OEMWriter.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.ccsds;

  19. import java.io.IOException;
  20. import java.util.LinkedHashMap;
  21. import java.util.List;
  22. import java.util.Map;

  24. import org.orekit.errors.OrekitIllegalArgumentException;
  25. import org.orekit.errors.OrekitMessages;
  26. import org.orekit.files.ccsds.OEMFile.CovarianceMatrix;
  27. import org.orekit.files.ccsds.OEMFile.EphemeridesBlock;
  28. import org.orekit.files.ccsds.StreamingOemWriter.Segment;
  29. import org.orekit.files.general.EphemerisFile;
  30. import org.orekit.files.general.EphemerisFile.EphemerisSegment;
  31. import org.orekit.files.general.EphemerisFileWriter;
  32. import org.orekit.time.TimeScale;
  33. import org.orekit.utils.TimeStampedPVCoordinates;

  35. /**
  36.  * An OEM Writer class that can take in a general {@link EphemerisFile} object
  37.  * and export it as a valid OEM file.
  38.  *
  39.  * @author Hank Grabowski
  40.  * @author Evan Ward
  41.  * @since 9.0
  42.  * @see <a href="https://public.ccsds.org/Pubs/502x0b2c1.pdf">CCSDS 502.0-B-2 Orbit Data
  43.  *      Messages</a>
  44.  * @see <a href="https://public.ccsds.org/Pubs/500x0g4.pdf">CCSDS 500.0-G-4 Navigation
  45.  *      Data Definitions and Conventions</a>
  46.  * @see StreamingOemWriter
  47.  */
  48. public class OEMWriter implements EphemerisFileWriter {

  50.     /** Version number implemented. **/
  51.     public static final String CCSDS_OEM_VERS = "2.0";

  53.     /** Default interpolation method if the user specifies none. **/
  54.     public static final InterpolationMethod DEFAULT_INTERPOLATION_METHOD = InterpolationMethod.LAGRANGE;

  56.     /** Default originator field value if user specifies none. **/
  57.     public static final String DEFAULT_ORIGINATOR = "OREKIT";

  59.     /** The interpolation method for ephemeris data. */
  60.     private final InterpolationMethod interpolationMethod;

  62.     /** Originator name, usually the organization and/or country. **/
  63.     private final String originator;

  65.     /**
  66.      * Space object ID, usually an official international designator such as
  67.      * "1998-067A".
  68.      **/
  69.     private final String spaceObjectId;

  71.     /** Space object name, usually a common name for an object like "ISS". **/
  72.     private final String spaceObjectName;

  74.     /** Format for position ephemeris data output. */
  75.     private final String positionFormat;

  77.     /** Format for velocity ephemeris data output. */
  78.     private final String velocityFormat;

  80.     /**
  81.      * Standard default constructor that creates a writer with default
  82.      * configurations.
  83.      */
  84.     public OEMWriter() {
  85.         this(DEFAULT_INTERPOLATION_METHOD, DEFAULT_ORIGINATOR, null, null,
  86.              StreamingOemWriter.DEFAULT_POSITION_FORMAT,
  87.              StreamingOemWriter.DEFAULT_VELOCITY_FORMAT);
  88.     }

  90.     /**
  91.      * Constructor used to create a new OEM writer configured with the necessary
  92.      * parameters to successfully fill in all required fields that aren't part
  93.      * of a standard {@link EphemerisFile} object and using default formatting for
  94.      * {@link StreamingOemWriter#DEFAULT_POSITION_FORMAT position} and
  95.      * {@link StreamingOemWriter#DEFAULT_VELOCITY_FORMAT velocity} ephemeris data output.
  96.      *
  97.      * @param interpolationMethod
  98.      *            the interpolation method to specify in the OEM file
  99.      * @param originator
  100.      *            the originator field string
  101.      * @param spaceObjectId
  102.      *            the spacecraft ID
  103.      * @param spaceObjectName
  104.      *            the space object common name
  105.      */
  106.     public OEMWriter(final InterpolationMethod interpolationMethod, final String originator,
  107.             final String spaceObjectId, final String spaceObjectName) {
  108.         this(interpolationMethod, originator, spaceObjectId, spaceObjectName,
  109.                 StreamingOemWriter.DEFAULT_POSITION_FORMAT,
  110.                 StreamingOemWriter.DEFAULT_VELOCITY_FORMAT);
  111.     }

  113.     /**
  114.      * Constructor used to create a new OEM writer configured with the necessary
  115.      * parameters to successfully fill in all required fields that aren't part
  116.      * of a standard {@link EphemerisFile} object and user-defined position and
  117.      * velocity ephemeris data output {@link java.util.Formatter format}.
  118.      *
  119.      * @param interpolationMethod
  120.      *            the interpolation method to specify in the OEM file
  121.      * @param originator
  122.      *            the originator field string
  123.      * @param spaceObjectId
  124.      *            the spacecraft ID
  125.      * @param spaceObjectName
  126.      *            the space object common name
  127.      * @param positionFormat
  128.      *            format parameters for position ephemeris data output
  129.      * @param velocityFormat
  130.      *            format parameters for velocity ephemeris data output
  131.      */
  132.     public OEMWriter(final InterpolationMethod interpolationMethod, final String originator,
  133.             final String spaceObjectId, final String spaceObjectName,
  134.             final String positionFormat, final String velocityFormat) {
  135.         this.interpolationMethod = interpolationMethod;
  136.         this.originator = originator;
  137.         this.spaceObjectId = spaceObjectId;
  138.         this.spaceObjectName = spaceObjectName;
  139.         this.positionFormat = positionFormat;
  140.         this.velocityFormat = velocityFormat;
  141.     }

