STKEphemerisFile.java

  1. /* Copyright 2002-2025 Andrew Goetz
  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.files.stk;

  19. import java.util.ArrayList;
  20. import java.util.Collections;
  21. import java.util.HashMap;
  22. import java.util.List;
  23. import java.util.Locale;
  24. import java.util.Map;
  25. import java.util.Objects;

  27. import org.orekit.errors.OrekitException;
  28. import org.orekit.errors.OrekitMessages;
  29. import org.orekit.files.general.EphemerisFile;
  30. import org.orekit.files.stk.STKEphemerisFile.STKEphemerisSegment;
  31. import org.orekit.frames.Frame;
  32. import org.orekit.time.AbsoluteDate;
  33. import org.orekit.utils.CartesianDerivativesFilter;
  34. import org.orekit.utils.TimeStampedPVCoordinates;

  36. /**
  37.  * STK ephemeris file.
  38.  *
  39.  * @author Andrew Goetz
  40.  * @since 12.0
  41.  */
  42. public class STKEphemerisFile implements EphemerisFile<TimeStampedPVCoordinates, STKEphemerisSegment> {

  44.     /** STK version. */
  45.     private final String stkVersion;

  47.     /** Unmodifiable mapping with a single key-value pair from satellite id to ephemeris. */
  48.     private final Map<String, STKEphemeris> satellites;

  50.     /**
  51.      * Constructs a {@link STKEphemerisFile} instance.
  52.      * @param stkVersion STK version string (example: "stk.v.11.0")
  53.      * @param satelliteId satellite id
  54.      * @param ephemeris ephemeris
  55.      */
  56.     public STKEphemerisFile(final String stkVersion, final String satelliteId, final STKEphemeris ephemeris) {
  57.         this.stkVersion = Objects.requireNonNull(stkVersion);
  58.         final Map<String, STKEphemeris> tempMap = new HashMap<>();
  59.         tempMap.put(satelliteId, ephemeris);
  60.         this.satellites = Collections.unmodifiableMap(tempMap);
  61.     }

  63.     /**
  64.      * Returns the STK version string.
  65.      * @return STK version string
  66.      */
  67.     public String getSTKVersion() {
  68.         return stkVersion;
  69.     }

  71.     /**
  72.      * {@inheritDoc}
  73.      * <p>
  74.      * STK ephemeris files define ephemeris for a single satellite, so the returned
  75.      * map will have a single entry.
  76.      * </p>
  77.      */
  78.     @Override
  79.     public Map<String, STKEphemeris> getSatellites() {
  80.         return satellites;
  81.     }

  83.     /**
  84.      * Ephemeris segment from an STK ephemeris file.
  85.      */
  86.     public static class STKEphemerisSegment implements EphemerisFile.EphemerisSegment<TimeStampedPVCoordinates> {

  88.         /** Gravitational parameter (m^3/s^2). */
  89.         private final double mu;

  91.         /** Reference frame. */
  92.         private final Frame frame;

  94.         /** Number of samples to use in interpolation. */
  95.         private final int interpolationSamples;

  97.         /** Cartesian derivatives filter. */
  98.         private final CartesianDerivativesFilter cartesianDerivativesFilter;

  100.         /** Time-sorted time/position/velocity data. */
  101.         private final List<TimeStampedPVCoordinates> timeStampedPVCoordinates;

  103.         /**
  104.          * Constructs a {@link STKEphemerisSegment} instance.
  105.          * @param mu gravitational parameter (m^3/s^2)
  106.          * @param frame frame
  107.          * @param interpolationSamples number of samples to use in interpolation
  108.          * @param cartesianDerivativesFilter Cartesian derivatives filter
  109.          * @param timeStampedPVCoordinates time-sorted time/position/velocity data
  110.          */
  111.         public STKEphemerisSegment(final double mu, final Frame frame, final int interpolationSamples,
  112.                 final CartesianDerivativesFilter cartesianDerivativesFilter,
  113.                 final List<TimeStampedPVCoordinates> timeStampedPVCoordinates) {
  114.             this.mu = mu;
  115.             this.frame = Objects.requireNonNull(frame);
  116.             this.interpolationSamples = interpolationSamples;
  117.             this.cartesianDerivativesFilter = Objects.requireNonNull(cartesianDerivativesFilter);
  118.             this.timeStampedPVCoordinates = Collections.unmodifiableList(new ArrayList<>(timeStampedPVCoordinates));
  119.         }

  121.         @Override
  122.         public double getMu() {
  123.             return mu;
  124.         }

