org.geotools.referencing.operation.projection
Class Mercator

Object
  extended by Formattable
      extended by AbstractMathTransform
          extended by MapProjection
              extended by Mercator
All Implemented Interfaces:
Serializable, MathTransform, MathTransform2D
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 Mercator_1SP (EPSG code 9804), the line of contact is the equator. For Mercator_2SP (EPSG code 9805) lines of contact are symmetrical about the equator.

References:

Since:
2.1
Author:
André Gosselin, Martin Desruisseaux (PMO, IRD), Rueben Schulz, Simone Giannecchini
See Also:
Mercator projection on MathWorld, "mercator_1sp" on RemoteSensing.org, "mercator_2sp" on RemoteSensing.org, Serialized Form
Module:

Nested Class Summary
 
Nested classes/interfaces inherited from class MapProjection
MapProjection.AbstractProvider
 
Field Summary
protected  double standardParallel
          Standard Parallel used for the Mercator2SP case.
 
Fields inherited from class MapProjection
centralMeridian, excentricity, excentricitySquared, falseEasting, falseNorthing, globalScale, isSpherical, latitudeOfOrigin, LOGGER, scaleFactor, semiMajor, semiMinor
 
Fields inherited from class Formattable
SINGLE_LINE
 
Constructor Summary
protected Mercator(ParameterValueGroup parameters)
          Constructs a new map projection from the supplied parameters.
 
Method Summary
 boolean equals(Object object)
          Compares the specified object with this map projection for equality.
 ParameterValueGroup getParameterValues()
          Returns the parameter values for this map projection.
 int hashCode()
          Returns a hash value for this projection.
protected  Point2D inverseTransformNormalized(double x, double y, Point2D ptDst)
          Transforms the specified (x,y) coordinates and stores the result in ptDst.
protected  Point2D transformNormalized(double x, double y, Point2D ptDst)
          Transforms the specified (λ,φ) coordinates (units in radians) and stores the result in ptDst (linear distance on a unit sphere).
 
Methods inherited from class MapProjection
getParameterDescriptors, getSourceDimensions, getTargetDimensions, getToleranceForAssertions, inverse, resetWarnings, transform, transform, transform
 
Methods inherited from class AbstractMathTransform
createTransformedShape, derivative, derivative, ensureNonNull, formatWKT, getName, isIdentity, needCopy, rollLongitude, transform, transform, transform
 
Methods inherited from class Formattable
toString, toWKT, toWKT, toWKT
 
Methods inherited from class Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface MathTransform2D
createTransformedShape, derivative
 
Methods inherited from interface MathTransform
derivative, isIdentity, toWKT, transform
 

Field Detail

standardParallel

protected final double standardParallel
Standard Parallel used for the Mercator2SP case. Set to Double.NaN for the Mercator1SP case.

Constructor Detail

Mercator

protected Mercator(ParameterValueGroup parameters)
            throws ParameterNotFoundException
Constructs a new map projection from the supplied parameters.

Parameters:
parameters - The parameter values in standard units.
Throws:
ParameterNotFoundException - if a mandatory parameter is missing.
Method Detail

getParameterValues

public 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.
See Also:
Operation.getParameterValues()

transformNormalized

protected Point2D transformNormalized(double x,
                                      double y,
                                      Point2D ptDst)
                               throws ProjectionException
Transforms the specified (λ,φ) coordinates (units in radians) and stores the result in ptDst (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 ptSrc, or null. 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 in ptDst.
Throws:
ProjectionException - if the point can't be transformed.

inverseTransformNormalized

protected Point2D inverseTransformNormalized(double x,
                                             double y,
                                             Point2D ptDst)
                                      throws ProjectionException
Transforms the specified (x,y) coordinates and stores the result in ptDst.

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 ptSrc, or null. Ordinates will be in radians.
Returns:
the coordinate point after transforming x, y and storing the result in ptDst.
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(Object object)
Compares the specified object with this map projection for equality.

Overrides:
equals in class MapProjection
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.


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