  143.     /** {@inheritDoc} */
  144.     @Override
  145.     public void write(final Appendable writer, final EphemerisFile ephemerisFile)
  146.             throws IOException {

  148.         if (writer == null) {
  149.             throw new OrekitIllegalArgumentException(OrekitMessages.NULL_ARGUMENT, "writer");
  150.         }

  152.         if (ephemerisFile == null) {
  153.             return;
  154.         }

  156.         final String idToProcess;
  157.         if (spaceObjectId != null) {
  158.             if (ephemerisFile.getSatellites().containsKey(spaceObjectId)) {
  159.                 idToProcess = spaceObjectId;
  160.             } else {
  161.                 throw new OrekitIllegalArgumentException(OrekitMessages.VALUE_NOT_FOUND, spaceObjectId, "ephemerisFile");
  162.             }
  163.         } else if (ephemerisFile.getSatellites().keySet().size() == 1) {
  164.             idToProcess = ephemerisFile.getSatellites().keySet().iterator().next();
  165.         } else {
  166.             throw new OrekitIllegalArgumentException(OrekitMessages.EPHEMERIS_FILE_NO_MULTI_SUPPORT);
  167.         }

  169.         // Get satellite and ephemeris segments to output.
  170.         final EphemerisFile.SatelliteEphemeris satEphem = ephemerisFile.getSatellites().get(idToProcess);
  171.         final List<? extends EphemerisSegment> segments = satEphem.getSegments();
  172.         if (segments.isEmpty()) {
  173.             // no data -> no output
  174.             return;
  175.         }
  176.         final EphemerisSegment firstSegment = segments.get(0);

  178.         final String objectName = this.spaceObjectName == null ?
  179.                 idToProcess : this.spaceObjectName;
  180.         // Only one time scale per OEM file, see Section 5.2.4.5
  181.         final TimeScale timeScale = firstSegment.getTimeScale();
  182.         // metadata that is constant for the whole OEM file
  183.         final Map<Keyword, String> metadata = new LinkedHashMap<>();
  184.         metadata.put(Keyword.TIME_SYSTEM, firstSegment.getTimeScaleString());
  185.         metadata.put(Keyword.ORIGINATOR, this.originator);
  186.         // Only one object in an OEM file, see Section 2.1
  187.         metadata.put(Keyword.OBJECT_ID, idToProcess);
  188.         metadata.put(Keyword.OBJECT_NAME, objectName);
  189.         metadata.put(Keyword.INTERPOLATION, this.interpolationMethod.toString());

  191.         // Header comments. If header comments are presents, they are assembled together in a single line
  192.         if (ephemerisFile instanceof OEMFile) {
  193.             // Cast to OEMFile
  194.             final OEMFile oemFile = (OEMFile) ephemerisFile;
  195.             if (!oemFile.getHeaderComment().isEmpty()) {
  196.                 // Loop on comments
  197.                 final StringBuffer buffer = new StringBuffer();
  198.                 for (String comment : oemFile.getHeaderComment()) {
  199.                     buffer.append(comment);
  200.                 }
  201.                 // Update metadata
  202.                 metadata.put(Keyword.COMMENT, buffer.toString());
  203.             }
  204.         }

  206.         final StreamingOemWriter oemWriter =
  207.                 new StreamingOemWriter(writer, timeScale, metadata, positionFormat, velocityFormat);
  208.         oemWriter.writeHeader();

  210.         for (final EphemerisSegment segment : segments) {
  211.             // segment specific metadata
  212.             metadata.clear();
  213.             metadata.put(Keyword.CENTER_NAME, segment.getFrameCenterString());
  214.             metadata.put(Keyword.REF_FRAME, segment.getFrameString());
  215.             metadata.put(Keyword.START_TIME, segment.getStart().toString(timeScale));
  216.             metadata.put(Keyword.STOP_TIME, segment.getStop().toString(timeScale));
  217.             metadata.put(Keyword.INTERPOLATION_DEGREE,
  218.                     String.valueOf(segment.getInterpolationSamples() - 1));

  220.             final Segment segmentWriter = oemWriter.newSegment(null, metadata);
  221.             segmentWriter.writeMetadata();
  222.             for (final TimeStampedPVCoordinates coordinates : segment.getCoordinates()) {
  223.                 segmentWriter.writeEphemerisLine(coordinates);
  224.             }

  226.             if (segment instanceof EphemeridesBlock) {
  227.                 final EphemeridesBlock curr_ephem_block = (EphemeridesBlock) segment;
  228.                 final List<CovarianceMatrix> covarianceMatrices = curr_ephem_block.getCovarianceMatrices();
  229.                 if (!covarianceMatrices.isEmpty()) {
  230.                     segmentWriter.writeCovarianceMatrices(covarianceMatrices);
  231.                 }
  232.             }
  233.         }
  234.     }

  236.     /** OEM interpolation method. See Table 5-3. */
  237.     public enum InterpolationMethod {
  238.         /** Hermite interpolation. */
  239.         HERMITE,
  240.         /** Lagrange interpolation. */
  241.         LAGRANGE,
  242.         /** Linear interpolation. */
  243.         LINEAR
  244.     }

  246. }
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