Class MapProjection
 Object

 Formattable

 AbstractMathTransform

 MapProjection

 All Implemented Interfaces:
Serializable
,MathTransform
,MathTransform2D
 Direct Known Subclasses:
AlbersEqualArea
,AzimuthalEquidistant.Abstract
,CassiniSoldner
,CylindricalEqualArea
,EckertIV
,EqualArea
,EquidistantConic
,EquidistantCylindrical
,GeneralOblique
,GeostationarySatellite
,Gnomonic
,Homolosine
,Krovak
,LambertAzimuthalEqualArea
,LambertConformal
,Mercator
,MeteosatSG
,Mollweide
,NewZealandMapGrid
,ObliqueMercator
,Orthographic
,Polyconic.Abstract
,Robinson
,RotatedPole
,Sinusoidal
,Stereographic
,TransverseMercator
,WinkelTripel
,WorldVanDerGrintenI
public abstract class MapProjection extends AbstractMathTransform implements MathTransform2D, Serializable
Base class for transformation services between ellipsoidal and cartographic projections. This base class provides the basic feature needed for all methods (no need to overrides methods). Subclasses must "only" implements the following methods:getParameterValues()
transformNormalized(double, double, java.awt.geom.Point2D)
inverseTransformNormalized(double, double, java.awt.geom.Point2D)
NOTE:Serialization of this class is appropriate for shortterm storage or RMI use, but will probably not be compatible with future version. For long term storage, WKT (Well Know Text) or XML (not yet implemented) are more appropriate.
 Since:
 2.0
 Author:
 André Gosselin, Martin Desruisseaux (PMO, IRD), Rueben Schulz
 See Also:
 Map projections on MathWorld, Map projections on the atlas of Canada, Serialized Form


Nested Class Summary
Nested Classes Modifier and Type Class Description static class
MapProjection.AbstractProvider
The base provider forMapProjection
s.

Field Summary
Fields Modifier and Type Field Description protected double
centralMeridian
Central longitude in radians.protected double
en0
Constant needed for themlfn
method.
protected double
en1
Constant needed for themlfn
method.
protected double
en2
Constant needed for themlfn
method.
protected double
en3
Constant needed for themlfn
method.
protected double
en4
Constant needed for themlfn
method.
protected double
excentricity
Ellipsoid excentricity, equals tosqrt(
.excentricitySquared
)protected double
excentricitySquared
The square of excentricity: e² = (a²b²)/a² where e is the excentricity, a is the semi major axis length and b is the semi minor axis length.protected double
falseEasting
False easting, in metres.protected double
falseNorthing
False northing, in metres.protected double
globalScale
Global scale factor.protected boolean
invertible
Marks if the projection is invertible.protected boolean
isSpherical
true
if this projection is spherical.protected double
latitudeOfOrigin
Latitude of origin in radians.protected static Logger
LOGGER
The projection package loggerprotected double
scaleFactor
The scale factor.protected double
semiMajor
Length of semimajor axis, in metres.protected double
semiMinor
Length of semiminor axis, in metres.static boolean
SKIP_SANITY_CHECKS
A global variable use to disable the reciprocal distance checks made when assertions are enabled.
Fields inherited from class Formattable
SINGLE_LINE


Constructor Summary
Constructors Modifier Constructor Description protected
MapProjection(ParameterValueGroup values)
Constructs a new map projection from the suplied parameters.

Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description protected boolean
checkReciprocal(Point2D point, Point2D target, boolean inverse)
Check if the transform ofpoint
is close enough totarget
.boolean
equals(Object object)
Compares the specified object with this map projection for equality.abstract ParameterDescriptorGroup
getParameterDescriptors()
Returns the parameter descriptors for this map projection.ParameterValueGroup
getParameterValues()
Returns the parameter values for this map projection.int
getSourceDimensions()
Returns the dimension of input points.int
getTargetDimensions()
Returns the dimension of output points.protected double
getToleranceForAssertions(double longitude, double latitude)
Maximal error (in metres) tolerated for assertions, if enabled.int
hashCode()
Returns a hash value for this map projection.protected double
inv_mlfn(double arg)
Calculates the latitude (phi
) from a meridian distance.MathTransform2D
inverse()
Returns the inverse of this map projection.protected abstract Point2D
inverseTransformNormalized(double x, double y, Point2D ptDst)
Transforms the specified coordinate and stores the result inptDst
.protected double
mlfn(double phi, double sphi, double cphi)
Calculates the meridian distance.protected double
orthodromicDistance(Point2D source, Point2D target)
Returns the orthodromic distance between the two specified points using a spherical approximation.static void
resetWarnings()
Resets the warning status of all projections in the current JVM.void
transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts)
Transforms a list of coordinate point ordinal values.void
transform(float[] srcPts, int srcOff, float[] dstPts, int dstOff, int numPts)
Transforms a list of coordinate point ordinal values.Point2D
transform(Point2D ptSrc, Point2D ptDst)
Transforms the specifiedptSrc
and stores the result inptDst
.protected abstract Point2D
transformNormalized(double lambda, double phi, Point2D ptDst)
Transforms the specified coordinate and stores the result inptDst
.
Methods inherited from class AbstractMathTransform
createTransformedShape, derivative, derivative, ensureNonNull, formatWKT, getName, isIdentity, needCopy, normalizeAngle, rollLongitude, transform, transform, transform

Methods inherited from class Formattable
cleanupThreadLocals, toString, toWKT, toWKT, toWKT, toWKT

Methods inherited from interface MathTransform
derivative, isIdentity, toWKT, transform, transform, transform

Methods inherited from interface MathTransform2D
createTransformedShape, derivative




Field Detail

SKIP_SANITY_CHECKS
public static boolean SKIP_SANITY_CHECKS
A global variable use to disable the reciprocal distance checks made when assertions are enabled. This allows tests to work in "real world" conditions, where users often ask for points that are way to far from the correct area of usage of projections

LOGGER
protected static final Logger LOGGER
The projection package logger

excentricity
protected final double excentricity
Ellipsoid excentricity, equals tosqrt(
. Value 0 means that the ellipsoid is spherical.excentricitySquared
) See Also:
excentricitySquared
,isSpherical

excentricitySquared
protected final double excentricitySquared
The square of excentricity: e² = (a²b²)/a² where e is the excentricity, a is the semi major axis length and b is the semi minor axis length. See Also:
excentricity
,semiMajor
,semiMinor
,isSpherical

isSpherical
protected final boolean isSpherical
true
if this projection is spherical. Spherical model has identical semi major and semi minor axis length, and an excentricity zero. See Also:
excentricity
,semiMajor
,semiMinor

semiMajor
protected final double semiMajor
Length of semimajor axis, in metres. This is named 'a' or 'R' (Radius in spherical cases) in Snyder. See Also:
excentricity
,semiMinor

semiMinor
protected final double semiMinor
Length of semiminor axis, in metres. This is named 'b' in Snyder. See Also:
excentricity
,semiMajor

centralMeridian
protected double centralMeridian
Central longitude in radians. Default value is 0, the Greenwich meridian. This is called 'lambda0' in Snyder.Consider this field as final. It is not final only because some classes need to modify it at construction time.

latitudeOfOrigin
protected double latitudeOfOrigin
Latitude of origin in radians. Default value is 0, the equator. This is called 'phi0' in Snyder.Consider this field as final. It is not final only because some classes need to modify it at construction time.

scaleFactor
protected double scaleFactor
The scale factor. Default value is 1. Named 'k' in Snyder.Consider this field as final. It is not final only because some classes need to modify it at construction time.

falseEasting
protected final double falseEasting
False easting, in metres. Default value is 0.

