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Version 4.12. Revised projections

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ClemensF 2018-12-20 21:55:12 +01:00
parent 8cafe207cb
commit 90aa92def0
25 changed files with 390 additions and 167 deletions
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35
MapControl/Shared/WorldMercatorProjection.cs
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@ -10,17 +10,12 @@ using System.Windows;
namespace MapControl
{
/// <summary>
/// Transforms map coordinates according to the "World Mercator" Projection, EPSG:3395.
/// Longitude values are transformed linearly to X values in meters, by multiplying with TrueScale.
/// Latitude values are transformed according to the elliptical versions of the Mercator equations,
/// as shown in "Map Projections - A Working Manual" (https://pubs.usgs.gov/pp/1395/report.pdf), p.44.
/// Elliptical Mercator Projection, EPSG:3395.
/// See "Map Projections - A Working Manual" (https://pubs.usgs.gov/pp/1395/report.pdf), p.44-45.
/// </summary>
public class WorldMercatorProjection : MapProjection
{
public const double Wgs84Flattening = 1d / 298.257223563;
public static readonly double Wgs84Eccentricity = Math.Sqrt((2d - Wgs84Flattening) * Wgs84Flattening);
public static double MinLatitudeDelta = 1d / Wgs84EquatorialRadius; // corresponds to 1 meter
public static double ConvergenceTolerance = 1e-6;
public static int MaxIterations = 10;
public WorldMercatorProjection()
@ -31,7 +26,7 @@ namespace MapControl
public WorldMercatorProjection(string crsId)
{
CrsId = crsId;
IsCylindrical = true;
IsNormalCylindrical = true;
MaxLatitude = YToLatitude(180d);
}
@ -39,9 +34,9 @@ namespace MapControl
{
var lat = location.Latitude * Math.PI / 180d;
var eSinLat = Wgs84Eccentricity * Math.Sin(lat);
var scale = ViewportScale * Math.Sqrt(1d - eSinLat * eSinLat) / Math.Cos(lat);
var k = Math.Sqrt(1d - eSinLat * eSinLat) / Math.Cos(lat); // p.44 (7-8)
return new Vector(scale, scale);
return new Vector(ViewportScale * k, ViewportScale * k);
}
public override Point LocationToPoint(Location location)
@ -72,24 +67,24 @@ namespace MapControl
var lat = latitude * Math.PI / 180d;
return Math.Log(Math.Tan(lat / 2d + Math.PI / 4d) * ConformalFactor(lat)) / Math.PI * 180d;
return Math.Log(Math.Tan(lat / 2d + Math.PI / 4d)
* ConformalFactor(lat)) * 180d / Math.PI; // p.44 (7-7)
}
public static double YToLatitude(double y)
{
var t = Math.Exp(-y * Math.PI / 180d);
var lat = Math.PI / 2d - 2d * Math.Atan(t);
var latDelta = 1d;
var t = Math.Exp(-y * Math.PI / 180d); // p.44 (7-10)
var lat = Math.PI / 2d - 2d * Math.Atan(t); // p.44 (7-11)
var relChange = 1d;
for (int i = 0; i < MaxIterations && latDelta > MinLatitudeDelta; i++)
for (var i = 0; i < MaxIterations && relChange > ConvergenceTolerance; i++)
{
var newLat = Math.PI / 2d - 2d * Math.Atan(t * ConformalFactor(lat));
latDelta = Math.Abs(newLat - lat);
var newLat = Math.PI / 2d - 2d * Math.Atan(t * ConformalFactor(lat)); // p.44 (7-9)
relChange = Math.Abs(1d - newLat / lat);
lat = newLat;
}
return lat / Math.PI * 180d;
return lat * 180d / Math.PI;
}
private static double ConformalFactor(double lat)