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Add a basic implementation of CheapRuler and use it across code.

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Phyks (Lucas Verney) 2018-11-20 23:27:55 +01:00
parent 997beb0e96
commit 665b7096e8
5 changed files with 59 additions and 37 deletions
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brouter-util/src/main/java/btools/util/CheapRuler.java Normal file
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package btools.util;
public final class CheapRuler {
/**
* Cheap-Ruler Java implementation
* See
* https://blog.mapbox.com/fast-geodesic-approximations-with-cheap-ruler-106f229ad016
* for more details.
*
* Original code is at https://github.com/mapbox/cheap-ruler under ISC license.
*/
static int KILOMETERS_TO_METERS = 1000;
static double ILATLNG_TO_LATLNG = 1e-6;
static double DEG_TO_RAD = Math.PI / 180.;
/*
* @param ilon1 Integer longitude for the start point. this is (longitude in degrees + 180) * 1e6.
* @param ilat1 Integer latitude for the start point, this is (latitude + 90) * 1e6.
* @param ilon2 Integer longitude for the end point, this is (longitude + 180) * 1e6.
* @param ilat2 Integer latitude for the end point, this is (latitude + 90) * 1e6.
*
* @note Integer longitude is ((longitude in degrees) + 180) * 1e6.
* Integer latitude is ((latitude in degrees) + 90) * 1e6.
*/
static public double distance(int ilon1, int ilat1, int ilon2, int ilat2) {
double lat1 = ilat1 * ILATLNG_TO_LATLNG - 90.; // Real latitude, in degrees
double cos = Math.cos(lat1 * DEG_TO_RAD);
double cos2 = 2 * cos * cos - 1;
double cos3 = 2 * cos * cos2 - cos;
double cos4 = 2 * cos * cos3 - cos2;
double cos5 = 2 * cos * cos4 - cos3;
// Multipliers for converting integer longitude and latitude into distance
// (http://1.usa.gov/1Wb1bv7)
double kx = (111.41513 * cos - 0.09455 * cos3 + 0.00012 * cos5) * ILATLNG_TO_LATLNG * KILOMETERS_TO_METERS;
double ky = (111.13209 - 0.56605 * cos2 + 0.0012 * cos4) * ILATLNG_TO_LATLNG * KILOMETERS_TO_METERS;
double dlat = (ilat1 - ilat2) * ky;
double dlon = (ilon1 - ilon2) * kx;
return Math.sqrt(dlat * dlat + dlon * dlon); // in m
}
}