ElevationDetector.java

  1. /* Copyright 2002-2024 CS GROUP
  2.  * Licensed to CS GROUP (CS) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * CS licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *   http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.orekit.propagation.events;

  19. import org.hipparchus.ode.events.Action;
  20. import org.orekit.frames.TopocentricFrame;
  21. import org.orekit.models.AtmosphericRefractionModel;
  22. import org.orekit.propagation.SpacecraftState;
  23. import org.orekit.propagation.events.handlers.EventHandler;
  24. import org.orekit.propagation.events.handlers.StopOnDecreasing;
  25. import org.orekit.utils.ElevationMask;
  26. import org.orekit.utils.TrackingCoordinates;


  29. /**
  30.  * Finder for satellite raising/setting events that allows for the
  31.  * setting of azimuth and/or elevation bounds or a ground azimuth/elevation
  32.  * mask input. Each calculation be configured to use atmospheric refraction
  33.  * as well.
  34.  * <p>The default implementation behavior is to {@link Action#CONTINUE continue}
  35.  * propagation at raising and to {@link Action#STOP stop} propagation
  36.  * at setting. This can be changed by calling
  37.  * {@link #withHandler(EventHandler)} after construction.</p>
  38.  * @author Hank Grabowski
  39.  * @since 6.1
  40.  */
  41. public class ElevationDetector extends AbstractDetector<ElevationDetector> {

  43.     /** Elevation mask used for calculations, if defined. */
  44.     private final ElevationMask elevationMask;

  46.     /** Minimum elevation value used if mask is not defined. */
  47.     private final double minElevation;

  49.     /** Atmospheric Model used for calculations, if defined. */
  50.     private final AtmosphericRefractionModel refractionModel;

  52.     /** Topocentric frame in which elevation should be evaluated. */
  53.     private final TopocentricFrame topo;

  55.     /**
  56.      * Creates an instance of Elevation detector based on passed in topocentric frame
  57.      * and the minimum elevation angle.
  58.      * <p>
  59.      * uses default values for maximal checking interval ({@link #DEFAULT_MAXCHECK})
  60.      * and convergence threshold ({@link #DEFAULT_THRESHOLD}).</p>
  61.      * @param topo reference to a topocentric model
  62.      * @see #withConstantElevation(double)
  63.      * @see #withElevationMask(ElevationMask)
  64.      * @see #withRefraction(AtmosphericRefractionModel)
  65.      */
  66.     public ElevationDetector(final TopocentricFrame topo) {
  67.         this(DEFAULT_MAXCHECK, DEFAULT_THRESHOLD, topo);
  68.     }

  70.     /**
  71.      * Creates an instance of Elevation detector based on passed in topocentric frame
  72.      * and overrides of default maximal checking interval and convergence threshold values.
  73.      * @param maxCheck maximum checking interval (s)
  74.      * @param threshold maximum convergence threshold (s)
  75.      * @param topo reference to a topocentric model
  76.      * @see #withConstantElevation(double)
  77.      * @see #withElevationMask(ElevationMask)
  78.      * @see #withRefraction(AtmosphericRefractionModel)
  79.      */
  80.     public ElevationDetector(final double maxCheck, final double threshold,
  81.                              final TopocentricFrame topo) {
  82.         this(AdaptableInterval.of(maxCheck), threshold, topo);
  83.     }

  85.     /**
  86.      * Creates an instance of Elevation detector based on passed in topocentric frame
  87.      * and overrides of default maximal checking interval and convergence threshold values.
  88.      * @param maxCheck maximum checking adaptable interval
  89.      * @param threshold maximum convergence threshold (s)
  90.      * @param topo reference to a topocentric model
  91.      * @see org.orekit.propagation.events.intervals.ElevationDetectionAdaptableIntervalFactory
  92.      * @see #withConstantElevation(double)
  93.      * @see #withElevationMask(ElevationMask)
  94.      * @see #withRefraction(AtmosphericRefractionModel)
  95.      * @since 12.1
  96.      */
  97.     public ElevationDetector(final AdaptableInterval maxCheck, final double threshold,
  98.                              final TopocentricFrame topo) {
  99.         this(maxCheck, threshold, DEFAULT_MAX_ITER,
  100.              new StopOnDecreasing(),
  101.              0.0, null, null, topo);
  102.     }

  104.     /** Protected constructor with full parameters.
  105.      * <p>
  106.      * This constructor is not public as users are expected to use the builder
  107.      * API with the various {@code withXxx()} methods to set up the instance
  108.      * in a readable manner without using a huge amount of parameters.
  109.      * </p>
  110.      * @param maxCheck maximum checking interval
  111.      * @param threshold convergence threshold (s)
  112.      * @param maxIter maximum number of iterations in the event time search
  113.      * @param handler event handler to call at event occurrences
  114.      * @param minElevation minimum elevation in radians (rad)
  115.      * @param mask reference to elevation mask
  116.      * @param refractionModel reference to refraction model
  117.      * @param topo reference to a topocentric model
  118.      */
  119.     protected ElevationDetector(final AdaptableInterval maxCheck, final double threshold,
  120.                                 final int maxIter, final EventHandler handler,
  121.                                 final double minElevation, final ElevationMask mask,
  122.                                 final AtmosphericRefractionModel refractionModel,
  123.                                 final TopocentricFrame topo) {
  124.         super(maxCheck, threshold, maxIter, handler);
  125.         this.minElevation    = minElevation;
  126.         this.elevationMask   = mask;
  127.         this.refractionModel = refractionModel;
  128.         this.topo            = topo;
  129.     }

