Package gov.nasa.worldwind.globes.projections

Class ProjectionTransverseMercator

java.lang.Object

gov.nasa.worldwind.globes.projections.AbstractGeographicProjection

gov.nasa.worldwind.globes.projections.ProjectionTransverseMercator

All Implemented Interfaces:

GeographicProjection

Direct Known Subclasses:

ProjectionUTM

public class ProjectionTransverseMercator
extends AbstractGeographicProjection

Provides a Transverse Mercator ellipsoidal projection using the WGS84 ellipsoid. The projection's central meridian may be specified and defaults to the Prime Meridian (0 longitude). By default, the projection computes values for 30 degrees either side of the central meridian. This may be changed via the setWidth(gov.nasa.worldwind.geom.Angle) method, but the projection may fail for large widths.

The projection limits are modified to reflect the central meridian and the width, however the projection limits are clamped to a minimum of -180 degrees and a maximum of +180 degrees. It's therefore not possible to display a band whose central meridian is plus or minus 180.

Field Summary

Fields

Modifier and Type	Field	Description
protected Angle	centralLatitude
protected Angle	centralMeridian
protected static Angle	DEFAULT_CENTRAL_LATITUDE
protected static Angle	DEFAULT_CENTRAL_MERIDIAN
protected static Angle	DEFAULT_WIDTH
protected Angle	width

Fields inherited from class gov.nasa.worldwind.globes.projections.AbstractGeographicProjection

projectionLimits

Constructor Summary

Constructors

Constructor	Description
ProjectionTransverseMercator()	Creates a projection whose central meridian is the Prime Meridian and central latitude is 0.
ProjectionTransverseMercator(Angle centralMeridian)	Creates a projection with a specified central meridian and a central latitude of 0.
ProjectionTransverseMercator(Angle centralMeridian, Angle centralLatitude)	Creates a projection with a specified central meridian and central latitude.

Method Summary

Modifier and Type	Method	Description
Position	cartesianToGeographic(Globe globe, Vec4 cart, Vec4 offset)	Converts a Cartesian point in meters to a geographic position.
boolean	equals(java.lang.Object o)
Vec4	geographicToCartesian(Globe globe, Angle latitude, Angle longitude, double metersElevation, Vec4 offset)	Converts a geographic position to meters in Cartesian coordinates.
void	geographicToCartesian(Globe globe, Sector sector, int numLat, int numLon, double[] metersElevation, Vec4 offset, Vec4[] out)	Converts a grid of geographic positions to a grid of points in Cartesian coordinates.
Angle	getCentralLatitude()	Indicates this projection's central latitude.
Angle	getCentralMeridian()	Indicates this projection's central meridian.
java.lang.String	getName()	Returns the projection name.
protected double	getScale()
Angle	getWidth()	Indicates the region in which positions are mapped.
int	hashCode()
boolean	isContinuous()	Indicates whether it makes sense to treat this projection as contiguous with itself.
protected static Sector	makeProjectionLimits(Angle centralMeridian, Angle width)
Vec4	northPointingTangent(Globe globe, Angle latitude, Angle longitude)	Computes a Cartesian vector that points north and is tangent to the meridian at the specified geographic location.
void	setCentralLatitude(Angle centralLatitude)	Set this projection's central latitude.
void	setCentralMeridian(Angle centralMeridian)	Specifies this projections central meridian.
void	setWidth(Angle width)	Specifies the region in which positions are mapped.

Methods inherited from class gov.nasa.worldwind.globes.projections.AbstractGeographicProjection

getProjectionLimits, setProjectionLimits

Methods inherited from class java.lang.Object

clone, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_WIDTH

protected static Angle DEFAULT_WIDTH

DEFAULT_CENTRAL_MERIDIAN

protected static Angle DEFAULT_CENTRAL_MERIDIAN

DEFAULT_CENTRAL_LATITUDE

protected static Angle DEFAULT_CENTRAL_LATITUDE

width

protected Angle width

centralMeridian

protected Angle centralMeridian

centralLatitude

protected Angle centralLatitude

Constructor Detail

ProjectionTransverseMercator

public ProjectionTransverseMercator()

Creates a projection whose central meridian is the Prime Meridian and central latitude is 0.

ProjectionTransverseMercator

public ProjectionTransverseMercator(Angle centralMeridian)

Creates a projection with a specified central meridian and a central latitude of 0.

Parameters:

centralMeridian - The projection's central meridian.

ProjectionTransverseMercator

public ProjectionTransverseMercator(Angle centralMeridian,
                                    Angle centralLatitude)

Creates a projection with a specified central meridian and central latitude.

Parameters:

centralMeridian - The projection's central meridian.

centralLatitude - The projection's central latitude.

Method Detail

getName

public java.lang.String getName()

Description copied from interface: GeographicProjection

Returns the projection name.

Returns:

The projection name.

getCentralMeridian

public Angle getCentralMeridian()

Indicates this projection's central meridian.

Returns:

This projection's central meridian.

setCentralMeridian

public void setCentralMeridian(Angle centralMeridian)

Specifies this projections central meridian.

