OrekitEphemerisFile.java

  1. /* Copyright 2016 Applied Defense Solutions (ADS)
  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.  * ADS 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.files.general;

  19. import java.util.ArrayList;
  20. import java.util.Collections;
  21. import java.util.List;
  22. import java.util.Map;
  23. import java.util.concurrent.ConcurrentHashMap;

  25. import org.orekit.annotation.DefaultDataContext;
  26. import org.orekit.bodies.CelestialBody;
  27. import org.orekit.data.DataContext;
  28. import org.orekit.errors.OrekitIllegalArgumentException;
  29. import org.orekit.errors.OrekitMessages;
  30. import org.orekit.frames.Frame;
  31. import org.orekit.propagation.SpacecraftState;
  32. import org.orekit.time.AbsoluteDate;
  33. import org.orekit.time.TimeScale;
  34. import org.orekit.utils.CartesianDerivativesFilter;
  35. import org.orekit.utils.TimeStampedPVCoordinates;

  37. /**
  38.  * A class for encapsulating Orekit propagators within an {@link EphemerisFile}
  39.  * complaint object that makes for easy serialization to external ephemeris
  40.  * formats like OEM.
  41.  *
  42.  * @author Hank Grabowski
  43.  * @since 9.0
  44.  *
  45.  */
  46. public class OrekitEphemerisFile
  47.     implements EphemerisFile<TimeStampedPVCoordinates, OrekitEphemerisFile.OrekitEphemerisSegment> {

  49.     /** Hashmap of satellite ephemeris. **/
  50.     private final Map<String, OrekitSatelliteEphemeris> satellites;

  52.     /**
  53.      * Standard default constructor.
  54.      */
  55.     public OrekitEphemerisFile() {
  56.         this.satellites = new ConcurrentHashMap<String, OrekitSatelliteEphemeris>();
  57.     }

  59.     /** {@inheritDoc} */
  60.     @Override
  61.     public Map<String, OrekitSatelliteEphemeris> getSatellites() {
  62.         return Collections.unmodifiableMap(satellites);
  63.     }

  65.     /**
  66.      * Adds a new satellite to this object.
  67.      *
  68.      * @param id
  69.      *            ID to use for this satellite
  70.      * @return the new satellite object
  71.      */
  72.     public OrekitSatelliteEphemeris addSatellite(final String id) {
  73.         final OrekitSatelliteEphemeris newSat = new OrekitSatelliteEphemeris(id);
  74.         this.satellites.put(id, newSat);
  75.         return newSat;
  76.     }

  78.     /**
  79.      * Inner class of {@link OrekitEphemerisFile} that defines the
  80.      * {@link OrekitSatelliteEphemeris} corresponding object for this ephemeris type.
  81.      */
  82.     public static class OrekitSatelliteEphemeris
  83.         implements EphemerisFile.SatelliteEphemeris<TimeStampedPVCoordinates, OrekitEphemerisSegment> {

  85.         /**
  86.          * Defines the default interpolation sample size if it is not specified
  87.          * on a segment.
  88.          **/
  89.         public static final int DEFAULT_INTERPOLATION_SIZE = 2;

  91.         /** ID of the space object encapsulated here. **/
  92.         private final String id;

  94.         /** Earliest date of this file. **/
  95.         private AbsoluteDate startDate;

  97.         /** Latest date of this file. **/
  98.         private AbsoluteDate stopDate;

  100.         /** List of segments in the file. **/
  101.         private final List<OrekitEphemerisSegment> segments;

  103.         /**
  104.          * Standard constructor for building the satellite Ephemeris object.
  105.          *
  106.          * @param id
  107.          *            the ID of the space object for this data
  108.          */
  109.         public OrekitSatelliteEphemeris(final String id) {
  110.             this.id = id;
  111.             this.segments = new ArrayList<>();
  112.         }

  114.         /** {@inheritDoc} */
  115.         @Override
  116.         public String getId() {
  117.             return id;
  118.         }

  120.         /** {@inheritDoc} */
  121.         @Override
  122.         public double getMu() {
  123.             if (this.segments.size() == 0) {
  124.                 return 0;
  125.             } else {
  126.                 return this.segments.get(0).getMu();
  127.             }
  128.         }

  130.         /** {@inheritDoc} */
  131.         @Override
  132.         public List<OrekitEphemerisSegment> getSegments() {
  133.             return Collections.unmodifiableList(this.segments);
  134.         }

