public static Double DistanceBetweenKilometers(GeodeticCoordinate from, GeodeticCoordinate to)
{
var fromLatitudeRadians = DegreesToRadians(from.Latitude);
var toLatitudeRadians = DegreesToRadians(to.Latitude);
var deltaLongitudeRadians = DegreesToRadians(to.Longitude - from.Longitude);
var deltaLatidudeRadians = DegreesToRadians(to.Latitude - from.Latitude);
// haversine formula https://en.wikipedia.org/wiki/Haversine_formula
var distance = EarthRadiusKilometers * 2 *
Math.Asin(Math.Sqrt(
Math.Pow(Math.Sin(deltaLatidudeRadians / 2), 2) +
Math.Cos(fromLatitudeRadians) *
Math.Cos(toLatitudeRadians) *
Math.Pow(Math.Sin(deltaLongitudeRadians / 2), 2))
);
return(distance);
}
public static GeodeticCoordinate NextGeodeticCoordinate(this Random random)
{
// generate random coordinates on a sphere using Alternative Method 2 in
// http://corysimon.github.io/articles/uniformdistn-on-sphere/
while (true)
{
var uniformCartesianX = random.NextDoubleFromNegativeOneToOne();
var uniformCartesianY = random.NextDoubleFromNegativeOneToOne();
var uniformCartesianZ = random.NextDoubleFromNegativeOneToOne();
var distanceFromOrigin = DistanceFromOrigin(uniformCartesianX, uniformCartesianY, uniformCartesianZ);
var isCurrentPointOutsideUnitSphere = distanceFromOrigin > 1;
if (isCurrentPointOutsideUnitSphere)
{
continue;
}
// convert to spherical using conversions on
// https://en.wikipedia.org/wiki/Spherical_coordinate_system
var sphericalTheta = Math.Acos(uniformCartesianZ / distanceFromOrigin);
var sphericalPhi = Math.Atan2(uniformCartesianY, uniformCartesianX);
var latitude = RadiansToDegrees(sphericalTheta) - 90.0;
var longitude = RadiansToDegrees(sphericalPhi);
var result = new GeodeticCoordinate
{
Latitude = latitude,
Longitude = longitude
};
return(result);
}
}
