001 /*
002 * GeoAPI - Java interfaces for OGC/ISO standards
003 * http://www.geoapi.org
004 *
005 * Copyright (C) 2004-2012 Open Geospatial Consortium, Inc.
006 * All Rights Reserved. http://www.opengeospatial.org/ogc/legal
007 *
008 * Permission to use, copy, and modify this software and its documentation, with
009 * or without modification, for any purpose and without fee or royalty is hereby
010 * granted, provided that you include the following on ALL copies of the software
011 * and documentation or portions thereof, including modifications, that you make:
012 *
013 * 1. The full text of this NOTICE in a location viewable to users of the
014 * redistributed or derivative work.
015 * 2. Notice of any changes or modifications to the OGC files, including the
016 * date changes were made.
017 *
018 * THIS SOFTWARE AND DOCUMENTATION IS PROVIDED "AS IS," AND COPYRIGHT HOLDERS MAKE
019 * NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
020 * TO, WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE OR THAT
021 * THE USE OF THE SOFTWARE OR DOCUMENTATION WILL NOT INFRINGE ANY THIRD PARTY
022 * PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS.
023 *
024 * COPYRIGHT HOLDERS WILL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL OR
025 * CONSEQUENTIAL DAMAGES ARISING OUT OF ANY USE OF THE SOFTWARE OR DOCUMENTATION.
026 *
027 * The name and trademarks of copyright holders may NOT be used in advertising or
028 * publicity pertaining to the software without specific, written prior permission.
029 * Title to copyright in this software and any associated documentation will at all
030 * times remain with copyright holders.
031 */
032 package org.opengis.referencing.crs;
033
034 import org.opengis.referencing.ReferenceSystem;
035 import org.opengis.referencing.cs.CoordinateSystem;
036 import org.opengis.annotation.UML;
037
038 import static org.opengis.annotation.Specification.*;
039
040
041 /**
042 * Abstract coordinate reference system, usually defined by a
043 * {@linkplain org.opengis.referencing.cs.CoordinateSystem coordinate system} and a
044 * {@linkplain org.opengis.referencing.datum.Datum datum}. The concept of a coordinate
045 * reference system (CRS) captures the choice of values for the parameters that constitute
046 * the degrees of freedom of the coordinate space. The fact that such a choice has to be made,
047 * either arbitrarily or by adopting values from survey measurements, leads to the large number
048 * of coordinate reference systems in use around the world. It is also the cause of the little
049 * understood fact that the latitude and longitude of a point are not unique. Without the full
050 * specification of the coordinate reference system, coordinates are ambiguous at best and
051 * meaningless at worst. However for some interchange purposes it is sufficient to confirm the
052 * {@linkplain #getName identity of the system} without necessarily having the full system
053 * definition.
054 * <p>
055 * The concept of coordinates may be expanded from a strictly spatial context to include time.
056 * Time is then added as another coordinate to the coordinate tuple. It is even possible to add
057 * two time-coordinates, provided the two coordinates describe different independent quantities.
058 * An example of the latter is the time/space position of a subsurface point of which the vertical
059 * coordinate is expressed as the two-way travel time of a sound signal in milliseconds, as is
060 * common in seismic imaging. A second time-coordinate indicates the time of observation, usually
061 * expressed in whole years.
062 *
063 * @author Martin Desruisseaux (IRD)
064 * @version 3.0
065 * @since 1.0
066 *
067 * @navassoc 1 - - CoordinateSystem
068 */
069 @UML(identifier="SC_CRS", specification=ISO_19111)
070 public interface CoordinateReferenceSystem extends ReferenceSystem {
071 /**
072 * Returns a relevant coordinate system instance. Special cases:
073 *
074 * <ul>
075 * <li><p>If the CRS instance on which this method is invoked is an instance of the
076 * {@linkplain SingleCRS single CRS} interface, then the CS instance which is
077 * returned shall be one of the defined sub-interfaces of {@linkplain CoordinateSystem
078 * coordinate system}.</p></li>
079 *
080 * <li><p>If the CRS instance on which this method is invoked is an instance of the
081 * {@linkplain CompoundCRS compound CRS} interface, then the CS instance which is
082 * returned shall have dimension and axis components obtained from different
083 * {@linkplain CompoundCRS#getComponents components} of the instance CRS.</p></li>
084 * </ul>
085 *
086 * @return The coordinate system.
087 *
088 * @departure generalization
089 * ISO 19111 defines this method for <code>SingleCRS</code> only. GeoAPI declares this method
090 * in this parent interface for user convenience, since CS dimension and axes are commonly
091 * requested information and will always be available, directly or indirectly,
092 * even for <code>CompoundCRS</code>.
093 */
094 CoordinateSystem getCoordinateSystem();
095 }