org.cts.datum
Class GeodeticDatum

java.lang.Object
  org.cts.IdentifiableComponent
      org.cts.datum.AbstractDatum
          org.cts.datum.GeodeticDatum

All Implemented Interfaces:

Datum, Identifiable

public class GeodeticDatum
extends AbstractDatum

Geodetic Datum or horizontal Datum : a Datum used to determine positions relative to the Earth (longitude / latitude)

It is recommended that every GeodeticDatum has a toWGS84 SevenParameterTransformation attribute (which may eventually be a Translation or the Identity transformation). This operation must be the standard 3D transformation from/to the GeocentricCoordinateSystem defined by this Datum to/from the GeocentricCoordinateSystem defined by WGS84 Datum.

Moreover, a GeodeticDatum also contains a map which may contain other org.cts.CoordinateOperations from the standard Geographic2DCRS or Geographic3DCRS associated with this Datum to the one associated to another Datum.

Author:

Michaël Michaud, Jules Party

Field Summary

static Map<String,GeodeticDatum>	datumFromName datumFromName associates each datum to a short string used to recognize it in CTS.
static GeodeticDatum	ED50 European Datum 1950.
static GeodeticDatum	NAD27
static GeodeticDatum	NAD83
static GeodeticDatum	NTF Nouvelle Triangulation Française.
static GeodeticDatum	NTF_PARIS Nouvelle Triangulation Française (Paris).
static GeodeticDatum	RGF93 Réseau géodésique français 1993.
static GeodeticDatum	WGS84 World Geodetic System 1984.
static GeodeticDatum	WGS84GUAD
static GeodeticDatum	WGS84MART
static GeodeticDatum	WGS84SBSM

Fields inherited from interface org.cts.Identifiable

DEFAULT, LOCAL, UNKNOWN

Constructor Summary

GeodeticDatum(Identifier identifier, PrimeMeridian primeMeridian, Ellipsoid ellipsoid, GeographicExtent extent, String origin, String epoch)
Creates a new Datum.

GeodeticDatum(PrimeMeridian primeMeridian, Ellipsoid ellipsoid)
Creates a new Datum.

GeodeticDatum(PrimeMeridian primeMeridian, Ellipsoid ellipsoid, CoordinateOperation toWGS84)
Creates a new Datum.

Method Summary

void	addCoordinateOperation(Datum datum, CoordinateOperation coordOp) Add a Transformation to another Datum.
GeodeticDatum	checkExistingGeodeticDatum() If the GeodeticDatum is equal to one of the wellknown GeodeticDatum (WGS84, RGF93, NTF, NTF_PARIS and ED50), the method return this wellknown GeodeticDatum.
boolean	equals(Object o) Returns true if object is equals to this.
List<CoordinateOperation>	getCoordinateOperations(GeodeticDatum datum) Get a transformation to another datum.
Ellipsoid	getEllipsoid() Return the ellipsoid of this Datum.
PrimeMeridian	getPrimeMeridian() Return the PrimeMeridian of this Datum.
CoordinateOperation	getToWGS84() Returns the default transformation to WGS84 of this Datum.
int	hashCode() Returns the hash code for this GeodeticDatum.
void	setDefaultToWGS84Operation(CoordinateOperation toWGS84) Set the default transformation to WGS84 in two forms : toWGS84 Geocentric transformation toWGS84 is an operation to transform geocentric coordinates based on this datum to geocentric coordinates based on WGS84 datum, generally a translation or a SevenParameterTransformation (ex.
void	setToOtherDatumOperation(CoordinateOperation toOtherDatum, GeodeticDatum targetDatum) Set a transformation to a target Datum.
String	toString() Returns a String representation of this GeodeticDatum.
String	toWKT() Returns a WKT representation of the geodetic datum.

Methods inherited from class org.cts.datum.AbstractDatum

getEpoch, getExtent, getOrigin

Methods inherited from class org.cts.IdentifiableComponent

addAlias, addRemark, getAliases, getAuthorityKey, getAuthorityName, getCode, getComponent, getIdentifier, getName, getRemarks, getShortName, setIdentifier, setRemarks, setShortName

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.cts.Identifiable

addAlias, addRemark, getAliases, getAuthorityKey, getAuthorityName, getCode, getName, getRemarks, getShortName, setRemarks, setShortName

Field Detail

datumFromName

public static final Map<String,GeodeticDatum> datumFromName

datumFromName associates each datum to a short string used to recognize it in CTS.

WGS84

public static final GeodeticDatum WGS84

World Geodetic System 1984.

NTF_PARIS

public static final GeodeticDatum NTF_PARIS

Nouvelle Triangulation Française (Paris).

NTF

public static final GeodeticDatum NTF

Nouvelle Triangulation Française.

RGF93

public static final GeodeticDatum RGF93

Réseau géodésique français 1993.

ED50

public static final GeodeticDatum ED50

European Datum 1950.

WGS84GUAD

public static final GeodeticDatum WGS84GUAD

WGS84MART

public static final GeodeticDatum WGS84MART

WGS84SBSM

public static final GeodeticDatum WGS84SBSM

NAD27

public static final GeodeticDatum NAD27

NAD83

public static final GeodeticDatum NAD83

Constructor Detail

GeodeticDatum

public GeodeticDatum(PrimeMeridian primeMeridian,
                     Ellipsoid ellipsoid)

Creates a new Datum.

