MSACLineCorrespondenceProjectiveTransformation2DRobustEstimator.java
/*
* Copyright (C) 2015 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.algebra.AlgebraException;
import com.irurueta.geometry.CoincidentLinesException;
import com.irurueta.geometry.Line2D;
import com.irurueta.geometry.ProjectiveTransformation2D;
import com.irurueta.numerical.robust.MSACRobustEstimator;
import com.irurueta.numerical.robust.MSACRobustEstimatorListener;
import com.irurueta.numerical.robust.RobustEstimator;
import com.irurueta.numerical.robust.RobustEstimatorException;
import com.irurueta.numerical.robust.RobustEstimatorMethod;
import java.util.List;
/**
* Finds the best projective 2D transformation for provided collections of matched
* 2D lines using MSAC algorithm.
*/
@SuppressWarnings("DuplicatedCode")
public class MSACLineCorrespondenceProjectiveTransformation2DRobustEstimator
extends LineCorrespondenceProjectiveTransformation2DRobustEstimator {
/**
* Constant defining default threshold to determine whether lines are
* inliers or not.
* Residuals to determine whether lines are inliers or not are computed by
* comparing two lines algebraically (e.g. doing the dot product of their
* parameters).
* A residual of 0 indicates that dot product was 1 or -1 and lines were
* equal.
* A residual of 1 indicates that dot product was 0 and lines were
* orthogonal.
* If dot product between lines is -1, then although their director vectors
* are opposed, lines are considered equal, since sign changes are not taken
* into account and their residuals will be 0.
*/
public static final double DEFAULT_THRESHOLD = 1e-6;
/**
* Minimum value that can be set as threshold.
* Threshold must be strictly greater than 0.0.
*/
public static final double MIN_THRESHOLD = 0.0;
/**
* Threshold to determine whether lines are inliers or not when testing
* possible estimation solutions.
* The threshold refers to the amount of error (i.e. distance and director
* vector angle difference) a possible solution has on a matched pair of
* lines.
*/
private double threshold;
/**
* Constructor.
*/
public MSACLineCorrespondenceProjectiveTransformation2DRobustEstimator() {
super();
threshold = DEFAULT_THRESHOLD;
}
/**
* Constructor with lists of lines to be used to estimate a projective 2D
* transformation.
* Lines 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 inputLines list of input lines to be used to estimate a projective
* 2D transformation.
* @param outputLines list of output lines to be used to estimate a
* projective 2D transformation.
* @throws IllegalArgumentException if provided lists of lines don't have
* the same size or their size is smaller than MINIMUM_SIZE.
*/
public MSACLineCorrespondenceProjectiveTransformation2DRobustEstimator(
final List<Line2D> inputLines, final List<Line2D> outputLines) {
super(inputLines, outputLines);
threshold = DEFAULT_THRESHOLD;
}
/**
* Constructor.
*
* @param listener listener to be notified of events such as when estimation
* starts, ends or its progress significantly changes.
*/
public MSACLineCorrespondenceProjectiveTransformation2DRobustEstimator(
final ProjectiveTransformation2DRobustEstimatorListener listener) {
super(listener);
threshold = DEFAULT_THRESHOLD;
}
/**
* Constructor with listener and lists of lines to be used to estimate a
* projective 2D transformation.
* Lines 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 inputLines list of input lines to be used to estimate a projective
* 2D transformation.
* @param outputLines list of output lines to be used to estimate a
* projective 2D transformation.
* @throws IllegalArgumentException if provided lists of lines don't have
* the same size or their size is smaller than MINIMUM_SIZE.
*/
public MSACLineCorrespondenceProjectiveTransformation2DRobustEstimator(
final ProjectiveTransformation2DRobustEstimatorListener listener,
final List<Line2D> inputLines, final List<Line2D> outputLines) {
super(listener, inputLines, outputLines);
threshold = DEFAULT_THRESHOLD;
}
/**
* Returns threshold to determine whether lines are inliers or not when
* testing possible estimation solutions.
* Residuals to determine whether lines are inliers or not are computed by
* comparing two lines algebraically (e.g. doing the dot product of their
* parameters).
* A residual of 0 indicates that dot product was 1 or -1 and lines were
* equal.
* A residual of 1 indicates that dot product was 0 and lines were
* orthogonal.
* If dot product between lines is -1, then although their director vectors
* are opposed, lines are considered equal, since sign changes are not taken
* into account and their residuals will be 0.
