AbsolutePVCoordinates.java
- /* Copyright 2002-2020 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
- * limitations under the License.
- */
- package org.orekit.utils;
- import java.io.Serializable;
- import java.util.stream.Stream;
- import org.hipparchus.analysis.differentiation.DerivativeStructure;
- import org.hipparchus.analysis.interpolation.HermiteInterpolator;
- import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
- import org.hipparchus.geometry.euclidean.threed.Vector3D;
- import org.hipparchus.util.FastMath;
- import org.orekit.annotation.DefaultDataContext;
- import org.orekit.data.DataContext;
- import org.orekit.errors.OrekitException;
- import org.orekit.errors.OrekitIllegalArgumentException;
- import org.orekit.errors.OrekitInternalError;
- import org.orekit.errors.OrekitMessages;
- import org.orekit.frames.Frame;
- import org.orekit.frames.Transform;
- import org.orekit.time.AbsoluteDate;
- import org.orekit.time.TimeInterpolable;
- import org.orekit.time.TimeStamped;
- /** Position - Velocity - Acceleration linked to a date and a frame.
- */
- public class AbsolutePVCoordinates extends TimeStampedPVCoordinates
- implements TimeStamped, TimeInterpolable<AbsolutePVCoordinates>,
- Serializable, PVCoordinatesProvider {
- /** Serializable UID. */
- private static final long serialVersionUID = 20150824L;
- /** Frame in which are defined the coordinates. */
- private final Frame frame;
- /** Build from position, velocity, acceleration.
- * @param frame the frame in which the coordinates are defined
- * @param date coordinates date
- * @param position the position vector (m)
- * @param velocity the velocity vector (m/s)
- * @param acceleration the acceleration vector (m/sÂý)
- */
- public AbsolutePVCoordinates(final Frame frame, final AbsoluteDate date,
- final Vector3D position, final Vector3D velocity, final Vector3D acceleration) {
- super(date, position, velocity, acceleration);
- this.frame = frame;
- }
- /** Build from position and velocity. Acceleration is set to zero.
- * @param frame the frame in which the coordinates are defined
- * @param date coordinates date
- * @param position the position vector (m)
- * @param velocity the velocity vector (m/s)
- */
- public AbsolutePVCoordinates(final Frame frame, final AbsoluteDate date,
- final Vector3D position,
- final Vector3D velocity) {
- this(frame, date, position, velocity, Vector3D.ZERO);
- }
- /** Build from frame, date and PVA coordinates.
- * @param frame the frame in which the coordinates are defined
- * @param date date of the coordinates
- * @param pva TimeStampedPVCoordinates
- */
- public AbsolutePVCoordinates(final Frame frame, final AbsoluteDate date, final PVCoordinates pva) {
- super(date, pva);
- this.frame = frame;
- }
- /** Build from frame and TimeStampedPVCoordinates.
- * @param frame the frame in which the coordinates are defined
- * @param pva TimeStampedPVCoordinates
- */
- public AbsolutePVCoordinates(final Frame frame, final TimeStampedPVCoordinates pva) {
- super(pva.getDate(), pva);
- this.frame = frame;
- }
- /** Multiplicative constructor
- * <p>Build a AbsolutePVCoordinates from another one and a scale factor.</p>
- * <p>The TimeStampedPVCoordinates built will be a * AbsPva</p>
- * @param date date of the built coordinates
- * @param a scale factor
- * @param AbsPva base (unscaled) AbsolutePVCoordinates
- */
- public AbsolutePVCoordinates(final AbsoluteDate date,
- final double a, final AbsolutePVCoordinates AbsPva) {
- super(date, a, AbsPva);
- this.frame = AbsPva.frame;
- }
- /** Subtractive constructor
- * <p>Build a relative AbsolutePVCoordinates from a start and an end position.</p>
- * <p>The AbsolutePVCoordinates built will be end - start.</p>
- * <p>In case start and end use two different pseudo-inertial frames,
- * the new AbsolutePVCoordinates arbitrarily be defined in the start frame. </p>
- * @param date date of the built coordinates
- * @param start Starting AbsolutePVCoordinates
