RANSACMetricTransformation2DRobustEstimator

/*
 * Copyright (C) 2017 Alberto Irurueta Carro (alberto@irurueta.com)
 *
 * Licensed 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 com.irurueta.geometry.estimators;

import com.irurueta.geometry.CoordinatesType;
import com.irurueta.geometry.MetricTransformation2D;
import com.irurueta.geometry.Point2D;
import com.irurueta.numerical.robust.RANSACRobustEstimator;
import com.irurueta.numerical.robust.RANSACRobustEstimatorListener;
import com.irurueta.numerical.robust.RobustEstimator;
import com.irurueta.numerical.robust.RobustEstimatorException;
import com.irurueta.numerical.robust.RobustEstimatorMethod;

import java.util.ArrayList;
import java.util.List;

/**
 * Finds the best metric 2D transformation for provided collections of
 * matched 2D points using RANSAC algorithm.
 */
public class RANSACMetricTransformation2DRobustEstimator extends MetricTransformation2DRobustEstimator {

    /**
     * Constant defining default threshold to determine whether points are
     * inliers or not.
     * By default, 1.0 is considered a good value for cases where measures are
     * done on pixels, since typically the minimum resolution is 1 pixel.
     */
    public static final double DEFAULT_THRESHOLD = 1.0;

    /**
     * Minimum value that can be set as threshold.
     * Threshold must be strictly greater than 0.0.
     */
    public static final double MIN_THRESHOLD = 0.0;

    /**
     * Indicates that by default inliers will only be computed but not kept.
     */
    public static final boolean DEFAULT_COMPUTE_AND_KEEP_INLIERS = false;

    /**
     * Indicates that by default residuals will only be computed but not kept.
     */
    public static final boolean DEFAULT_COMPUTE_AND_KEEP_RESIDUALS = false;

    /**
     * Threshold to determine whether points are inliers or not when testing
     * possible estimation solutions.
     * The threshold refers to the amount of error (i.e. distance) a possible
     * solution has on a matched pair of points.
     */
    private double threshold;

    /**
     * Indicates whether inliers must be computed and kept.
     */
    private boolean computeAndKeepInliers;

    /**
     * Indicates whether residuals must be computed and kept.
     */
    private boolean computeAndKeepResiduals;

    /**
     * Constructor.
     */
    public RANSACMetricTransformation2DRobustEstimator() {
        super();
        threshold = DEFAULT_THRESHOLD;
        computeAndKeepInliers = DEFAULT_COMPUTE_AND_KEEP_INLIERS;
        computeAndKeepResiduals = DEFAULT_COMPUTE_AND_KEEP_RESIDUALS;
    }

    /**
     * Constructor with lists of points to be used to estimate a metric 2D
     * transformation.
     * Points in the list located at the same position are considered to be
     * matched. Hence, both lists must have the same size, and their size must
     * be greater or equal than MINIMUM_SIZE.
     *
     * @param inputPoints  list of input points to be used to estimate a
     *                     metric 2D transformation.
     * @param outputPoints list of output points to be used to estimate a
     *                     metric 2D transformation.
     * @throws IllegalArgumentException if provided lists of points don't have
     *                                  the same size or their size is smaller than MINIMUM_SIZE.
     */
    public RANSACMetricTransformation2DRobustEstimator(
            final List<Point2D> inputPoints, final List<Point2D> outputPoints) {
        super(inputPoints, outputPoints);
        threshold = DEFAULT_THRESHOLD;
        computeAndKeepInliers = DEFAULT_COMPUTE_AND_KEEP_INLIERS;
        computeAndKeepResiduals = DEFAULT_COMPUTE_AND_KEEP_RESIDUALS;
    }

    /**
     * Constructor.
     *
     * @param listener listener to be notified of events such as when estimation
     *                 starts, ends or its progress significantly changes.
     */
    public RANSACMetricTransformation2DRobustEstimator(final MetricTransformation2DRobustEstimatorListener listener) {
        super(listener);
        threshold = DEFAULT_THRESHOLD;
        computeAndKeepInliers = DEFAULT_COMPUTE_AND_KEEP_INLIERS;
        computeAndKeepResiduals = DEFAULT_COMPUTE_AND_KEEP_RESIDUALS;
    }

