TIRFProvider.java
/* Copyright 2002-2024 CS GROUP
* Licensed to CS GROUP (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
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*/
package org.orekit.frames;
import java.io.Serializable;
import org.hipparchus.CalculusFieldElement;
import org.hipparchus.geometry.euclidean.threed.FieldRotation;
import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
import org.hipparchus.geometry.euclidean.threed.Rotation;
import org.hipparchus.geometry.euclidean.threed.RotationConvention;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.hipparchus.util.MathUtils;
import org.orekit.annotation.DefaultDataContext;
import org.orekit.data.DataContext;
import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitInternalError;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.FieldAbsoluteDate;
import org.orekit.time.TimeScalarFunction;
import org.orekit.time.TimeScale;
import org.orekit.utils.Constants;
/** Terrestrial Intermediate Reference Frame.
* <p> The pole motion is not considered : Pseudo Earth Fixed Frame. It handles
* the earth rotation angle, its parent frame is the {@link CIRFProvider}</p>
*/
class TIRFProvider implements EOPBasedTransformProvider {
/** Serializable UID. */
private static final long serialVersionUID = 20130919L;
/** Angular velocity of the Earth, in rad/s. */
private static final double AVE = 7.292115146706979e-5;
/** EOP history. */
private final EOPHistory eopHistory;
/** UT1 time scale. */
private final transient TimeScale ut1;
/** ERA function. */
private final transient TimeScalarFunction era;
/** Simple constructor.
* @param eopHistory EOP history
* @param ut1 the UT1 time scale.
*/
protected TIRFProvider(final EOPHistory eopHistory, final TimeScale ut1) {
this.ut1 = ut1;
this.eopHistory = eopHistory;
this.era = eopHistory.getConventions().getEarthOrientationAngleFunction(
ut1,
eopHistory.getTimeScales().getTAI());
}
/** {@inheritDoc} */
@Override
public EOPHistory getEOPHistory() {
return eopHistory;
}
/** {@inheritDoc} */
@Override
public TIRFProvider getNonInterpolatingProvider() {
return new TIRFProvider(eopHistory.getEOPHistoryWithoutCachedTidalCorrection(), ut1);
}
/** {@inheritDoc} */
@Override
public Transform getTransform(final AbsoluteDate date) {
return new Transform(date, getRotation(date), getRotationRate(date));
}
/** {@inheritDoc} */
@Override
public KinematicTransform getKinematicTransform(final AbsoluteDate date) {
return KinematicTransform.of(date, getRotation(date), getRotationRate(date));
}
/** {@inheritDoc} */
@Override
public StaticTransform getStaticTransform(final AbsoluteDate date) {
return StaticTransform.of(date, getRotation(date));
}
/** Form rotation to parent CIRF.
* @param date transform date
* @return rotation to parent at date
* @since 12.1
*/
private Rotation getRotation(final AbsoluteDate date) {
// compute proper rotation
final double correctedERA = era.value(date);
// set up the transform from parent CIRF
return new Rotation(Vector3D.PLUS_K, correctedERA, RotationConvention.FRAME_TRANSFORM);
}
/** Form rotation rate w.r.t. parent CIRF.
* @param date transform date
* @return rotation rate at date
* @since 12.1
*/
private Vector3D getRotationRate(final AbsoluteDate date) {
// compute true angular rotation of Earth, in rad/s
final double lod = (eopHistory == null) ? 0.0 : eopHistory.getLOD(date);
final double omp = AVE * (1 - lod / Constants.JULIAN_DAY);
return new Vector3D(omp, Vector3D.PLUS_K);
}
/** {@inheritDoc} */
@Override
public <T extends CalculusFieldElement<T>> FieldTransform<T> getTransform(final FieldAbsoluteDate<T> date) {
return new FieldTransform<>(date, getRotation(date), getRotationRate(date));
}
/** {@inheritDoc} */
@Override
public <T extends CalculusFieldElement<T>> FieldKinematicTransform<T> getKinematicTransform(final FieldAbsoluteDate<T> date) {
return FieldKinematicTransform.of(date, getRotation(date), getRotationRate(date));
}
/** {@inheritDoc} */
@Override
public <T extends CalculusFieldElement<T>> FieldStaticTransform<T> getStaticTransform(final FieldAbsoluteDate<T> date) {
return FieldStaticTransform.of(date, getRotation(date));
}
/** Form rotation to parent CIRF.
* @param <T> type of the elements
* @param date transform date
* @return rotation to parent at date
* @since 12.1
*/
private <T extends CalculusFieldElement<T>> FieldRotation<T> getRotation(final FieldAbsoluteDate<T> date) {
// compute proper rotation
final T correctedERA = era.value(date);
// set up the transform from parent CIRF
return new FieldRotation<>(
FieldVector3D.getPlusK(date.getField()),
correctedERA,
RotationConvention.FRAME_TRANSFORM);
}
/** Form rotation rate w.r.t. parent CIRF.
* @param <T> type of the elements
* @param date transform date
* @return rotation rate at date
* @since 12.1
*/
private <T extends CalculusFieldElement<T>> FieldVector3D<T> getRotationRate(final FieldAbsoluteDate<T> date) {
// compute true angular rotation of Earth, in rad/s
final T lod = (eopHistory == null) ? date.getField().getZero() : eopHistory.getLOD(date);
final T omp = lod.divide(Constants.JULIAN_DAY).subtract(1).multiply(-AVE);
return new FieldVector3D<>(omp, Vector3D.PLUS_K);
}
/** Get the Earth Rotation Angle at the current date.
* @param date the date
* @return Earth Rotation Angle at the current date in radians
*/
public double getEarthRotationAngle(final AbsoluteDate date) {
return MathUtils.normalizeAngle(era.value(date), 0);
}
/** 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
*/
@DefaultDataContext
private Object writeReplace() {
return new DataTransferObject(eopHistory);
}
/** Internal class used only for serialization. */
@DefaultDataContext
private static class DataTransferObject implements Serializable {
/** Serializable UID. */
private static final long serialVersionUID = 20131209L;
/** EOP history. */
private final EOPHistory eopHistory;
/** Simple constructor.
* @param eopHistory EOP history
*/
DataTransferObject(final EOPHistory eopHistory) {
this.eopHistory = eopHistory;
}
/** Replace the deserialized data transfer object with a {@link TIRFProvider}.
* @return replacement {@link TIRFProvider}
*/
private Object readResolve() {
try {
// retrieve a managed frame
return new TIRFProvider(eopHistory,
DataContext.getDefault().getTimeScales().getUT1(eopHistory));
} catch (OrekitException oe) {
throw new OrekitInternalError(oe);
}
}
}
}