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 1-dimensional coordinate system used to record the heights or depths of points.
027 * Such a coordinate system is usually dependent on the planet's gravity field, perhaps
028 * loosely as when atmospheric pressure is the basis for the vertical coordinate system axis.
029 * An exact definition is deliberately not provided as the complexities of the subject fall
030 * outside the scope of the ISO 19111 specification.
031 *
032 * <p>This type of <abbr>CS</abbr> can be used by coordinate reference systems of type
033 * {@link org.opengis.referencing.crs.VerticalCRS}, potentially in combination with
034 * {@link org.opengis.referencing.crs.DerivedCRS}.
035 * The following examples describe some possible axes for vertical CS used with the above-cited CRS:</p>
036 *
037 * <table class="ogc">
038 *   <caption>Example 1: positive values above sea level</caption>
039 *   <tr><th>Axis name</th> <th>Abbr.</th> <th>Direction</th> <th>Unit</th></tr>
040 *   <tr><td>Gravity-related height</td> <td>H</td> <td>{@link AxisDirection#UP}</td> <td>metre</td></tr>
041 * </table>
042 *
043 * <table class="ogc">
044 *   <caption>Example 2: positive values below sea level</caption>
045 *   <tr><th>Axis name</th> <th>Abbr.</th> <th>Direction</th> <th>Unit</th></tr>
046 *   <tr><td>Depth</td> <td>D</td> <td>{@link AxisDirection#DOWN}</td> <td>metre</td></tr>
047 * </table>
048 *
049 * @author  OGC Topic 2 (for abstract model and documentation)
050 * @author  Martin Desruisseaux (IRD, Geomatys)
051 * @version 3.1
052 * @since   1.0
053 *
054 * @see CSAuthorityFactory#createVerticalCS(String)
055 * @see CSFactory#createVerticalCS(Map, CoordinateSystemAxis)
056 */
057@UML(identifier="VerticalCS", specification=ISO_19111)
058public interface VerticalCS extends CoordinateSystem {
059    /**
060     * Returns the number of dimensions, which is 1 for this type of coordinate system.
061     *
062     * @return always 1.
063     */
064    @Override
065    default int getDimension() {
066        return 1;
067    }
068}