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Fixed RelativeTransform of azimuthal projections

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ClemensFischer 2026-01-28 09:52:11 +01:00
parent 8d25310b8e
commit 3922297e7b
12 changed files with 72 additions and 39 deletions
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25
MapControl/Shared/MapProjection.cs
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@ -207,5 +207,30 @@ namespace MapControl
{
return CrsId;
}
/// <summary>
/// Used by azimuthal projections, where local skewing can not be directly calculated.
/// </summary>
protected Matrix RelativeTransform(double latitude, double longitude, double scaleX, double scaleY)
{
var north = LocationToMap(latitude - 1e-3, longitude);
var south = LocationToMap(latitude + 1e-3, longitude);
var west = LocationToMap(latitude, longitude - 1e-3);
var east = LocationToMap(latitude, longitude + 1e-3);
var tanSkewX = 0d;
var tanSkewY = 0d;
if (north.HasValue && south.HasValue && west.HasValue && east.HasValue)
{
var dx1 = east.Value.X - west.Value.X;
var dy1 = east.Value.Y - west.Value.Y;
var dx2 = north.Value.X - south.Value.X;
var dy2 = north.Value.Y - south.Value.Y;
tanSkewX = -dx2 / dy2;
tanSkewY = -dy1 / dx1;
}
return new Matrix(scaleX, scaleX * tanSkewY, scaleY * tanSkewX, scaleY, 0d, 0d);
}
}
}