InterSensorsOptimizationProblemBuilder.java

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 * CS licenses this file to You under the Apache License, Version 2.0
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package org.orekit.rugged.adjustment;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.hipparchus.analysis.differentiation.Gradient;
import org.hipparchus.linear.Array2DRowRealMatrix;
import org.hipparchus.linear.ArrayRealVector;
import org.hipparchus.linear.RealMatrix;
import org.hipparchus.linear.RealVector;
import org.hipparchus.optim.ConvergenceChecker;
import org.hipparchus.optim.nonlinear.vector.leastsquares.LeastSquaresBuilder;
import org.hipparchus.optim.nonlinear.vector.leastsquares.LeastSquaresProblem;
import org.hipparchus.optim.nonlinear.vector.leastsquares.MultivariateJacobianFunction;
import org.hipparchus.optim.nonlinear.vector.leastsquares.ParameterValidator;
import org.hipparchus.util.Pair;
import org.orekit.rugged.adjustment.measurements.Observables;
import org.orekit.rugged.adjustment.measurements.SensorToSensorMapping;
import org.orekit.rugged.api.Rugged;
import org.orekit.rugged.errors.RuggedException;
import org.orekit.rugged.errors.RuggedMessages;
import org.orekit.rugged.linesensor.LineSensor;
import org.orekit.rugged.linesensor.SensorPixel;
import org.orekit.rugged.utils.SpacecraftToObservedBody;
import org.orekit.time.AbsoluteDate;
import org.orekit.utils.ParameterDriver;

/** Constructs the optimization problem for a list of tie points.
 * @author Guylaine Prat
 * @author Lucie Labat Allee
 * @author Jonathan Guinet
 * @author Luc Maisonobe
 * @since 2.0
 */
public class InterSensorsOptimizationProblemBuilder extends OptimizationProblemBuilder {

    /** Key for target. */
    private static final String TARGET = "Target";

    /** Key for weight. */
    private static final String WEIGHT = "Weight";

    /** List of rugged instance to refine.*/
    private Map<String, Rugged> ruggedMap;

    /** Sensor to ground mapping to generate target tab for optimization.*/
    private List<SensorToSensorMapping> sensorToSensorMappings;

    /** Targets and weights of optimization problem. */
    private HashMap<String, double[] > targetAndWeight;

    /** Constructor.
     * @param sensors list of sensors to refine
     * @param measurements set of observables
     * @param ruggedList names of rugged to refine
     */
    public InterSensorsOptimizationProblemBuilder(final List<LineSensor> sensors,
                                                  final Observables measurements, final Collection<Rugged> ruggedList) {

        super(sensors, measurements);
        this.ruggedMap = new LinkedHashMap<String, Rugged>();
        for (final Rugged rugged : ruggedList) {
            this.ruggedMap.put(rugged.getName(), rugged);
        }
        this.initMapping();
    }

    /** {@inheritDoc} */
    @Override
    protected void initMapping() {

        this.sensorToSensorMappings = new ArrayList<>();

        for (final String ruggedNameA : this.ruggedMap.keySet()) {
            for (final String ruggedNameB : this.ruggedMap.keySet()) {

                for (final LineSensor sensorA : this.getSensors()) {
                    for (final LineSensor sensorB : this.getSensors()) {

                        final String sensorNameA = sensorA.getName();
                        final String sensorNameB = sensorB.getName();
                        final SensorToSensorMapping mapping = this.getMeasurements().getInterMapping(ruggedNameA, sensorNameA, ruggedNameB, sensorNameB);

                        if (mapping != null) {
                            this.sensorToSensorMappings.add(mapping);
                        }
                    }
                }
            }
        }
    }

    /** {@inheritDoc} */
    @Override
    protected void createTargetAndWeight() {

        int n = 0;
        for (final SensorToSensorMapping reference : this.sensorToSensorMappings) {
            n += reference.getMapping().size();
        }
        if (n == 0) {
            throw new RuggedException(RuggedMessages.NO_REFERENCE_MAPPINGS);
        }

        n = 2 * n;

        final double[] target = new double[n];
        final double[] weight = new double[n];

        int k = 0;
        for (final SensorToSensorMapping reference : this.sensorToSensorMappings) {

            // Get central body constraint weight
            final double bodyConstraintWeight = reference.getBodyConstraintWeight();

            int i = 0;
            for (Iterator<Map.Entry<SensorPixel, SensorPixel>> gtIt = reference.getMapping().iterator(); gtIt.hasNext(); i++) {

                if (i == reference.getMapping().size()) {
                    break;
                }