falseNorthing
protected final double falseNorthing
False northing, in metres. Default value is 0.

globalScale
protected double globalScale
Global scale factor. Default valueglobalScale
is equal tosemiMajor
×scaleFactor
.Consider this field as final. It is not final only because some classes need to modify it at construction time.

en0
protected double en0
Constant needed for themlfn
method. Setup at construction time.

en1
protected double en1
Constant needed for themlfn
method. Setup at construction time.

en2
protected double en2
Constant needed for themlfn
method. Setup at construction time.

en3
protected double en3
Constant needed for themlfn
method. Setup at construction time.

en4
protected double en4
Constant needed for themlfn
method. Setup at construction time.

invertible
protected boolean invertible
Marks if the projection is invertible. The vast majority is, subclasses can override.


Constructor Detail

MapProjection
protected MapProjection(ParameterValueGroup values) throws ParameterNotFoundException
Constructs a new map projection from the suplied parameters. Parameters:
values
 The parameter values in standard units. The following parameter are recognized: "semi_major" (mandatory: no default)
 "semi_minor" (mandatory: no default)
 "central_meridian" (default to 0°)
 "latitude_of_origin" (default to 0°)
 "scale_factor" (default to 1 )
 "false_easting" (default to 0 )
 "false_northing" (default to 0 )
 Throws:
ParameterNotFoundException
 if a mandatory parameter is missing.


Method Detail

getParameterDescriptors
public abstract ParameterDescriptorGroup getParameterDescriptors()
Returns the parameter descriptors for this map projection. This is used for a providing a default implementation ofgetParameterValues()
, as well as arguments checking. Overrides:
getParameterDescriptors
in classAbstractMathTransform
 Returns:
 The parameter descriptors for this math transform, or
null
.  See Also:
OperationMethod.getParameters()

getParameterValues
public ParameterValueGroup getParameterValues()
Returns the parameter values for this map projection. Overrides:
getParameterValues
in classAbstractMathTransform
 Returns:
 A copy of the parameter values for this map projection.
 See Also:
Operation.getParameterValues()

getSourceDimensions
public final int getSourceDimensions()
Returns the dimension of input points. Specified by:
getSourceDimensions
in interfaceMathTransform
 Specified by:
getSourceDimensions
in classAbstractMathTransform
 Returns:
 The dimension of input points.

getTargetDimensions
public final int getTargetDimensions()
Returns the dimension of output points. Specified by:
getTargetDimensions
in interfaceMathTransform
 Specified by:
getTargetDimensions
in classAbstractMathTransform
 Returns:
 The dimension of output points.

orthodromicDistance
protected double orthodromicDistance(Point2D source, Point2D target)
Returns the orthodromic distance between the two specified points using a spherical approximation. This is used for assertions only.

checkReciprocal
protected boolean checkReciprocal(Point2D point, Point2D target, boolean inverse) throws ProjectionException
Check if the transform ofpoint
is close enough totarget
. "Close enough" means that the two points are separated by a distance shorter thangetToleranceForAssertions(double, double)
. This method is used for assertions with J2SE 1.4. Parameters:
point
 Point to transform, in decimal degrees ifinverse
isfalse
.target
 Point to compare to, in metres ifinverse
isfalse
.inverse
true
for an inverse transform instead of a direct one. Returns:
true
if the two points are close enough. Throws:
ProjectionException