    /**
     * Constructor with listener and lists of points to be used to estimate a
     * metric 2D transformation.
     * Points in the list located at the same position are considered to be
     * matched. Hence, both lists must have the same size, and their size must
     * be greater or equal than MINIMUM_SIZE.
     *
     * @param listener     listener to be notified of events such as when estimation
     *                     starts, ends or its progress significantly changes.
     * @param inputPoints  list of input points to be used to estimate a
     *                     metric 2D transformation.
     * @param outputPoints list of output points to be used to estimate a
     *                     metric 2D transformation.
     * @throws IllegalArgumentException if provided lists of points don't have
     *                                  the same size or their size is smaller than MINIMUM_SIZE.
     */
    public RANSACMetricTransformation2DRobustEstimator(
            final MetricTransformation2DRobustEstimatorListener listener,
            final List<Point2D> inputPoints, final List<Point2D> outputPoints) {
        super(listener, inputPoints, outputPoints);
        threshold = DEFAULT_THRESHOLD;
        computeAndKeepInliers = DEFAULT_COMPUTE_AND_KEEP_INLIERS;
        computeAndKeepResiduals = DEFAULT_COMPUTE_AND_KEEP_RESIDUALS;
    }

    /**
     * Constructor.
     *
     * @param weakMinimumSizeAllowed true allows 2 points, false requires 3.
     */
    public RANSACMetricTransformation2DRobustEstimator(final boolean weakMinimumSizeAllowed) {
        super(weakMinimumSizeAllowed);
        threshold = DEFAULT_THRESHOLD;
        computeAndKeepInliers = DEFAULT_COMPUTE_AND_KEEP_INLIERS;
        computeAndKeepResiduals = DEFAULT_COMPUTE_AND_KEEP_RESIDUALS;
    }

    /**
     * Constructor with lists of points to be used to estimate a metric 2D
     * transformation.
     * Points in the list located at the same position are considered to be
     * matched. Hence, both lists must have the same size, and their size must
     * be greater or equal than MINIMUM_SIZE.
     *
     * @param inputPoints            list of input points to be used to estimate a
     *                               metric 2D transformation.
     * @param outputPoints           list of output points to be used to estimate a
     *                               metric 2D transformation.
     * @param weakMinimumSizeAllowed true allows 2 points, false requires 3.
     * @throws IllegalArgumentException if provided lists of points don't have
     *                                  the same size or their size is smaller than MINIMUM_SIZE.
     */
    public RANSACMetricTransformation2DRobustEstimator(
            final List<Point2D> inputPoints, final List<Point2D> outputPoints, final boolean weakMinimumSizeAllowed) {
        super(inputPoints, outputPoints, weakMinimumSizeAllowed);
        threshold = DEFAULT_THRESHOLD;
        computeAndKeepInliers = DEFAULT_COMPUTE_AND_KEEP_INLIERS;
        computeAndKeepResiduals = DEFAULT_COMPUTE_AND_KEEP_RESIDUALS;
    }

    /**
     * Constructor.
     *
     * @param listener               listener to be notified of events such as when estimation
     *                               starts, ends or its progress significantly changes.
     * @param weakMinimumSizeAllowed true allows 2 points, false requires 3.
     */
    public RANSACMetricTransformation2DRobustEstimator(
            final MetricTransformation2DRobustEstimatorListener listener, final boolean weakMinimumSizeAllowed) {
        super(listener, weakMinimumSizeAllowed);
        threshold = DEFAULT_THRESHOLD;
        computeAndKeepInliers = DEFAULT_COMPUTE_AND_KEEP_INLIERS;
        computeAndKeepResiduals = DEFAULT_COMPUTE_AND_KEEP_RESIDUALS;
    }

    /**
     * Constructor with listener and lists of points to be used to estimate a
     * metric 2D transformation.
     * Points in the list located at the same position are considered to be
     * matched. Hence, both lists must have the same size, and their size must
     * be greater or equal than MINIMUM_SIZE.
     *
     * @param listener               listener to be notified of events such as when estimation
     *                               starts, ends or its progress significantly changes.
     * @param inputPoints            list of input points to be used to estimate a
     *                               metric 2D transformation.
     * @param outputPoints           list of output points to be used to estimate a
     *                               metric 2D transformation.
     * @param weakMinimumSizeAllowed true allows 2 points, false requires 3.
     * @throws IllegalArgumentException if provided lists of points don't have
     *                                  the same size or their size is smaller than MINIMUM_SIZE.
     */
    public RANSACMetricTransformation2DRobustEstimator(
            final MetricTransformation2DRobustEstimatorListener listener,
            final List<Point2D> inputPoints, final List<Point2D> outputPoints, final boolean weakMinimumSizeAllowed) {
        super(listener, inputPoints, outputPoints, weakMinimumSizeAllowed);
        threshold = DEFAULT_THRESHOLD;
        computeAndKeepInliers = DEFAULT_COMPUTE_AND_KEEP_INLIERS;
        computeAndKeepResiduals = DEFAULT_COMPUTE_AND_KEEP_RESIDUALS;
    }