  131.     /** {@inheritDoc} */
  132.     @Override
  133.     protected ElevationDetector create(final AdaptableInterval newMaxCheck, final double newThreshold,
  134.                                        final int newMaxIter, final EventHandler newHandler) {
  135.         return new ElevationDetector(newMaxCheck, newThreshold, newMaxIter, newHandler,
  136.                                      minElevation, elevationMask, refractionModel, topo);
  137.     }

  139.     /**
  140.      * Returns the currently configured elevation mask.
  141.      * @return elevation mask
  142.      * (null if instance has been configured with {@link #withConstantElevation(double)}
  143.      * @see #withElevationMask(ElevationMask)
  144.      */
  145.     public ElevationMask getElevationMask() {
  146.         return this.elevationMask;
  147.     }

  149.     /**
  150.      * Returns the currently configured minimum valid elevation value.
  151.      * @return minimum elevation value
  152.      * ({@code Double.NaN} if instance has been configured with {@link #withElevationMask(ElevationMask)}
  153.      * @see #withConstantElevation(double)
  154.      */
  155.     public double getMinElevation() {
  156.         return this.minElevation;
  157.     }

  159.     /**
  160.      * Returns the currently configured refraction model.
  161.      * @return refraction model
  162.      * @see #withRefraction(AtmosphericRefractionModel)
  163.      */
  164.     public AtmosphericRefractionModel getRefractionModel() {
  165.         return this.refractionModel;
  166.     }

  168.     /**
  169.      * Returns the currently configured topocentric frame definitions.
  170.      * @return topocentric frame definition
  171.      */
  172.     public TopocentricFrame getTopocentricFrame() {
  173.         return this.topo;
  174.     }

  176.     /** Compute the value of the switching function.
  177.      * This function measures the difference between the current elevation
  178.      * (and azimuth if necessary) and the reference mask or minimum value.
  179.      * @param s the current state information: date, kinematics, attitude
  180.      * @return value of the switching function
  181.      */
  182.     @Override
  183.     public double g(final SpacecraftState s) {

  185.         final TrackingCoordinates tc = topo.getTrackingCoordinates(s.getPosition(), s.getFrame(), s.getDate());

  187.         final double calculatedElevation;
  188.         if (refractionModel != null) {
  189.             calculatedElevation = tc.getElevation() + refractionModel.getRefraction(tc.getElevation());
  190.         } else {
  191.             calculatedElevation = tc.getElevation();
  192.         }

  194.         if (elevationMask != null) {
  195.             return calculatedElevation - elevationMask.getElevation(tc.getAzimuth());
  196.         } else {
  197.             return calculatedElevation - minElevation;
  198.         }

  200.     }

  202.     /**
  203.      * Setup the minimum elevation for detection.
  204.      * <p>
  205.      * This will override an elevation mask if it has been configured as such previously.
  206.      * </p>
  207.      * @param newMinElevation minimum elevation for visibility in radians (rad)
  208.      * @return a new detector with updated configuration (the instance is not changed)
  209.      * @see #getMinElevation()
  210.      * @since 6.1
  211.      */
  212.     public ElevationDetector withConstantElevation(final double newMinElevation) {
  213.         return new ElevationDetector(getMaxCheckInterval(), getThreshold(), getMaxIterationCount(), getHandler(),
  214.                                      newMinElevation, null, refractionModel, topo);
  215.     }

  217.     /**
  218.      * Setup the elevation mask for detection using the passed in mask object.
  219.      * @param newElevationMask elevation mask to use for the computation
  220.      * @return a new detector with updated configuration (the instance is not changed)
  221.      * @since 6.1
  222.      * @see #getElevationMask()
  223.      */
  224.     public ElevationDetector withElevationMask(final ElevationMask newElevationMask) {
  225.         return new ElevationDetector(getMaxCheckInterval(), getThreshold(), getMaxIterationCount(), getHandler(),
  226.                                      Double.NaN, newElevationMask, refractionModel, topo);
  227.     }

  229.     /**
  230.      * Setup the elevation detector to use an atmospheric refraction model in its
  231.      * calculations.
  232.      * <p>
  233.      * To disable the refraction when copying an existing elevation
  234.      * detector, call this method with a null argument.
  235.      * </p>
  236.      * @param newRefractionModel refraction model to use for the computation
  237.      * @return a new detector with updated configuration (the instance is not changed)
  238.      * @since 6.1
  239.      * @see #getRefractionModel()
  240.      */
  241.     public ElevationDetector withRefraction(final AtmosphericRefractionModel newRefractionModel) {
  242.         return new ElevationDetector(getMaxCheckInterval(), getThreshold(), getMaxIterationCount(), getHandler(),
  243.                                      minElevation, elevationMask, newRefractionModel, topo);
  244.     }

  246. }
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