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Created April 14, 2021 15:29
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index.html
<body>
<script src="jtsk.js"></script>
Velbloud je na <span data-jstk-x="1043019.76" data-jstk-y="738380.15" id="adresa"></span>
<script>
text = document.getElementById("adresa");
x = parseFloat(text.dataset.jstkX);
y = parseFloat(text.dataset.jstkY)
prevod = new JTSK_Converter();
vysledek = prevod.JTSKtoWGS84(x, y);
text.innerHTML = "<a href=\"?lat=" + vysledek.lat + "&lon=" + vysledek.lon + "\">odkaz</a>";
</script>
</body>
Raw
jtsk.js
(function (window){
'use strict';
/**
* Class JTSK_Converter
* @author Josef Zamrzla
*
* JTSK coordinates converter
* This is a Javascript port of Pascal code that was originally published at
* http://www.geospeleos.com/Mapovani/WGS84toSJTSK/WGS84toSJTSK.htm
* Original author: Jakub Kerhat
*/
var JTSK_Converter = function () {
/**
* Calculate distance between two points
* @param x1
* @param y1
* @param x2
* @param y2
* @returns {*}
*/
this.distPoints = function (x1, y1, x2, y2)
{
var dist = this.hypot(x1 - x2, y1 - y2);
if (dist < this.EPS) {
return 0;
}
return dist;
};
/**
* Coordinates transformation
* @param xs
* @param ys
* @param zs
* @returns {Array}
*/
this.transformCoords = function (xs, ys, zs)
{
// coeficients of transformation from WGS-84 to JTSK
var dx = -570.69, dy = -85.69, dz = -462.84; // shift
var wx = 4.99821/3600 * Math.PI / 180, wy = 1.58676/3600 * Math.PI / 180, wz = 5.2611/3600 * Math.PI / 180; // rotation
var m = -3.543e-6; // scale
var xn = dx + (1 + m) * (+xs + wz * ys - wy * zs);
var yn = dy + (1 + m) * (-wz * xs + ys + wx * zs);
var zn = dz + (1 + m) * (+wy * xs - wx * ys + zs);
return [xn, yn, zn];
};
// helper Math functions
this.deg2rad = function (deg) {
return (deg / 180) * Math.PI;
};
this.rad2deg = function (rad) {
return rad / Math.PI * 180;
};
this.hypot = function (x, y) {
return Math.sqrt(x * x + y * y) || 0;
};
};
JTSK_Converter.prototype.EPS = 1e-4; // relative accuracy
/**
* Conversion from JTSK to WGS-84 (by iteration)
* @param x
* @param y
* @returns {{lat: number, lon: number}}
*/
JTSK_Converter.prototype.JTSKtoWGS84 = function (x, y)
{
if (!(x && y)) {
return {'lat': 0, 'lon': 0};
}
var delta = 5;
var latitude = 49;
var longitude = 14;
var steps = 0;
var jtsk, v1, v2, v3, v4;
do {
jtsk = this.WGS84toJTSK(latitude - delta, longitude - delta);
if (jtsk.x && jtsk.y) {
v1 = this.distPoints(jtsk.x, jtsk.y, x, y);
} else {
v1 = 1e32;
}
jtsk = this.WGS84toJTSK(latitude - delta, longitude + delta);
if (jtsk.x && jtsk.y) {
v2 = this.distPoints(jtsk.x, jtsk.y, x, y);
} else {
v2 = 1e32;
}
jtsk = this.WGS84toJTSK(latitude + delta, longitude - delta);
if (jtsk.x && jtsk.y) {
v3 = this.distPoints(jtsk.x, jtsk.y, x, y);
} else {
v3 = 1e32;
}
jtsk = this.WGS84toJTSK(latitude + delta, longitude + delta);
if (jtsk.x && jtsk.y) {
v4 = this.distPoints(jtsk.x, jtsk.y, x, y);
} else {
v4 = 1e32;
}
if ((v1 <= v2) && (v1 <= v3) && (v1 <= v4)) {
latitude = latitude - delta / 2;
longitude = longitude - delta / 2;
}
if ((v2 <= v1) && (v2 <= v3) && (v2 <= v4)) {
latitude = latitude - delta / 2;
longitude = longitude + delta / 2;
}
if ((v3 <= v1) && (v3 <= v2) && (v3 <= v4)) {
latitude = latitude + delta / 2;
longitude = longitude - delta / 2;
}
if ((v4 <= v1) && (v4 <= v2) && (v4 <= v3)) {
latitude = latitude + delta / 2;
longitude = longitude + delta / 2;
}
delta *= 0.55;
steps += 4;
} while (!((delta < 0.00001) || (steps > 1000)));
return {'lat': latitude, 'lon': longitude};
};
/**
* Conversion from WGS-84 to JTSK
