Javascript Function for transforming WGS84 to EPSG:5514

Question

I'am searching for JavaScript function which converts WGS84 coordinates to this special coordinate format EPSG:5514 https://epsg.io/5514.

Function should looks like function wgs2sjtsk(lat,long) and output will be coordinates in EPSG:5514 (sjtsk).

Answer 1

Proj4JS is the JS implementation of the Proj4 library: http://proj4js.org/ - you'll just need to write your conversion function as a wrapper round some of the Proj4JS functions.

Answer 2

Did you explore the OpenLayers 3 API?

There is a function that looks like this:

ol.proj.transform([23.4, 42.5], 'EPSG:4326','EPSG:5514');

Answer 3

I found js with pure algorithm, which works good from this website: https://www.pecina.cz/krovak.html

function convert(lat,lon, H) {
  var d2r = Math.PI/180;
  var a = 6378137.0;
  var f1 = 298.257223563;
  var dx = -570.69;
  var dy = -85.69;
  var dz = -462.84;
  var wx = 4.99821/3600*Math.PI/180;
  var wy = 1.58676/3600*Math.PI/180;
  var wz = 5.2611/3600*Math.PI/180;
  var m  = -3.543e-6;

  var f = document.forms[0];

  var B = lat*d2r;
  var L = lon*d2r;

  var e2 = 1 - sqr(1-1/f1);
  var rho = a/Math.sqrt(1-e2*sqr(Math.sin(B)));
  var x1 = (rho+H) * Math.cos(B)*Math.cos(L);
  var y1 = (rho+H) * Math.cos(B)*Math.sin(L);
  var z1 = ((1-e2)*rho+H) * Math.sin(B);

  var x2 = dx + (1+m)*(x1 + wz*y1 - wy*z1);
  var y2 = dy + (1+m)*(-wz*x1 + y1 + wx*z1);
  var z2 = dz + (1+m)*(wy*x1 - wx*y1 + z1);

  a = 6377397.15508;
  f1 = 299.152812853;
  var ab = f1/(f1-1);
  var p = Math.sqrt(sqr(x2) + sqr(y2));
  e2 = 1-sqr(1-1/f1);
  var th = Math.atan(z2*ab/p);
  var st = Math.sin(th);
  var ct = Math.cos(th);
  var t = (z2 + e2*ab*a*(st*st*st))/(p - e2*a*(ct*ct*ct));

  B = Math.atan(t);
  H = Math.sqrt(1+t*t) * (p-a/Math.sqrt(1+(1-e2)*t*t));
  L = 2*Math.atan(y2/(p+x2));

  a = 6377397.15508;
  var e = 0.081696831215303;
  var n = 0.97992470462083;
  var rho0 = 12310230.12797036;
  var sinUQ = 0.863499969506341;
  var cosUQ = 0.504348889819882;
  var sinVQ = 0.420215144586493;
  var cosVQ = 0.907424504992097;
  var alpha  = 1.000597498371542;
  var k2 = 1.00685001861538;

  var sinB = Math.sin(B);
  t = (1-e*sinB)/(1+e*sinB);
  t = sqr(1+sinB)/(1-sqr(sinB)) * Math.exp(e*Math.log(t));
  t = k2 * Math.exp(alpha*Math.log(t));

  var sinU = (t-1)/(t+1);
  var cosU = Math.sqrt(1-sinU*sinU);
  var V = alpha*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);
  rho = rho0*Math.exp(-n*Math.log((1+sinS)/cosS));

  var CX = rho*Math.sin(eps);
  var CY = rho*Math.cos(eps);

  return Array(CX, CY);

}


function sqr(x) {
  return x*x;
}