org.geotoolkit.referencing.cs
Class AbstractCS

Object
  FormattableObject
      AbstractIdentifiedObject
          AbstractCS

All Implemented Interfaces:

Serializable, Formattable, LenientComparable, CoordinateSystem, IdentifiedObject

Direct Known Subclasses:

DefaultAffineCS, DefaultCompoundCS, DefaultCylindricalCS, DefaultEllipsoidalCS, DefaultLinearCS, DefaultPolarCS, DefaultSphericalCS, DefaultTimeCS, DefaultUserDefinedCS, DefaultVerticalCS

@Immutable
public class AbstractCS
extends AbstractIdentifiedObject
implements CoordinateSystem

The set of coordinate system axes that spans a given coordinate space. A coordinate system (CS) is derived from a set of (mathematical) rules for specifying how coordinates in a given space are to be assigned to points. The coordinate values in a coordinate tuple shall be recorded in the order in which the coordinate system axes are recorded, whenever those coordinates use a coordinate reference system that uses this coordinate system.

This class is conceptually abstract, even if it is technically possible to instantiate it. Typical applications should create instances of the most specific subclass with Default prefix instead. An exception to this rule may occurs when it is not possible to identify the exact type. For example it is not possible to infer the exact coordinate system from Well Known Text is some cases (e.g. in a LOCAL_CS element). In such exceptional situation, a plain AbstractCS object may be instantiated.

Since:

2.0

Version:

3.19

Author:

Martin Desruisseaux (IRD, Geomatys)

See Also:

DefaultCoordinateSystemAxis, Unit, AbstractDatum, AbstractCRS, Serialized Form

Module:

referencing/geotk-referencing (download)

View source code for this class

Field Summary

Fields inherited from class FormattableObject

EPSG, GEOTIFF, INTERNAL, OGC, SINGLE_LINE

Fields inherited from interface IdentifiedObject

ALIAS_KEY, IDENTIFIERS_KEY, NAME_KEY, REMARKS_KEY

Constructor Summary

AbstractCS(CoordinateSystem cs)
Constructs a new coordinate system with the same values than the specified one.

AbstractCS(Map<String,?> properties, CoordinateSystemAxis... axis)
Constructs a coordinate system from a set of properties.

AbstractCS(String name, CoordinateSystemAxis... axis)
Constructs a coordinate system from a name.

Method Summary

protected int	computeHashCode() Computes a hash value for this identified object.
Measure	distance(double[] coord1, double[] coord2) Computes the distance between two points.
boolean	equals(Object object, ComparisonMode mode) Compares the specified object with this coordinate system for equality.
String	formatWKT(Formatter formatter) Format the inner part of a Well Known Text (WKT) element.
CoordinateSystemAxis	getAxis(int dimension) Returns the axis for this coordinate system at the specified dimension.
int	getDimension() Returns the dimension of the coordinate system.
protected boolean	isCompatibleDirection(AxisDirection direction) Returns true if the specified axis direction is allowed for this coordinate system.
protected boolean	isCompatibleUnit(AxisDirection direction, Unit<?> unit) Returns true is the specified unit is legal for the specified axis direction.
static CoordinateSystem	standard(CoordinateSystem cs) Returns a coordinate system with "standard" axis order and units.
static Matrix	swapAndScaleAxis(CoordinateSystem sourceCS, CoordinateSystem targetCS) Returns an affine transform between two coordinate systems.

Methods inherited from class AbstractIdentifiedObject

equals, getAlias, getIdentifier, getIdentifiers, getName, getName, getRemarks, hashCode, nameMatches

Methods inherited from class FormattableObject

getDefaultIndentation, print, setDefaultIndentation, toString, toWKT, toWKT, toWKT

Methods inherited from class Object

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

Methods inherited from interface IdentifiedObject

getAlias, getIdentifiers, getName, getRemarks, toWKT

Constructor Detail

AbstractCS

public AbstractCS(CoordinateSystem cs)

Constructs a new coordinate system with the same values than the specified one. This copy constructor provides a way to convert an arbitrary implementation into a Geotk one or a user-defined one (as a subclass), usually in order to leverage some implementation-specific API. This constructor performs a shallow copy, i.e. the properties are not cloned.

Parameters:

cs - The coordinate system to copy.

Since:

2.2

AbstractCS

public AbstractCS(String name,
                  CoordinateSystemAxis... axis)

Constructs a coordinate system from a name.

Parameters:

name - The coordinate system name.

axis - The set of axis.

AbstractCS

public AbstractCS(Map<String,?> properties,
                  CoordinateSystemAxis... axis)

Constructs a coordinate system from a set of properties. The properties map is given unchanged to the super-class constructor.

Parameters:

properties - Set of properties. Should contains at least "name".

axis - The set of axis.

Method Detail

isCompatibleDirection

protected boolean isCompatibleDirection(AxisDirection direction)

Returns true if the specified axis direction is allowed for this coordinate system. This method is invoked at construction time for checking argument validity. The default implementation returns true for all axis directions. Subclasses will overrides this method in order to put more restrictions on allowed axis directions.

Parameters:

direction - The direction to test for compatibility.