- * @param end ending AbsolutePVCoordinates
- */
- public AbsolutePVCoordinates(final AbsoluteDate date,
- final AbsolutePVCoordinates start, final AbsolutePVCoordinates end) {
- super(date, start, end);
- ensureIdenticalFrames(start, end);
- this.frame = start.frame;
- }
- /** Linear constructor
- * <p>Build a AbsolutePVCoordinates from two other ones and corresponding scale factors.</p>
- * <p>The AbsolutePVCoordinates built will be a1 * u1 + a2 * u2</p>
- * <p>In case the AbsolutePVCoordinates use different pseudo-inertial frames,
- * the new AbsolutePVCoordinates arbitrarily be defined in the first frame. </p>
- * @param date date of the built coordinates
- * @param a1 first scale factor
- * @param absPv1 first base (unscaled) AbsolutePVCoordinates
- * @param a2 second scale factor
- * @param absPv2 second base (unscaled) AbsolutePVCoordinates
- */
- public AbsolutePVCoordinates(final AbsoluteDate date,
- final double a1, final AbsolutePVCoordinates absPv1,
- final double a2, final AbsolutePVCoordinates absPv2) {
- super(date, a1, absPv1.getPVCoordinates(), a2, absPv2.getPVCoordinates());
- ensureIdenticalFrames(absPv1, absPv2);
- this.frame = absPv1.getFrame();
- }
- /** Linear constructor
- * <p>Build a AbsolutePVCoordinates from three other ones and corresponding scale factors.</p>
- * <p>The AbsolutePVCoordinates built will be a1 * u1 + a2 * u2 + a3 * u3</p>
- * <p>In case the AbsolutePVCoordinates use different pseudo-inertial frames,
- * the new AbsolutePVCoordinates arbitrarily be defined in the first frame. </p>
- * @param date date of the built coordinates
- * @param a1 first scale factor
- * @param absPv1 first base (unscaled) AbsolutePVCoordinates
- * @param a2 second scale factor
- * @param absPv2 second base (unscaled) AbsolutePVCoordinates
- * @param a3 third scale factor
- * @param absPv3 third base (unscaled) AbsolutePVCoordinates
- */
- public AbsolutePVCoordinates(final AbsoluteDate date,
- final double a1, final AbsolutePVCoordinates absPv1,
- final double a2, final AbsolutePVCoordinates absPv2,
- final double a3, final AbsolutePVCoordinates absPv3) {
- super(date, a1, absPv1.getPVCoordinates(), a2, absPv2.getPVCoordinates(),
- a3, absPv3.getPVCoordinates());
- ensureIdenticalFrames(absPv1, absPv2);
- ensureIdenticalFrames(absPv1, absPv3);
- this.frame = absPv1.getFrame();
- }
- /** Linear constructor
- * <p>Build a AbsolutePVCoordinates from four other ones and corresponding scale factors.</p>
- * <p>The AbsolutePVCoordinates built will be a1 * u1 + a2 * u2 + a3 * u3 + a4 * u4</p>
- * <p>In case the AbsolutePVCoordinates use different pseudo-inertial frames,
- * the new AbsolutePVCoordinates arbitrarily be defined in the first frame. </p>
- * @param date date of the built coordinates
- * @param a1 first scale factor
- * @param absPv1 first base (unscaled) AbsolutePVCoordinates
- * @param a2 second scale factor
- * @param absPv2 second base (unscaled) AbsolutePVCoordinates
- * @param a3 third scale factor
- * @param absPv3 third base (unscaled) AbsolutePVCoordinates
- * @param a4 fourth scale factor
- * @param absPv4 fourth base (unscaled) AbsolutePVCoordinates
- */
- public AbsolutePVCoordinates(final AbsoluteDate date,
- final double a1, final AbsolutePVCoordinates absPv1,
- final double a2, final AbsolutePVCoordinates absPv2,
- final double a3, final AbsolutePVCoordinates absPv3,
- final double a4, final AbsolutePVCoordinates absPv4) {
- super(date, a1, absPv1.getPVCoordinates(), a2, absPv2.getPVCoordinates(),
- a3, absPv3.getPVCoordinates(), a4, absPv4.getPVCoordinates());
- ensureIdenticalFrames(absPv1, absPv2);
- ensureIdenticalFrames(absPv1, absPv3);
- ensureIdenticalFrames(absPv1, absPv4);
- this.frame = absPv1.getFrame();
- }
- /** Builds a AbsolutePVCoordinates triplet from a {@link FieldVector3D}<{@link DerivativeStructure}>.
- * <p>
- * The vector components must have time as their only derivation parameter and
- * have consistent derivation orders.
