EclipticProvider.java
- /* Contributed in the public domain.
- * 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.hipparchus.RealFieldElement;
- 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.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.utils.IERSConventions;
- /**
- * An inertial frame aligned with the ecliptic.
- * <p>
- * The IAU defines the ecliptic as "the plane perpendicular to the mean heliocentric
- * orbital angular momentum vector of the Earth-Moon barycentre in the BCRS (IAU 2006
- * Resolution B1)." The +z axis is aligned with the angular momentum vector, and the +x
- * axis is aligned with +x axis of {@link FramesFactory#getMOD(IERSConventions) MOD}.
- * </p>
- *
- * <p>
- * This implementation agrees with the JPL 406 ephemerides to within 0.5 arc seconds.
- * </p>
- *
- * @since 7.0
- */
- public class EclipticProvider implements TransformProvider {
- /** Serializable UID. */
- private static final long serialVersionUID = 20140516L;
- /** IERS conventions. */
- private final IERSConventions conventions;
- /** the obliquity of the ecliptic, in radians as a function of time. */
- private final transient TimeScalarFunction obliquity;
- /**
- * Create a transform provider from MOD to an ecliptically aligned frame.
- * @param conventions IERS conventions
- * @throws OrekitException if the mean obliquity of the ecliptic function can not be
- * loaded.
- */
- public EclipticProvider(final IERSConventions conventions) throws OrekitException {
- this.conventions = conventions;
- this.obliquity = conventions.getMeanObliquityFunction();
- }
- @Override
- public Transform getTransform(final AbsoluteDate date) throws OrekitException {
- //mean obliquity of date
- final double epsA = obliquity.value(date);
- return new Transform(date, new Rotation(Vector3D.MINUS_I, epsA, RotationConvention.VECTOR_OPERATOR));
- }
- @Override
- public <T extends RealFieldElement<T>> FieldTransform<T> getTransform(final FieldAbsoluteDate<T> date)
- throws OrekitException {
- //mean obliquity of date
- final T epsA = obliquity.value(date);
- return new FieldTransform<>(date, new FieldRotation<>(FieldVector3D.getMinusI(date.getField()),
- epsA,
- RotationConvention.VECTOR_OPERATOR));
- }
- /** 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);
- }
- /** Internal class used only for serialization. */
- private static class DataTransferObject implements Serializable {
- /** Serializable UID. */
- private static final long serialVersionUID = 20140516L;
- /** IERS conventions. */
- private final IERSConventions conventions;
- /** Simple constructor.
- * @param conventions IERS conventions
- */
- DataTransferObject(final IERSConventions conventions) {
- this.conventions = conventions;
- }
- /** Replace the deserialized data transfer object with a {@link EclipticProvider}.
- * @return replacement {@link EclipticProvider}
- */
- private Object readResolve() {
- try {
- // retrieve a transform
- return new EclipticProvider(conventions);
- } catch (OrekitException oe) {
- throw new OrekitInternalError(oe);
- }
- }
- }
- }