CircularFieldOfViewDetector.java
- /* Copyright 2002-2017 CS Systèmes d'Information
- * Licensed to CS Systèmes d'Information (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.propagation.events;
- import org.hipparchus.geometry.euclidean.threed.Vector3D;
- import org.orekit.errors.OrekitException;
- import org.orekit.propagation.SpacecraftState;
- import org.orekit.propagation.events.handlers.EventHandler;
- import org.orekit.propagation.events.handlers.StopOnDecreasing;
- import org.orekit.utils.PVCoordinatesProvider;
- /** Finder for target entry/exit events with respect to a satellite sensor Field Of View.
- * <p>This class handle fields of view with a circular boundary.</p>
- * <p>The default implementation behavior is to {@link
- * org.orekit.propagation.events.handlers.EventHandler.Action#CONTINUE continue}
- * propagation at FOV entry and to {@link
- * org.orekit.propagation.events.handlers.EventHandler.Action#STOP stop} propagation
- * at FOV exit. This can be changed by calling
- * {@link #withHandler(EventHandler)} after construction.</p>
- * @see org.orekit.propagation.Propagator#addEventDetector(EventDetector)
- * @see FieldOfViewDetector
- * @author Véronique Pommier-Maurussane
- */
- public class CircularFieldOfViewDetector extends AbstractDetector<CircularFieldOfViewDetector> {
- /** Serializable UID. */
- private static final long serialVersionUID = 20131118L;
- /** Position/velocity provider of the considered target. */
- private final PVCoordinatesProvider targetPVProvider;
- /** Direction of the FOV center. */
- private final Vector3D center;
- /** FOV half aperture angle. */
- private final double halfAperture;
- /** Build a new instance.
- * <p>The maximal interval between distance to FOV boundary checks should
- * be smaller than the half duration of the minimal pass to handle,
- * otherwise some short passes could be missed.</p>
- * @param maxCheck maximal interval in seconds
- * @param pvTarget Position/velocity provider of the considered target
- * @param center Direction of the FOV center, in spacecraft frame
- * @param halfAperture FOV half aperture angle
- */
- public CircularFieldOfViewDetector(final double maxCheck,
- final PVCoordinatesProvider pvTarget,
- final Vector3D center,
- final double halfAperture) {
- this(maxCheck, 1.0e-3, DEFAULT_MAX_ITER, new StopOnDecreasing<CircularFieldOfViewDetector>(),
- pvTarget, center, halfAperture);
- }
- /** Private constructor with full parameters.
- * <p>
- * This constructor is private as users are expected to use the builder
- * API with the various {@code withXxx()} methods to set up the instance
- * in a readable manner without using a huge amount of parameters.
- * </p>
- * @param maxCheck maximum checking interval (s)
- * @param threshold convergence threshold (s)
- * @param maxIter maximum number of iterations in the event time search
- * @param handler event handler to call at event occurrences
- * @param pvTarget Position/velocity provider of the considered target
- * @param center Direction of the FOV center, in spacecraft frame
- * @param halfAperture FOV half aperture angle
- * @since 6.1
- */
- private CircularFieldOfViewDetector(final double maxCheck, final double threshold,
- final int maxIter, final EventHandler<? super CircularFieldOfViewDetector> handler,
- final PVCoordinatesProvider pvTarget,
- final Vector3D center,
- final double halfAperture) {
- super(maxCheck, threshold, maxIter, handler);
- this.targetPVProvider = pvTarget;
- this.center = center;
- this.halfAperture = halfAperture;
- }
- /** {@inheritDoc} */
- @Override
- protected CircularFieldOfViewDetector create(final double newMaxCheck, final double newThreshold,
- final int newMaxIter, final EventHandler<? super CircularFieldOfViewDetector> newHandler) {
- return new CircularFieldOfViewDetector(newMaxCheck, newThreshold, newMaxIter, newHandler,
- targetPVProvider, center, halfAperture);
- }
- /** Get the position/velocity provider of the target .
- * @return the position/velocity provider of the target
- */
- public PVCoordinatesProvider getPVTarget() {
- return targetPVProvider;
- }
- /** Get the direction of FOV center.
- * @return the direction of FOV center
- */
- public Vector3D getCenter() {
- return center;
- }
- /** Get FOV half aperture angle.
- * @return the FOV half aperture angle
- */
- public double getHalfAperture() {
- return halfAperture;
- }
- /** {@inheritDoc}
- * <p>
- * The g function value is the difference between FOV half aperture and the
- * absolute value of the angle between target direction and field of view center.
- * It is positive inside the FOV and negative outside.
- * </p>
- */
- public double g(final SpacecraftState s) throws OrekitException {
- // Compute target position/velocity at date in spacecraft frame
- final Vector3D targetPosInert = new Vector3D(1, targetPVProvider.getPVCoordinates(s.getDate(), s.getFrame()).getPosition(),
- -1, s.getPVCoordinates().getPosition());
- final Vector3D targetPosSat = s.getAttitude().getRotation().applyTo(targetPosInert);
- // Target is in the field of view if the absolute value that angle is smaller than FOV half aperture.
- // g function value is the difference between FOV half aperture and the absolute value of the angle between
- // target direction and field of view center. It is positive inside the FOV and negative outside.
- return halfAperture - Vector3D.angle(targetPosSat, center);
- }
- }