ucar.unidata.geoloc.projection

Class FlatEarth

java.lang.Object

ucar.unidata.geoloc.projection.AbstractProjection

ucar.unidata.geoloc.projection.FlatEarth

All Implemented Interfaces:

Projection

@Immutable
public class FlatEarth
extends AbstractProjection

FlatEarth Projection This projection surface is tangent at some point (lat0, lon0) and has a y axis rotated from true North by some angle.

We call it "flat" because it should only be used where the spherical geometry of the earth is not significant. In actuallity, we use the simple "arclen" routine which computes dy along a meridian, and dx along a latitude circle. We rotate the coordinate system to/from a true north system.

See John Snyder, Map Projections used by the USGS, Bulletin 1532, 2nd edition (1983), p 145

Field Summary

Fields

Modifier and Type	Field and Description
static String	ROTATIONANGLE

Fields inherited from class ucar.unidata.geoloc.projection.AbstractProjection

atts, EARTH_RADIUS, INDEX_LAT, INDEX_LON, INDEX_X, INDEX_Y, isLatLon, name, PI, PI_OVER_2, PI_OVER_4, TOLERANCE

Constructor Summary

Constructors

Constructor and Description
FlatEarth() Constructor with default parameters
FlatEarth(double lat0, double lon0)
FlatEarth(double lat0, double lon0, double rotAngle)
FlatEarth(double lat0, double lon0, double rotAngle, double radius) Construct a FlatEarth Projection, two standard parellels.

Method Summary

Modifier and Type	Method and Description
Projection	constructCopy() copy constructor - avoid clone !!
boolean	crossSeam(ProjectionPoint pt1, ProjectionPoint pt2) This returns true when the line between pt1 and pt2 crosses the seam.
boolean	equals(Object o)
double	getOriginLat() Get the origin latitude in degrees.
double	getOriginLon() Get the origin longitude in degrees.
String	getProjectionTypeLabel() Get the label to be used in the gui for this type of projection.
double	getRotationAngle() Get the rotation angle.
int	hashCode()
ProjectionPoint	latLonToProj(LatLonPoint latLon) Convert a LatLonPoint to projection coordinates.
String	paramsToString() String representation of the projection parameters.
LatLonPoint	projToLatLon(ProjectionPoint world) Convert projection coordinates to a LatLonPoint.
String	toString() Get a String representation of this projection.

Methods inherited from class ucar.unidata.geoloc.projection.AbstractProjection

addParameter, addParameter, addParameter, addParameter, findProjectionParameter, getClassName, getHeader, getMinOrMaxLon, getName, getProjectionAttributes, getProjectionParameters, isLatLon, latLonToProjBB, projToLatLonBB

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface ucar.unidata.geoloc.Projection

latLonToProj, projToLatLon

Field Detail

ROTATIONANGLE

public static final String ROTATIONANGLE

See Also:

Constant Field Values

Constructor Detail

FlatEarth

public FlatEarth()

Constructor with default parameters

FlatEarth

public FlatEarth(double lat0,
                 double lon0)

FlatEarth

public FlatEarth(double lat0,
                 double lon0,
                 double rotAngle)

FlatEarth

public FlatEarth(double lat0,
                 double lon0,
                 double rotAngle,
                 double radius)

Construct a FlatEarth Projection, two standard parellels. For the one standard parellel case, set them both to the same value.

Parameters:

lat0 - lat origin of the coord. system on the projection plane

lon0 - lon origin of the coord. system on the projection plane

rotAngle - angle of rotation, in degrees

radius - earth radius in km

Throws:

IllegalArgumentException - if lat0, par1, par2 = +/-90 deg

Method Detail

constructCopy

public Projection constructCopy()

Description copied from class: AbstractProjection

copy constructor - avoid clone !!

Specified by:

constructCopy in class AbstractProjection

Returns:

a copy of this Projection.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

getOriginLon

public double getOriginLon()

Get the origin longitude in degrees.

Returns:

the origin longitude in degrees.

getOriginLat

public double getOriginLat()

Get the origin latitude in degrees.

Returns:

the origin latitude in degrees.

getRotationAngle

public double getRotationAngle()

Get the rotation angle.

Returns:

the origin latitude.

getProjectionTypeLabel

public String getProjectionTypeLabel()

Description copied from class: AbstractProjection

Get the label to be used in the gui for this type of projection. This defaults to call getClassName

Overrides:

getProjectionTypeLabel in class AbstractProjection

Returns:

Type label

paramsToString

public String paramsToString()

Description copied from interface: Projection

String representation of the projection parameters.

Specified by:

paramsToString in interface Projection

Specified by:

paramsToString in class AbstractProjection

toString

public String toString()

Description copied from class: AbstractProjection

Get a String representation of this projection.

Overrides:

toString in class AbstractProjection

Returns:

the name of the projection. This is what gets displayed when you add the projection object to a UI widget (e.g. label, combobox)

latLonToProj

public ProjectionPoint latLonToProj(LatLonPoint latLon)

Description copied from interface: Projection

Convert a LatLonPoint to projection coordinates.

projToLatLon

public LatLonPoint projToLatLon(ProjectionPoint world)

Description copied from interface: Projection

Convert projection coordinates to a LatLonPoint.

crossSeam

public boolean crossSeam(ProjectionPoint pt1,
                         ProjectionPoint pt2)

This returns true when the line between pt1 and pt2 crosses the seam. When the cone is flattened, the "seam" is lon0 +- 180.

Parameters:

pt1 - the line goes between these two points

pt2 - the line goes between these two points

Returns:

false if there is no seam, or the line does not cross it.