org.gicentre.utils.spatial

Class UTM

java.lang.Object

org.gicentre.utils.spatial.UTM

All Implemented Interfaces:

MapProjection

Direct Known Subclasses:

OSGB

public class UTM
extends java.lang.Object
implements MapProjection

Class for representing Universal Transverse Mercator projections. Includes forward and inverse transforms from/to lat,long. Uses transformation equations from Snyder (1987) Atlas of Map Projections, and the Ordnance Survey (2002) A Guide to Coordinate Systems of Great Britain. If explicit projection origins are not given, an appropriate UTM zone should be set before transforming in either direction. This can be determined by passing a reasonably central longitude/latitude coordinate pair to the constructor.

Version:

3.4, 5th February, 2016.

Author:

Jo Wood, giCentre, City University London.

Field Summary

Fields

Modifier and Type	Field and Description
static int	FROM_LAT_LONG Indicates a transformation from longitude/latitude
static int	TO_LAT_LONG Indicates a transformation to longitude/latitude

Constructor Summary

Constructors

Constructor and Description
UTM(Ellipsoid ellipsoid, float lat, float lng) Initialises the UTM converter with the given ellipsoid.
UTM(Ellipsoid ellipsoid, int zoneNumber, char zoneLetter) Initialises the UTM converter with the given ellipsoid and zone.

Method Summary

Modifier and Type	Method and Description
boolean	doInterpolation() Indicates whether the transformation should use nearest neighbour (false) or some interpolator (true).
java.lang.String	getDescription() Provides a general description of the transformation.
Ellipsoid	getEllipsoid() Reports the ellipsoid used in the transformation.
java.lang.String	getZone() Reports the full UTM zone of currently used by the projection.
char	getZoneLetter() Reports the UTM zone letter currently used by the projection.
int	getZoneNumber() Reports the UTM zone currently used by the projection.
processing.core.PVector	invTransformCoords(processing.core.PVector p) Performs an inverse UTM transform on the given location.
processing.core.PVector	latLongToUTM(processing.core.PVector p) Converts the given (lat,lng) coordinates into a UTM location.
processing.core.PVector	latLongToUTM(processing.core.PVector p, double lngOrigin, double latOrigin, double xOffset, double yOffset, double scaleFactor) Converts the given (lng,lat) coordinates into a UTM location using the given scale factor and origins.
void	setInterpolation(boolean doInterpolation) Sets whether the transformation should use nearest neighbour (false) or some interpolator (true).
void	setZone(float lat, float lng) Sets the UTM zone determined by the given (lat,lng) location.
void	setZone(int zoneNumber, char zoneLetter) Sets the zone number and letter for subsequent transformations.
processing.core.PVector	transformCoords(processing.core.PVector p) Performs a forward transform on the given location.
processing.core.PVector	UTMToLatLong(processing.core.PVector p) Converts the given UTM coordinates into a longitude/latitude location.
processing.core.PVector	UTMToLatLong(processing.core.PVector p, double lngOrigin, double latOrigin, double xOffset, double yOffset, double scaleFactor) Converts the given UTM coordinates into a (lng,lat) referenced location.

Methods inherited from class java.lang.Object

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

Field Detail

FROM_LAT_LONG

public static final int FROM_LAT_LONG

Indicates a transformation from longitude/latitude

See Also:

Constant Field Values

TO_LAT_LONG

public static final int TO_LAT_LONG

Indicates a transformation to longitude/latitude

See Also:

Constant Field Values

Constructor Detail

UTM

public UTM(Ellipsoid ellipsoid,
           int zoneNumber,
           char zoneLetter)

Initialises the UTM converter with the given ellipsoid and zone. The forward transformation will be from UTM to longitude/latitude.

Parameters:

ellipsoid - to use in projection.

zoneNumber - Zone number of UTM projection.

zoneLetter - Zone letter of UTM projection.

UTM

public UTM(Ellipsoid ellipsoid,
           float lat,
           float lng)

Initialises the UTM converter with the given ellipsoid. The initial longitude/latitude location sets the default UTM zone. This can be changed by calling the setZone() method. The forward transformation will be from longitude/latitude to UTM.

Parameters:

ellipsoid - to use in projection.

lat - Initial latitude coordinate.

lng - Initial longitude coordinate.

Method Detail

transformCoords

public processing.core.PVector transformCoords(processing.core.PVector p)

Performs a forward transform on the given location.

Specified by:

transformCoords in interface MapProjection

Parameters:

p - Point coordinates to transform.

Returns:

Transformed footprint.

invTransformCoords

public processing.core.PVector invTransformCoords(processing.core.PVector p)

Performs an inverse UTM transform on the given location.

