001/*
002 *    GeoAPI - Java interfaces for OGC/ISO standards
003 *    Copyright © 2003-2023 Open Geospatial Consortium, Inc.
004 *    http://www.geoapi.org
005 *
006 *    Licensed under the Apache License, Version 2.0 (the "License");
007 *    you may not use this file except in compliance with the License.
008 *    You may obtain a copy of the License at
009 *
010 *        http://www.apache.org/licenses/LICENSE-2.0
011 *
012 *    Unless required by applicable law or agreed to in writing, software
013 *    distributed under the License is distributed on an "AS IS" BASIS,
014 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 *    See the License for the specific language governing permissions and
016 *    limitations under the License.
017 */
018package org.opengis.referencing.cs;
019
020import java.util.Map;
021import org.opengis.annotation.UML;
022import static org.opengis.annotation.Specification.*;
023
024
025/**
026 * A 2-dimensional polar coordinate system.
027 * Position is specified by the distance from the origin and the angle
028 * between the line from the origin to a point and a reference direction.
029 *
030 * <p>This type of <abbr>CS</abbr> can be used by coordinate reference systems of type
031 * {@link org.opengis.referencing.crs.EngineeringCRS}, potentially in combination with
032 * {@link org.opengis.referencing.crs.DerivedCRS}.
033 * The following examples describe some possible set of axes for polar CS used with the above-cited CRS:</p>
034 *
035 * <table class="ogc">
036 *   <caption>Example: used with an Engineering CRS</caption>
037 *   <tr><th>Axis name</th> <th>Abbr.</th> <th>Direction</th> <th>Unit</th></tr>
038 *   <tr><td>Distance</td> <td>r</td> <td>{@link AxisDirection#AWAY_FROM}</td> <td>metre</td></tr>
039 *   <tr><td>Bearing</td>  <td>Θ</td> <td>{@link AxisDirection#CLOCKWISE}</td> <td>degree</td></tr>
040 * </table>
041 *
042 * @author  OGC Topic 2 (for abstract model and documentation)
043 * @author  Martin Desruisseaux (IRD, Geomatys)
044 * @version 3.1
045 * @since   1.0
046 *
047 * @see CylindricalCS
048 * @see CSAuthorityFactory#createPolarCS(String)
049 * @see CSFactory#createPolarCS(Map, CoordinateSystemAxis, CoordinateSystemAxis)
050 */
051@UML(identifier="PolarCS", specification=ISO_19111)
052public interface PolarCS extends CoordinateSystem {
053    /**
054     * Returns the number of dimensions, which is 2 for this type of coordinate system.
055     *
056     * @return always 2.
057     */
058    @Override
059    default int getDimension() {
060        return 2;
061    }
062}