()

Method Detail

getName

public java.lang.String getName()

Description copied from interface: Proj

Replies a human readable name of this projection.

Specified by:

getName in interface Proj

Returns:

The projection name. must not be null.

getProj4Id

public java.lang.String getProj4Id()

Description copied from interface: Proj

Replies the Proj.4 identifier.

Specified by:

getProj4Id in interface Proj

Returns:

The Proj.4 identifier (as reported by cs2cs -lp). If no id exists, return null.

initialize

public void initialize(ProjParameters params)
                throws ProjectionConfigurationException

Description copied from interface: Proj

Initialize the projection using the provided parameters.

Specified by:

initialize in interface Proj

Parameters:

params - The projection parameters

Throws:

ProjectionConfigurationException - in case parameters are not suitable

project

public double[] project(double phi,
                        double lambda)

Converts a latitude/longitude pair to x and y coordinates in the Transverse Mercator projection. Note that Transverse Mercator is not the same as UTM; a scale factor is required to convert between them. Reference: Hoffmann-Wellenhof, B., Lichtenegger, H., and Collins, J., GPS: Theory and Practice, 3rd ed. New York: Springer-Verlag Wien, 1994.

Specified by:

project in interface Proj

Parameters:

phi - Latitude of the point, in radians

lambda - Longitude of the point, in radians

Returns:

A 2-element array containing the x and y coordinates of the computed point

invproject

public double[] invproject(double x,
                           double y)

Converts x and y coordinates in the Transverse Mercator projection to a latitude/longitude pair. Note that Transverse Mercator is not the same as UTM; a scale factor is required to convert between them. Reference: Hoffmann-Wellenhof, B., Lichtenegger, H., and Collins, J., GPS: Theory and Practice, 3rd ed. New York: Springer-Verlag Wien, 1994. Remarks: The local variables Nf, nuf2, tf, and tf2 serve the same purpose as N, nu2, t, and t2 in MapLatLonToXY, but they are computed with respect to the footpoint latitude phif. x1frac, x2frac, x2poly, x3poly, etc. are to enhance readability and to optimize computations.

Specified by:

invproject in interface Proj

Parameters:

x - The easting of the point, in meters, divided by the semi major axis of the ellipsoid

y - The northing of the point, in meters, divided by the semi major axis of the ellipsoid

Returns:

A 2-element containing the latitude and longitude in radians

ArcLengthOfMeridian

private double ArcLengthOfMeridian(double phi)

ArcLengthOfMeridian Computes the ellipsoidal distance from the equator to a point at a given latitude. Reference: Hoffmann-Wellenhof, B., Lichtenegger, H., and Collins, J., GPS: Theory and Practice, 3rd ed. New York: Springer-Verlag Wien, 1994.

Parameters:

phi - Latitude of the point, in radians

Returns:

The ellipsoidal distance of the point from the equator (in meters, divided by the semi major axis of the ellipsoid)

footpointLatitude

private double footpointLatitude(double y)

FootpointLatitude Computes the footpoint latitude for use in converting transverse Mercator coordinates to ellipsoidal coordinates. Reference: Hoffmann-Wellenhof, B., Lichtenegger, H., and Collins, J., GPS: Theory and Practice, 3rd ed. New York: Springer-Verlag Wien, 1994.

Parameters:

y - northing coordinate, in meters, divided by the semi major axis of the ellipsoid

Returns:

The footpoint latitude, in radians