    /**
     * Returns threshold to determine whether points are inliers or not when
     * testing possible estimation solutions.
     * The threshold refers to the amount of error (i.e. Euclidean distance) a
     * possible solution has on a matched pair of points.
     *
     * @return threshold to determine whether points are inliers or not when
     * testing possible estimation solutions.
     */
    public double getThreshold() {
        return threshold;
    }

    /**
     * Sets threshold to determine whether points are inliers or not when
     * testing possible estimation solutions.
     * The threshold refers to the amount of error (i.e. Euclidean distance) a
     * possible solution has on a matched pair of points.
     *
     * @param threshold threshold to be set.
     * @throws IllegalArgumentException if provided value is equal or less than
     *                                  zero.
     * @throws LockedException          if robust estimator is locked because an
     *                                  estimation is already in progress.
     */
    public void setThreshold(final double threshold) throws LockedException {
        if (isLocked()) {
            throw new LockedException();
        }
        if (threshold <= MIN_THRESHOLD) {
            throw new IllegalArgumentException();
        }
        this.threshold = threshold;
    }

    /**
     * Indicates whether inliers must be computed and kept.
     *
     * @return true if inliers must be computed and kept, false if inliers only
     * need to be computed but not kept.
     */
    public boolean isComputeAndKeepInliersEnabled() {
        return computeAndKeepInliers;
    }

    /**
     * Specifies whether inliers must be computed and kept.
     *
     * @param computeAndKeepInliers true if inliers must be computed and kept,
     *                              false if inliers only need to be computed but not kept.
     * @throws LockedException if estimator is locked.
     */
    public void setComputeAndKeepInliersEnabled(final boolean computeAndKeepInliers) throws LockedException {
        if (isLocked()) {
            throw new LockedException();
        }
        this.computeAndKeepInliers = computeAndKeepInliers;
    }

    /**
     * Indicates whether residuals must be computed and kept.
     *
     * @return true if residuals must be computed and kept, false if residuals
     * only need to be computed but not kept.
     */
    public boolean isComputeAndKeepResidualsEnabled() {
        return computeAndKeepResiduals;
    }

    /**
     * Specifies whether residuals must be computed and kept.
     *
     * @param computeAndKeepResiduals true if residuals must be computed and
     *                                kept, false if residuals only need to be computed but not kept.
     * @throws LockedException if estimator is locked.
     */
    public void setComputeAndKeepResidualsEnabled(final boolean computeAndKeepResiduals) throws LockedException {
        if (isLocked()) {
            throw new LockedException();
        }
        this.computeAndKeepResiduals = computeAndKeepResiduals;
    }

    /**
     * Estimates a metric 2D transformation using a robust estimator and
     * the best set of matched 2D point correspondences found using the robust
     * estimator.
     *
     * @return a metric 2D transformation.
     * @throws LockedException          if robust estimator is locked because an
     *                                  estimation is already in progress.
     * @throws NotReadyException        if provided input data is not enough to start
     *                                  the estimation.
     * @throws RobustEstimatorException if estimation fails for any reason
     *                                  (i.e. numerical instability, no solution available, etc).
     */
    @SuppressWarnings("DuplicatedCode")
    @Override
    public MetricTransformation2D estimate() throws LockedException, NotReadyException, RobustEstimatorException {
        if (isLocked()) {
            throw new LockedException();
        }
        if (!isReady()) {
            throw new NotReadyException();
        }

        final var innerEstimator = new RANSACRobustEstimator<>(
                new RANSACRobustEstimatorListener<MetricTransformation2D>() {

