From 19cba8978bda04335cabd83a24a848772b144fb4 Mon Sep 17 00:00:00 2001
From: ClemensFischer <fischer.clemens@gmail.com>
Date: Sun, 18 Jan 2026 21:03:25 +0100
Subject: [PATCH] Updated PolarStereographicProjection

---
 MapControl/Shared/Location.cs                    | 16 ++++------------
 .../Shared/PolarStereographicProjection.cs       | 12 +++++++-----
 MapProjections/Shared/Wgs84UpsProjections.cs     |  4 ++--
 3 files changed, 13 insertions(+), 19 deletions(-)

diff --git a/MapControl/Shared/Location.cs b/MapControl/Shared/Location.cs
index efd196dd..92b0cd1f 100644
--- a/MapControl/Shared/Location.cs
+++ b/MapControl/Shared/Location.cs
@@ -112,24 +112,16 @@ namespace MapControl
         {
             var lat1 = Latitude * Math.PI / 180d;
             var lon1 = Longitude * Math.PI / 180d;
-            var cosD = Math.Cos(distance);
-            var sinD = Math.Sin(distance);
-            var cosA = Math.Cos(azimuth);
-            var sinA = Math.Sin(azimuth);
             var cosLat1 = Math.Cos(lat1);
             var sinLat1 = Math.Sin(lat1);
+            var cosA = Math.Cos(azimuth);
+            var sinA = Math.Sin(azimuth);
+            var cosD = Math.Cos(distance);
+            var sinD = Math.Sin(distance);
             var lat2 = Math.Asin(sinLat1 * cosD + cosLat1 * sinD * cosA);
             var lon2 = lon1 + Math.Atan2(sinD * sinA, cosLat1 * cosD - sinLat1 * sinD * cosA);
 
             return new Location(lat2 * 180d / Math.PI, lon2 * 180d / Math.PI);
         }
-
-        /// <summary>
-        /// Calculates the Location on a great circle at the specified azimuth in degrees and distance in meters from this Location.
-        /// </summary>
-        public Location GetLocation(double azimuth, double distance, double earthRadius = MapProjection.Wgs84MeanRadius)
-        {
-            return GetLocation(azimuth * Math.PI / 180d, distance / earthRadius);
-        }
     }
 }
diff --git a/MapControl/Shared/PolarStereographicProjection.cs b/MapControl/Shared/PolarStereographicProjection.cs
index 8e35483a..d467aa07 100644
--- a/MapControl/Shared/PolarStereographicProjection.cs
+++ b/MapControl/Shared/PolarStereographicProjection.cs
@@ -26,7 +26,7 @@ namespace MapControl
         public double FalseNorthing { get; set; } = 2e6;
         public Hemisphere Hemisphere { get; set; }
 
-        public static double RelativeScale(Hemisphere hemisphere, double equatorialRadius, double flattening, double scaleFactor, double latitude)
+        public static double RelativeScale(Hemisphere hemisphere, double flattening, double scaleFactor, double latitude)
         {
             var sign = hemisphere == Hemisphere.North ? 1d : -1d;
             var phi = sign * latitude * Math.PI / 180d;
@@ -36,17 +36,19 @@ namespace MapControl
 
             var t = Math.Tan(Math.PI / 4d - phi / 2d)
                   / Math.Pow((1d - eSinPhi) / (1d + eSinPhi), e / 2d); // p.161 (15-9)
-            var r = 2d * equatorialRadius * scaleFactor * t
+
+            // r == ρ/a
+            var r = 2d * scaleFactor * t
                   / Math.Sqrt(Math.Pow(1d + e, 1d + e) * Math.Pow(1d - e, 1d - e)); // p.161 (21-33)
 
             var m = Math.Cos(phi) / Math.Sqrt(1d - eSinPhi * eSinPhi); // p.160 (14-15)
 
-            return r / (equatorialRadius * m); // p.161 (21-32)
+            return r / m; // p.161 (21-32)
         }
 
         public override Point RelativeScale(double latitude, double longitude)
         {
-            var k = RelativeScale(Hemisphere, EquatorialRadius, Flattening, ScaleFactor, latitude);
+            var k = RelativeScale(Hemisphere, Flattening, ScaleFactor, latitude);
 
             return new Point(k, k);
         }
@@ -62,7 +64,7 @@ namespace MapControl
 
             var t = Math.Tan(Math.PI / 4d - phi / 2d)
                   / Math.Pow((1d - eSinPhi) / (1d + eSinPhi), e / 2d); // p.161 (15-9)
-
+            // ρ
             var r = 2d * EquatorialRadius * ScaleFactor * t
                   / Math.Sqrt(Math.Pow(1d + e, 1d + e) * Math.Pow(1d - e, 1d - e)); // p.161 (21-33)
 
diff --git a/MapProjections/Shared/Wgs84UpsProjections.cs b/MapProjections/Shared/Wgs84UpsProjections.cs
index d5cfb7cd..a1628e6d 100644
--- a/MapProjections/Shared/Wgs84UpsProjections.cs
+++ b/MapProjections/Shared/Wgs84UpsProjections.cs
@@ -25,7 +25,7 @@ namespace MapControl.Projections
 
         public override Point RelativeScale(double latitude, double longitude)
         {
-            var k = PolarStereographicProjection.RelativeScale(Hemisphere.North, Wgs84EquatorialRadius, Wgs84Flattening, 0.994, latitude);
+            var k = PolarStereographicProjection.RelativeScale(Hemisphere.North, Wgs84Flattening, 0.994, latitude);
 
             return new Point(k, k);
         }
@@ -50,7 +50,7 @@ namespace MapControl.Projections
 
         public override Point RelativeScale(double latitude, double longitude)
         {
-            var k = PolarStereographicProjection.RelativeScale(Hemisphere.South, Wgs84EquatorialRadius, Wgs84Flattening, 0.994, latitude);
+            var k = PolarStereographicProjection.RelativeScale(Hemisphere.South, Wgs84Flattening, 0.994, latitude);
 
             return new Point(k, k);
         }