Parameters:

centralMeridian - This projection's central meridian. The default is 0.

getCentralLatitude

public Angle getCentralLatitude()

Indicates this projection's central latitude.

Returns:

This projection's central latitude.

setCentralLatitude

public void setCentralLatitude(Angle centralLatitude)

Set this projection's central latitude.

Parameters:

centralLatitude - This projection's central latitude. The default is 0.

getWidth

public Angle getWidth()

Indicates the region in which positions are mapped. The default is 30 degrees either side of this projection's central meridian.

Returns:

This projection's width.

setWidth

public void setWidth(Angle width)

Specifies the region in which positions are mapped. The default is 30 degrees either side of this projection's central meridian.

Parameters:

width - This projection's width.

makeProjectionLimits

protected static Sector makeProjectionLimits(Angle centralMeridian,
                                             Angle width)

getScale

protected double getScale()

geographicToCartesian

public Vec4 geographicToCartesian(Globe globe,
                                  Angle latitude,
                                  Angle longitude,
                                  double metersElevation,
                                  Vec4 offset)

Description copied from interface: GeographicProjection

Converts a geographic position to meters in Cartesian coordinates.

Note: The input arguments are not checked for null prior to being used. The caller, typically a Globe2D implementation, is expected do perform that check prior to calling this method.

Parameters:

globe - The globe this projection is applied to.

latitude - The latitude of the position.

longitude - The longitude of the position.

metersElevation - The elevation of the position, in meters.

offset - An optional offset to be applied to the Cartesian output. Typically only projections that are continuous (see GeographicProjection.isContinuous() apply this offset. Others ignore it. May be null.

Returns:

The Cartesian point, in meters, corresponding to the input position.

See Also:

GeographicProjection.cartesianToGeographic(Globe, gov.nasa.worldwind.geom.Vec4, gov.nasa.worldwind.geom.Vec4)

geographicToCartesian

public void geographicToCartesian(Globe globe,
                                  Sector sector,
                                  int numLat,
                                  int numLon,
                                  double[] metersElevation,
                                  Vec4 offset,
                                  Vec4[] out)

Description copied from interface: GeographicProjection

Converts a grid of geographic positions to a grid of points in Cartesian coordinates.

This method provides an interface for efficient generation of a grid of cartesian points within a sector. The grid is constructed by dividing the sector into numLon x numLat evenly separated points in geographic coordinates. The first and last points in latitude and longitude are placed at the sector's minimum and maximum boundary, and the remaining points are spaced evenly between those boundary points.

For each grid point within the sector, an elevation value is specified via an array of elevations. The calculation at each position incorporates the associated elevation.

Parameters:

globe - The globe this projection is applied to.

sector - The sector over which to generate the points.

numLat - The number of points to generate latitudinally.

numLon - The number of points to generate longitudinally.

metersElevation - An array of elevations to incorporate in the point calculations. There must be one elevation value in the array for each generated point, so the array must have a length of at least numLon x numLat. Elevations are read from this array in row major order, beginning with the row of minimum latitude.

offset - An optional offset to be applied to the Cartesian output. Typically only projections that are continuous (see GeographicProjection.isContinuous() apply this offset. Others ignore it. May be null.

out - An array to hold the computed cartesian points. It must have a length of at least numLon x numLat. Points are written to this array in row major order, beginning with the row of minimum latitude.

cartesianToGeographic

public Position cartesianToGeographic(Globe globe,
                                      Vec4 cart,
                                      Vec4 offset)

Description copied from interface: GeographicProjection

Converts a Cartesian point in meters to a geographic position.

Note: The input arguments are not checked for null prior to being used. The caller, typically a Globe2D implementation, is expected do perform that check prior to calling this method.

Parameters:

globe - The globe this projection is applied to.

cart - The Cartesian point, in meters.

offset - An optional offset to be applied to the Cartesian input prior to converting it. Typically only projections that are continuous (see GeographicProjection.isContinuous() apply this offset. Others ignore it. May be null.

Returns:

The geographic position corresponding to the input point.

See Also:

GeographicProjection.geographicToCartesian(Globe, gov.nasa.worldwind.geom.Angle, gov.nasa.worldwind.geom.Angle, double, gov.nasa.worldwind.geom.Vec4)

northPointingTangent

public Vec4 northPointingTangent(Globe globe,
                                 Angle latitude,
                                 Angle longitude)

Description copied from interface: GeographicProjection

Computes a Cartesian vector that points north and is tangent to the meridian at the specified geographic location.

Parameters:

globe - The globe this projection is applied to.

latitude - The latitude of the location.

longitude - The longitude of the location.

Returns:

The north pointing tangent corresponding to the input location.

isContinuous

public boolean isContinuous()

Description copied from interface: GeographicProjection

Indicates whether it makes sense to treat this projection as contiguous with itself. If true, the scene controller will make the globe using the projection appear to scroll continuously horizontally.

Returns:

true if it makes sense to treat this projection as continuous, otherwise false.

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object