org.opengis.referencing.crs
Interface CoordinateReferenceSystem

All Superinterfaces:
IdentifiedObject, ReferenceSystem
All Known Subinterfaces:
CompoundCRS, DerivedCRS, EngineeringCRS, GeneralDerivedCRS, GeocentricCRS, GeodeticCRS, GeographicCRS, ImageCRS, ProjectedCRS, SingleCRS, TemporalCRS, VerticalCRS

@UML(identifier="SC_CRS",
     specification=ISO_19111)
public interface CoordinateReferenceSystem
extends ReferenceSystem

Abstract coordinate reference system, usually defined by a coordinate system and a datum. The concept of a coordinate reference system (CRS) captures the choice of values for the parameters that constitute the degrees of freedom of the coordinate space. The fact that such a choice has to be made, either arbitrarily or by adopting values from survey measurements, leads to the large number of coordinate reference systems in use around the world. It is also the cause of the little understood fact that the latitude and longitude of a point are not unique. Without the full specification of the coordinate reference system, coordinates are ambiguous at best and meaningless at worst. However for some interchange purposes it is sufficient to confirm the identity of the system without necessarily having the full system definition.

The concept of coordinates may be expanded from a strictly spatial context to include time. Time is then added as another coordinate to the coordinate tuple. It is even possible to add two time-coordinates, provided the two coordinates describe different independent quantities. An example of the latter is the time/space position of a subsurface point of which the vertical coordinate is expressed as the two-way travel time of a sound signal in milliseconds, as is common in seismic imaging. A second time-coordinate indicates the time of observation, usually expressed in whole years.

Since:
GeoAPI 1.0

Field Summary
 
Fields inherited from interface ReferenceSystem
DOMAIN_OF_VALIDITY_KEY, SCOPE_KEY
 
Fields inherited from interface IdentifiedObject
ALIAS_KEY, IDENTIFIERS_KEY, NAME_KEY, REMARKS_KEY
 
Method Summary
 CoordinateSystem getCoordinateSystem()
          Returns a relevant coordinate system instance.
 
Methods inherited from interface ReferenceSystem
getDomainOfValidity, getScope
 
Methods inherited from interface IdentifiedObject
getAlias, getIdentifiers, getName, getRemarks, toWKT
 

Method Detail

getCoordinateSystem

CoordinateSystem getCoordinateSystem()
Returns a relevant coordinate system instance. Special cases:

Returns:
The coordinate system.
Departure from OGC/ISO specification:
ISO 19111 defines this method for SingleCRS only. GeoAPI declares this method in this parent interface for user convenience, since CS dimension and axes are commonly requested information and will always be available, directly or indirectly, even for CompoundCRS.


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