inverseTransformNormalized
protected abstract Point2D inverseTransformNormalized(double x, double y, Point2D ptDst) throws ProjectionException
Transforms the specified coordinate and stores the result inptDst
. This method returns longitude as x values in the range[PI..PI]
and latitude as y values in the range[PI/2..PI/2]
. It will be checked by the caller, so this method doesn't need to performs this check.Input coordinates have the
falseEasting
andfalseNorthing
removed and are divided byglobalScale
before this method is invoked. After this method is invoked, thecentralMeridian
is added to thex
results inptDst
. This means that projections that implement this method are performed on an ellipse (or sphere) with a semimajor axis of 1.In PROJ.4, the same standardization, described above, is handled by
pj_inv.c
. Therefore when porting projections from PROJ.4, the inverse transform equations can be used directly here with minimal change. In the equations of Snyder,falseEasting
,falseNorthing
andscaleFactor
are usually not given. When implementing these equations here, you will not need to add thecentralMeridian
to the output longitude or remove thesemiMajor
(a or R). Parameters:
x
 The easting of the coordinate, linear distance on a unit sphere or ellipse.y
 The northing of the coordinate, linear distance on a unit sphere or ellipse.ptDst
 the specified coordinate point that stores the result of transformingptSrc
, ornull
. Ordinates will be in radians. Returns:
 the coordinate point after transforming
x
,y
and storing the result inptDst
.  Throws:
ProjectionException
 if the point can't be transformed.

transformNormalized
protected abstract Point2D transformNormalized(double lambda, double phi, Point2D ptDst) throws ProjectionException
Transforms the specified coordinate and stores the result inptDst
. This method is usually (but not guaranteed) to be invoked with values of x in the range[PI..PI]
and values of y in the range[PI/2..PI/2]
. Values outside those ranges are accepted (sometime with a warning logged) on the assumption that most implementations use those values only in trigonometric functions like sin and cos.Coordinates have the
centralMeridian
removed from lambda before this method is invoked. After this method is invoked, the results inptDst
are multiplied byglobalScale
, and thefalseEasting
andfalseNorthing
are added. This means that projections that implement this method are performed on an ellipse (or sphere) with a semimajor axis of 1.In PROJ.4, the same standardization, described above, is handled by
pj_fwd.c
. Therefore when porting projections from PROJ.4, the forward transform equations can be used directly here with minimal change. In the equations of Snyder,falseEasting
,falseNorthing
andscaleFactor
are usually not given. When implementing these equations here, you will not need to remove thecentralMeridian
from lambda or apply thesemiMajor
(a or R). Parameters:
lambda
 The longitude of the coordinate, in radians.phi
 The latitude of the coordinate, in radians.ptDst
 the specified coordinate point that stores the result of transformingptSrc
, ornull
. Ordinates will be in a dimensionless unit, as a linear distance on a unit sphere or ellipse. Returns:
 the coordinate point after transforming (
lambda
,phi
) and storing the result inptDst
.  Throws:
ProjectionException
 if the point can't be transformed.

transform
public final Point2D transform(Point2D ptSrc, Point2D ptDst) throws ProjectionException
Transforms the specifiedptSrc
and stores the result inptDst
.This method standardizes the source
x
coordinate by removing thecentralMeridian
, before invokingtransformNormalized
(x, y, ptDst)globalScale
and adds thefalseEasting
andfalseNorthing
to the point returned by thetransformNormalized(...)
call. Specified by:
transform
in interfaceMathTransform2D
 Overrides:
transform
in classAbstractMathTransform
 Parameters:
ptSrc
 the specified coordinate point to be transformed. Ordinates must be in decimal degrees.ptDst
 the specified coordinate point that stores the result of transformingptSrc
, ornull
. Ordinates will be in metres. Returns:
 the coordinate point after transforming
ptSrc
and storing the result inptDst
.  Throws:
ProjectionException
 if the point can't be transformed. See Also:
MathTransform2D.transform(Point2D,Point2D)

transform
public final void transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts) throws ProjectionException
Transforms a list of coordinate point ordinal values. Ordinates must be (longitude,latitude) pairs in decimal degrees. Specified by:
transform
in interfaceMathTransform
 Parameters:
srcPts
 the array containing the source point coordinates.srcOff
 the offset to the first point to be transformed in the source array.dstPts
 the array into which the transformed point coordinates are returned. May be the same thansrcPts
.dstOff
 the offset to the location of the first transformed point that is stored in the destination array.numPts
 the number of point objects to be transformed. Throws:
ProjectionException
 if a point can't be transformed. This method tries to transform every points even if some of them can't be transformed. Nontransformable points will have valueDouble.NaN
. If more than one point can't be transformed, then this exception may be about an arbitrary point.

