GroundFieldOfViewDetector.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.frames.Frame;
- import org.orekit.propagation.SpacecraftState;
- import org.orekit.propagation.events.handlers.EventHandler;
- import org.orekit.propagation.events.handlers.StopOnIncreasing;
- /**
- * Finder for satellite entry/exit events with respect to a sensor {@link
- * FieldOfView Field Of View} attached to an arbitrary frame.
- *
- * <p> If you only want to compute access times then you should probably use
- * {@link ElevationDetector}.
- *
- * <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>
- *
- * @author Luc Maisonobe
- * @author Evan Ward
- * @see org.orekit.propagation.Propagator#addEventDetector(EventDetector)
- * @see FieldOfViewDetector
- * @see ElevationDetector
- * @since 7.1
- */
- public class GroundFieldOfViewDetector extends AbstractDetector<GroundFieldOfViewDetector> {
- /** Serializable UID. */
- private static final long serialVersionUID = 20160114L;
- /** the reference frame attached to the sensor. */
- private final Frame frame;
- /** Field of view of the sensor. */
- 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 frame the reference frame attached to the sensor.
- * @param fov Field Of View of the sensor.
- */
- public GroundFieldOfViewDetector(final Frame frame,
- final FieldOfView fov) {
- this(DEFAULT_MAXCHECK, DEFAULT_THRESHOLD, DEFAULT_MAX_ITER,
- new StopOnIncreasing<GroundFieldOfViewDetector>(),
- frame, 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 frame the reference frame attached to the sensor.
- * @param fov Field Of View of the sensor.
- */
- private GroundFieldOfViewDetector(final double maxCheck,
- final double threshold,
- final int maxIter,
- final EventHandler<? super GroundFieldOfViewDetector> handler,
- final Frame frame,
- final FieldOfView fov) {
- super(maxCheck, threshold, maxIter, handler);
- this.frame = frame;
- this.fov = fov;
- }
- /** {@inheritDoc} */
- @Override
- protected GroundFieldOfViewDetector create(final double newMaxCheck,
- final double newThreshold,
- final int newMaxIter,
- final EventHandler<? super GroundFieldOfViewDetector> newHandler) {
- return new GroundFieldOfViewDetector(newMaxCheck, newThreshold,
- newMaxIter, newHandler, this.frame, this.fov);
- }
- /**
- * Get the sensor reference frame.
- *
- * @return the reference frame attached to the sensor.
- */
- public Frame getFrame() {
- return this.frame;
- }
- /**
- * 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 satellite and
- * the {@link FieldOfView#offsetFromBoundary(Vector3D) Field Of View
- * boundary}. It is negative if the satellite 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 satellite enters the Field
- * Of View, a decreasing event is generated, and when the satellite leaves
- * the Field Of View, an increasing event is generated. </p>
- */
- public double g(final SpacecraftState s) throws OrekitException {
- // get line of sight in sensor frame
- final Vector3D los = s.getPVCoordinates(this.frame).getPosition();
- return this.fov.offsetFromBoundary(los);
- }
- }