GeodeticPoint.java
/* Copyright 2002-2024 CS GROUP
* Licensed to CS GROUP (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.orekit.bodies;
import java.io.Serializable;
import java.text.NumberFormat;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.hipparchus.util.CompositeFormat;
import org.hipparchus.util.FastMath;
import org.hipparchus.util.MathUtils;
import org.hipparchus.util.SinCos;
/** Point location relative to a 2D body surface.
* <p>Instance of this class are guaranteed to be immutable.</p>
* @see BodyShape
* @see FieldGeodeticPoint
* @author Luc Maisonobe
*/
public class GeodeticPoint implements Serializable {
/** North pole.
* @since 10.0
*/
public static final GeodeticPoint NORTH_POLE = new GeodeticPoint(+0.5 * FastMath.PI, 0.0, 0.0);
/** South pole.
* @since 10.0
*/
public static final GeodeticPoint SOUTH_POLE = new GeodeticPoint(-0.5 * FastMath.PI, 0.0, 0.0);
/** Serializable UID. */
private static final long serialVersionUID = 7862466825590075399L;
/** Latitude of the point (rad). */
private final double latitude;
/** Longitude of the point (rad). */
private final double longitude;
/** Altitude of the point (m). */
private final double altitude;
/** Zenith direction. */
private transient Vector3D zenith;
/** Nadir direction. */
private transient Vector3D nadir;
/** North direction. */
private transient Vector3D north;
/** South direction. */
private transient Vector3D south;
/** East direction. */
private transient Vector3D east;
/** West direction. */
private transient Vector3D west;
/**
* Build a new instance. The angular coordinates will be normalized so that
* the latitude is between ±π/2 and the longitude is between ±π.
*
* @param latitude latitude of the point (rad)
* @param longitude longitude of the point (rad)
* @param altitude altitude of the point (m)
*/
public GeodeticPoint(final double latitude, final double longitude,
final double altitude) {
double lat = MathUtils.normalizeAngle(latitude, FastMath.PI / 2);
double lon = MathUtils.normalizeAngle(longitude, 0);
if (lat > FastMath.PI / 2.0) {
// latitude is beyond the pole -> add 180 to longitude
lat = FastMath.PI - lat;
lon = MathUtils.normalizeAngle(longitude + FastMath.PI, 0);
}
this.latitude = lat;
this.longitude = lon;
this.altitude = altitude;
}
/** Get the latitude.
* @return latitude, an angular value in the range [-π/2, π/2]
*/
public double getLatitude() {
return latitude;
}
/** Get the longitude.
* @return longitude, an angular value in the range [-π, π]
*/
public double getLongitude() {
return longitude;
}
/** Get the altitude.
* @return altitude
*/
public double getAltitude() {
return altitude;
}
/** Get the direction above the point, expressed in parent shape frame.
* <p>The zenith direction is defined as the normal to local horizontal plane.</p>
* @return unit vector in the zenith direction
* @see #getNadir()
*/
public Vector3D getZenith() {
if (zenith == null) {
final SinCos scLat = FastMath.sinCos(latitude);
final SinCos scLon = FastMath.sinCos(longitude);
zenith = new Vector3D(scLon.cos() * scLat.cos(), scLon.sin() * scLat.cos(), scLat.sin());
}
return zenith;
}
/** Get the direction below the point, expressed in parent shape frame.
* <p>The nadir direction is the opposite of zenith direction.</p>
* @return unit vector in the nadir direction
* @see #getZenith()
*/
public Vector3D getNadir() {
if (nadir == null) {
nadir = getZenith().negate();
}
return nadir;
}
/** Get the direction to the north of point, expressed in parent shape frame.
* <p>The north direction is defined in the horizontal plane
* (normal to zenith direction) and following the local meridian.</p>
* @return unit vector in the north direction
* @see #getSouth()
*/
public Vector3D getNorth() {
if (north == null) {
final SinCos scLat = FastMath.sinCos(latitude);
final SinCos scLon = FastMath.sinCos(longitude);
north = new Vector3D(-scLon.cos() * scLat.sin(), -scLon.sin() * scLat.sin(), scLat.cos());
}
return north;
}
/** Get the direction to the south of point, expressed in parent shape frame.
* <p>The south direction is the opposite of north direction.</p>
* @return unit vector in the south direction
* @see #getNorth()
*/
public Vector3D getSouth() {
if (south == null) {
south = getNorth().negate();
}
return south;
}
/** Get the direction to the east of point, expressed in parent shape frame.
* <p>The east direction is defined in the horizontal plane
* in order to complete direct triangle (east, north, zenith).</p>
* @return unit vector in the east direction
* @see #getWest()
*/
public Vector3D getEast() {
if (east == null) {
final SinCos scLon = FastMath.sinCos(longitude);
east = new Vector3D(-scLon.sin(), scLon.cos(), 0);
}
return east;
}
/** Get the direction to the west of point, expressed in parent shape frame.
* <p>The west direction is the opposite of east direction.</p>
* @return unit vector in the west direction
* @see #getEast()
*/
public Vector3D getWest() {
if (west == null) {
west = getEast().negate();
}
return west;
}
@Override
public boolean equals(final Object object) {
if (object instanceof GeodeticPoint) {
final GeodeticPoint other = (GeodeticPoint) object;
return this.getLatitude() == other.getLatitude() &&
this.getLongitude() == other.getLongitude() &&
this.getAltitude() == other.getAltitude();
}
return false;
}
@Override
public int hashCode() {
return Double.valueOf(this.getLatitude()).hashCode() ^
Double.valueOf(this.getLongitude()).hashCode() ^
Double.valueOf(this.getAltitude()).hashCode();
}
@Override
public String toString() {
final NumberFormat format = CompositeFormat.getDefaultNumberFormat();
return "{lat: " +
format.format(FastMath.toDegrees(this.getLatitude())) +
" deg, lon: " +
format.format(FastMath.toDegrees(this.getLongitude())) +
" deg, alt: " +
format.format(this.getAltitude()) +
"}";
}
}