/// <summary>
/// Calculate the distance between two geographic points, taking into consideration the earth's curvature.
/// </summary>
/// <param name="first"></param>
/// <param name="second"></param>
/// <returns></returns>
public static double Distance(GeoPoint first, GeoPoint second)
{
// Use the haversine formula to calculate distance.
//var R = 6371e3; // metres
//var φ1 = lat1.toRadians();
//var φ2 = lat2.toRadians();
//var Δφ = (lat2 - lat1).toRadians();
//var Δλ = (lon2 - lon1).toRadians();
//var a = Math.sin(Δφ / 2) * Math.sin(Δφ / 2) +
// Math.cos(φ1) * Math.cos(φ2) *
// Math.sin(Δλ / 2) * Math.sin(Δλ / 2);
//var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
//var d = R * c;
var lat1 = ArgumentUtils.ToRadians(first.Latitude);
var lat2 = ArgumentUtils.ToRadians(second.Latitude);
var deltaLat = ArgumentUtils.ToRadians(second.Latitude - first.Latitude);
var deltaLon = ArgumentUtils.ToRadians(second.Longitude - first.Longitude);
var a = Math.Sin(deltaLat / 2) * Math.Sin(deltaLat / 2)
+ Math.Cos(lat1) * Math.Cos(lat2)
* Math.Sin(deltaLon / 2) * Math.Sin(deltaLon / 2);
var c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
return(ArgumentUtils.MeanEarthRadius * c);
}
public static double Bearing(GeoPoint first, GeoPoint second)
{
//var y = Math.sin(λ2 - λ1) * Math.cos(φ2);
//var x = Math.cos(φ1) * Math.sin(φ2) -
// Math.sin(φ1) * Math.cos(φ2) * Math.cos(λ2 - λ1);
//var brng = Math.atan2(y, x).toDegrees();
var deltaLat = ArgumentUtils.ToRadians(second.Latitude - first.Latitude);
var deltaLon = ArgumentUtils.ToRadians(second.Longitude - first.Longitude);
var lat1 = ArgumentUtils.ToRadians(first.Latitude);
var lat2 = ArgumentUtils.ToRadians(second.Latitude);
var y = Math.Sin(deltaLon) * Math.Cos(lat2);
var x = Math.Cos(lat1) * Math.Sin(lat2)
- Math.Sin(lat1) * Math.Cos(lat2) * Math.Cos(deltaLat);
return(ArgumentUtils.ToDegrees(Math.Atan2(y, x)));
}
private static double ToY(double latitude, int zoomLevel)
{
var zoomFactor = K * Math.Pow(2, zoomLevel);
return(zoomFactor * (Math.PI - Math.Log(Math.Tan(Math.PI / 4 + ArgumentUtils.ToRadians(latitude) / 2))));
}
private static double ToX(double longitude, int zoomLevel)
{
var zoomFactor = K * Math.Pow(2, zoomLevel);
return(zoomFactor * (ArgumentUtils.ToRadians(longitude) + Math.PI));
}