Convert from Longitude/Latitude (4326) to 3857 (Spherical Mercator)

convert_4326_3857

public static double[] ToSphericalMercatorFromWgs84(double Longitude, double Latitude)
{
    var x = Longitude * 20037508.34 / 180;
    var y = Math.Log(Math.Tan((90 + Latitude) * Math.PI / 360)) / (Math.PI / 180);
    y = y * 20037508.34 / 180;
    return new double[] { x, y };
}

public static double[] ToWgs84FromSphericalMercator(double x, double y)
{
    var lon = x * 180 / 20037508.34;
    var lat = Math.Atan(Math.Exp(y * Math.PI / 20037508.34)) * 360 / Math.PI - 90;
    return new double[] { lon, lat };
}