org.geotools.referencing.operation.projection
Class Mercator

java.lang.Object
  org.geotools.referencing.wkt.Formattable
      org.geotools.referencing.operation.transform.AbstractMathTransform
          org.geotools.referencing.operation.projection.MapProjection
              org.geotools.referencing.operation.projection.Mercator

All Implemented Interfaces:

org.opengis.referencing.operation.MathTransform, org.opengis.referencing.operation.MathTransform2D, java.io.Serializable

Direct Known Subclasses:

Mercator1SP, Mercator2SP

public abstract class Mercator

extends MapProjection

Mercator Cylindrical Projection. The parallels and the meridians are straight lines and cross at right angles; this projection thus produces rectangular charts. The scale is true along the equator (by default) or along two parallels equidistant of the equator (if a scale factor other than 1 is used). This projection is used to represent areas close to the equator. It is also often used for maritime navigation because all the straight lines on the chart are loxodrome lines, i.e. a ship following this line would keep a constant azimuth on its compass.

This implementation handles both the 1 and 2 stardard parallel cases. For (EPSG code 9804), the line of contact is the equator. For (EPSG code 9805) lines of contact are symmetrical about the equator.

References:

• John P. Snyder (Map Projections - A Working Manual,
  U.S. Geological Survey Professional Paper 1395, 1987)
• "Coordinate Conversions and Transformations including Formulas",
  EPSG Guidence Note Number 7, Version 19.

Since:

2.1

Version:

$Id: Mercator.java 17672 2006-01-19 00:25:55Z desruisseaux $

Author:

Andr? Gosselin, Martin Desruisseaux, Rueben Schulz

See Also:

Mercator projection on MathWorld, "mercator_1sp" on Remote Sensing, "mercator_2sp" on Remote Sensing, Serialized Form

Nested Class Summary

Nested classes inherited from class org.geotools.referencing.operation.projection.MapProjection

MapProjection.AbstractProvider

Field Summary

protected double

standardParallel Standard Parallel used for the case.

Fields inherited from class org.geotools.referencing.operation.projection.MapProjection

centralMeridian, excentricity, excentricitySquared, falseEasting, falseNorthing, globalScale, isSpherical, latitudeOfOrigin, scaleFactor, semiMajor, semiMinor

Constructor Summary

protected

Mercator(org.opengis.parameter.ParameterValueGroup parameters) Constructs a new map projection from the supplied parameters.

Method Summary

boolean	equals(java.lang.Object object) Compares the specified object with this map projection for equality.
org.opengis.parameter.ParameterValueGroup	getParameterValues() Returns the parameter values for this map projection.
int	hashCode() Returns a hash value for this projection.
protected java.awt.geom.Point2D	inverseTransformNormalized(double x, double y, java.awt.geom.Point2D ptDst) Transforms the specified (x,y) coordinate and stores the result in .
protected java.awt.geom.Point2D	transformNormalized(double x, double y, java.awt.geom.Point2D ptDst) Transforms the specified (x,y) coordinate (units in radians) and stores the result in (linear distance on a unit sphere).

Methods inherited from class org.geotools.referencing.operation.projection.MapProjection

getParameterDescriptors, getSourceDimensions, getTargetDimensions, getToleranceForAssertions, inverse, transform, transform, transform

Methods inherited from class org.geotools.referencing.operation.transform.AbstractMathTransform

createTransformedShape, derivative, derivative, ensureNonNull, formatWKT, getDimSource, getDimTarget, isIdentity, needCopy, rollLongitude, transform

Methods inherited from class org.geotools.referencing.wkt.Formattable

toString, toWKT, toWKT, toWKT

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.opengis.referencing.operation.MathTransform2D

createTransformedShape, derivative

Methods inherited from interface org.opengis.referencing.operation.MathTransform

derivative, isIdentity, toWKT, transform

Field Detail

standardParallel

protected final double standardParallel

Standard Parallel used for the case. Set to Double.NaN for the case.

Constructor Detail

Mercator

protected Mercator(org.opengis.parameter.ParameterValueGroup parameters)
            throws org.opengis.parameter.ParameterNotFoundException

Constructs a new map projection from the supplied parameters.

Parameters:

parameters - The parameter values in standard units.

Throws:

org.opengis.parameter.ParameterNotFoundException - if a mandatory parameter is missing.

Method Detail

getParameterValues

public org.opengis.parameter.ParameterValueGroup getParameterValues()

Returns the parameter values for this map projection.

Overrides:

getParameterValues in class MapProjection

Returns:

A copy of the parameter values for this map projection.

transformNormalized

protected java.awt.geom.Point2D transformNormalized(double x,
                                                    double y,
                                                    java.awt.geom.Point2D ptDst)
                                             throws ProjectionException

Transforms the specified (x,y) coordinate (units in radians) and stores the result in (linear distance on a unit sphere).

Specified by:

transformNormalized in class MapProjection

Parameters:

x - The longitude of the coordinate, in radians.

y - The latitude of the coordinate, in radians.

ptDst - the specified coordinate point that stores the result of transforming , or . Ordinates will be in a dimensionless unit, as a linear distance on a unit sphere or ellipse.

Returns:

the coordinate point after transforming , and storing the result in .

Throws:

ProjectionException - if the point can't be transformed.

inverseTransformNormalized

protected java.awt.geom.Point2D inverseTransformNormalized(double x,
                                                           double y,
                                                           java.awt.geom.Point2D ptDst)
                                                    throws ProjectionException

Transforms the specified (x,y) coordinate and stores the result in .

Specified by:

inverseTransformNormalized in class MapProjection

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 transforming , or . Ordinates will be in radians.

Returns:

the coordinate point after transforming , and storing the result in .

Throws:

ProjectionException - if the point can't be transformed.

hashCode

public int hashCode()

Returns a hash value for this projection.

Overrides:

hashCode in class MapProjection

equals

public boolean equals(java.lang.Object object)

Compares the specified object with this map projection for equality.

Overrides:

equals in class MapProjection