prajna.geo

Class Projection

java.lang.Object

prajna.geo.Projection

Direct Known Subclasses:

Equirect, Mercator, Miller, Orthographic, StretchRect

public abstract class Projection
extends java.lang.Object

Abstract class for all geographic projections. A projection is defined by its type, and the area the earth's surface is being projected onto. The projection algorithms are consistent with the Java-style coordinate system with the origin in the upper left corner.

Author:

Edward Swing

Constructor Summary

Constructors

Constructor and Description
Projection()

Method Summary

Methods

Modifier and Type	Method and Description
abstract GeoCoord	getCoord(java.awt.Point point) Get the geographic coordinate which projects to the given screen coordinate.
GeoBounds	getGeoBounds() Get the geographic bounds for the projection.
Geoid	getGeoid() Get the geoid used for projections.
GeoCoord	getProjCenter() Get the center of projection
java.awt.Rectangle	getViewBounds() Get the view bounds.
abstract java.awt.Shape	getWorldShape() Get the world shape for this projection.
abstract java.awt.Point	project(GeoCoord coord) Project a geographic coordinate into screen coordinates
abstract java.awt.Point[]	project(GeoCoord[] coords) Project a series of geographic coordinate into screen coordinates.
protected abstract void	rescale() Rescales the projection.
void	setGeoBounds(GeoBounds bounds) Set the geographic bounds for the projection.
void	setGeoid(Geoid projGeoid) Set the geoid used for projections.
void	setProjCenter(GeoCoord projCenter) Set the center of projection
void	setViewBounds(java.awt.Rectangle bounds) Set the view bounds.
java.lang.String	toString() Provide a string representation of the projection.

Methods inherited from class java.lang.Object

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

Constructor Detail

Projection

public Projection()

Method Detail

getCoord

public abstract GeoCoord getCoord(java.awt.Point point)
                           throws ProjectionException

Get the geographic coordinate which projects to the given screen coordinate.

Parameters:

point - a point in screen coordinates

Returns:

the geographic coordinate

Throws:

ProjectionException - if the reverse projection cannot be performed

getGeoBounds

public GeoBounds getGeoBounds()

Get the geographic bounds for the projection. The exact area displayed is dependent on the projection.

Returns:

the geographic bounds

getGeoid

public Geoid getGeoid()

Get the geoid used for projections.

Returns:

the geoid

getProjCenter

public GeoCoord getProjCenter()

Get the center of projection

Returns:

the center of projection

getViewBounds

public java.awt.Rectangle getViewBounds()

Get the view bounds. This should return the bounds in view coordinates - e.g., pixels on the screen

Returns:

the view bounds

getWorldShape

public abstract java.awt.Shape getWorldShape()

Get the world shape for this projection. This method determines the shape of the world extent, and returns the corresponding shape.

Returns:

the shape of the world extent.

project

public abstract java.awt.Point project(GeoCoord coord)
                                throws ProjectionException

Project a geographic coordinate into screen coordinates

Parameters:

coord - the geographic coordinate

Returns:

the screen coordinate

Throws:

ProjectionException - if the projection cannot be performed

project

public abstract java.awt.Point[] project(GeoCoord[] coords)

Project a series of geographic coordinate into screen coordinates. If a coordinate cannot be performed for a particular coordinate, a null value should be placed in the resulting array for the coordinate.

Parameters:

coords - the geographic coordinates

Returns:

the series of screen coordinates

rescale

protected abstract void rescale()

Rescales the projection. This method is called whenever the extents are changed. Projections should ensure that any scaling values are updated as a result of this method call.

setGeoBounds

public void setGeoBounds(GeoBounds bounds)

Set the geographic bounds for the projection. The exact area displayed is dependent on the projection. The bounds are in radian coordinates

Parameters:

bounds - the geographic bounds

setGeoid

public void setGeoid(Geoid projGeoid)

Set the geoid used for projections. In most cases, the default geoid, with a spherical earth, should provide enough accuracy. Other geoids are useful if precisely accurate measurements are necessary.

Parameters:

projGeoid - the geoid representing the earth or other body

setProjCenter

public void setProjCenter(GeoCoord projCenter)

Set the center of projection

Parameters:

projCenter - the center of projection

setViewBounds

public void setViewBounds(java.awt.Rectangle bounds)

Set the view bounds. The view bounds are specified in view coordinates - e.g., pixels on the screen

Parameters:

bounds - the view bounds for the projection

toString

public java.lang.String toString()

Provide a string representation of the projection. The default implementation simply returns the class name.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of the projection