  136.         /** {@inheritDoc} */
  137.         @Override
  138.         public AbsoluteDate getStart() {
  139.             return this.startDate;
  140.         }

  142.         /** {@inheritDoc} */
  143.         @Override
  144.         public AbsoluteDate getStop() {
  145.             return this.stopDate;
  146.         }

  148.         /**
  149.          * Injects pre-computed satellite states into this ephemeris file
  150.          * object, returning the generated {@link OrekitEphemerisSegment} that
  151.          * has been stored internally. Defaults the celestial body to earth and
  152.          * the interpolation size to the default.
  153.          *
  154.          * <p>This method uses the {@link DataContext#getDefault() default data context}.
  155.          *
  156.          * @param states
  157.          *            a list of {@link SpacecraftState} that will comprise this
  158.          *            new unit.
  159.          * @return the generated {@link OrekitEphemerisSegment}
  160.          * @see #addNewSegment(List, CelestialBody, int, TimeScale)
  161.          */
  162.         @DefaultDataContext
  163.         public OrekitEphemerisSegment addNewSegment(final List<SpacecraftState> states) {
  164.             return this.addNewSegment(states, DEFAULT_INTERPOLATION_SIZE);
  165.         }

  167.         /**
  168.          * Injects pre-computed satellite states into this ephemeris file
  169.          * object, returning the generated {@link OrekitEphemerisSegment} that
  170.          * has been stored internally. Defaults the Celestial Body to be Earths
  171.          *
  172.          * <p>This method uses the {@link DataContext#getDefault() default data context}.
  173.          *
  174.          * @param states
  175.          *            a list of {@link SpacecraftState} that will comprise this
  176.          *            new unit.
  177.          * @param interpolationSampleSize
  178.          *            the number of interpolation samples that should be used
  179.          *            when processed by another system
  180.          * @return the generated {@link OrekitEphemerisSegment}
  181.          * @see #addNewSegment(List, CelestialBody, int, TimeScale)
  182.          */
  183.         @DefaultDataContext
  184.         public OrekitEphemerisSegment addNewSegment(final List<SpacecraftState> states,
  185.                 final int interpolationSampleSize) {
  186.             return this.addNewSegment(
  187.                     states,
  188.                     DataContext.getDefault().getCelestialBodies().getEarth(),
  189.                     interpolationSampleSize);
  190.         }

  192.         /**
  193.          * Injects pre-computed satellite states into this ephemeris file
  194.          * object, returning the generated {@link OrekitEphemerisSegment} that
  195.          * has been stored internally.
  196.          *
  197.          * <p>This method uses the {@link DataContext#getDefault() default data context}.
  198.          *
  199.          * @param states
  200.          *            a list of {@link SpacecraftState} that will comprise this
  201.          *            new unit.
  202.          * @param body
  203.          *            the celestial body the state's frames are with respect to
  204.          * @param interpolationSampleSize
  205.          *            the number of interpolation samples that should be used
  206.          *            when processed by another system
  207.          * @return the generated {@link OrekitEphemerisSegment}
  208.          * @see #addNewSegment(List, CelestialBody, int, TimeScale)
  209.          */
  210.         @DefaultDataContext
  211.         public OrekitEphemerisSegment addNewSegment(final List<SpacecraftState> states, final CelestialBody body,
  212.                                                     final int interpolationSampleSize) {
  213.             return addNewSegment(states, body, interpolationSampleSize,
  214.                     DataContext.getDefault().getTimeScales().getUTC());
  215.         }

  217.         /**
  218.          * Injects pre-computed satellite states into this ephemeris file
  219.          * object, returning the generated {@link OrekitEphemerisSegment} that
  220.          * has been stored internally.
  221.          *
  222.          * @param states
  223.          *            a list of {@link SpacecraftState} that will comprise this
  224.          *            new unit.
  225.          * @param body
  226.          *            the celestial body from which the frames are defined
  227.          * @param interpolationSampleSize
  228.          *            the number of interpolation samples that should be used
  229.          *            when processed by another system
  230.          * @param timeScale
  231.          *            the time scale used in the new segment.
  232.          * @return the generated {@link OrekitEphemerisSegment}
  233.          * @since 10.1
  234.          */
  235.         public OrekitEphemerisSegment addNewSegment(final List<SpacecraftState> states,
  236.                                                     final CelestialBody body,
  237.                                                     final int interpolationSampleSize,
  238.                                                     final TimeScale timeScale) {
  239.             final int minimumSampleSize = 2;
  240.             if (states == null || states.size() == 0) {
  241.                 throw new OrekitIllegalArgumentException(OrekitMessages.NULL_ARGUMENT, "states");
  242.             }

