TODProvider.java
- /* Copyright 2002-2013 CS Systèmes d'Information
- * Licensed to CS Systèmes d'Information (CS) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * CS licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- package org.orekit.frames;
- import java.io.Serializable;
- import org.apache.commons.math3.geometry.euclidean.threed.Rotation;
- import org.apache.commons.math3.geometry.euclidean.threed.Vector3D;
- import org.orekit.errors.OrekitException;
- import org.orekit.errors.TimeStampedCacheException;
- import org.orekit.time.AbsoluteDate;
- import org.orekit.time.TimeFunction;
- import org.orekit.utils.IERSConventions;
- /** Provider for True of Date (ToD) frame.
- * <p>This frame handles nutation effects according to selected IERS conventions.</p>
- * <p>Transform is computed with reference to the {@link MODProvider Mean of Date} frame.</p>
- * @author Pascal Parraud
- */
- class TODProvider implements TransformProvider {
- /** Serializable UID. */
- private static final long serialVersionUID = 20131209L;
- /** Conventions. */
- private final IERSConventions conventions;
- /** EOP history. */
- private final EOPHistory eopHistory;
- /** Function computing the mean obliquity. */
- private final transient TimeFunction<Double> obliquityFunction;
- /** Function computing the nutation angles. */
- private final transient TimeFunction<double[]> nutationFunction;
- /** Simple constructor.
- * @param conventions IERS conventions to apply
- * @param eopHistory EOP history
- * @exception OrekitException if IERS conventions tables cannot be read
- */
- public TODProvider(final IERSConventions conventions, final EOPHistory eopHistory)
- throws OrekitException {
- this.conventions = conventions;
- this.eopHistory = eopHistory;
- this.obliquityFunction = conventions.getMeanObliquityFunction();
- this.nutationFunction = conventions.getNutationFunction();
- }
- /** Get the EOP history.
- * @return EOP history
- */
- EOPHistory getEOPHistory() {
- return eopHistory;
- }
- /** Get the LoD (Length of Day) value.
- * <p>The data provided comes from the IERS files. It is smoothed data.</p>
- * @param date date at which the value is desired
- * @return LoD in seconds (0 if date is outside covered range)
- * @exception TimeStampedCacheException if EOP data cannot be retrieved
- */
- double getLOD(final AbsoluteDate date) throws TimeStampedCacheException {
- return (eopHistory == null) ? 0.0 : eopHistory.getLOD(date);
- }
- /** Get the pole IERS Reference Pole correction.
- * <p>The data provided comes from the IERS files. It is smoothed data.</p>
- * @param date date at which the correction is desired
- * @return pole correction ({@link PoleCorrection#NULL_CORRECTION
- * PoleCorrection.NULL_CORRECTION} if date is outside covered range)
- */
- public PoleCorrection getPoleCorrection(final AbsoluteDate date) {
- return (eopHistory == null) ? PoleCorrection.NULL_CORRECTION : eopHistory.getPoleCorrection(date);
- }
- /** Get the transform from Mean Of Date at specified date.
- * <p>The update considers the nutation effects from IERS data.</p>
- * @param date new value of the date
- * @return transform at the specified date
- * @exception OrekitException if the nutation model data embedded in the
- * library cannot be read
- */
- public Transform getTransform(final AbsoluteDate date) throws OrekitException {
- // compute nutation angles
- final double[] angles = nutationFunction.value(date);
- // compute the mean obliquity of the ecliptic
- final double moe = obliquityFunction.value(date);
- double dpsi = angles[0];
- double deps = angles[1];
- if (eopHistory != null) {
- // apply the corrections for the nutation parameters
- final double[] correction = eopHistory.getEquinoxNutationCorrection(date);
- dpsi += correction[0];
- deps += correction[1];
- }
- // compute the true obliquity of the ecliptic
- final double toe = moe + deps;
- // set up the elementary rotations for nutation
- final Rotation r1 = new Rotation(Vector3D.PLUS_I, toe);
- final Rotation r2 = new Rotation(Vector3D.PLUS_K, dpsi);
- final Rotation r3 = new Rotation(Vector3D.PLUS_I, -moe);
- // complete nutation
- final Rotation nutation = r1.applyTo(r2.applyTo(r3));
- // set up the transform from parent MOD
- return new Transform(date, nutation);
- }
- /** Replace the instance with a data transfer object for serialization.
- * <p>
- * This intermediate class serializes only the frame key.
- * </p>
- * @return data transfer object that will be serialized
- */
- private Object writeReplace() {
- return new DataTransferObject(conventions, eopHistory);
- }
- /** Internal class used only for serialization. */
- private static class DataTransferObject implements Serializable {
- /** Serializable UID. */
- private static final long serialVersionUID = 20131209L;
- /** Conventions. */
- private final IERSConventions conventions;
- /** EOP history. */
- private final EOPHistory eopHistory;
- /** Simple constructor.
- * @param conventions IERS conventions to apply
- * @param eopHistory EOP history
- */
- public DataTransferObject(final IERSConventions conventions, final EOPHistory eopHistory) {
- this.conventions = conventions;
- this.eopHistory = eopHistory;
- }
- /** Replace the deserialized data transfer object with a {@link TODProvider}.
- * @return replacement {@link TODProvider}
- */
- private Object readResolve() {
- try {
- // retrieve a managed frame
- return new TODProvider(conventions, eopHistory);
- } catch (OrekitException oe) {
- throw OrekitException.createInternalError(oe);
- }
- }
- }
- }