Parameters:

primeMeridian - the prime meridian to use with this datum

ellipsoid - the ellipsoid to use with this datum

GeodeticDatum

public GeodeticDatum(PrimeMeridian primeMeridian,
                     Ellipsoid ellipsoid,
                     CoordinateOperation toWGS84)

Creates a new Datum.

Parameters:

primeMeridian - the prime meridian to use with this datum

ellipsoid - the ellipsoid to use with this datum

GeodeticDatum

public GeodeticDatum(Identifier identifier,
                     PrimeMeridian primeMeridian,
                     Ellipsoid ellipsoid,
                     GeographicExtent extent,
                     String origin,
                     String epoch)

Creates a new Datum.

Parameters:

identifier - identifier.

primeMeridian - the prime meridian to use with this datum

ellipsoid - the ellipsoid to use with this datum

extent - this datum extension

origin - origin decription this datum

epoch - realization epoch of this datum

Method Detail

getPrimeMeridian

public PrimeMeridian getPrimeMeridian()

Return the PrimeMeridian of this Datum.

getEllipsoid

public Ellipsoid getEllipsoid()

Return the ellipsoid of this Datum.

setDefaultToWGS84Operation

public final void setDefaultToWGS84Operation(CoordinateOperation toWGS84)

Set the default transformation to WGS84 in two forms :

toWGS84 Geocentric transformation

toWGS84 is an operation to transform geocentric coordinates based on this datum to geocentric coordinates based on WGS84 datum, generally a translation or a SevenParameterTransformation (ex. Bursa-Wolf).

toWGS84 does not use PrimeMerdian nor ellipsoid parameters.

datumTransformations map (direct Geographic3D transformations)

The toWGS84 transformation is also stored in the datumTransformations map, inherited from AbstractDatum, but this time, the operation is not stored as Geocentric to Geocentric transformation but as a Geographic3D to Geographic3D transformation.

The convention for this transformation is to start from Geographic3D coordinates in radians, to include required longitude rotation, and ellipsoid transformations, and to return GeographicCoordinates in radian. Advantage is that it makes it possible to use algorithm which do not involve Geographic to Geocentric transformation like the use of NTv2 grids.

Parameters:

toWGS84 - geocentric transformation from this to geocentric WGS 84

setToOtherDatumOperation

public final void setToOtherDatumOperation(CoordinateOperation toOtherDatum,
                                           GeodeticDatum targetDatum)

Set a transformation to a target Datum.

toOtherDatum is an operation to transform geocentric coordinates based on this datum to geocentric coordinates based on target datum, generally a translation or a SevenParameterTransformation (ex. Bursa-Wolf).

toOtherDatum does not use PrimeMerdian nor ellipsoid parameters.

The toOtherDatum transformation is stored in the datumTransformations map, inherited from AbstractDatum. The operation is not stored as Geocentric to Geocentric transformation but as a Geographic3D to Geographic3D transformation.

The convention for this transformation is to start from Geographic3D coordinates in radians, to include required longitude rotation, and ellipsoid transformations, and to return GeographicCoordinates in radian. Advantage is that it makes it possible to use algorithm which do not involve Geographic to Geocentric transformation like the use of NTv2 grids.

Parameters:

toOtherDatum - geocentric transformation from this to targetDatum

targetDatum - the GeodeticDatum to which the transformation is defined

addCoordinateOperation

public void addCoordinateOperation(Datum datum,
                                   CoordinateOperation coordOp)

Add a Transformation to another Datum.

Parameters:

datum - the target datum of the transformation to add

coordOp - the transformation linking this Datum and the target datum

getCoordinateOperations

public List<CoordinateOperation> getCoordinateOperations(GeodeticDatum datum)

Get a transformation to another datum.

Parameters:

datum - the datum that must be a target for returned transformation

getToWGS84

public CoordinateOperation getToWGS84()

Returns the default transformation to WGS84 of this Datum.

checkExistingGeodeticDatum

public GeodeticDatum checkExistingGeodeticDatum()

If the GeodeticDatum is equal to one of the wellknown GeodeticDatum (WGS84, RGF93, NTF, NTF_PARIS and ED50), the method return this wellknown GeodeticDatum. If there is no such datum, the method return the GeodeticDatum to which the method is applied.

toWKT

public String toWKT()

Returns a WKT representation of the geodetic datum.

toString

public String toString()

Returns a String representation of this GeodeticDatum.

Overrides:

toString in class AbstractDatum

equals

public boolean equals(Object o)

Returns true if object is equals to this. Tests equality between identifiers, then tests if the components of this ProjectedCRS are equals : the toWGS84 transformations, the Ellipsoid and the PrimeMeridian.

Overrides:

equals in class IdentifiableComponent

Parameters:

object - The object to compare this GeodeticDatum against

hashCode

public int hashCode()

Returns the hash code for this GeodeticDatum.

Overrides:

hashCode in class IdentifiableComponent