001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.feature.local.matcher;
031
032import java.util.ArrayList;
033import java.util.List;
034
035import org.openimaj.feature.DoubleFVComparison;
036import org.openimaj.feature.local.LocalFeature;
037import org.openimaj.util.pair.Pair;
038
039import gnu.trove.map.hash.TObjectIntHashMap;
040import gnu.trove.procedure.TObjectIntProcedure;
041
042/**
043 * Matcher that uses minimum Euclidean distance to find matches. Model and
044 * object are compared both ways. Matches that are oneway are rejected, as are
045 * one->many matches.
046 *
047 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
048 *
049 * @param <T>
050 */
051public class BasicTwoWayMatcher<T extends LocalFeature<?, ?>> implements LocalFeatureMatcher<T> {
052        protected List<T> modelKeypoints;
053        protected List<Pair<T>> matches;
054
055        @Override
056        public void setModelFeatures(List<T> modelkeys) {
057                this.modelKeypoints = modelkeys;
058        }
059
060        /**
061         * This searches through the keypoints in klist for the closest match to key.
062         */
063        protected T findMatch(T query, List<T> features) {
064                double distsq = Double.MAX_VALUE;
065                T minkey = null;
066
067                // find closest match
068                for (final T target : features) {
069                        final double dsq = target.getFeatureVector().asDoubleFV()
070                                        .compare(query.getFeatureVector().asDoubleFV(), DoubleFVComparison.SUM_SQUARE);
071
072                        if (dsq < distsq) {
073                                distsq = dsq;
074                                minkey = target;
075                        }
076                }
077
078                return minkey;
079        }
080
081        @Override
082        public boolean findMatches(List<T> queryfeatures) {
083                matches = new ArrayList<Pair<T>>();
084
085                final TObjectIntHashMap<T> targets = new TObjectIntHashMap<T>();
086
087                for (final T query : queryfeatures) {
088                        final T modeltarget = findMatch(query, modelKeypoints);
089                        if (modeltarget == null)
090                                continue;
091
092                        final T querytarget = findMatch(modeltarget, queryfeatures);
093
094                        if (querytarget == query) {
095                                matches.add(new Pair<T>(query, modeltarget));
096                                targets.adjustOrPutValue(modeltarget, 1, 1);
097                        }
098                }
099
100                final ArrayList<Pair<T>> matchesToRemove = new ArrayList<Pair<T>>();
101                targets.forEachEntry(new TObjectIntProcedure<T>() {
102                        @Override
103                        public boolean execute(T a, int b) {
104                                if (b > 1) {
105                                        for (final Pair<T> p : matches) {
106                                                if (p.secondObject() == a)
107                                                        matchesToRemove.add(p);
108                                        }
109                                }
110                                return true;
111                        }
112                });
113
114                matches.removeAll(matchesToRemove);
115
116                return matches.size() > 0;
117        }
118
119        @Override
120        public List<Pair<T>> getMatches() {
121                return matches;
122        }
123}