                    // point to be reused when computing residuals
                    private final Point2D testPoint = Point2D.create(CoordinatesType.HOMOGENEOUS_COORDINATES);

                    private final MetricTransformation2DEstimator nonRobustEstimator =
                            new MetricTransformation2DEstimator(isWeakMinimumSizeAllowed());

                    private final List<Point2D> subsetInputPoints = new ArrayList<>();
                    private final List<Point2D> subsetOutputPoints = new ArrayList<>();

                    @Override
                    public double getThreshold() {
                        return threshold;
                    }

                    @Override
                    public int getTotalSamples() {
                        return inputPoints.size();
                    }

                    @Override
                    public int getSubsetSize() {
                        return nonRobustEstimator.getMinimumPoints();
                    }

                    @Override
                    public void estimatePreliminarSolutions(
                            final int[] samplesIndices, final List<MetricTransformation2D> solutions) {
                        subsetInputPoints.clear();
                        subsetOutputPoints.clear();
                        for (final var samplesIndex : samplesIndices) {
                            subsetInputPoints.add(inputPoints.get(samplesIndex));
                            subsetOutputPoints.add(outputPoints.get(samplesIndex));
                        }

                        try {
                            nonRobustEstimator.setPoints(subsetInputPoints, subsetOutputPoints);
                            solutions.add(nonRobustEstimator.estimate());
                        } catch (final Exception e) {
                            // if points are coincident, no solution is added
                        }
                    }

                    @Override
                    public double computeResidual(final MetricTransformation2D currentEstimation, final int i) {
                        final var inputPoint = inputPoints.get(i);
                        final var outputPoint = outputPoints.get(i);

                        // transform input point and store result in mTestPoint
                        currentEstimation.transform(inputPoint, testPoint);

                        return outputPoint.distanceTo(testPoint);
                    }

                    @Override
                    public boolean isReady() {
                        return RANSACMetricTransformation2DRobustEstimator.this.isReady();
                    }

                    @Override
                    public void onEstimateStart(final RobustEstimator<MetricTransformation2D> estimator) {
                        if (listener != null) {
                            listener.onEstimateStart(RANSACMetricTransformation2DRobustEstimator.this);
                        }
                    }

                    @Override
                    public void onEstimateEnd(final RobustEstimator<MetricTransformation2D> estimator) {
                        if (listener != null) {
                            listener.onEstimateEnd(RANSACMetricTransformation2DRobustEstimator.this);
                        }
                    }

                    @Override
                    public void onEstimateNextIteration(
                            final RobustEstimator<MetricTransformation2D> estimator, final int iteration) {
                        if (listener != null) {
                            listener.onEstimateNextIteration(
                                    RANSACMetricTransformation2DRobustEstimator.this, iteration);
                        }
                    }

                    @Override
                    public void onEstimateProgressChange(
                            final RobustEstimator<MetricTransformation2D> estimator, final float progress) {
                        if (listener != null) {
                            listener.onEstimateProgressChange(
                                    RANSACMetricTransformation2DRobustEstimator.this, progress);
                        }
                    }
                });

        try {
            locked = true;
            inliersData = null;
            innerEstimator.setComputeAndKeepInliersEnabled(computeAndKeepInliers || refineResult);
            innerEstimator.setComputeAndKeepResidualsEnabled(computeAndKeepResiduals || refineResult);
            innerEstimator.setConfidence(confidence);
            innerEstimator.setMaxIterations(maxIterations);
            innerEstimator.setProgressDelta(progressDelta);
            final var transformation = innerEstimator.estimate();
            inliersData = innerEstimator.getInliersData();
            return attemptRefine(transformation);
        } catch (final com.irurueta.numerical.LockedException e) {
            throw new LockedException(e);
        } catch (final com.irurueta.numerical.NotReadyException e) {
            throw new NotReadyException(e);
        } finally {
            locked = false;
        }
    }

    /**
     * Returns method being used for robust estimation.
     *
     * @return method being used for robust estimation.
     */
    @Override
    public RobustEstimatorMethod getMethod() {
        return RobustEstimatorMethod.RANSAC;
    }

    /**
     * Gets standard deviation used for Levenberg-Marquardt fitting during
     * refinement.
     * Returned value gives an indication of how much variance each residual
     * has.
     * Typically, this value is related to the threshold used on each robust
     * estimation, since residuals of found inliers are within the range of
     * such threshold.
     *
     * @return standard deviation used for refinement.
     */
    @Override
    protected double getRefinementStandardDeviation() {
        return threshold;
    }
}