org.footware.server.gpx.model.GPSHelperFunctions.java Source code

Introduction

Here is the source code for org.footware.server.gpx.model.GPSHelperFunctions.java

Source

/*
 * Copyright 2010 Andreas Brauchli, Ren Buffat, Florian Widmer
 *
 * 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 org.footware.server.gpx.model;

import org.joda.time.DateTime;
import org.joda.time.Period;

public class GPSHelperFunctions {

    private static int EARTHRADIUS = 6371000;

    /**
     * returns the distance in meter between two points approximated by the haversine
     * formula.
     * 
     * @param startPoint
     *            the start point to calculate the distance from
     * @param endPoint
     *            the end point to calculate the distance to
     * @return
     */
    public static double getDistance(GPXTrackPoint startPoint, GPXTrackPoint endPoint) {
        double lat1 = startPoint.getLatitude().doubleValue();
        double lat2 = endPoint.getLatitude().doubleValue();
        double lon1 = startPoint.getLongitude().doubleValue();
        double lon2 = endPoint.getLongitude().doubleValue();
        double dLat = Math.toRadians(lat2 - lat1);
        double dLon = Math.toRadians(lon2 - lon1);
        double a = Math.sin(dLat / 2) * Math.sin(dLat / 2) + Math.cos(Math.toRadians(lat1))
                * Math.cos(Math.toRadians(lat2)) * Math.sin(dLon / 2) * Math.sin(dLon / 2);
        double c = 2 * Math.asin(Math.sqrt(a));
        return EARTHRADIUS * c;
    }

    public static Period getTimeDifference(GPXTrackPoint startPoint, GPXTrackPoint endPoint) {
        DateTime startTime = startPoint.getTime();
        DateTime endTime = endPoint.getTime();
        return new Period(startTime, endTime);
    }

    /**
     * Return the speed in m/s 
     * @param startPoint the start point
     * @param endPoint the end point
     * @return
     */
    public static double getSpeed(GPXTrackPoint startPoint, GPXTrackPoint endPoint) {
        double distance = getDistance(startPoint, endPoint);
        Period time = getTimeDifference(startPoint, endPoint);
        return distance / time.getSeconds();
    }

}