transform
public final void transform(float[] srcPts, int srcOff, float[] dstPts, int dstOff, int numPts) throws ProjectionException
Transforms a list of coordinate point ordinal values. Ordinates must be (longitude,latitude) pairs in decimal degrees. Specified by:
transform
in interfaceMathTransform
 Overrides:
transform
in classAbstractMathTransform
 Parameters:
srcPts
 the array containing the source point coordinates.srcOff
 the offset to the first point to be transformed in the source array.dstPts
 the array into which the transformed point coordinates are returned. May be the same thansrcPts
.dstOff
 the offset to the location of the first transformed point that is stored in the destination array.numPts
 the number of point objects to be transformed. Throws:
ProjectionException
 if a point can't be transformed. This method tries to transform every points even if some of them can't be transformed. Nontransformable points will have valueFloat.NaN
. If more than one point can't be transformed, then this exception may be about an arbitrary point.

inverse
public final MathTransform2D inverse() throws NoninvertibleTransformException
Returns the inverse of this map projection. Specified by:
inverse
in interfaceMathTransform
 Specified by:
inverse
in interfaceMathTransform2D
 Overrides:
inverse
in classAbstractMathTransform
 Returns:
 The inverse transform.
 Throws:
NoninvertibleTransformException
 if the transform can't be inversed.

getToleranceForAssertions
protected double getToleranceForAssertions(double longitude, double latitude)
Maximal error (in metres) tolerated for assertions, if enabled. When assertions are enabled, every direct projection is followed by an inverse projection, and the result is compared to the original coordinate. If a distance greater than the tolerance level is found, then anProjectionException
will be thrown. Subclasses should override this method if they need to relax the tolerance level. Parameters:
longitude
 The longitude in decimal degrees.latitude
 The latitude in decimal degrees. Returns:
 The tolerance level for assertions, in meters.

resetWarnings
public static void resetWarnings()
Resets the warning status of all projections in the current JVM. EveryMapProjection
instance may log a warning the first time they are given coordinates outside their area of validity. Subsequent coordinates outside the area of validity are silently projected in order to avoid flowing the log with warnings. In case of suspicion, this method may be invoked in order to force all projections to log again their first outofbounds coordinates.Multithreading
Calls to this method have immediate effect in the invoker's thread. The effect in other threads may be delayed by some arbitrary amount of time. This method works only on a "best effort" basis. Since:
 2.5
 See Also:
CRS.reset(java.lang.String)

hashCode
public int hashCode()
Returns a hash value for this map projection. Overrides:
hashCode
in classAbstractMathTransform

equals
public boolean equals(Object object)
Compares the specified object with this map projection for equality. Overrides:
equals
in classAbstractMathTransform
 Parameters:
object
 The object to compare with this transform. Returns:
true
if the given object is a transform of the same class and if, given identical source position, the transformed position would be the equals.

mlfn
protected final double mlfn(double phi, double sphi, double cphi)
Calculates the meridian distance. This is the distance along the central meridian from the equator tophi
. Accurate to < 1e5 meters when used in conjuction with typical major axis values. Parameters:
phi
 latitude to calculate meridian distance for.sphi
 sin(phi).cphi
 cos(phi). Returns:
 meridian distance for the given latitude.

inv_mlfn
protected final double inv_mlfn(double arg) throws ProjectionException
Calculates the latitude (phi
) from a meridian distance. Determines phi to TOL (1e11) radians, about 1e6 seconds. Parameters:
arg
 meridian distance to calulate latitude for. Returns:
 the latitude of the meridian distance.
 Throws:
ProjectionException
 if the itteration does not converge.