Specified by:

invTransformCoords in interface MapProjection

Parameters:

p - Point coordinates to transform.

Returns:

Transformed footprint.

getDescription

public java.lang.String getDescription()

Provides a general description of the transformation.

Specified by:

getDescription in interface MapProjection

Returns:

Description of the transformation.

doInterpolation

public boolean doInterpolation()

Indicates whether the transformation should use nearest neighbour (false) or some interpolator (true).

Returns:

True if transformation should perform some local interpolation.

setInterpolation

public void setInterpolation(boolean doInterpolation)

Sets whether the transformation should use nearest neighbour (false) or some interpolator (true).

Parameters:

doInterpolation - True if transformation should perform some local interpolation.

latLongToUTM

public processing.core.PVector latLongToUTM(processing.core.PVector p)

Converts the given (lat,lng) coordinates into a UTM location. longitude/latitude should be in decimal degrees with positive North and positive East. The UTM zone to use should already have been set though the constructor or a call to setzone().

Parameters:

p - Longitude/latitude point. Longitude varies within +-180 degrees, latitude within +-90 degrees.

Returns:

UTM location.

latLongToUTM

public processing.core.PVector latLongToUTM(processing.core.PVector p,
                                            double lngOrigin,
                                            double latOrigin,
                                            double xOffset,
                                            double yOffset,
                                            double scaleFactor)

Converts the given (lng,lat) coordinates into a UTM location using the given scale factor and origins. longitude/latitude should be in decimal degrees with positive North and positive East. This version of the conversion does not require a UTM zone to be set as the origin is set explicitly.

Parameters:

p - Longitude/latitude point. Longitude varies within +-180 degrees, latitude within +-90 degrees.

lngOrigin - Origin longitude (+-180.0).

latOrigin - Origin latitude (+-90.0).

xOffset - UTM coordinate X origin.

yOffset - UTM coordinate Y origin.

scaleFactor - Scale factor on central meridian used in transformation.

Returns:

UTM location.

UTMToLatLong

public processing.core.PVector UTMToLatLong(processing.core.PVector p)

Converts the given UTM coordinates into a longitude/latitude location. This requires a UTM zone to have been set (via constructor) in order to complete the conversion. longitude/latitude will be in decimal degrees with positive North and positive East.

Parameters:

p - Location of point as an easting and northing in the UTM projection (metres from local origin).

Returns:

location in geographical coordinates (longitude,latitude).

UTMToLatLong

public processing.core.PVector UTMToLatLong(processing.core.PVector p,
                                            double lngOrigin,
                                            double latOrigin,
                                            double xOffset,
                                            double yOffset,
                                            double scaleFactor)

Converts the given UTM coordinates into a (lng,lat) referenced location. Longitude/latitude will be in decimal degrees with positive North and positive East. This transformation is independent of the UTM zone defined by the constructor since all parameters are given explicitly.

Parameters:

p - Location of point as an easting and northing in the UTM projection (metres from local origin).

lngOrigin - Origin longitude (+-180)

latOrigin - Origin latitude (+-90)

xOffset - UTM coordinate X origin.

yOffset - UTM coordinate Y origin.

scaleFactor - Scale factor on central meridian used in transformation.

Returns:

location in geographical coordinates (longitude,latitude).

setZone

public void setZone(float lat,
                    float lng)

Sets the UTM zone determined by the given (lat,lng) location. Numbers vary from 1 to 60, where 1 is around 175W, and 60 is 175E. Letters vary from N,M,O...X going north from equator and M,L,K...C going south from equator.

Parameters:

lat - Latitude (+-90)

lng - Longitude (+-180)

setZone

public void setZone(int zoneNumber,
                    char zoneLetter)

Sets the zone number and letter for subsequent transformations.

Parameters:

zoneNumber - Zone number to use.

zoneLetter - Zone letter to use.

getZoneNumber

public int getZoneNumber()

Reports the UTM zone currently used by the projection. Numbers vary from 1 to 60, where 1 is around 175W, and 60 is 175E.

Returns:

UTM zone number (longitudinal zone).

getZoneLetter

public char getZoneLetter()

Reports the UTM zone letter currently used by the projection. Letters vary from N,M,O...X going north from equator and M,L,K...C going south from equator. Returns Z if outside 84N or 80S.

Returns:

UTM zone letter (latitudinal zone).

getZone

public java.lang.String getZone()

Reports the full UTM zone of currently used by the projection.

Returns:

UTM zone (e.g 19F for southern tip of South America).

getEllipsoid

public Ellipsoid getEllipsoid()

Reports the ellipsoid used in the transformation.

Returns:

Ellipsoid used in the UTM transformation.