- * </p>
- * @param frame the frame in which the parameters are defined
- * @param date date of the built coordinates
- * @param p vector with time-derivatives embedded within the coordinates
- */
- public AbsolutePVCoordinates(final Frame frame, final AbsoluteDate date,
- final FieldVector3D<DerivativeStructure> p) {
- super(date, p);
- this.frame = frame;
- }
- /** Ensure that the frames from two AbsolutePVCoordinates are identical.
- * @param absPv1 first AbsolutePVCoordinates
- * @param absPv2 first AbsolutePVCoordinates
- * @throws OrekitIllegalArgumentException if frames are different
- */
- private static void ensureIdenticalFrames(final AbsolutePVCoordinates absPv1, final AbsolutePVCoordinates absPv2)
- throws OrekitIllegalArgumentException {
- if (!absPv1.frame.equals(absPv2.frame)) {
- throw new OrekitIllegalArgumentException(OrekitMessages.INCOMPATIBLE_FRAMES,
- absPv1.frame.getName(), absPv2.frame.getName());
- }
- }
- /** Get a time-shifted state.
- * <p>
- * The state can be slightly shifted to close dates. This shift is based on
- * a simple Taylor expansion. It is <em>not</em> intended as a replacement for
- * proper orbit propagation (it is not even Keplerian!) but should be sufficient
- * for either small time shifts or coarse accuracy.
- * </p>
- * @param dt time shift in seconds
- * @return a new state, shifted with respect to the instance (which is immutable)
- */
- public AbsolutePVCoordinates shiftedBy(final double dt) {
- final TimeStampedPVCoordinates spv = super.shiftedBy(dt);
- return new AbsolutePVCoordinates(frame, spv);
- }
- /** Create a local provider using simply Taylor expansion through {@link #shiftedBy(double)}.
- * <p>
- * The time evolution is based on a simple Taylor expansion. It is <em>not</em> intended as a
- * replacement for proper orbit propagation (it is not even Keplerian!) but should be sufficient
- * for either small time shifts or coarse accuracy.
- * </p>
- * @return provider based on Taylor expansion, for small time shifts around instance date
- */
- public PVCoordinatesProvider toTaylorProvider() {
- return new PVCoordinatesProvider() {
- /** {@inheritDoc} */
- public TimeStampedPVCoordinates getPVCoordinates(final AbsoluteDate d, final Frame f) {
- final TimeStampedPVCoordinates shifted = shiftedBy(d.durationFrom(getDate()));
- final Transform transform = frame.getTransformTo(f, d);
- return transform.transformPVCoordinates(shifted);
- }
- };
- }
- /** Get the frame in which the coordinates are defined.
- * @return frame in which the coordinates are defined
- */
- public Frame getFrame() {
- return frame;
- }
- /** Get the TimeStampedPVCoordinates.
- * @return TimeStampedPVCoordinates
- */
- public TimeStampedPVCoordinates getPVCoordinates() {
- return this;
- }
- /** Get the TimeStampedPVCoordinates in a specified frame.
- * @param outputFrame frame in which the position/velocity coordinates shall be computed
- * @return TimeStampedPVCoordinates
- * @exception OrekitException if transformation between frames cannot be computed
- * @see #getPVCoordinates()
- */
- public TimeStampedPVCoordinates getPVCoordinates(final Frame outputFrame) {
- // If output frame requested is the same as definition frame,
- // PV coordinates are returned directly
- if (outputFrame == frame) {
- return getPVCoordinates();
- }
- // Else, PV coordinates are transformed to output frame
- final Transform t = frame.getTransformTo(outputFrame, getDate());
- return t.transformPVCoordinates(getPVCoordinates());
- }
- @Override
- public TimeStampedPVCoordinates getPVCoordinates(final AbsoluteDate otherDate, final Frame outputFrame) {
- return shiftedBy(otherDate.durationFrom(getDate())).getPVCoordinates(outputFrame);
- }
- @Override
- public AbsolutePVCoordinates interpolate(final AbsoluteDate date, final Stream<AbsolutePVCoordinates> sample) {
- return interpolate(getFrame(), date, CartesianDerivativesFilter.USE_PVA, sample);
- }
- /** Interpolate position-velocity.
- * <p>
- * The interpolated instance is created by polynomial Hermite interpolation
- * ensuring velocity remains the exact derivative of position.
