FieldOfViewDetector.java
- /* Copyright 2002-2016 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.StopOnIncreasing;
- import org.orekit.utils.PVCoordinatesProvider;
- /** Finder for target entry/exit events with respect to a satellite sensor
- * {@link FieldOfView Field Of View}.
- * <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 CircularFieldOfViewDetector
- * @see FootprintOverlapDetector
- * @author Luc Maisonobe
- * @since 7.1
- */
- public class FieldOfViewDetector extends AbstractDetector<FieldOfViewDetector> {
- /** Serializable UID. */
- private static final long serialVersionUID = 20160114L;
- /** Position/velocity provider of the considered target. */
- private final PVCoordinatesProvider targetPVProvider;
- /** Field of view. */
- private final FieldOfView fov;
- /** 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 pvTarget Position/velocity provider of the considered target
- * @param fov Field Of View
- */
- public FieldOfViewDetector(final PVCoordinatesProvider pvTarget, final FieldOfView fov) {
- this(DEFAULT_MAXCHECK, DEFAULT_THRESHOLD, DEFAULT_MAX_ITER,
- new StopOnIncreasing<FieldOfViewDetector>(),
- pvTarget, fov);
- }
- /** 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 fov Field Of View
- */
- private FieldOfViewDetector(final double maxCheck, final double threshold, final int maxIter,
- final EventHandler<? super FieldOfViewDetector> handler,
- final PVCoordinatesProvider pvTarget, final FieldOfView fov) {
- super(maxCheck, threshold, maxIter, handler);
- this.targetPVProvider = pvTarget;
- this.fov = fov;
- }
- /** {@inheritDoc} */
- @Override
- protected FieldOfViewDetector create(final double newMaxCheck, final double newThreshold,
- final int newMaxIter,
- final EventHandler<? super FieldOfViewDetector> newHandler) {
- return new FieldOfViewDetector(newMaxCheck, newThreshold, newMaxIter, newHandler,
- targetPVProvider, fov);
- }
- /** Get the position/velocity provider of the target .
- * @return the position/velocity provider of the target
- */
- public PVCoordinatesProvider getPVTarget() {
- return targetPVProvider;
- }
- /** Get the Field Of View.
- * @return Field Of View
- */
- public FieldOfView getFieldOfView() {
- return fov;
- }
- /** {@inheritDoc}
- * <p>
- * The g function value is the angular offset between the
- * target and the {@link FieldOfView#offsetFromBoundary(Vector3D)
- * Field Of View boundary}. It is negative if the target is
- * visible within the Field Of View and positive if it is outside of the
- * Field Of View, including the margin.
- * </p>
- * <p>
- * As per the previous definition, when the target enters the Field Of
- * View, a decreasing event is generated, and when the target leaves
- * the Field Of View, an increasing event is generated.
- * </p>
- */
- public double g(final SpacecraftState s) throws OrekitException {
- // get line of sight in spacecraft frame
- final Vector3D targetPosInert =
- targetPVProvider.getPVCoordinates(s.getDate(), s.getFrame()).getPosition();
- final Vector3D lineOfSightSC = s.toTransform().transformPosition(targetPosInert);
- return fov.offsetFromBoundary(lineOfSightSC);
- }
- }