EphemerisSegmentAttitudeProvider.java

  1. /* Copyright 2002-2020 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.files.general;

  18. import java.util.List;
  19. import java.util.stream.Collectors;

  20. import org.hipparchus.RealFieldElement;
  21. import org.orekit.attitudes.Attitude;
  22. import org.orekit.attitudes.AttitudeProvider;
  23. import org.orekit.attitudes.BoundedAttitudeProvider;
  24. import org.orekit.attitudes.FieldAttitude;
  25. import org.orekit.files.general.AttitudeEphemerisFile.AttitudeEphemerisSegment;
  26. import org.orekit.frames.Frame;
  27. import org.orekit.time.AbsoluteDate;
  28. import org.orekit.time.FieldAbsoluteDate;
  29. import org.orekit.utils.FieldPVCoordinatesProvider;
  30. import org.orekit.utils.ImmutableTimeStampedCache;
  31. import org.orekit.utils.PVCoordinatesProvider;
  32. import org.orekit.utils.TimeStampedAngularCoordinates;
  33. import org.orekit.utils.TimeStampedFieldAngularCoordinates;

  34. /**
  35.  * An {@link AttitudeProvider} based on an {@link AttitudeEphemerisSegment}.
  36.  * @author Bryan Cazabonne
  37.  * @since 10.3
  38.  */
  39. public class EphemerisSegmentAttitudeProvider implements BoundedAttitudeProvider {

  40.     /** Cached attitude table. */
  41.     private final transient ImmutableTimeStampedCache<TimeStampedAngularCoordinates> table;

  42.     /** Tabular data from which this attitude provider is built. */
  43.     private final AttitudeEphemerisSegment segment;

  44.     /**
  45.      * Constructor.
  46.      * @param segment segment containing the attitude data for this provider.
  47.      */
  48.     public EphemerisSegmentAttitudeProvider(final AttitudeEphemerisSegment segment) {
  49.         this.segment = segment;
  50.         this.table   = new ImmutableTimeStampedCache<TimeStampedAngularCoordinates>(segment.getInterpolationSamples(),
  51.                                                                                     segment.getAngularCoordinates());
  52.     }

  53.     /** {@inheritDoc} */
  54.     @Override
  55.     public Attitude getAttitude(final PVCoordinatesProvider pvProv, final AbsoluteDate date,
  56.                                 final Frame frame) {

  57.         // Get attitudes sample on which interpolation will be performed
  58.         final List<TimeStampedAngularCoordinates> attitudeSample = table.getNeighbors(date).collect(Collectors.toList());

  59.         // Interpolate attitude data
  60.         final TimeStampedAngularCoordinates interpolatedAttitude =
  61.                 TimeStampedAngularCoordinates.interpolate(date, segment.getAvailableDerivatives(), attitudeSample);

  62.         // Build the interpolated attitude
  63.         return new Attitude(segment.getReferenceFrame(), interpolatedAttitude);

  64.     }

  65.     /** {@inheritDoc} */
  66.     @Override
  67.     public <T extends RealFieldElement<T>> FieldAttitude<T> getAttitude(final FieldPVCoordinatesProvider<T> pvProv,
  68.                                                                         final FieldAbsoluteDate<T> date, final Frame frame) {

  69.         // Get attitudes sample on which interpolation will be performed
  70.         final List<TimeStampedFieldAngularCoordinates<T>> attitudeSample = table.getNeighbors(date.toAbsoluteDate()).
  71.                         map(ac -> new TimeStampedFieldAngularCoordinates<>(date.getField(), ac)).
  72.                         collect(Collectors.toList());

  73.         // Interpolate attitude data
  74.         final TimeStampedFieldAngularCoordinates<T> interpolatedAttitude =
  75.                 TimeStampedFieldAngularCoordinates.interpolate(date, segment.getAvailableDerivatives(), attitudeSample);

  76.         // Build the interpolated attitude
  77.         return new FieldAttitude<>(segment.getReferenceFrame(), interpolatedAttitude);

  78.     }

  79.     /** {@inheritDoc} */
  80.     @Override
  81.     public AbsoluteDate getMinDate() {
  82.         return segment.getStart();
  83.     }

  84.     /** {@inheritDoc} */
  85.     @Override
  86.     public AbsoluteDate getMaxDate() {
  87.         return segment.getStop();
  88.     }

  89. }