                // Get LOS distance
                final Double losDistance  = reference.getLosDistance(i);

                weight[k] = 1.0 - bodyConstraintWeight;
                target[k++] = losDistance.doubleValue();

                // Get central body distance (constraint)
                final Double bodyDistance  = reference.getBodyDistance(i);
                weight[k] = bodyConstraintWeight;
                target[k++] = bodyDistance.doubleValue();
            }
        }

        this.targetAndWeight = new HashMap<String, double[]>();
        this.targetAndWeight.put(TARGET, target);
        this.targetAndWeight.put(WEIGHT, weight);
    }

    /** {@inheritDoc} */
    @Override
    protected MultivariateJacobianFunction createFunction() {

        // model function
        final MultivariateJacobianFunction model = point -> {

            // set the current parameters values
            int i = 0;
            for (final ParameterDriver driver : this.getDrivers()) {
                driver.setNormalizedValue(point.getEntry(i++));
            }

            final double[] target = this.targetAndWeight.get(TARGET);

            // compute distance and its partial derivatives
            final RealVector value = new ArrayRealVector(target.length);
            final RealMatrix jacobian = new Array2DRowRealMatrix(target.length, this.getNbParams());

            int l = 0;
            for (final SensorToSensorMapping reference : this.sensorToSensorMappings) {

                final String ruggedNameA = reference.getRuggedNameA();
                final String ruggedNameB = reference.getRuggedNameB();
                final Rugged ruggedA = this.ruggedMap.get(ruggedNameA);
                if (ruggedA == null) {
                    throw new RuggedException(RuggedMessages.INVALID_RUGGED_NAME);
                }

                final Rugged ruggedB = this.ruggedMap.get(ruggedNameB);
                if (ruggedB == null) {
                    throw new RuggedException(RuggedMessages.INVALID_RUGGED_NAME);
                }

                for (final Map.Entry<SensorPixel, SensorPixel> mapping : reference.getMapping()) {

                    final SensorPixel spA = mapping.getKey();
                    final SensorPixel spB = mapping.getValue();

                    final LineSensor lineSensorB = ruggedB.getLineSensor(reference.getSensorNameB());
                    final LineSensor lineSensorA = ruggedA.getLineSensor(reference.getSensorNameA());

                    final AbsoluteDate dateA = lineSensorA.getDate(spA.getLineNumber());
                    final AbsoluteDate dateB = lineSensorB.getDate(spB.getLineNumber());

                    final double pixelA = spA.getPixelNumber();
                    final double pixelB = spB.getPixelNumber();

                    final SpacecraftToObservedBody scToBodyA = ruggedA.getScToBody();

                    final Gradient[] ilResult =
                            ruggedB.distanceBetweenLOSderivatives(lineSensorA, dateA, pixelA, scToBodyA,
                                    lineSensorB, dateB, pixelB, this.getGenerator());

                    // extract the value
                    value.setEntry(l, ilResult[0].getValue());
                    value.setEntry(l + 1, ilResult[1].getValue());

                    // extract the Jacobian
                    final int[] orders = new int[this.getNbParams()];
                    int m = 0;

                    for (final ParameterDriver driver : this.getDrivers()) {
                        final double scale = driver.getScale();
                        orders[m] = 1;
                        jacobian.setEntry(l, m, ilResult[0].getPartialDerivative(orders) * scale);
                        jacobian.setEntry(l + 1, m, ilResult[1].getPartialDerivative(orders) * scale);
                        orders[m] = 0;
                        m++;
                    }

                    l += 2; // pass to the next evaluation
                }
            }

            // distance result with Jacobian for all reference points
            return new Pair<RealVector, RealMatrix>(value, jacobian);
        };

        return model;
    }


    /** Least square problem builder.
     * @param maxEvaluations maxIterations and evaluations
     * @param convergenceThreshold parameter convergence threshold
     * @return the least square problem
     */
    @Override
    public final LeastSquaresProblem build(final int maxEvaluations, final double convergenceThreshold) {

        this.createTargetAndWeight();
        final double[] target = this.targetAndWeight.get(TARGET);
        final double[] start = this.createStartTab();
        final ParameterValidator validator = this.createParameterValidator();
        final ConvergenceChecker<LeastSquaresProblem.Evaluation> checker = this.createChecker(convergenceThreshold);
        final MultivariateJacobianFunction model = this.createFunction();
        return new LeastSquaresBuilder()
                        .lazyEvaluation(false).maxIterations(maxEvaluations)
                        .maxEvaluations(maxEvaluations).weight(null).start(start)
                        .target(target).parameterValidator(validator).checker(checker)
                        .model(model).build();
    }
}