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Revised Location calculations

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ClemensFischer 2025-03-10 15:47:33 +01:00
parent d4f39c5cd9
commit 3c88a81b0d
6 changed files with 64 additions and 101 deletions
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29
MapControl/Shared/LocationCollection.cs
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@ -67,31 +67,29 @@ namespace MapControl
/// <summary>
/// Calculates a series of Locations on a great circle, or orthodrome, that connects the two specified Locations,
/// with an optional angular resolution specified in degrees.
///
/// See https://en.wikipedia.org/wiki/Great-circle_navigation
/// https://en.wikipedia.org/wiki/Great-circle_navigation
/// </summary>
public static LocationCollection OrthodromeLocations(Location location1, Location location2, double resolution = 1d)
{
if (resolution <= 0d)
{
throw new ArgumentOutOfRangeException(
nameof(resolution), "The resolution argument must be greater than zero.");
nameof(resolution), $"The {nameof(resolution)} argument must be greater than zero.");
}
var lat1 = location1.Latitude * Math.PI / 180d;
var lon1 = location1.Longitude * Math.PI / 180d;
var lat2 = location2.Latitude * Math.PI / 180d;
var lon2 = location2.Longitude * Math.PI / 180d;
var cosLat1 = Math.Cos(lat1);
var sinLat1 = Math.Sin(lat1);
var cosLat2 = Math.Cos(lat2);
var sinLat2 = Math.Sin(lat2);
var cosLon12 = Math.Cos(lon2 - lon1);
var sinLon12 = Math.Sin(lon2 - lon1);
var a = cosLat1 * sinLat2 - sinLat1 * cosLat2 * cosLon12;
var b = cosLat2 * sinLon12;
var a = cosLat2 * sinLon12;
var b = cosLat1 * sinLat2 - sinLat1 * cosLat2 * cosLon12;
// σ12
var s12 = Math.Atan2(Math.Sqrt(a * a + b * b), sinLat1 * sinLat2 + cosLat1 * cosLat2 * cosLon12);
var n = (int)Math.Ceiling(s12 / resolution * 180d / Math.PI); // s12 in radians
@ -100,15 +98,18 @@ namespace MapControl
if (n > 1)
{
var az1 = Math.Atan2(sinLon12, cosLat1 * sinLat2 / cosLat2 - sinLat1 * cosLon12);
// https://en.wikipedia.org/wiki/Great-circle_navigation#Finding_way-points
// α1
var az1 = Math.Atan2(a, b);
var cosAz1 = Math.Cos(az1);
var sinAz1 = Math.Sin(az1);
// α0
var az0 = Math.Atan2(sinAz1 * cosLat1, Math.Sqrt(cosAz1 * cosAz1 + sinAz1 * sinAz1 * sinLat1 * sinLat1));
var sinAz0 = Math.Sin(az0);
var cosAz0 = Math.Cos(az0);
var sinAz0 = Math.Sin(az0);
// σ01
var s01 = Math.Atan2(sinLat1, cosLat1 * cosAz1);
// λ0
var lon0 = lon1 - Math.Atan2(sinAz0 * Math.Sin(s01), Math.Cos(s01));
for (var i = 1; i < n; i++)
@ -139,7 +140,7 @@ namespace MapControl
if (resolution <= 0d)
{
throw new ArgumentOutOfRangeException(
nameof(resolution), "The resolution argument must be greater than zero.");
nameof(resolution), $"The {nameof(resolution)} argument must be greater than zero.");
}
var lat1 = location1.Latitude;
@ -153,13 +154,13 @@ namespace MapControl
if (double.IsInfinity(y1))
{
throw new ArgumentOutOfRangeException(
nameof(location1), "The location1 argument must have an absolute latitude value of less than 90.");
nameof(location1), $"The {nameof(location1)} argument must have an absolute latitude value of less than 90.");
}
if (double.IsInfinity(y2))
{
throw new ArgumentOutOfRangeException(
nameof(location2), "The location2 argument must have an absolute latitude value of less than 90.");
nameof(location2), $"The {nameof(location2)} argument must have an absolute latitude value of less than 90.");
}
var dlat = lat2 - lat1;