Updated TransverseMercatorProjection

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ClemensFischer 2026-01-12 11:31:35 +01:00
parent 28146cbb20
commit c50551d4fe

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@ -14,9 +14,15 @@ namespace MapControl
/// </summary>
public class TransverseMercatorProjection : MapProjection
{
private readonly double[] alpha = new double[3]; // α_j
private readonly double[] beta = new double[3]; // β_j
private readonly double[] delta = new double[3]; // δ_j
private double a1; // α1
private double a2; // α2
private double a3; // α3
private double b1; // β1
private double b2; // β2
private double b3; // β3
private double d1; // δ1
private double d2; // δ2
private double d3; // δ3
private double f1; // A / a
private double f2; // 2 * sqrt(n) / (1+n)
@ -26,26 +32,20 @@ namespace MapControl
set
{
field = value;
// n, n^2, n^3
var n = field / (2d - field);
var n2 = n * n;
var n3 = n * n2;
// A / a
f1 = (1d + n2 / 4d + n2 * n2 / 64d) / (1d + n);
// 2 * sqrt(n) / (1+n)
var nn = n * n;
var nnn = n * nn;
a1 = n / 2d - nn * 2d / 3d + nnn * 5d / 16d;
a2 = nn * 13d / 48d - nnn * 3d / 5d;
a3 = nnn * 61d / 240d;
b1 = n / 2d - nn * 2d / 3d + nnn * 37d / 96d;
b2 = nn / 48d + nnn / 15d;
b3 = nnn * 17d / 480d;
d1 = n * 2d - nn * 2d / 3d - nnn * 2d;
d2 = nn * 7d / 3d - nnn * 8d / 5d;
d3 = nnn * 56d / 15d;
f1 = (1d + nn / 4d + nn * nn / 64d) / (1d + n);
f2 = 2d * Math.Sqrt(n) / (1d + n);
// α_j
alpha[0] = n / 2d - n2 * 2d / 3d + n3 * 5d / 16d;
alpha[1] = n2 * 13d / 48d - n3 * 3d / 5d;
alpha[2] = n3 * 61d / 240d;
// β_j
beta[0] = n / 2d - n2 * 2d / 3d + n3 * 37d / 96d;
beta[1] = n2 / 48d + n3 / 15d;
beta[2] = n3 * 17d / 480d;
// δ_j
delta[0] = n * 2d - n2 * 2d / 3d - n3 * 2d;
delta[1] = n2 * 7d / 3d - n3 * 8d / 5d;
delta[2] = n3 * 56d / 15d;
}
}
@ -63,7 +63,7 @@ namespace MapControl
public override Point RelativeScale(double latitude, double longitude)
{
return new Point(ScaleFactor, ScaleFactor);
return new Point(ScaleFactor, ScaleFactor); // sufficiently precise
}
public override Point? LocationToMap(double latitude, double longitude)
@ -73,7 +73,7 @@ namespace MapControl
#else
static double Atanh(double x) => Math.Atanh(x);
#endif
// k_0 * A
// k0 * A
var k0A = ScaleFactor * EquatorialRadius * f1;
// φ
var phi = latitude * Math.PI / 180d;
@ -88,14 +88,14 @@ namespace MapControl
var eta_ = Atanh(Math.Sin(lambda) / Math.Sqrt(1d + t * t));
// ξ
var xi = xi_
+ alpha[0] * Math.Sin(2d * xi_) * Math.Cosh(2d * eta_)
+ alpha[1] * Math.Sin(4d * xi_) * Math.Cosh(4d * eta_)
+ alpha[2] * Math.Sin(6d * xi_) * Math.Cosh(6d * eta_);
+ a1 * Math.Sin(2d * xi_) * Math.Cosh(2d * eta_)
+ a2 * Math.Sin(4d * xi_) * Math.Cosh(4d * eta_)
+ a3 * Math.Sin(6d * xi_) * Math.Cosh(6d * eta_);
// η
var eta = eta_
+ alpha[0] * Math.Cos(2d * xi_) * Math.Sinh(2d * eta_)
+ alpha[1] * Math.Cos(4d * xi_) * Math.Sinh(4d * eta_)
+ alpha[2] * Math.Cos(6d * xi_) * Math.Sinh(6d * eta_);
+ a1 * Math.Cos(2d * xi_) * Math.Sinh(2d * eta_)
+ a2 * Math.Cos(4d * xi_) * Math.Sinh(4d * eta_)
+ a3 * Math.Cos(6d * xi_) * Math.Sinh(6d * eta_);
return new Point(
k0A * eta + FalseEasting,
@ -104,7 +104,7 @@ namespace MapControl
public override Location MapToLocation(double x, double y)
{
// k_0 * A
// k0 * A
var k0A = ScaleFactor * EquatorialRadius * f1;
// ξ
var xi = (y - FalseNorthing) / k0A;
@ -112,21 +112,21 @@ namespace MapControl
var eta = (x - FalseEasting) / k0A;
// ξ'
var xi_ = xi
- beta[0] * Math.Sin(2d * xi) * Math.Cosh(2d * eta)
- beta[1] * Math.Sin(4d * xi) * Math.Cosh(4d * eta)
- beta[2] * Math.Sin(6d * xi) * Math.Cosh(6d * eta);
- b1 * Math.Sin(2d * xi) * Math.Cosh(2d * eta)
- b2 * Math.Sin(4d * xi) * Math.Cosh(4d * eta)
- b3 * Math.Sin(6d * xi) * Math.Cosh(6d * eta);
// η'
var eta_ = eta
- beta[0] * Math.Cos(2d * xi) * Math.Sinh(2d * eta)
- beta[1] * Math.Cos(4d * xi) * Math.Sinh(4d * eta)
- beta[2] * Math.Cos(6d * xi) * Math.Sinh(6d * eta);
- b1 * Math.Cos(2d * xi) * Math.Sinh(2d * eta)
- b2 * Math.Cos(4d * xi) * Math.Sinh(4d * eta)
- b3 * Math.Cos(6d * xi) * Math.Sinh(6d * eta);
// χ
var chi = Math.Asin(Math.Sin(xi_) / Math.Cosh(eta_));
// φ
var phi = chi
+ delta[0] * Math.Sin(2d * chi)
+ delta[1] * Math.Sin(4d * chi)
+ delta[2] * Math.Sin(6d * chi);
+ d1 * Math.Sin(2d * chi)
+ d2 * Math.Sin(4d * chi)
+ d3 * Math.Sin(6d * chi);
// λ - λ0
var lambda = Math.Atan(Math.Sinh(eta_) / Math.Cos(xi_));