Version 4.12. Revised projections

MapProjections/Shared/WorldMercatorProjection.cs

@@ -0,0 +1,48 @@
+// XAML Map Control - https://github.com/ClemensFischer/XAML-Map-Control
+// © 2018 Clemens Fischer
+// Licensed under the Microsoft Public License (Ms-PL)
+
+using System;
+#if !WINDOWS_UWP
+using System.Windows;
+#endif
+
+namespace MapControl.Projections
+{
+    /// <summary>
+    /// Elliptical Mercator Projection implemented by setting the WKT property of a GeoApiProjection.
+    /// See "Map Projections - A Working Manual" (https://pubs.usgs.gov/pp/1395/report.pdf), p.44-45.
+    /// </summary>
+    public class WorldMercatorProjection : GeoApiProjection
+    {
+        public WorldMercatorProjection()
+        {
+            IsNormalCylindrical = true;
+            WKT = "PROJCS[\"WGS 84 / World Mercator\","
+                + "GEOGCS[\"WGS 84\","
+                + "DATUM[\"WGS_1984\", SPHEROID[\"WGS 84\", 6378137, 298.257223563, AUTHORITY[\"EPSG\", \"7030\"]], AUTHORITY[\"EPSG\", \"6326\"]],"
+                + "PRIMEM[\"Greenwich\", 0, AUTHORITY[\"EPSG\", \"8901\"]],"
+                + "UNIT[\"degree\", 0.0174532925199433, AUTHORITY[\"EPSG\", \"9122\"]],"
+                + "AUTHORITY[\"EPSG\", \"4326\"]],"
+                + "PROJECTION[\"Mercator_1SP\"],"
+                + "PARAMETER[\"latitude_of_origin\", 0],"
+                + "PARAMETER[\"central_meridian\", 0],"
+                + "PARAMETER[\"scale_factor\", 1],"
+                + "PARAMETER[\"false_easting\", 0],"
+                + "PARAMETER[\"false_northing\", 0],"
+                + "UNIT[\"metre\", 1, AUTHORITY[\"EPSG\", \"9001\"]],"
+                + "AXIS[\"Easting\", EAST],"
+                + "AXIS[\"Northing\", NORTH],"
+                + "AUTHORITY[\"EPSG\", \"3395\"]]";
+        }
+
+        public override Vector GetMapScale(Location location)
+        {
+            var lat = location.Latitude * Math.PI / 180d;
+            var eSinLat = Wgs84Eccentricity * Math.Sin(lat);
+            var k = Math.Sqrt(1d - eSinLat * eSinLat) / Math.Cos(lat); // p.44 (7-8)
+
+            return new Vector(ViewportScale * k, ViewportScale * k);
+        }
+    }
+}