# Get XY coordinates in UTM from web-mercator where UTM zone is not known

How to get XY(northing/easting) coordinates in UTM where data is WGS_1984_Web_Mercator_Auxiliary_Sphere(WKID: 3857) coordinate system and UTM zone is unknown. For e.g. India falls under multiple UTM zones and map is in Web_Mercator_Auxiliary_Sphere. I am trying to replicate Google earth's UTM coordinate display using ArcGIS Javascript API. Thanks.

Nagesh

This is how you change it to UTM, First you have yo change it to wgs, and then call the function to do the rest

``````  function showCoordinates(evt) {
var wgs = webMercatorUtils.webMercatorToGeographic(evt.mapPoint);
var mp = evt.mapPoint;
// Converting The WGS to UTM
document.getElementById("utmCoordinates").innerHTML = myFunction(wgs.x, wgs.y);
function myFunction(lan1, fi)

{

var a = 6378137.000;
var b = 6356752.314;
var f = (a - b) / a;
var e2 = Math.sqrt((Math.pow(a, 2) - Math.pow(b, 2)) / Math.pow(b, 2));
var e = Math.sqrt((Math.pow(a, 2) - Math.pow(b, 2)) / Math.pow(a, 2));

var zone;
var lan0;
if (lan1 > 0) {
var zone = 30 + Math.ceil(lan1 / 6);
lan0 = Math.floor(lan1 / 6) * 6 + 3;
}
else {
var zone = 30 - Math.floor(Math.abs(lan1) / 6);
lan0 = -Math.floor(Math.abs(lan1) / 6) * 6 - 3;
}

//-----------------------------------------------

var lan = lan1 - lan0;
lan = lan * Math.PI / 180;
fi = fi * Math.PI / 180;
var N = a / Math.pow(1 - Math.pow(e, 2) * Math.pow(Math.sin(fi), 2), 0.5);
var M = a * (1 - Math.pow(e, 2)) / Math.pow((1 - (Math.pow(e, 2) * Math.pow(Math.sin(fi), 2))), (3 / 2));
var t = Math.tan(fi);
var p = N / M;

//----------------------------------------------
var k0 = 0.9996;

var term1 = Math.pow(lan, 2) * p * Math.pow(Math.cos(fi), 2) / 2;
var term2 = Math.pow(lan, 4) * Math.pow(Math.cos(fi), 4) * (4 * Math.pow(p, 3) * (1 - 6 * Math.pow(t, 2)) + Math.pow(p, 2) * (1 + 24 * Math.pow(t, 2)) - 4 * p * Math.pow(t, 2)) / 24;
var term3 = Math.pow(lan, 6) * Math.pow(Math.cos(fi), 6) * (61 - 148 * Math.pow(t, 2) + 16 * Math.pow(t, 4)) / 720;

var Kutm = k0 * (term1 + term2 + term3);

//----------------------------------------------
term1 = Math.pow(lan, 2) * p * Math.pow(Math.cos(fi), 2) * (p - Math.pow(t, 2)) / 6;
term2 = Math.pow(lan, 4) * Math.pow(Math.cos(fi), 4) * (4 * Math.pow(p, 3) * (1 - 6 * Math.pow(t, 2)) + Math.pow(p, 2) * (1 + 8 * Math.pow(t, 2)) - Math.pow(p, 2) * Math.pow(t, 2) + Math.pow(t, 4)) / 120;
term3 = Math.pow(lan, 6) * Math.pow(Math.cos(fi), 6) * (61 - 479 * Math.pow(t, 2) + 179 * Math.pow(t, 4) - Math.pow(t, 6)) / 5040;

var Xutm = 500000 + k0 * lan * N * Math.cos(fi) * (1 + term1 + term2 + term3);

//----------------------------------------------

var A0 = 1 - 0.25 * Math.pow(e, 2) - 3 / 64 * Math.pow(e, 4) - 5 / 256 * Math.pow(e, 6);
var A2 = 3 / 8 * (Math.pow(e, 2) + 0.25 * Math.pow(e, 4) + 15 / 128 * Math.pow(e, 6));
var A4 = 15 / 256 * (Math.pow(e, 4) + 0.75 * Math.pow(e, 6));
var A6 = 35 / 3072 * Math.pow(e, 6);

var sfi = a * (A0 * fi - A2 * Math.sin(2 * fi) + A4 * Math.sin(4 * fi) - A6 * Math.sin(6 * fi));

//----------------------------------------------

term1 = Math.pow(lan, 2) * N * Math.sin(fi) * Math.cos(fi) / 2;
term2 = Math.pow(lan, 4) * N * Math.sin(fi) * Math.pow(Math.cos(fi), 3) * (4 * Math.pow(p, 2) + p - Math.pow(t, 2)) / 24;
term3 = Math.pow(lan, 6) * N * Math.sin(fi) * Math.pow(Math.cos(fi), 5) * (8 * Math.pow(p, 4) * (11 - 24 * Math.pow(t, 2)) - 28 * Math.pow(p, 3) * (1 - 6 * Math.pow(t, 2)) + Math.pow(p, 2) * (1 - 32 * Math.pow(t, 2)) - p * 2 * Math.pow(t, 2) + Math.pow(t, 4));
var term4 = Math.pow(lan, 8) * N * Math.sin(fi) * Math.pow(Math.cos(fi), 7) * (1385 - 3111 * Math.pow(t, 2) + 543 * Math.pow(t, 4) - Math.pow(t, 6));

var Yutm = k0 * (sfi + term1 + term2 + term3 + term4);
UTMx = Xutm.toFixed(5);
UTMy = Yutm.toFixed(5);
return (Xutm.toFixed(5).toString() + "," + Yutm.toFixed(5).toString());

//return Xutm.toString().concat(" ; " + Yutm.toString() + " " + zone.toString());
}
``````