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ykj2wgs84

Viljelysuunnitteluprojektissa olennaisena osana ovat luonnollisesti pellot. Suomalaiset maanviljelijät saavat omat peltotietonsa koordinaatteineen maaseutuviraston GISistä. Teimme oman parsijan, joka parsii koordinaatit ja peltojen nimet mavin viljelijäpalvelusta. Koordinaatit ovat palvelussa YKJ tasokoordinaatistossa ja ne täytyy muuttaa karttapalveluja ja mobiiliosan GPS träkkeriä varten WGS84 koordinaateiksi.

Tein muunnosoperaatiota varten melko mielenkiintoisen metodin

public double[] ykj2wgs84(double E, double N) {

  double f = 1.0D / 297.0;
  double el = f / (2 - f);
  double a = 6378388.0;
  double A1 = (a / (1 + el))
    * (1 + (Math.pow(el, 2) / 4) + (Math.pow(el, 4) / 64));
  double E0 = 3500000.0;
  double lambda_0 = 27 * (Math.PI / 180);
  double k_0 = 1.0D;

  double eps = N / (A1 * k_0);
  double n = (E - E0) / (A1 * k_0);

  double h1 = ((((1.0D / 2.0) * el) - ((2.0 / 3.0) * Math.pow(el, 2))) + ((37.0 / 96.0) * Math
    .pow(el, 3))) - ((1.0D / 360.0) * Math.pow(el, 4));
  double h2 = (((1.0D / 48.0) * Math.pow(el, 2)) + ((1.0D / 15.0) * Math
    .pow(el, 3))) - ((437.0 / 1140.0) * Math.pow(el, 4));
  double h3 = ((17.0 / 480.0) * Math.pow(el, 3))
    - ((37.0 / 840.0) * Math.pow(el, 4));
  double h4 = (4397.0 / 161280.0) * Math.pow(el, 4);

  double r1 = h1 * Math.sin(2 * eps) * Math.cosh(2 * n);
  double r2 = h2 * Math.sin(4 * eps) * Math.cosh(4 * n);
  double r3 = h3 * Math.sin(6 * eps) * Math.cosh(6 * n);
  double r4 = h4 * Math.sin(8 * eps) * Math.cosh(8 * n);

  double s1 = h1 * Math.sinh(2 * n) * Math.cos(2 * eps);
  double s2 = h2 * Math.sinh(4 * n) * Math.cos(4 * eps);
  double s3 = h3 * Math.sinh(6 * n) * Math.cos(6 * eps);
  double s4 = h4 * Math.sinh(8 * n) * Math.cos(8 * eps);

  double eps_f = eps - (r1 + r2 + r3 + r4);
  double n_f = n - (s1 + s2 + s3 + s4);
  double e = Math.sqrt((2 * f) - Math.pow(f, 2));

  double beta = Math.asin(sech(n_f) * Math.sin(eps_f));
  double l = Math.asin(Math.tanh(n_f) / (Math.cos(beta)));

  double Q1 = asinh(Math.tan(beta));
  double Q = Q1 + (e * atanh(Math.tanh(Q1) * e));
  Q = Q1 + (e * atanh(Math.tanh(Q) * e));
  Q = Q1 + (e * atanh(Math.tanh(Q) * e));
  Q = Q1 + (e * atanh(Math.tanh(Q) * e));

  double phi = Math.atan(Math.sinh(Q));
  double lambda_r = lambda_0 + l;
  double lambda = lambda_r;

  double NN = a
    * Math.pow((1 - (Math.pow(e, 2) * Math.pow(Math.sin(phi), 2))),
      -1.0D / 2.0);
  double X0 = (NN + 50) * Math.cos(phi) * Math.cos(lambda);
  double Y0 = (NN + 50) * Math.cos(phi) * Math.sin(lambda);
  double Z0 = ((NN * (1 - Math.pow(e, 2))) + 50) * Math.sin(phi);

  double DX = -96.062;
  double DY = -82.428;
  double DZ = -121.754;
  double Rx = -4.801 * (1.0D / 3600.0) * (Math.PI / 180.0);
  double Ry = -0.345 * (1.0D / 3600.0) * (Math.PI / 180.0);
  double Rz = 1.376 * (1.0D / 3600.0) * (Math.PI / 180.0);
  double m = 1.496;

  double X1 = DX
    + ((1 + (m / 1000000)) * (((1 * X0) + (Rz * Y0)) - (Ry * Z0)));
  double Y1 = DY
    + ((1 + (m / 1000000)) * ((-Rz * X0) + (1 * Y0) + (Rx * Z0)));
  double Z1 = DZ
    + ((1 + (m / 1000000)) * (((Ry * X0) - (Rx * Y0)) + (1 * Z0)));

  lambda = Math.atan(Y1 / X1);
  double a_grs = 6378137.0;
  double f_grs = 1 / 298.2572;
  double e_grs = Math.pow(((2 * f_grs) - Math.pow(f_grs, 2)), 0.5);
  double phi_0 = Math.atan(Z1
    / ((1 - Math.pow(e_grs, 2)) * Math.pow(
      (Math.pow(X1, 2) + Math.pow(Y1, 2)), (0.5))));
  double phi_i = phi_0;
  double N_i = 0.0;
  double h_i = 0.0;
  for (int i = 0; i < 3; i++) {
   N_i = a_grs
     * Math.pow((1 - (Math.pow(e_grs, 2) * Math.pow(
       Math.sin(phi_i), 2))), (-0.5));
   if (Math.abs(phi_0) < (45.0 * (Math.PI / 180.0))) {
    h_i = ((Math.sqrt((Math.pow(X1, 2) + Math.pow(Y1, 2)))) / (Math
      .cos(phi_i))) - N_i;
   } else {
    h_i = (Z1 / (Math.sin(phi_i)))
      - ((1.0 - Math.pow(e_grs, 2)) * N_i);
   }
   phi_i = Math
     .atan((Z1 / Math.sqrt(Math.pow(X1, 2) + Math.pow(Y1, 2)))
       * (1.0D / (1.0D - ((Math.pow(e_grs, 2) * N_i) / (N_i + h_i)))));
  }

  return new double[] { phi_i * (180.0 / Math.PI),
    lambda * (180.0 / Math.PI) };
 }

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