VEISProvider.java
- /* Copyright 2002-2019 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 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.hipparchus.util.MathUtils;
- import org.orekit.time.AbsoluteDate;
- import org.orekit.time.DateComponents;
- import org.orekit.time.FieldAbsoluteDate;
- import org.orekit.time.TimeScalesFactory;
- import org.orekit.utils.Constants;
- /** Veis 1950 Frame.
- * <p>Its parent frame is the {@link GTODProvider} without EOP correction application.
- * <p>This frame is mainly provided for consistency with legacy softwares.</p>
- * @author Pascal Parraud
- */
- class VEISProvider implements TransformProvider {
- /** Serializable UID. */
- private static final long serialVersionUID = 20130530L;
- /** Reference date. */
- private static AbsoluteDate VST_REFERENCE =
- new AbsoluteDate(DateComponents.FIFTIES_EPOCH, TimeScalesFactory.getTAI());
- /** 1st coef for Veis sidereal time computation in radians (100.075542 deg). */
- private static final double VST0 = 1.746647708617871;
- /** 2nd coef for Veis sidereal time computation in rad/s (0.985612288 deg/s). */
- private static final double VST1 = 0.17202179573714597e-1;
- /** Veis sidereal time derivative in rad/s. */
- private static final double VSTD = 7.292115146705209e-5;
- /** Constructor for the singleton.
- */
- VEISProvider() {
- }
- /** {@inheritDoc} */
- @Override
- public Transform getTransform(final AbsoluteDate date) {
- // offset from FIFTIES epoch (UT1 scale)
- final double dtai = date.durationFrom(VST_REFERENCE);
- final double dutc = TimeScalesFactory.getUTC().offsetFromTAI(date);
- final double dut1 = 0.0; // fixed at 0 since Veis parent is GTOD frame WITHOUT EOP corrections
- final double tut1 = dtai + dutc + dut1;
- final double ttd = tut1 / Constants.JULIAN_DAY;
- final double rdtt = ttd - (int) ttd;
- // compute Veis sidereal time, in radians
- final double vst = (VST0 + VST1 * ttd + MathUtils.TWO_PI * rdtt) % MathUtils.TWO_PI;
- // compute angular rotation of Earth, in rad/s
- final Vector3D rotationRate = new Vector3D(-VSTD, Vector3D.PLUS_K);
- // set up the transform from parent GTOD
- return new Transform(date,
- new Rotation(Vector3D.PLUS_K, vst, RotationConvention.VECTOR_OPERATOR),
- rotationRate);
- }
- /** {@inheritDoc} */
- @Override
- public <T extends RealFieldElement<T>> FieldTransform<T> getTransform(final FieldAbsoluteDate<T> date) {
- // offset from FIFTIES epoch (UT1 scale)
- final T dtai = date.durationFrom(VST_REFERENCE);
- final double dutc = TimeScalesFactory.getUTC().offsetFromTAI(date.toAbsoluteDate());
- final double dut1 = 0.0; // fixed at 0 since Veis parent is GTOD frame WITHOUT EOP corrections
- final T tut1 = dtai.add(dutc + dut1);
- final T ttd = tut1.divide(Constants.JULIAN_DAY);
- final T rdtt = ttd.subtract((int) ttd.getReal());
- // compute Veis sidereal time, in radians
- final T vst = ttd.multiply(VST1).add(rdtt.multiply(MathUtils.TWO_PI)).add(VST0).remainder(MathUtils.TWO_PI);
- // compute angular rotation of Earth, in rad/s
- final FieldVector3D<T> rotationRate = new FieldVector3D<>(date.getField().getZero().add(-VSTD),
- Vector3D.PLUS_K);
- // set up the transform from parent GTOD
- return new FieldTransform<>(date,
- new FieldRotation<>(FieldVector3D.getPlusK(date.getField()), vst,
- RotationConvention.VECTOR_OPERATOR),
- rotationRate);
- }
- }