All Implemented Interfaces:
Serializable, Parameterized, LenientComparable, org.opengis.referencing.operation.MathTransform, org.opengis.referencing.operation.MathTransform2D
Direct Known Subclasses:
Mercator.Spherical

public class Mercator extends ConformalProjection
Mercator Cylindrical projection (EPSG codes 9804, 9805, 1026, 1024, 1044, 9841). See the following references for an overview:

Description

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 standard parallel cases. For Mercator (variant A) (EPSG code 9804), the line of contact is the equator. For Mercator (variant B) (EPSG code 9805) lines of contact are symmetrical about the equator.

Behavior at poles

The projection of 90°N gives positive infinity. The projection of 90°S gives negative infinity. Projection of a latitude outside the [-90 … 90]° range produces NaN.
Since:
0.6
Version:
1.3
See Also:
  • Field Details

  • Constructor Details

    • Mercator

      public Mercator(org.opengis.referencing.operation.OperationMethod method, Parameters parameters)
      Creates a Mercator projection from the given parameters. The method argument can be the description of one of the following:
      • "Mercator (variant A)", also known as "Mercator (1SP)".
      • "Mercator (variant B)", also known as "Mercator (2SP)".
      • "Mercator (variant C)".
      • "Mercator (Spherical)".
      • "Mercator Auxiliary Sphere".
      • "Popular Visualisation Pseudo Mercator".
      • "Miller Cylindrical".
      Parameters:
      method - description of the projection parameters.
      parameters - the parameter values of the projection to create.
    • Mercator

      @Workaround(library="JDK", version="1.7") private Mercator(Initializer initializer)
      Work around for RFE #4093999 in Sun's bug database ("Relax constraint on placement of this()/super() call in constructors").
    • Mercator

      Mercator(Mercator other)
      Creates a new projection initialized to the same parameters than the given one.
  • Method Details

    • initializer

      @Workaround(library="JDK", version="1.7") private static Initializer initializer(org.opengis.referencing.operation.OperationMethod method, Parameters parameters)
      Work around for RFE #4093999 in Sun's bug database ("Relax constraint on placement of this()/super() call in constructors").
    • createMapProjection

      public org.opengis.referencing.operation.MathTransform createMapProjection(org.opengis.referencing.operation.MathTransformFactory factory) throws org.opengis.util.FactoryException
      Returns the sequence of normalizationthisdenormalization transforms as a whole. The transform returned by this method expects (longitude, latitude) coordinates in degrees and returns (x,y) coordinates in metres.

      The non-linear part of the returned transform will be this transform, except if the ellipsoid is spherical. In the latter case, this transform may be replaced by a simplified implementation.

      Overrides:
      createMapProjection in class NormalizedProjection
      Parameters:
      factory - the factory to use for creating the transform.
      Returns:
      the map projection from (λ,φ) to (x,y) coordinates.
      Throws:
      org.opengis.util.FactoryException - if an error occurred while creating a transform.
      See Also:
    • getDomain

      public Optional<org.opengis.geometry.Envelope> getDomain(DomainDefinition criteria)
      Returns the domain of input coordinates. For a Mercator projection other than Miller variant, the limit is arbitrarily set to 84° of latitude North and South. This is consistent with the "World Mercator" domain of validity defined by EPSG:3395, which is 80°S to 84°N.

      The range of longitude values is set to an arbitrary range larger than −180° … +180°, because the Mercator projection is mathematically capable to handle coordinates beyond that range even if those coordinates have no real world meaning. This expansion can facilitate the projection of envelopes, geometries or rasters.

      Overrides:
      getDomain in class AbstractMathTransform
      Parameters:
      criteria - controls the definition of transform domain.
      Returns:
      estimation of a domain where this transform is considered numerically applicable.
      Since:
      1.3
      See Also:
    • transform

      public org.opengis.referencing.operation.Matrix transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, boolean derivate) throws ProjectionException
      Projects the specified coordinates (implementation-specific units) and stores the result in dstPts. In addition, opportunistically computes the projection derivative if derivate is true. The results must be multiplied by the denormalization matrix before to get linear distances.
      Specified by:
      transform in class NormalizedProjection
      Parameters:
      srcPts - the array containing the source point coordinates, as (longitude, latitude) angles in radians.
      srcOff - the offset of the single coordinate tuple to be converted in the source array.
      dstPts - the array into which the converted coordinates is returned (may be the same than srcPts). Coordinates will be expressed in a dimensionless unit, as a linear distance on a unit sphere or ellipse.
      dstOff - the offset of the location of the converted coordinates that is stored in the destination array.
      derivate - true for computing the derivative, or false if not needed.
      Returns:
      the matrix of the projection derivative at the given source position, or null if the derivate argument is false.
      Throws:
      ProjectionException - if the coordinates cannot be converted.
      See Also:
    • transform

      public void transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts) throws org.opengis.referencing.operation.TransformException
      Converts a list of coordinate tuples. This method performs the same calculation than above transform(double[], int, double[], int, boolean) method, but is overridden for efficiency.
      Specified by:
      transform in interface org.opengis.referencing.operation.MathTransform
      Overrides:
      transform in class AbstractMathTransform
      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 than srcPts.
      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:
      org.opengis.referencing.operation.TransformException - if a point cannot be converted.
    • inverseTransform

      protected void inverseTransform(double[] srcPts, int srcOff, double[] dstPts, int dstOff) throws ProjectionException
      Converts the specified (x,y) coordinates and stores the result in dstPts (angles in radians).
      Specified by:
      inverseTransform in class NormalizedProjection
      Parameters:
      srcPts - the array containing the source point coordinates, as linear distance on a unit sphere or ellipse.
      srcOff - the offset of the point to be converted in the source array.
      dstPts - the array into which the converted point coordinates is returned (may be the same than srcPts). Coordinates will be (longitude, latitude) angles in radians.
      dstOff - the offset of the location of the converted point that is stored in the destination array.
      Throws:
      ProjectionException - if the point cannot be converted.
    • tryConcatenate

      final org.opengis.referencing.operation.MathTransform tryConcatenate(boolean projectedSpace, org.opengis.referencing.operation.Matrix affine, org.opengis.referencing.operation.MathTransformFactory factory) throws org.opengis.util.FactoryException
      Invoked when NormalizedProjection.tryConcatenate(boolean, MathTransform, MathTransformFactory) detected a (inverse) → (affine) → (this) transforms sequence. If the affine transform in the middle does not change the latitude value, then we can take advantage of the fact that longitude conversion is linear.
      Overrides:
      tryConcatenate in class NormalizedProjection
      Parameters:
      projectedSpace - true if affine transform is applied in projected instead of geographic space.
      affine - the affine transform in the middle of (inverse) → (affine) → (this) transform sequence.
      factory - the factory to use for creating new transform, or null.
      Returns:
      the optimized concatenation, or null if none.
      Throws:
      org.opengis.util.FactoryException