Application: gvSIG desktop » gvSIG projections

/**

 * gvSIG. Desktop Geographic Information System.

 *

 * Copyright (C) 2018 gvSIG Association.

 * 

 * This file has been adapted from GeoAPI, see 

 * the original copyright headers bellow.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,

 * MA  02110-1301, USA.

 *

 * For any additional information, do not hesitate to contact us

 * at info AT gvsig.com, or visit our website www.gvsig.com.

 * 

 * ----------

 * 

 *    GeoAPI - Java interfaces for OGC/ISO standards

 *    http://www.geoapi.org

 *

 *    Copyright (C) 2004-2017 Open Geospatial Consortium, Inc.

 *    All Rights Reserved. http://www.opengeospatial.org/ogc/legal

 *

 *    Permission to use, copy, and modify this software and its documentation, with

 *    or without modification, for any purpose and without fee or royalty is hereby

 *    granted, provided that you include the following on ALL copies of the software

 *    and documentation or portions thereof, including modifications, that you make:

 *

 *    1. The full text of this NOTICE in a location viewable to users of the

 *       redistributed or derivative work.

 *    2. Notice of any changes or modifications to the OGC files, including the

 *       date changes were made.

 *

 *    THIS SOFTWARE AND DOCUMENTATION IS PROVIDED "AS IS," AND COPYRIGHT HOLDERS MAKE

 *    NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED

 *    TO, WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE OR THAT

 *    THE USE OF THE SOFTWARE OR DOCUMENTATION WILL NOT INFRINGE ANY THIRD PARTY

 *    PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS.

 *

 *    COPYRIGHT HOLDERS WILL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL OR

 *    CONSEQUENTIAL DAMAGES ARISING OUT OF ANY USE OF THE SOFTWARE OR DOCUMENTATION.

 *

 *    The name and trademarks of copyright holders may NOT be used in advertising or

 *    publicity pertaining to the software without specific, written prior permission.

 *    Title to copyright in this software and any associated documentation will at all

 *    times remain with copyright holders.

 */

package org.gvsig.proj.catalogue.datum;

import javax.measure.quantity.Length;

import javax.measure.unit.Unit;

/**

 * Geometric figure that can be used to describe the approximate shape of the earth.

 * In mathematical terms, it is a surface formed by the rotation of an ellipse about

 * its minor axis. An ellipsoid requires two defining parameters:

 *

 * <ul>

 *   <li>{@linkplain #getSemiMajorAxis() semi-major axis} and

 *       {@linkplain #getInverseFlattening() inverse flattening}, or</li>

 *   <li>{@linkplain #getSemiMajorAxis() semi-major axis} and

 *       {@linkplain #getSemiMinorAxis() semi-minor axis}.</li>

 * </ul>

 *

 * There is not just one ellipsoid. An ellipsoid is a matter of choice, and therefore many

 * choices are possible. The size and shape of an ellipsoid was traditionally chosen such

 * that the surface of the geoid is matched as closely as possible locally, e.g. in a country.

 * A number of global best-fit ellipsoids are now available. An association of an ellipsoid with

 * the earth is made through the definition of the size and shape of the ellipsoid and the position

 * and orientation of this ellipsoid with respect to the earth. Collectively this choice is captured

 * by the concept of "geodetic datum". A change of size, shape, position

 * or orientation of an ellipsoid will result in a change of geographic coordinates of a point and

 * be described as a different geodetic datum. Conversely geographic coordinates are unambiguous

 * only when associated with a geodetic datum.

 *

 * Note: gvSIG derived these interfaces from GeoAPI in order to have a simpler API and also to

 * avoid namespace collisions (e.g. GeoAPI 3 vs GeoTools interfaces). There is no plans

 * to evolve these interfaces to adapt them to future GeoAPI versions.

 * 

 * @author  gvSIG Team

 * @author  Martin Desruisseaux (IRD)

 */

public interface Ellipsoid {

            /**

             * Returns the linear unit of the {@linkplain #getSemiMajorAxis() semi-major}

             * and {@linkplain #getSemiMinorAxis() semi-minor} axis values.

             *

             * @return the axis linear unit.

             */

            Unit<Length> getAxisUnit();

            /**

             * Length of the semi-major axis of the ellipsoid. This is the

             * equatorial radius in {@linkplain #getAxisUnit() axis linear unit}.

             *

             * @return length of semi-major axis.

             * @unitof Length

             */

            double getSemiMajorAxis();

            /**

             * Length of the semi-minor axis of the ellipsoid. This is the

             * polar radius in {@linkplain #getAxisUnit() axis linear unit}.

             *

             * @return length of semi-minor axis.

             * @unitof Length

             */

            double getSemiMinorAxis();

            /**

             * Returns the value of the inverse of the flattening constant. The inverse

             * flattening is related to the equatorial/polar radius by the formula

             *

             * <var>ivf</var>&nbsp;=&nbsp;<var>r</var><sub>e</sub>/(<var>r</var><sub>e</sub>-<var>r</var><sub>p</sub>).

             *

             * For perfect spheres (i.e. if {@link #isSphere()} returns {@code true}),

             * the {@link Double#POSITIVE_INFINITY POSITIVE_INFINITY} value is used.

             *

             * @return the inverse flattening value.

             * @unitof Scale

             */

            double getInverseFlattening();

            /**

             * Indicates if the {@linkplain #getInverseFlattening() inverse flattening} is definitive for

             * this ellipsoid. Some ellipsoids use the IVF as the defining value, and calculate the polar

             * radius whenever asked. Other ellipsoids use the polar radius to calculate the IVF whenever

             * asked. This distinction can be important to avoid floating-point rounding errors.

             *

             * @return {@code true} if the {@linkplain #getInverseFlattening() inverse flattening} is

             *         definitive, or {@code false} if the {@linkplain #getSemiMinorAxis() polar radius}

             *         is definitive.

             */

            boolean isIvfDefinitive();

            /**

             * {@code true} if the ellipsoid is degenerate and is actually a sphere. The sphere is

             * completely defined by the {@linkplain #getSemiMajorAxis() semi-major axis}, which is

             * the radius of the sphere.

             *

             * @return {@code true} if the ellipsoid is degenerate and is actually a sphere.

             */

            boolean isSphere();

}