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 gnu.trove.map.hash.TObjectIntHashMap;
033import gnu.trove.procedure.TObjectIntProcedure;
034
035import java.util.ArrayList;
036import java.util.List;
037
038import org.openimaj.feature.DoubleFVComparison;
039import org.openimaj.feature.local.LocalFeature;
040import org.openimaj.util.pair.Pair;
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
062         * key.
063         */
064        protected T findMatch(T query, List<T> features)
065        {
066                double distsq = Double.MAX_VALUE;
067                T minkey = null;
068
069                // find closest match
070                for (final T target : features) {
071                        final double dsq = target.getFeatureVector().asDoubleFV()
072                                        .compare(query.getFeatureVector().asDoubleFV(), DoubleFVComparison.EUCLIDEAN);
073
074                        if (dsq < distsq) {
075                                distsq = dsq;
076                                minkey = target;
077                        }
078                }
079
080                return minkey;
081        }
082
083        @Override
084        public boolean findMatches(List<T> queryfeatures) {
085                matches = new ArrayList<Pair<T>>();
086
087                final TObjectIntHashMap<T> targets = new TObjectIntHashMap<T>();
088
089                for (final T query : queryfeatures) {
090                        final T modeltarget = findMatch(query, modelKeypoints);
091                        if (modeltarget == null)
092                                continue;
093
094                        final T querytarget = findMatch(modeltarget, queryfeatures);
095
096                        if (querytarget == query) {
097                                matches.add(new Pair<T>(query, modeltarget));
098                                targets.adjustOrPutValue(modeltarget, 1, 1);
099                        }
100                }
101
102                final ArrayList<Pair<T>> matchesToRemove = new ArrayList<Pair<T>>();
103                targets.forEachEntry(new TObjectIntProcedure<T>() {
104                        @Override
105                        public boolean execute(T a, int b) {
106                                if (b > 1) {
107                                        for (final Pair<T> p : matches) {
108                                                if (p.secondObject() == a)
109                                                        matchesToRemove.add(p);
110                                        }
111                                }
112                                return true;
113                        }
114                });
115
116                matches.removeAll(matchesToRemove);
117
118                return matches.size() > 0;
119        }
120
121        @Override
122        public List<Pair<T>> getMatches() {
123                return matches;
124        }
125}