- * </p>
- * <p>
- * Note that even if first time derivatives (velocities)
- * from sample can be ignored, the interpolated instance always includes
- * interpolated derivatives. This feature can be used explicitly to
- * compute these derivatives when it would be too complex to compute them
- * from an analytical formula: just compute a few sample points from the
- * explicit formula and set the derivatives to zero in these sample points,
- * then use interpolation to add derivatives consistent with the positions.
- * </p>
- * @param frame frame for the interpolted instance
- * @param date interpolation date
- * @param filter filter for derivatives from the sample to use in interpolation
- * @param sample sample points on which interpolation should be done
- * @return a new position-velocity, interpolated at specified date
- * @exception OrekitIllegalArgumentException if some elements in the sample do not
- * have the same defining frame as other
- */
- public static AbsolutePVCoordinates interpolate(final Frame frame, final AbsoluteDate date,
- final CartesianDerivativesFilter filter,
- final Stream<AbsolutePVCoordinates> sample) {
- // set up an interpolator taking derivatives into account
- final HermiteInterpolator interpolator = new HermiteInterpolator();
- // add sample points
- switch (filter) {
- case USE_P :
- // populate sample with position data, ignoring velocity
- sample.forEach(pv -> {
- final Vector3D position = pv.getPosition();
- interpolator.addSamplePoint(pv.getDate().durationFrom(date),
- position.toArray());
- });
- break;
- case USE_PV :
- // populate sample with position and velocity data
- sample.forEach(pv -> {
- final Vector3D position = pv.getPosition();
- final Vector3D velocity = pv.getVelocity();
- interpolator.addSamplePoint(pv.getDate().durationFrom(date),
- position.toArray(), velocity.toArray());
- });
- break;
- case USE_PVA :
- // populate sample with position, velocity and acceleration data
- sample.forEach(pv -> {
- final Vector3D position = pv.getPosition();
- final Vector3D velocity = pv.getVelocity();
- final Vector3D acceleration = pv.getAcceleration();
- interpolator.addSamplePoint(pv.getDate().durationFrom(date),
- position.toArray(), velocity.toArray(), acceleration.toArray());
- });
- break;
- default :
- // this should never happen
- throw new OrekitInternalError(null);
- }
- // interpolate
- final double[][] p = interpolator.derivatives(0.0, 2);
- // build a new interpolated instance
- return new AbsolutePVCoordinates(frame, date, new Vector3D(p[0]), new Vector3D(p[1]), new Vector3D(p[2]));
- }
- /** Replace the instance with a data transfer object for serialization.
- * @return data transfer object that will be serialized
- */
- @DefaultDataContext
- private Object writeReplace() {
- return new DTO(this);
- }
- /** Internal class used only for serialization. */
- @DefaultDataContext
- private static class DTO implements Serializable {
- /** Serializable UID. */
- private static final long serialVersionUID = 20150916L;
- /** Double values. */
- private double[] d;
- /** Frame in which acoordinates are defined. */
- private final Frame frame;
- /** Simple constructor.
- * @param absPva instance to serialize
- */
- private DTO(final AbsolutePVCoordinates absPva) {
- // decompose date
- final AbsoluteDate j2000Epoch =
- DataContext.getDefault().getTimeScales().getJ2000Epoch();
- final double epoch = FastMath.floor(absPva.getDate().durationFrom(j2000Epoch));
- final double offset = absPva.getDate().durationFrom(j2000Epoch.shiftedBy(epoch));
- this.d = new double[] {
- epoch, offset,
- absPva.getPosition().getX(), absPva.getPosition().getY(), absPva.getPosition().getZ(),
- absPva.getVelocity().getX(), absPva.getVelocity().getY(), absPva.getVelocity().getZ(),
- absPva.getAcceleration().getX(), absPva.getAcceleration().getY(), absPva.getAcceleration().getZ()
- };
- this.frame = absPva.frame;
- }
- /** Replace the deserialized data transfer object with a {@link AbsolutePVCoordinates}.
- * @return replacement {@link AbsolutePVCoordinates}
- */
- private Object readResolve() {
- final AbsoluteDate j2000Epoch =
- DataContext.getDefault().getTimeScales().getJ2000Epoch();
- return new AbsolutePVCoordinates(frame,
- j2000Epoch.shiftedBy(d[0]).shiftedBy(d[1]),
- new Vector3D(d[2], d[3], d[ 4]),
- new Vector3D(d[5], d[6], d[ 7]),
- new Vector3D(d[8], d[9], d[10]));
- }
- }
- }