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);
}
}