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.math.geometry.path.resample;
031
032import org.openimaj.math.geometry.line.Line2d;
033import org.openimaj.math.geometry.path.Polyline;
034import org.openimaj.math.geometry.point.Point2d;
035import org.openimaj.math.util.Interpolation;
036import org.openimaj.util.function.Function;
037import org.openimaj.util.function.Operation;
038
039/**
040 * Simple linear resampling. Only the end points are guaranteed to be preserved.
041 */
042public class LinearResampler implements Function<Polyline, Polyline>, Operation<Polyline> {
043        int targetVertices;
044
045        /**
046         * Construct with the given number of target vertices for lines to have
047         *
048         * @param targetVertices
049         *            number of required vertices
050         */
051        public LinearResampler(int targetVertices) {
052                this.targetVertices = targetVertices;
053        }
054
055        @Override
056        public Polyline apply(Polyline in) {
057                final double length = in.calculateLength();
058                final double step = length / (targetVertices - 1);
059
060                final Polyline out = new Polyline();
061                out.points.add(in.begin().copy());
062
063                Point2d begin = in.points.get(0);
064                Point2d end = in.points.get(1);
065                double lastLength = Line2d.distance(begin, end);
066                double distance = lastLength;
067                double pos = step;
068                for (int i = 1, c = 1; i < targetVertices - 1; i++, pos += step) {
069                        while (pos > distance) {
070                                // move through segments until we find the correct one
071                                begin = end;
072                                c++;
073                                end = in.points.get(c);
074                                lastLength = Line2d.distance(begin, end);
075                                distance += lastLength;
076                        }
077
078                        final double offset = lastLength - (distance - pos);
079
080                        final Point2d np = begin.copy();
081                        for (int j = 0; j < 2; j++) {
082                                final double n = Interpolation.lerp(offset, 0, begin.getOrdinate(j).doubleValue(), lastLength, end
083                                                .getOrdinate(j).doubleValue());
084                                np.setOrdinate(j, n);
085                        }
086                        out.points.add(np);
087                }
088                out.points.add(in.end().copy());
089
090                return out;
091        }
092
093        /**
094         * Apply the resampling operation in-place
095         */
096        @Override
097        public void perform(Polyline object) {
098                final Polyline n = apply(object);
099                object.points = n.points;
100        }
101}