001/*
002 *    GeoAPI - Java interfaces for OGC/ISO standards
003 *    Copyright © 2003-2024 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.crs;
019
020import java.util.Map;
021import org.opengis.referencing.cs.VerticalCS;
022import org.opengis.referencing.datum.VerticalDatum;
023import org.opengis.referencing.datum.DatumEnsemble;
024import org.opengis.annotation.UML;
025
026import static org.opengis.annotation.Obligation.*;
027import static org.opengis.annotation.Specification.*;
028
029
030/**
031 * A 1-dimensional <abbr>CRS</abbr> used for recording heights or depths.
032 * Vertical <abbr>CRS</abbr>s make use of the direction of gravity to define the concept of height or depth,
033 * but the relationship with gravity may not be straightforward.
034 *
035 * <p>By implication, ellipsoidal heights (<var>h</var>) cannot be captured in a vertical <abbr>CRS</abbr>.
036 * Ellipsoidal heights cannot exist independently, but only as inseparable part of a 3D coordinate tuple
037 * defined in a geographic or projected 3D <abbr>CRS</abbr>.</p>
038 *
039 * <h2>Permitted coordinate systems</h2>
040 * This type of <abbr>CRS</abbr> can be used with coordinate systems of type {@link VerticalCS} only.
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 CRSAuthorityFactory#createVerticalCRS(String)
048 * @see CRSFactory#createVerticalCRS(Map, VerticalDatum, DatumEnsemble, VerticalCS)
049 */
050@UML(identifier="VerticalCRS", specification=ISO_19111)
051public interface VerticalCRS extends SingleCRS {
052    /**
053     * Returns the coordinate system, which shall be vertical.
054     *
055     * @return the vertical coordinate system.
056     */
057    @Override
058    @UML(identifier="coordinateSystem", obligation=MANDATORY, specification=ISO_19111)
059    VerticalCS getCoordinateSystem();
060
061    /**
062     * Returns the reference frame, which shall be vertical.
063     * This property may be null if this <abbr>CRS</abbr> is related to an object
064     * identified only by a {@linkplain #getDatumEnsemble() datum ensemble}.
065     *
066     * @return the reference frame, or {@code null} if this <abbr>CRS</abbr> is related to
067     *         an object identified only by a {@linkplain #getDatumEnsemble() datum ensemble}.
068     *
069     * @condition Mandatory if the {@linkplain #getDatumEnsemble() datum ensemble} is not documented.
070     */
071    @Override
072    @UML(identifier="datum", obligation=CONDITIONAL, specification=ISO_19111)
073    VerticalDatum getDatum();
074
075    /**
076     * Returns the datum ensemble, which shall have vertical datum members.
077     * This property may be null if this <abbr>CRS</abbr> is related to an object
078     * identified only by a single {@linkplain #getDatum() datum}.
079     *
080     * <p>The default implementation returns {@code null}.</p>
081     *
082     * @return the datum ensemble, or {@code null} if this <abbr>CRS</abbr> is related
083     *         to an object identified only by a single {@linkplain #getDatum() datum}.
084     *
085     * @condition Mandatory if the {@linkplain #getDatum() datum} is not documented.
086     * @since 3.1
087     */
088    @Override
089    @UML(identifier="datum", obligation=CONDITIONAL, specification=ISO_19111)
090    default DatumEnsemble<VerticalDatum> getDatumEnsemble() {
091        return null;
092    }
093}