ClemensFischer/XAML-Map-Control
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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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16
MapControl/Shared/WebMercatorProjection.cs
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@ -10,10 +10,8 @@ using System.Windows;
namespace MapControl
{
/// <summary>
/// Transforms map coordinates according to the Web (or Pseudo) Mercator Projection, EPSG:3857.
/// Longitude values are transformed linearly to X values in meters, by multiplying with TrueScale.
/// Latitude values in the interval [-MaxLatitude .. MaxLatitude] are transformed to Y values in meters
/// in the interval [-R*pi .. R*pi], R=Wgs84EquatorialRadius.
/// Spherical Mercator Projection, EPSG:3857.
/// See "Map Projections - A Working Manual" (https://pubs.usgs.gov/pp/1395/report.pdf), p.41-44.
/// </summary>
public class WebMercatorProjection : MapProjection
{
@ -25,16 +23,16 @@ namespace MapControl
public WebMercatorProjection(string crsId)
{
CrsId = crsId;
IsCylindrical = true;
IsNormalCylindrical = true;
IsWebMercator = true;
MaxLatitude = YToLatitude(180d);
}
public override Vector GetMapScale(Location location)
{
var scale = ViewportScale / Math.Cos(location.Latitude * Math.PI / 180d);
var k = 1d / Math.Cos(location.Latitude * Math.PI / 180d); // p.44 (7-3)
return new Vector(scale, scale);
return new Vector(ViewportScale * k, ViewportScale * k);
}
public override Point LocationToPoint(Location location)
@ -63,12 +61,12 @@ namespace MapControl
return double.PositiveInfinity;
}
return Math.Log(Math.Tan((latitude + 90d) * Math.PI / 360d)) / Math.PI * 180d;
return Math.Log(Math.Tan((latitude + 90d) * Math.PI / 360d)) * 180d / Math.PI;
}
public static double YToLatitude(double y)
{
return 90d - Math.Atan(Math.Exp(-y * Math.PI / 180d)) / Math.PI * 360d;
return 90d - Math.Atan(Math.Exp(-y * Math.PI / 180d)) * 360d / Math.PI;
}
}
}