ClemensFischer/XAML-Map-Control
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Updated projections

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ClemensFischer 2026-01-13 23:24:48 +01:00
parent da3a9a18fb
commit 91dfeee19c
6 changed files with 49 additions and 43 deletions
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41
MapControl/Shared/WorldMercatorProjection.cs
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@ -30,9 +30,7 @@ namespace MapControl
public override Point RelativeScale(double latitude, double longitude)
{
var lat = latitude * Math.PI / 180d;
var eSinLat = Wgs84Eccentricity * Math.Sin(lat);
var k = Math.Sqrt(1d - eSinLat * eSinLat) / Math.Cos(lat); // p.44 (7-8)
var k = ScaleFactor(latitude);
return new Point(k, k);
}
@ -51,6 +49,14 @@ namespace MapControl
x / Wgs84MeterPerDegree);
}
public static double ScaleFactor(double latitude)
{
var phi = latitude * Math.PI / 180d;
var eSinPhi = Wgs84Eccentricity * Math.Sin(phi);
return Math.Sqrt(1d - eSinPhi * eSinPhi) / Math.Cos(phi); // p.44 (7-8)
}
public static double LatitudeToY(double latitude)
{
if (latitude <= -90d)
@ -63,11 +69,11 @@ namespace MapControl
return double.PositiveInfinity;
}
var lat = latitude * Math.PI / 180d;
var eSinLat = Wgs84Eccentricity * Math.Sin(lat);
var f = Math.Pow((1d - eSinLat) / (1d + eSinLat), Wgs84Eccentricity / 2d);
var phi = latitude * Math.PI / 180d;
var eSinPhi = Wgs84Eccentricity * Math.Sin(phi);
var f = Math.Pow((1d - eSinPhi) / (1d + eSinPhi), Wgs84Eccentricity / 2d);
return Math.Log(Math.Tan(lat / 2d + Math.PI / 4d) * f) * 180d / Math.PI; // p.44 (7-7)
return Math.Log(Math.Tan(phi / 2d + Math.PI / 4d) * f) * 180d / Math.PI; // p.44 (7-7)
}
public static double YToLatitude(double y)
@ -79,18 +85,17 @@ namespace MapControl
internal static double ApproximateLatitude(double e, double t)
{
var e_2 = e * e;
var e_4 = e_2 * e_2;
var e_6 = e_2 * e_4;
var e_8 = e_2 * e_6;
var e2 = e * e;
var e4 = e2 * e2;
var e6 = e2 * e4;
var e8 = e2 * e6;
var chi = Math.PI / 2d - 2d * Math.Atan(t); // p.45 (7-13)
var lat = Math.PI / 2d - 2d * Math.Atan(t); // p.45 (7-13)
return lat
+ (e_2 / 2d + 5d * e_4 / 24d + e_6 / 12d + 13d * e_8 / 360d) * Math.Sin(2d * lat)
+ (7d * e_4 / 48d + 29d * e_6 / 240d + 811d * e_8 / 11520d) * Math.Sin(4d * lat)
+ (7d * e_6 / 120d + 81d * e_8 / 1120d) * Math.Sin(6d * lat)
+ 4279d * e_8 / 161280d * Math.Sin(8d * lat); // p.45 (3-5)
return chi
+ (e2 / 2d + 5d * e4 / 24d + e6 / 12d + 13d * e8 / 360d) * Math.Sin(2d * chi)
+ (7d * e4 / 48d + 29d * e6 / 240d + 811d * e8 / 11520d) * Math.Sin(4d * chi)
+ (7d * e6 / 120d + 81d * e8 / 1120d) * Math.Sin(6d * chi)
+ 4279d * e8 / 161280d * Math.Sin(8d * chi); // p.45 (3-5)
}
}
}