/// <summary>
/// Convert a position in space to a latitude and longitude.
/// </summary>
/// <param name="relativeToOrigin">A position marking the latitude and longitude of (0,0).</param>
/// <param name="location">The position to convert to latitude and longitude.</param>
/// <returns>A position indicating the latitude and longitude of the location.</returns>
public static Position MetersToLatLon(Position relativeToOrigin, Vector3 location)
{
var phi = Units.DegreesToRadians(relativeToOrigin.Latitude);
var locationX = location.X / Math.Cos(phi);
var locationY = location.Y / Math.Cos(phi);
var lon = XToLon(locationX) + relativeToOrigin.Longitude;
var lat = YToLat(locationY) + relativeToOrigin.Latitude;
return(new Position(lat, lon));
}
/// <summary>
/// Convert Latitude and Longitude to meters relative to a base position.
/// </summary>
/// <param name="relativeToOrigin">A position marking the latitude and longitude of (0,0)</param>
/// <param name="lat">The latitude in degrees</param>
/// <param name="lon">The longitude in degrees</param>
/// <returns>A Vector3 in meters specifying the offset from the origin for this location.</returns>
public static Vector3 LatLonToMeters(Position relativeToOrigin, double lat, double lon)
{
var originX = LonToX(relativeToOrigin.Longitude);
var originY = LatToY(relativeToOrigin.Latitude);
var phi = Units.DegreesToRadians(relativeToOrigin.Latitude);
var x = (LonToX(lon) - originX) * Math.Cos(phi);
var y = (LatToY(lat) - originY) * Math.Cos(phi);
return(new Vector3(x, y));
}
/// <summary>
/// Get the y coordinate, in the Mercator projection, of the specified latitude.
/// The units will be in meters at the equator, and distorted elsewhere. Utilize LatLonToMeters() for a conversion
/// relative to a basepoint.
/// </summary>
/// <param name="lat">The latitude to convert, within the range [-89.5, 89.5]. Values outside this range will be clamped.</param>
/// <returns></returns>
public static double LatToY(double lat)
{
lat = Math.Min(89.5, Math.Max(lat, -89.5));
double phi = Units.DegreesToRadians(lat);
double sinphi = Math.Sin(phi);
double con = ECCENT * sinphi;
con = Math.Pow(((1.0 - con) / (1.0 + con)), COM);
double ts = Math.Tan(0.5 * ((Math.PI * 0.5) - phi)) / con;
return(0 - R_MAJOR * Math.Log(ts));
}
/// <summary>
/// Get the tile size, in meters.
/// </summary>
/// <param name="lat">The latitude of the tile, in degrees.</param>
/// <param name="zoom">The zoom level of the tile.</param>
public static double GetTileSizeMeters(double lat, int zoom)
{
// Circumference of the earth * cos(latitude) divided by 2^zoom
return((2 * Math.PI * EARTH_RADIUS * Math.Cos(Units.DegreesToRadians(lat))) / Math.Pow(2, zoom));
}
/// <summary>
/// Get the x coordinate, in the Mercator projection, of the specified longitude.
/// The units will be in meters at the equator, and distorted elsewhere. Utilize LatLonToMeters() for a conversion
/// relative to a basepoint.
/// </summary>
/// <param name="lon"></param>
/// <returns></returns>
public static double LonToX(double lon)
{
return(R_MAJOR * Units.DegreesToRadians(lon));
}
