only use half of rulers because earth is symmetric

This commit is contained in:
Huyen Chau Nguyen 2018-04-25 16:18:36 -04:00 committed by Patrick Niklaus
parent 4e68f3a7e1
commit b573485c31

View File

@ -25,20 +25,20 @@ namespace
class CheapRulerContainer {
public:
CheapRulerContainer(const int number_of_rulers)
: cheap_ruler_cache(number_of_rulers, mapbox::cheap_ruler::CheapRuler(0)), step(180. / number_of_rulers){
: cheap_ruler_cache(number_of_rulers, mapbox::cheap_ruler::CheapRuler(0)), step(90.0 / number_of_rulers) {
for (int n = 0; n < number_of_rulers; n++) {
cheap_ruler_cache[n] = mapbox::cheap_ruler::CheapRuler(-90 + step * n, mapbox::cheap_ruler::CheapRuler::Meters);
cheap_ruler_cache[n] = mapbox::cheap_ruler::CheapRuler(step * (n + 0.5), mapbox::cheap_ruler::CheapRuler::Meters);
}
};
mapbox::cheap_ruler::CheapRuler& getRuler(const double lat) {
return cheap_ruler_cache[std::min((int)std::round((lat + 90)/step), (int)cheap_ruler_cache.size() - 1)];
return cheap_ruler_cache[std::min((int)std::floor(abs(lat)/step), (int)cheap_ruler_cache.size() - 1)];
};
private:
std::vector<mapbox::cheap_ruler::CheapRuler> cheap_ruler_cache;
const double step;
};
CheapRulerContainer cheap_ruler_container(3600);
CheapRulerContainer cheap_ruler_container(1800);
}
// Does not project the coordinates!
@ -65,7 +65,7 @@ double fccApproximateDistance(const Coordinate coordinate_1, const Coordinate co
const auto lat1 = static_cast<double>(util::toFloating(coordinate_1.lat));
const auto lon2 = static_cast<double>(util::toFloating(coordinate_2.lon));
const auto lat2 = static_cast<double>(util::toFloating(coordinate_2.lat));
return cheap_ruler_container.getRuler(lat1).distance({lon1, lat1}, {lon2, lat2});
return cheap_ruler_container.getRuler(0.5*(lat1+lat2)).distance({lon1, lat1}, {lon2, lat2});
}
double haversineDistance(const Coordinate coordinate_1, const Coordinate coordinate_2)