*
* @return threshold to determine whether matched lines are inliers or not.
*/
public double getThreshold() {
return threshold;
}
/**
* Sets threshold to determine whether lines are inliers or not when
* testing possible estimation solutions.
* Residuals to determine whether lines are inliers or not are computed by
* comparing two lines algebraically (e.g. doing the dot product of their
* parameters).
* A residual of 0 indicates that dot product was 1 or -1 and lines were
* equal.
* A residual of 1 indicates that dot product was 0 and lines were
* orthogonal.
* If dot product between lines is -1, then although their director vectors
* are opposed, lines are considered equal, since sign changes are not taken
* into account and their residuals will be 0.
*
* @param threshold threshold to determine whether matched lines are inliers
* or not.
* @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;
}
/**
* Estimates a projective 2D transformation using a robust estimator and
* the best set of matched 2D lines correspondences found using the robust
* estimator.
*
* @return a projective 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).
*/
@Override
public ProjectiveTransformation2D estimate() throws LockedException, NotReadyException, RobustEstimatorException {
if (isLocked()) {
throw new LockedException();
}
if (!isReady()) {
throw new NotReadyException();
}
final var innerEstimator = new MSACRobustEstimator<>(
new MSACRobustEstimatorListener<ProjectiveTransformation2D>() {
// line to be reused when computing residuals
private final Line2D testLine = new Line2D();
@Override
public double getThreshold() {
return threshold;
}
@Override
public int getTotalSamples() {
return inputLines.size();
}
@Override
public int getSubsetSize() {
return ProjectiveTransformation2DRobustEstimator.MINIMUM_SIZE;
}
@Override
public void estimatePreliminarSolutions(
final int[] samplesIndices, final List<ProjectiveTransformation2D> solutions) {
final var inputLine1 = inputLines.get(samplesIndices[0]);
final var inputLine2 = inputLines.get(samplesIndices[1]);
final var inputLine3 = inputLines.get(samplesIndices[2]);
final var inputLine4 = inputLines.get(samplesIndices[3]);
final var outputLine1 = outputLines.get(samplesIndices[0]);
final var outputLine2 = outputLines.get(samplesIndices[1]);
final var outputLine3 = outputLines.get(samplesIndices[2]);
final var outputLine4 = outputLines.get(samplesIndices[3]);
try {
final var transformation = new ProjectiveTransformation2D(inputLine1, inputLine2,
inputLine3, inputLine4, outputLine1, outputLine2, outputLine3, outputLine4);
solutions.add(transformation);
} catch (final CoincidentLinesException e) {
// if lines are coincident, no solution is added
}
}
@Override
public double computeResidual(final ProjectiveTransformation2D currentEstimation, final int i) {
final var inputLine = inputLines.get(i);
final var outputLine = outputLines.get(i);
// transform input line and store result in mTestLine
try {
currentEstimation.transform(inputLine, testLine);
return getResidual(outputLine, testLine);
} catch (final AlgebraException e) {
// this happens when internal matrix of affine transformation
// cannot be reverse (i.e. transformation is not well-defined,
// numerical instabilities, etc.)
return Double.MAX_VALUE;
}
}
@Override
public boolean isReady() {
return MSACLineCorrespondenceProjectiveTransformation2DRobustEstimator.this.isReady();
}
@Override
public void onEstimateStart(final RobustEstimator<ProjectiveTransformation2D> estimator) {
if (listener != null) {
listener.onEstimateStart(
MSACLineCorrespondenceProjectiveTransformation2DRobustEstimator.this);
}
}
@Override
public void onEstimateEnd(final RobustEstimator<ProjectiveTransformation2D> estimator) {
if (listener != null) {
listener.onEstimateEnd(
MSACLineCorrespondenceProjectiveTransformation2DRobustEstimator.this);
}
}
@Override
public void onEstimateNextIteration(
final RobustEstimator<ProjectiveTransformation2D> estimator, final int iteration) {
if (listener != null) {
listener.onEstimateNextIteration(
MSACLineCorrespondenceProjectiveTransformation2DRobustEstimator.this,
iteration);
}
}
@Override
public void onEstimateProgressChange(
final RobustEstimator<ProjectiveTransformation2D> estimator, final float progress) {
if (listener != null) {
listener.onEstimateProgressChange(
MSACLineCorrespondenceProjectiveTransformation2DRobustEstimator.this,
progress);
}
}
});
try {
locked = true;
inliersData = null;
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.MSAC;
}
/**
* 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;
}
}