  126.         @Override
  127.         public Frame getFrame() {
  128.             return frame;
  129.         }

  131.         @Override
  132.         public int getInterpolationSamples() {
  133.             return interpolationSamples;
  134.         }

  136.         @Override
  137.         public CartesianDerivativesFilter getAvailableDerivatives() {
  138.             return cartesianDerivativesFilter;
  139.         }

  141.         @Override
  142.         public List<TimeStampedPVCoordinates> getCoordinates() {
  143.             return timeStampedPVCoordinates;
  144.         }

  146.         @Override
  147.         public AbsoluteDate getStart() {
  148.             return timeStampedPVCoordinates.get(0).getDate();
  149.         }

  151.         @Override
  152.         public AbsoluteDate getStop() {
  153.             return timeStampedPVCoordinates.get(timeStampedPVCoordinates.size() - 1).getDate();
  154.         }

  156.     }

  158.     /**
  159.      * Ephemeris from an STK ephemeris file.
  160.      */
  161.     public static class STKEphemeris implements SatelliteEphemeris<TimeStampedPVCoordinates, STKEphemerisSegment> {

  163.         /** Satellite id.*/
  164.         private final String satelliteId;

  166.         /** Gravitational parameter (m^3/s^2). */
  167.         private final double mu;

  169.         /** Unmodifiable list of ephemeris segments. */
  170.         private final List<STKEphemerisSegment> segments;

  172.         /**
  173.          * Constructs a {@link STKEphemeris} instance. This constructor shallowly copies the list of segments provided.
  174.          * @param satelliteId satellite id
  175.          * @param mu gravitational parameter (m^3/s^2)
  176.          * @param segments ephemeris segments
  177.          */
  178.         public STKEphemeris(final String satelliteId, final double mu, final List<STKEphemerisSegment> segments) {
  179.             this.satelliteId = Objects.requireNonNull(satelliteId);
  180.             this.mu = mu;
  181.             this.segments = Collections.unmodifiableList(new ArrayList<>(segments));
  182.         }

  184.         @Override
  185.         public String getId() {
  186.             return satelliteId;
  187.         }

  189.         @Override
  190.         public double getMu() {
  191.             return mu;
  192.         }

  194.         @Override
  195.         public List<STKEphemerisSegment> getSegments() {
  196.             return segments;
  197.         }

  199.         @Override
  200.         public AbsoluteDate getStart() {
  201.             return segments.get(0).getStart();
  202.         }

  204.         @Override
  205.         public AbsoluteDate getStop() {
  206.             return segments.get(segments.size() - 1).getStop();
  207.         }

  209.     }

  211.     /**
  212.      * STK coordinate system.
  213.      * <p>
  214.      * Currently, only Earth-centered coordinate systems are supported.
  215.      * </p>
  216.      */
  217.     public enum STKCoordinateSystem {

  219.         /** International Celestial Reference Frame. */
  220.         ICRF,

  222.         /** Mean equator and mean equinox of the J2000 epoch. */
  223.         J2000,

  225.         /** Central-body-dependent inertial frame, equivalent to ICRF for Earth. */
  226.         INERTIAL,

  228.         /** Fixed frame. */
  229.         FIXED,

  231.         /** True equator and true equinox of date. */
  232.         TRUE_OF_DATE,

  234.         /** Mean equator and mean equinox of date. */
  235.         MEAN_OF_DATE,

  237.         /** True equator and mean equinox of date. */
  238.         TEME_OF_DATE;

  240.         /**
  241.          * Parses a coordinate system from a string.
  242.          * @param s string
  243.          * @return coordinate system
  244.          */
  245.         public static STKCoordinateSystem parse(final String s) {
  246.             final String sUpper = s.toUpperCase(Locale.US);
  247.             switch (sUpper) {
  248.                 case "ICRF":
  249.                     return ICRF;
  250.                 case "J2000":
  251.                     return J2000;
  252.                 case "INERTIAL":
  253.                     return INERTIAL;
  254.                 case "FIXED":
  255.                     return FIXED;
  256.                 case "TRUEOFDATE":
  257.                     return TRUE_OF_DATE;
  258.                 case "MEANOFDATE":
  259.                     return MEAN_OF_DATE;
  260.                 case "TEMEOFDATE":
  261.                     return TEME_OF_DATE;
  262.                 default:
  263.                     throw new OrekitException(OrekitMessages.STK_INVALID_OR_UNSUPPORTED_COORDINATE_SYSTEM, s);
  264.             }
  265.         }

  267.     }

  269. }
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