ObservedMeasurement.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,
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* See the License for the specific language governing permissions and
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*/
package org.orekit.estimation.measurements;
import java.util.List;
import java.util.stream.Collectors;
import org.orekit.propagation.SpacecraftState;
import org.orekit.utils.ParameterDriver;
/** Interface for measurements used for orbit determination.
* <p>
* The most important methods of this interface allow to:
* <ul>
* <li>get the observed value,</li>
* <li>estimate the theoretical value of a measurement,</li>
* <li>compute the corresponding partial derivatives (with respect to state and parameters)</li>
* </ul>
*
* <p>
* The estimated theoretical values can be modified by registering one or several {@link
* EstimationModifier EstimationModifier} objects. These objects will manage notions
* like tropospheric delays, biases, ...
* </p>
* @param <T> the type of the measurement
* @author Luc Maisonobe
* @since 8.0
*/
public interface ObservedMeasurement<T extends ObservedMeasurement<T>> extends ComparableMeasurement {
/** Enable or disable a measurement.
* <p>
* Disabling a measurement allow to not consider it at
* one stage of the orbit determination (for example when
* it appears to be an outlier as per current estimated
* covariance).
* </p>
* @param enabled if true the measurement will be enabled,
* otherwise it will be disabled
*/
void setEnabled(boolean enabled);
/** Check if a measurement is enabled.
* @return true if the measurement is enabled
*/
boolean isEnabled();
/** Get the dimension of the measurement.
* <p>
* Dimension is the size of the array containing the
* value. It will be one for a scalar measurement like
* a range or range-rate, but 6 for a position-velocity
* measurement.
* </p>
* @return dimension of the measurement
*/
int getDimension();
/** Get the theoretical standard deviation.
* <p>
* The theoretical standard deviation is a theoretical value
* used for normalizing the residuals. It acts as a weighting
* factor to mix appropriately measurements with different units
* and different accuracy. The value has the same dimension as
* the measurement itself (i.e. when a residual is divided by
* this value, it becomes dimensionless).
* </p>
* @return expected standard deviation
* @see #getBaseWeight()
*/
double[] getTheoreticalStandardDeviation();
/** Get the base weight associated with the measurement
* <p>
* The base weight is used on residuals already normalized thanks to
* {@link #getTheoreticalStandardDeviation()} to increase or
* decrease relative effect of some measurements with respect to
* other measurements. It is a dimensionless value, typically between
* 0 and 1 (but it can really have any non-negative value).
* </p>
* @return base weight
* @see #getTheoreticalStandardDeviation()
* @see EstimatedMeasurement#getCurrentWeight()
*/
double[] getBaseWeight();
/** Add a modifier.
* <p>
* The modifiers are applied in the order in which they are added in order to
* {@link #estimate(int, int, SpacecraftState[]) estimate} the measurement.
* </p>
* @param modifier modifier to add
* @see #getModifiers()
*/
void addModifier(EstimationModifier<T> modifier);
/** Get the modifiers that apply to a measurement.
* @return modifiers that apply to a measurement
* @see #addModifier(EstimationModifier)
*/
List<EstimationModifier<T>> getModifiers();
/** Get the drivers for this measurement parameters, including its modifiers parameters.
* @return drivers for this measurement parameters, including its modifiers parameters
*/
List<ParameterDriver> getParametersDrivers();
/** Get the indices of the {@link org.orekit.propagation.Propagator propagators}
* related to this measurement.
* <p>
* The propagators are indexed starting from 0 and ordered according to
* the order of the {@link org.orekit.propagation.conversion.PropagatorBuilder
* propagators builders} in the orbit determination engine used.
* </p>
* @return indices of the {@link org.orekit.propagation.Propagator propagators}
* related to this measurement
* @since 9.0
* @deprecated as of 9.3, replaced by {@link #getSatellites()}
*/
@Deprecated
List<Integer> getPropagatorsIndices();
/** Get the satellites related to this measurement.
* @return satellites related to this measurement
* @since 9.3
*/
default List<ObservableSatellite> getSatellites() {
// this default implementation is temporary for the 9.3 release,
// it will be removed when getPropagatorsIndices() is removed at 10.0
return getPropagatorsIndices().stream().map(i -> new ObservableSatellite(i)).collect(Collectors.toList());
}
/** Estimate the theoretical value of the measurement.
* <p>
* The estimated value is the <em>combination</em> of the raw estimated
* value and all the modifiers that apply to the measurement.
* </p>
* @param iteration iteration number
* @param evaluation evaluations number
* @param states orbital states at measurement date
* @return estimated measurement
*/
EstimatedMeasurement<T> estimate(int iteration, int evaluation, SpacecraftState[] states);
}