/// <summary>
/// Calculate the distance between two positions.
/// </summary>
public double CalculateDistance(Position position1, Position position2, DistanceUnit distanceUnit)
{
var R = (distanceUnit == DistanceUnit.Miles) ? GeoConstants.EarthRadiusInMiles : GeoConstants.EarthRadiusInKilometers;
var dLat = angleConverter.ConvertDegreesToRadians(position2.Latitude) - angleConverter.ConvertDegreesToRadians(position1.Latitude);
var dLon = angleConverter.ConvertDegreesToRadians(position2.Longitude) - angleConverter.ConvertDegreesToRadians(position1.Longitude);
var a = Math.Sin(dLat / 2) * Math.Sin(dLat / 2) + Math.Cos(angleConverter.ConvertDegreesToRadians(position1.Latitude)) * Math.Cos(angleConverter.ConvertDegreesToRadians(position2.Latitude)) * Math.Sin(dLon / 2) * Math.Sin(dLon / 2);
var c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
var distance = c * R;
return Math.Round(distance, 2);
}
/// <summary>
/// Calculate the rhumb bearing between two positions.
/// </summary>
public double CalculateRhumbBearing(Position position1, Position position2)
{
var lat1 = angleConverter.ConvertDegreesToRadians(position1.Latitude);
var lat2 = angleConverter.ConvertDegreesToRadians(position2.Latitude);
var dLon = angleConverter.ConvertDegreesToRadians(position2.Longitude - position1.Longitude);
var dPhi = Math.Log(Math.Tan(lat2 / 2 + Math.PI / 4) / Math.Tan(lat1 / 2 + Math.PI / 4));
if (Math.Abs(dLon) > Math.PI) dLon = (dLon > 0) ? -(2 * Math.PI - dLon) : (2 * Math.PI + dLon);
var brng = Math.Atan2(dLon, dPhi);
return (angleConverter.ConvertRadiansToDegrees(brng) + 360) % 360;
}
/// <summary>
/// Calculate the bearing between two positions.
/// </summary>
public double CalculateBearing(Position position1, Position position2)
{
var lat1 = angleConverter.ConvertDegreesToRadians(position1.Latitude);
var lat2 = angleConverter.ConvertDegreesToRadians(position2.Latitude);
var dLon = angleConverter.ConvertDegreesToRadians(position2.Longitude) - angleConverter.ConvertDegreesToRadians(position1.Longitude);
var y = Math.Sin(dLon) * Math.Cos(lat2);
var x = Math.Cos(lat1) * Math.Sin(lat2) - Math.Sin(lat1) * Math.Cos(lat2) * Math.Cos(dLon);
var brng = Math.Atan2(y, x);
return (angleConverter.ConvertRadiansToDegrees(brng) + 360) % 360;
}
/// <summary>
/// Calculate the rhumb distance between two positions.
/// </summary>
public double CalculateRhumbDistance(Position position1, Position position2, DistanceUnit distanceUnit)
{
var R = (distanceUnit == DistanceUnit.Miles) ? GeoConstants.EarthRadiusInMiles : GeoConstants.EarthRadiusInKilometers;
var lat1 = angleConverter.ConvertDegreesToRadians(position1.Latitude);
var lat2 = angleConverter.ConvertDegreesToRadians(position2.Latitude);
var dLat = angleConverter.ConvertDegreesToRadians(position2.Latitude - position1.Latitude);
var dLon = angleConverter.ConvertDegreesToRadians(Math.Abs(position2.Longitude - position1.Longitude));
var dPhi = Math.Log(Math.Tan(lat2 / 2 + Math.PI / 4) / Math.Tan(lat1 / 2 + Math.PI / 4));
var q = Math.Cos(lat1);
if (dPhi != 0) q = dLat / dPhi; // E-W line gives dPhi=0
// if dLon over 180° take shorter rhumb across 180° meridian:
if (dLon > Math.PI) dLon = 2 * Math.PI - dLon;
var dist = Math.Sqrt(dLat * dLat + q * q * dLon * dLon) * R;
return dist;
}