* @param latitude
* @param longitude
* @returns {{x: number, y: number}}
*/
JTSK_Converter.prototype.WGS84toJTSK = function (latitude, longitude)
{
if ((latitude < 40) || (latitude > 60) || (longitude < 5) || (longitude > 25)) {
return {'x': 0, 'y': 0};
} else {
var lonlat = this.WGS84toBessel(latitude, longitude);
return this.BesseltoJTSK(lonlat[0], lonlat[1]);
}
};
/**
* Conversion from ellipsoid WGS-84 to Bessel's ellipsoid
* @param latitude
* @param longitude
* @param altitude
* @returns {Array}
*/
JTSK_Converter.prototype.WGS84toBessel = function (latitude, longitude, altitude)
{
var B = this.deg2rad(latitude);
var L = this.deg2rad(longitude);
var H = altitude || 0;
var xyz1 = this.BLHToGeoCoords(B, L, H);
var xyz2 = this.transformCoords(xyz1[0], xyz1[1], xyz1[2]);
var BLH = this.geoCoordsToBLH(xyz2[0], xyz2[1], xyz2[2]);
latitude = this.rad2deg(BLH[0]);
longitude = this.rad2deg(BLH[1]);
//Altitude = H;
return [latitude, longitude];
};
/**
* Conversion from Bessel's lat/lon to WGS-84
* @param latitude
* @param longitude
* @returns {{x: number, y: number}}
*/
JTSK_Converter.prototype.BesseltoJTSK = function (latitude, longitude)
{
var a = 6377397.15508;
var e = 0.081696831215303;
var n = 0.97992470462083;
var rho_0 = 12310230.12797036;
var sinUQ = 0.863499969506341;
var cosUQ = 0.504348889819882;
var sinVQ = 0.420215144586493;
var cosVQ = 0.907424504992097;
var alfa = 1.000597498371542;
var k_2 = 1.00685001861538;
var B = this.deg2rad(latitude);
var L = this.deg2rad(longitude);
var sinB = Math.sin(B);
var t = (1 - e * sinB) / (1 + e * sinB);
t = Math.pow(1 + sinB, 2) / (1 - Math.pow(sinB, 2)) * Math.exp(e * Math.log(t));
t = k_2 * Math.exp(alfa * Math.log(t));
var sinU = (t - 1) / (t + 1);
var cosU = Math.sqrt(1 - sinU * sinU);
var V = alfa * L;
var sinV = Math.sin(V);
var cosV = Math.cos(V);
var cosDV = cosVQ * cosV + sinVQ * sinV;
var sinDV = sinVQ * cosV - cosVQ * sinV;
var sinS = sinUQ * sinU + cosUQ * cosU * cosDV;
var cosS = Math.sqrt(1 - sinS * sinS);
var sinD = sinDV * cosU / cosS;
var cosD = Math.sqrt(1 - sinD * sinD);
var eps = n * Math.atan(sinD / cosD);
var rho = rho_0 * Math.exp(-n * Math.log((1 + sinS) / cosS));
return {'x': rho * Math.cos(eps), 'y': rho * Math.sin(eps)};
};
/**
* Conversion from geodetic coordinates to Cartesian coordinates
* @param B
* @param L
* @param H
* @returns {Array}
*/
JTSK_Converter.prototype.BLHToGeoCoords = function (B, L, H)
{
// WGS-84 ellipsoid parameters
var a = 6378137.0;
var f_1 = 298.257223563;
var e2 = 1 - Math.pow(1 - 1 / f_1, 2);
var rho = a / Math.sqrt(1 - e2 * Math.pow(Math.sin(B), 2));
var x = (rho + H) * Math.cos(B) * Math.cos(L);
var y = (rho + H) * Math.cos(B) * Math.sin(L);
var z = ((1 - e2) * rho + H) * Math.sin(B);
return [x, y, z];
};
/**
* Conversion from Cartesian coordinates to geodetic coordinates
* @param x
* @param y
* @param z
* @returns {Array}
*/
JTSK_Converter.prototype.geoCoordsToBLH = function (x, y, z)
{
// Bessel's ellipsoid parameters
var a = 6377397.15508;
var f_1 = 299.152812853;
var a_b = f_1 / (f_1-1);
var p = Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));
var e2 = 1 - Math.pow(1 - 1 / f_1, 2);
var th = Math.atan(z * a_b / p);
var st = Math.sin(th);
var ct = Math.cos(th);
var t = (z + e2 * a_b * a * Math.pow(st, 3)) / (p - e2 * a * Math.pow(ct, 3));
var B = Math.atan(t);
var H = Math.sqrt(1 + t * t) * (p - a / Math.sqrt(1 + (1 - e2) * t * t));
var L = 2 * Math.atan(y / (p + x));
return [B, L, H];
};
window.JTSK_Converter = JTSK_Converter;
})(this);
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