Package org.apache.sis.referencing

Base classes for reference systems used for general positioning.

See: Description

Package org.apache.sis.referencing Description

Base classes for reference systems used for general positioning. An explanation for this package is provided in the OpenGISĀ® javadoc. The remaining discussion on this page is specific to the SIS implementation.

The most commonly used kinds of Reference Systems in Apache SIS are the Coordinate Reference Systems (CRS), which handle coordinates of arbitrary dimensions. The SIS implementations can handle 2D and 3D coordinates, as well as 4D, 5D, etc. An other less-frequently used kind of Reference System uses labels instead, as in postal address. This package is the root for both kinds, with an emphasis on the one for coordinates.

Fetching geodetic object instances
Geodetic objects can be instantiated either directly by specifying all information to a factory method or constructor, or indirectly by specifying the identifier of an entry in a database. In particular, the EPSG database provides definitions for many geodetic objects, and Apache SIS provides convenience shortcuts for some of them in the CommonCRS enumerations.
The EPSG database
The EPSG geodetic parameter dataset is a structured database required to: Various programmatic elements in Apache SIS have a relationship with EPSG entries, including: Relationship with EPSG has two components documented in the javadoc: the object type and the EPSG code. The type specifies which AuthorityFactory method to invoke, while the code specifies the argument value to give to that method in order to get the EPSG object. For example the CommonCRS.WGS84 documentation said that object of type geodetic datum is associated to code EPSG:6326. This means that the EPSG object could be obtained by the following code:
DatumAuthorityFactory factory = ...; // TODO: document how to obtain an EPSG factory.
GeodeticDatum datum = factory.createGeodeticDatum("6326");
The EPSG objects can also be inspected online on the EPSG registry web site.

Defined in the sis-referencing module

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