Returns:

true if the given direction is compatible with this coordinate system.

isCompatibleUnit

protected boolean isCompatibleUnit(AxisDirection direction,
                                   Unit<?> unit)

Returns true is the specified unit is legal for the specified axis direction. This method is invoked at construction time for checking units compatibility. The default implementation returns true in all cases. Subclasses can override this method and check for compatibility with metre or degree units.

Parameters:

direction - The direction of the axis having the given unit.

unit - The unit to test for compatibility.

Returns:

true if the given unit is compatible with this coordinate system.

Since:

2.2

getDimension

public int getDimension()

Returns the dimension of the coordinate system. This is the number of axis.

Specified by:

getDimension in interface CoordinateSystem

getAxis

public CoordinateSystemAxis getAxis(int dimension)
                             throws IndexOutOfBoundsException

Returns the axis for this coordinate system at the specified dimension.

Specified by:

getAxis in interface CoordinateSystem

Parameters:

dimension - The zero based index of axis.

Returns:

The axis at the specified dimension.

Throws:

IndexOutOfBoundsException - if dimension is out of bounds.

swapAndScaleAxis

public static Matrix swapAndScaleAxis(CoordinateSystem sourceCS,
                                      CoordinateSystem targetCS)
                               throws IllegalArgumentException,
                                      ConversionException

Returns an affine transform between two coordinate systems. Only units and axis order (e.g. transforming from (NORTH,WEST) to (EAST,NORTH) are taken in account.

Example: If coordinates in sourceCS are (x,y) pairs in metres and coordinates in targetCS are (-y,x) pairs in centimetres, then the transformation can be performed as below:

┌      ┐   ┌                ┐ ┌     ┐
│-y(cm)│   │   0  -100    0 │ │ x(m)│
│ x(cm)│ = │ 100     0    0 │ │ y(m)│
│ 1    │   │   0     0    1 │ │ 1   │
└      ┘   └                ┘ └     ┘

Parameters:

sourceCS - The source coordinate system.

targetCS - The target coordinate system.

Returns:

The conversion from sourceCS to targetCS as an affine transform. Only axis direction and units are taken in account.

Throws:

IllegalArgumentException - if axis doesn't matches, or the CS doesn't have the same geometry.

ConversionException - if the units are not compatible, or the conversion is non-linear.

standard

public static CoordinateSystem standard(CoordinateSystem cs)
                                 throws IllegalArgumentException

Returns a coordinate system with "standard" axis order and units. Most of the time, this method returns one of the predefined constants with axis in (longitude,latitude) or (X,Y) order, and units in degrees or metres. In some particular cases like Cartesian CS, this method may create a new instance on the fly. In every cases this method attempts to return a right-handed coordinate system, but this is not guaranteed.

This method is typically used together with swapAndScaleAxis for the creation of a transformation step before some math transform. Example:

Matrix step1 = swapAndScaleAxis(sourceCS, standard(sourceCS));
Matrix step2 = ... some transform operating on standard axis ...
Matrix step3 = swapAndScaleAxis(standard(targetCS), targetCS);

A rational for standard axis order and units is explained in the Axis units and direction section in the description of map projection package.

Parameters:

cs - The coordinate system.

Returns:

A constant similar to the specified cs with "standard" axis.

Throws:

IllegalArgumentException - if the specified coordinate system is unknown to this method.

Since:

2.2

distance

public Measure distance(double[] coord1,
                        double[] coord2)
                 throws UnsupportedOperationException,
                        MismatchedDimensionException

Computes the distance between two points. This method is not available for all coordinate systems. For example, ellipsoidal CS doesn't have sufficient information.

Parameters:

coord1 - Coordinates of the first point.

coord2 - Coordinates of the second point.

Returns:

The distance between coord1 and coord2.

Throws:

UnsupportedOperationException - if this coordinate system can't compute distances.

MismatchedDimensionException - if a coordinate doesn't have the expected dimension.

TODO:

Provides a localized message in the exception.

equals

public boolean equals(Object object,
                      ComparisonMode mode)

Compares the specified object with this coordinate system for equality.

Specified by:

equals in interface LenientComparable

Overrides:

equals in class AbstractIdentifiedObject

Parameters:

object - The object to compare to this.

mode - STRICT for performing a strict comparison, or IGNORE_METADATA for comparing only properties relevant to transformations.

Returns:

true if both objects are equal.

computeHashCode

protected int computeHashCode()

Computes a hash value for this identified object. This method is invoked by AbstractIdentifiedObject.hashCode() when first needed.

Implementation specific feature
In the Geotk implementation, the name, identifiers and remarks are not used for hash code computation. Consequently two identified objects will return the same hash value if they are equal in the sense of equals(…, ComparisonMode.IGNORE_METADATA). This feature allows users to implement metadata-insensitive HashMap.

Overrides:

computeHashCode in class AbstractIdentifiedObject

Returns:

The hash code value. This value may change between different execution of the Geotk library.

formatWKT

public String formatWKT(Formatter formatter)

Format the inner part of a Well Known Text (WKT) element. Note that WKT is not yet defined for coordinate system. Current implementation list the axis contained in this CS.

Specified by:

formatWKT in interface Formattable

Overrides:

formatWKT in class FormattableObject

Parameters:

formatter - The formatter to use.

Returns:

The WKT element name. Current implementation default to the class name.

See Also:

FormattableObject.toWKT(), FormattableObject.toString()