  244.             if (interpolationSampleSize < minimumSampleSize) {
  245.                 throw new OrekitIllegalArgumentException(OrekitMessages.NOT_ENOUGH_DATA_FOR_INTERPOLATION,
  246.                         interpolationSampleSize);
  247.             }

  249.             final AbsoluteDate start = states.get(0).getDate();
  250.             final AbsoluteDate stop = states.get(states.size() - 1).getDate();

  252.             if (this.startDate == null || start.compareTo(this.startDate) < 0) {
  253.                 this.startDate = start;
  254.             }

  256.             if (this.stopDate == null || stop.compareTo(this.stopDate) > 0) {
  257.                 this.stopDate = stop;
  258.             }

  260.             final List<TimeStampedPVCoordinates> coordinates = new ArrayList<>();
  261.             for (SpacecraftState state : states) {
  262.                 coordinates.add(state.getPVCoordinates());
  263.             }

  265.             final Frame frame = states.get(0).getFrame();

  267.             final OrekitEphemerisSegment newSeg =
  268.                             new OrekitEphemerisSegment(coordinates, frame, body.getGM(), interpolationSampleSize);
  269.             this.segments.add(newSeg);

  271.             return newSeg;
  272.         }
  273.     }

  275.     public static class OrekitEphemerisSegment
  276.         implements EphemerisFile.EphemerisSegment<TimeStampedPVCoordinates> {

  278.         /** Coordinates for this ephemeris segment. **/
  279.         private final List<TimeStampedPVCoordinates> coordinates;

  281.         /** The reference frame for this ephemeris segment. **/
  282.         private final Frame frame;

  284.         /** Standard gravitational parameter for the satellite. **/
  285.         private final double mu;

  287.         /** The number of interpolation samples. */
  288.         private final int interpolationSamples;

  290.         /**
  291.          * constructor for OrekitEphemerisSegment.
  292.          *
  293.          * @param coordinates
  294.          *            coordinates making up the ephemeris for this segment
  295.          * @param frame
  296.          *            the frame the coordinates are in
  297.          * @param mu
  298.          *            the gravitational constant used in force model evaluations
  299.          * @param interpolationSamples
  300.          *            the number of samples to use during interpolation
  301.          */
  302.         public OrekitEphemerisSegment(final List<TimeStampedPVCoordinates> coordinates, final Frame frame,
  303.                                       final double mu, final int interpolationSamples) {
  304.             this.coordinates          = coordinates;
  305.             this.frame                = frame;
  306.             this.mu                   = mu;
  307.             this.interpolationSamples = interpolationSamples;
  308.         }

  310.         /** {@inheritDoc} */
  311.         @Override
  312.         public double getMu() {
  313.             return mu;
  314.         }

  316.         /** {@inheritDoc} */
  317.         @Override
  318.         public Frame getFrame() {
  319.             return frame;
  320.         }

  322.         /** {@inheritDoc} */
  323.         @Override
  324.         public Frame getInertialFrame() {
  325.             return frame;
  326.         }

  328.         /** {@inheritDoc} */
  329.         @Override
  330.         public int getInterpolationSamples() {
  331.             return interpolationSamples;
  332.         }

  334.         /** {@inheritDoc} */
  335.         @Override
  336.         public CartesianDerivativesFilter getAvailableDerivatives() {
  337.             return CartesianDerivativesFilter.USE_PV;
  338.         }

  340.         /** {@inheritDoc} */
  341.         @Override
  342.         public List<TimeStampedPVCoordinates> getCoordinates() {
  343.             return Collections.unmodifiableList(coordinates);
  344.         }

  346.         /** {@inheritDoc} */
  347.         @Override
  348.         public AbsoluteDate getStart() {
  349.             return coordinates.get(0).getDate();
  350.         }

  352.         /** {@inheritDoc} */
  353.         @Override
  354.         public AbsoluteDate getStop() {
  355.             return coordinates.get(coordinates.size() - 1).getDate();
  356.         }

  358.     }
  359. }
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