Interface Datum
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- All Superinterfaces:
IdentifiedObject
- All Known Subinterfaces:
EngineeringDatum
,GeodeticDatum
,ImageDatum
,TemporalDatum
,VerticalDatum
- All Known Implementing Classes:
AbstractDatum
,DefaultEngineeringDatum
,DefaultGeodeticDatum
,DefaultImageDatum
,DefaultTemporalDatum
,DefaultVerticalDatum
public interface Datum extends IdentifiedObject
Specifies the relationship of a coordinate system to the earth, thus creating a coordinate reference system. A datum uses a parameter or set of parameters that determine the location of the origin of the coordinate reference system. Each datum subtype can be associated with only specific types of coordinate systems.- Since:
- GeoAPI 1.0
- Author:
- Martin Desruisseaux (IRD)
- See Also:
CoordinateSystem
,CoordinateReferenceSystem
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Field Summary
Fields Modifier and Type Field Description static String
ANCHOR_POINT_KEY
static String
DOMAIN_OF_VALIDITY_KEY
static String
REALIZATION_EPOCH_KEY
static String
SCOPE_KEY
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Fields inherited from interface IdentifiedObject
ALIAS_KEY, IDENTIFIERS_KEY, NAME_KEY, REMARKS_KEY
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description InternationalString
getAnchorPoint()
Description, possibly including coordinates, of the point or points used to anchor the datum to the Earth.Extent
getDomainOfValidity()
Area or region or timeframe in which this datum is valid.Date
getRealizationEpoch()
The time after which this datum definition is valid.InternationalString
getScope()
Description of domain of usage, or limitations of usage, for which this datum object is valid.-
Methods inherited from interface IdentifiedObject
getAlias, getIdentifiers, getName, getRemarks, toWKT
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Field Detail
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ANCHOR_POINT_KEY
static final String ANCHOR_POINT_KEY
Key for the"anchorPoint"
property to be given to the datum factorycreateFoo(…)
methods. This is used for setting the value to be returned bygetAnchorPoint()
.- See Also:
getAnchorPoint()
, Constant Field Values
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REALIZATION_EPOCH_KEY
static final String REALIZATION_EPOCH_KEY
Key for the"realizationEpoch"
property to be given to the datum factorycreateFoo(…)
methods. This is used for setting the value to be returned bygetRealizationEpoch()
.- See Also:
getRealizationEpoch()
, Constant Field Values
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DOMAIN_OF_VALIDITY_KEY
static final String DOMAIN_OF_VALIDITY_KEY
Key for the"domainOfValidity"
property to be given to the datum factorycreateFoo(…)
methods. This is used for setting the value to be returned bygetDomainOfValidity()
.- Since:
- GeoAPI 2.1
- See Also:
getDomainOfValidity()
, Constant Field Values
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SCOPE_KEY
static final String SCOPE_KEY
Key for the"scope"
property to be given to the datum factorycreateFoo(…)
methods. This is used for setting the value to be returned bygetScope()
.- See Also:
getScope()
, Constant Field Values
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Method Detail
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getAnchorPoint
InternationalString getAnchorPoint()
Description, possibly including coordinates, of the point or points used to anchor the datum to the Earth. Also known as the "origin", especially for Engineering and Image Datums.- For a geodetic datum, this point is also known as the fundamental point, which is traditionally the point where the relationship between geoid and ellipsoid is defined. In some cases, the "fundamental point" may consist of a number of points. In those cases, the parameters defining the geoid/ellipsoid relationship have then been averaged for these points, and the averages adopted as the datum definition.
- For an engineering datum, the anchor point may be a physical point, or it may be a point with defined coordinates in another CRS.
- For an image datum, the anchor point is usually either the centre of the image or the corner of the image.
- For a temporal datum, this attribute is not defined. Instead of the anchor point, a
temporal datum carries a separate time origin of type
Date
.
- Returns:
- A description of the anchor point, or
null
if none.
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getRealizationEpoch
Date getRealizationEpoch()
The time after which this datum definition is valid. This time may be precise (e.g. 1997 for IRTF97) or merely a year (e.g. 1983 for NAD83). In the latter case, the epoch usually refers to the year in which a major recalculation of the geodetic control network, underlying the datum, was executed or initiated. An old datum can remain valid after a new datum is defined. Alternatively, a datum may be superseded by a later datum, in which case the realization epoch for the new datum defines the upper limit for the validity of the superseded datum.- Returns:
- The datum realization epoch, or
null
if not available.
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getDomainOfValidity
Extent getDomainOfValidity()
Area or region or timeframe in which this datum is valid.- Returns:
- The datum valid domain, or
null
if not available. - Since:
- GeoAPI 2.1
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getScope
InternationalString getScope()
Description of domain of usage, or limitations of usage, for which this datum object is valid.- Returns:
- A description of domain of usage, or
null
if none.
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