psg.org">EPSG database provides definitions for many prime meridians, and Apache SIS provides convenience shortcuts for some of them.
Choice 1 in the following list is the easiest but most restrictive way to get a prime meridian. The other choices provide more freedom. Each choice delegates its work to the subsequent items (in the default configuration), so this list can been seen as top to bottom API.
- Create a {@code PrimeMeridian} from one of the static convenience shortcuts listed in{@link org.apache.sis.referencing.CommonCRS#primeMeridian()}.
- Create a {@code PrimeMeridian} from an identifier in a database by invoking{@link org.opengis.referencing.datum.DatumAuthorityFactory#createPrimeMeridian(String)}.
- Create a {@code PrimeMeridian} by invoking the {@code createPrimeMeridian(…)}method defined in the {@link org.opengis.referencing.datum.DatumFactory} interface.
- Create a {@code DefaultPrimeMeridian} by invoking the{@linkplain #DefaultPrimeMeridian(Map,double,Unit) constructor}.
Example: the following code gets the Greenwich prime meridian: {@preformat javaPrimeMeridian pm = CommonCRS.WGS84.primeMeridian();}{@section Immutability and thread safety}This class is immutable and thus thread-safe if the property
values (not necessarily the map itself) given to the constructor are also immutable. Unless otherwise noted in the javadoc, this condition holds if all components were created using only SIS factories and static constants.
@author Martin Desruisseaux (IRD, Geomatys)
@author Cédric Briançon (Geomatys)
@since 0.4 (derived from geotk-1.2)
@version 0.4
@module
@see org.apache.sis.referencing.CommonCRS#primeMeridian()