ucar.unidata.geoloc.projection

Class FlatEarth

java.lang.Object

ucar.unidata.geoloc.ProjectionImpl

ucar.unidata.geoloc.projection.FlatEarth

All Implemented Interfaces:

Serializable, Projection

public class FlatEarth
extends ProjectionImpl

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

Author:

Unidata Development Team

See Also:

Projection, ProjectionImpl, Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static String	ROTATIONANGLE

Fields inherited from class ucar.unidata.geoloc.ProjectionImpl

atts, defaultMapArea, 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

Methods

Modifier and Type	Method and Description
ProjectionImpl	constructCopy() origin
boolean	crossSeam(ProjectionPoint pt1, ProjectionPoint pt2) This returns true when the line between pt1 and pt2 crosses the seam.
boolean	equals(Object o) Returns true if this represents the same Projection as proj.
double	getOriginLat() Get the origin latitude.
double	getOriginLon() Get the origin longitude.
String	getProjectionTypeLabel() Get the label to be used in the gui for this type of projection
double	getRotationAngle() Get the rotation angle.
int	hashCode()
double[][]	latLonToProj(double[][] from, double[][] to, int latIndex, int lonIndex) Convert lat/lon coordinates to projection coordinates.
float[][]	latLonToProj(float[][] from, float[][] to, int latIndex, int lonIndex) Convert lat/lon coordinates to projection coordinates.
ProjectionPoint	latLonToProj(LatLonPoint latLon, ProjectionPointImpl result) Convert a LatLonPoint to projection coordinates
static void	main(String[] args) Test
String	paramsToString() Create a String of the parameters.
double[][]	projToLatLon(double[][] from, double[][] to) Convert lat/lon coordinates to projection coordinates.
float[][]	projToLatLon(float[][] from, float[][] to) Convert lat/lon coordinates to projection coordinates.
LatLonPoint	projToLatLon(ProjectionPoint world, LatLonPointImpl result) Convert projection coordinates to a LatLonPoint Note: a new object is not created on each call for the return value.
String	toString() Get a String representation of this projection.

Methods inherited from class ucar.unidata.geoloc.ProjectionImpl

addParameter, addParameter, addParameter, findProjectionParameter, getClassName, getDefaultMapArea, getDefaultMapAreaLL, getHeader, getName, getProjectionParameters, isLatLon, latLonToProj, latLonToProj, latLonToProj, latLonToProj, latLonToProj, latLonToProj, latLonToProj, latLonToProj, latLonToProjBB, projToLatLon, projToLatLon, projToLatLon, projToLatLon, projToLatLonBB, projToLatLonBBold, setDefaultMapArea, setName

Methods inherited from class java.lang.Object

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

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 ProjectionImpl constructCopy()

origin

Specified by:

constructCopy in class ProjectionImpl

Returns:

a copy of this Projection

equals

public boolean equals(Object o)

Description copied from class: ProjectionImpl

Returns true if this represents the same Projection as proj.

Specified by:

equals in interface Projection

Specified by:

equals in class ProjectionImpl

Parameters:

o - projection in question

Returns:

true if this represents the same Projection as proj.

hashCode

public int hashCode()

Overrides:

hashCode in class Object

getOriginLon

public double getOriginLon()

Get the origin longitude.

Returns:

the origin longitude.

getOriginLat

public double getOriginLat()

Get the origin latitude.

Returns:

the origin latitude.

getRotationAngle

public double getRotationAngle()

Get the rotation angle.

Returns:

the origin latitude.

getProjectionTypeLabel

public String getProjectionTypeLabel()

Get the label to be used in the gui for this type of projection

Overrides:

getProjectionTypeLabel in class ProjectionImpl

Returns:

Type label

paramsToString

public String paramsToString()

Create a String of the parameters.

Specified by:

paramsToString in interface Projection

Specified by:

paramsToString in class ProjectionImpl

Returns:

a String of the parameters

toString

public String toString()

Description copied from class: ProjectionImpl

Get a String representation of this projection.

Overrides:

toString in class ProjectionImpl

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,
                           ProjectionPointImpl result)

Convert a LatLonPoint to projection coordinates

Specified by:

latLonToProj in interface Projection

Specified by:

latLonToProj in class ProjectionImpl

Parameters:

latLon - convert from these lat, lon coordinates

result - the object to write to

Returns:

the given result

projToLatLon

public LatLonPoint projToLatLon(ProjectionPoint world,
                       LatLonPointImpl result)

Convert projection coordinates to a LatLonPoint Note: a new object is not created on each call for the return value.

Specified by:

projToLatLon in interface Projection

Specified by:

projToLatLon in class ProjectionImpl

Parameters:

world - convert from these projection coordinates

result - the object to write to

Returns:

LatLonPoint convert to these lat/lon coordinates

latLonToProj

public float[][] latLonToProj(float[][] from,
                     float[][] to,
                     int latIndex,
                     int lonIndex)

Convert lat/lon coordinates to projection coordinates.

Overrides:

latLonToProj in class ProjectionImpl

Parameters:

from - array of lat/lon coordinates: from[2][n], where from[0][i], from[1][i] is the (lat,lon) coordinate of the ith point

to - resulting array of projection coordinates, where to[0][i], to[1][i] is the (x,y) coordinate of the ith point

latIndex - index of latitude in "from"

lonIndex - index of longitude in "from"

Returns:

the "to" array.

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.

Specified by:

crossSeam in interface Projection

Specified by:

crossSeam in class ProjectionImpl

Parameters:

pt1 - point 1

pt2 - point 2

Returns:

true when the line between pt1 and pt2 crosses the seam.

projToLatLon

public float[][] projToLatLon(float[][] from,
                     float[][] to)

Convert lat/lon coordinates to projection coordinates.

Overrides:

projToLatLon in class ProjectionImpl

Parameters:

from - array of lat/lon coordinates: from[2][n], where (from[0][i], from[1][i]) is the (lat,lon) coordinate of the ith point

to - resulting array of projection coordinates: to[2][n] where (to[0][i], to[1][i]) is the (x,y) coordinate of the ith point

Returns:

the "to" array

latLonToProj

public double[][] latLonToProj(double[][] from,
                      double[][] to,
                      int latIndex,
                      int lonIndex)

Convert lat/lon coordinates to projection coordinates.

Overrides:

latLonToProj in class ProjectionImpl

Parameters:

from - array of lat/lon coordinates: from[2][n], where from[0][i], from[1][i] is the (lat,lon) coordinate of the ith point

to - resulting array of projection coordinates, where to[0][i], to[1][i] is the (x,y) coordinate of the ith point

latIndex - index of latitude in "from"

lonIndex - index of longitude in "from"

Returns:

the "to" array.

projToLatLon

public double[][] projToLatLon(double[][] from,
                      double[][] to)

Convert lat/lon coordinates to projection coordinates.

Overrides:

projToLatLon in class ProjectionImpl

Parameters:

from - array of lat/lon coordinates: from[2][n], where (from[0][i], from[1][i]) is the (lat,lon) coordinate of the ith point

to - resulting array of projection coordinates: to[2][n] where (to[0][i], to[1][i]) is the (x,y) coordinate of the ith point

Returns:

the "to" array

main

public static void main(String[] args)

Test

Parameters:

args - not used