InterpolatingTransformProvider.java

  1. /* Copyright 2002-2022 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.  */

  18. package org.orekit.frames;

  20. import java.io.Serializable;
  21. import java.util.HashMap;
  22. import java.util.List;
  23. import java.util.Map;
  24. import java.util.stream.Collectors;
  25. import java.util.stream.Stream;

  27. import org.hipparchus.Field;
  28. import org.hipparchus.CalculusFieldElement;
  29. import org.orekit.time.AbsoluteDate;
  30. import org.orekit.time.FieldAbsoluteDate;
  31. import org.orekit.utils.AngularDerivativesFilter;
  32. import org.orekit.utils.CartesianDerivativesFilter;
  33. import org.orekit.utils.GenericTimeStampedCache;

  35. /** Transform provider using thread-safe interpolation on transforms sample.
  36.  * <p>
  37.  * The interpolation is a polynomial Hermite interpolation, which
  38.  * can either use or ignore the derivatives provided by the raw
  39.  * provider. This means that simple raw providers that do not compute
  40.  * derivatives can be used, the derivatives will be added appropriately
  41.  * by the interpolation process.
  42.  * </p>
  43.  * @see GenericTimeStampedCache
  44.  * @see ShiftingTransformProvider
  45.  * @author Luc Maisonobe
  46.  */
  47. public class InterpolatingTransformProvider implements TransformProvider {

  49.     /** Serializable UID. */
  50.     private static final long serialVersionUID = 20140723L;

  52.     /** Provider for raw (non-interpolated) transforms. */
  53.     private final TransformProvider rawProvider;

  55.     /** Filter for Cartesian derivatives to use in interpolation. */
  56.     private final CartesianDerivativesFilter cFilter;

  58.     /** Filter for angular derivatives to use in interpolation. */
  59.     private final AngularDerivativesFilter aFilter;

  61.     /** Grid points time step. */
  62.     private final double step;

  64.     /** Cache for sample points. */
  65.     private final transient GenericTimeStampedCache<Transform> cache;

  67.     /** Field caches for sample points. */
  68.     // we use Object as the value of fieldCaches because despite numerous attempts,
  69.     // we could not find a way to use GenericTimeStampedCache<FieldTransform<? extends CalculusFieldElement<?>>
  70.     // without the compiler complaining
  71.     private final transient Map<Field<? extends CalculusFieldElement<?>>, Object> fieldCaches;

  73.     /** Simple constructor.
  74.      * @param rawProvider provider for raw (non-interpolated) transforms
  75.      * @param cFilter filter for derivatives from the sample to use in interpolation
  76.      * @param aFilter filter for derivatives from the sample to use in interpolation
  77.      * @param gridPoints number of interpolation grid points
  78.      * @param step grid points time step
  79.      * @param maxSlots maximum number of independent cached time slots
  80.      * in the {@link GenericTimeStampedCache time-stamped cache}
  81.      * @param maxSpan maximum duration span in seconds of one slot
  82.      * in the {@link GenericTimeStampedCache time-stamped cache}
  83.      * @param newSlotInterval time interval above which a new slot is created
  84.      * in the {@link GenericTimeStampedCache time-stamped cache}
  85.      * @since 9.1
  86.      */
  87.     public InterpolatingTransformProvider(final TransformProvider rawProvider,
  88.                                           final CartesianDerivativesFilter cFilter,
  89.                                           final AngularDerivativesFilter aFilter,
  90.                                           final int gridPoints, final double step,
  91.                                           final int maxSlots, final double maxSpan, final double newSlotInterval) {
  92.         this.rawProvider = rawProvider;
  93.         this.cFilter     = cFilter;
  94.         this.aFilter     = aFilter;
  95.         this.step        = step;
  96.         this.cache       = new GenericTimeStampedCache<Transform>(gridPoints, maxSlots, maxSpan, newSlotInterval,
  97.                                                                   new TransformGenerator(gridPoints,
  98.                                                                                          rawProvider,
  99.                                                                                          step));
  100.         this.fieldCaches = new HashMap<>();
  101.     }

  103.     /** Get the underlying provider for raw (non-interpolated) transforms.
  104.      * @return provider for raw (non-interpolated) transforms
  105.      */
  106.     public TransformProvider getRawProvider() {
  107.         return rawProvider;
  108.     }

  110.     /** Get the number of interpolation grid points.
  111.      * @return number of interpolation grid points
  112.      */
  113.     public int getGridPoints() {
  114.         return cache.getNeighborsSize();
  115.     }

  117.     /** Get the grid points time step.
  118.      * @return grid points time step
  119.      */
  120.     public double getStep() {
  121.         return step;
  122.     }

  124.     /** {@inheritDoc} */
  125.     @Override
  126.     public Transform getTransform(final AbsoluteDate date) {
  127.         // retrieve a sample from the thread-safe cache
  128.         final List<Transform> sample = cache.getNeighbors(date).collect(Collectors.toList());

  130.         // interpolate to specified date
  131.         return Transform.interpolate(date, cFilter, aFilter, sample);
  132.     }

  134.     /** {@inheritDoc} */
  135.     @Override
  136.     public <T extends CalculusFieldElement<T>> FieldTransform<T> getTransform(final FieldAbsoluteDate<T> date) {
  137.         @SuppressWarnings("unchecked")
  138.         GenericTimeStampedCache<FieldTransform<T>> fieldCache =
  139.             (GenericTimeStampedCache<FieldTransform<T>>) fieldCaches.get(date.getField());
  140.         if (fieldCache == null) {
  141.             fieldCache =
  142.                 new GenericTimeStampedCache<FieldTransform<T>>(cache.getNeighborsSize(),
  143.                                                                cache.getMaxSlots(),
  144.                                                                cache.getMaxSpan(),
  145.                                                                cache.getNewSlotQuantumGap(),
  146.                                                                new FieldTransformGenerator<>(date.getField(),
  147.                                                                                              cache.getNeighborsSize(),
  148.                                                                                              rawProvider,
  149.                                                                                              step));
  150.             fieldCaches.put(date.getField(), fieldCache);
  151.         }

  153.         // retrieve a sample from the thread-safe cache
  154.         final Stream<FieldTransform<T>> sample = fieldCache.getNeighbors(date.toAbsoluteDate());

  156.         // interpolate to specified date
  157.         return FieldTransform.interpolate(date, cFilter, aFilter, sample);
  158.     }

  160.     /** Replace the instance with a data transfer object for serialization.
  161.      * <p>
  162.      * This intermediate class serializes only the data needed for generation,
  163.      * but does <em>not</em> serializes the cache itself (in fact the cache is
  164.      * not serializable).
  165.      * </p>
  166.      * @return data transfer object that will be serialized
  167.      */
  168.     private Object writeReplace() {
  169.         return new DTO(rawProvider, cFilter.getMaxOrder(), aFilter.getMaxOrder(),
  170.                        cache.getNeighborsSize(), step,
  171.                        cache.getMaxSlots(), cache.getMaxSpan(), cache.getNewSlotQuantumGap());
  172.     }

  174.     /** Internal class used only for serialization. */
  175.     private static class DTO implements Serializable {

  177.         /** Serializable UID. */
  178.         private static final long serialVersionUID = 20170823L;

  180.         /** Provider for raw (non-interpolated) transforms. */
  181.         private final TransformProvider rawProvider;

  183.         /** Cartesian derivatives to use in interpolation. */
  184.         private final int cDerivatives;

  186.         /** Angular derivatives to use in interpolation. */
  187.         private final int aDerivatives;

  189.         /** Number of grid points. */
  190.         private final int gridPoints;

  192.         /** Grid points time step. */
  193.         private final double step;

  195.         /** Maximum number of independent cached time slots. */
  196.         private final int maxSlots;

  198.         /** Maximum duration span in seconds of one slot. */
  199.         private final double maxSpan;

  201.         /** Time interval above which a new slot is created. */
  202.         private final double newSlotInterval;

  204.         /** Simple constructor.
  205.          * @param rawProvider provider for raw (non-interpolated) transforms
  206.          * @param cDerivatives derivation order for Cartesian coordinates
  207.          * @param aDerivatives derivation order for angular coordinates
  208.          * @param gridPoints number of interpolation grid points
  209.          * @param step grid points time step
  210.          * @param maxSlots maximum number of independent cached time slots
  211.          * in the {@link GenericTimeStampedCache time-stamped cache}
  212.          * @param maxSpan maximum duration span in seconds of one slot
  213.          * in the {@link GenericTimeStampedCache time-stamped cache}
  214.          * @param newSlotInterval time interval above which a new slot is created
  215.          * in the {@link GenericTimeStampedCache time-stamped cache}
  216.          */
  217.         private DTO(final TransformProvider rawProvider, final int cDerivatives, final int aDerivatives,
  218.                     final int gridPoints, final double step,
  219.                     final int maxSlots, final double maxSpan, final double newSlotInterval) {
  220.             this.rawProvider     = rawProvider;
  221.             this.cDerivatives    = cDerivatives;
  222.             this.aDerivatives    = aDerivatives;
  223.             this.gridPoints      = gridPoints;
  224.             this.step            = step;
  225.             this.maxSlots        = maxSlots;
  226.             this.maxSpan         = maxSpan;
  227.             this.newSlotInterval = newSlotInterval;
  228.         }

  230.         /** Replace the deserialized data transfer object with a {@link InterpolatingTransformProvider}.
  231.          * @return replacement {@link InterpolatingTransformProvider}
  232.          */
  233.         private Object readResolve() {
  234.             // build a new provider, with an empty cache
  235.             return new InterpolatingTransformProvider(rawProvider,
  236.                                                       CartesianDerivativesFilter.getFilter(cDerivatives),
  237.                                                       AngularDerivativesFilter.getFilter(aDerivatives),
  238.                                                       gridPoints, step,
  239.                                                       maxSlots, maxSpan, newSlotInterval);
  240.         }

  242.     }

  244. }
Created with JaCoCo 0.8.7.202105040129