How to convert from UTM to LatLng in python or Javascript

2013-09-04

An answer to this question on Stack Overflow.

Question

I have a bunch of files with coordinates in UTM form. For each coordinate I have easting, northing and zone. I need to convert this to LatLng for use with Google Map API to show the information in a map.

I have found some online calculators that does this, but no actual code or libraries. http://trac.osgeo.org/proj4js/ is a projection library for Javascript, but looking at the demo it doesn't include UTM projection.

I am still pretty fresh to the entire GIS domain, so what I want is something ala:

(lat,lng) = transform(easting, northing, zone)

Answer

You could use Proj4js, as follows.

Download Proj4JS from GitHub, using this link.

The following code will convert from UTM to longitude latitude

<html>
<head>
  <script src="proj4.js"></script>
  <script>
    var utm = "+proj=utm +zone=32";
    var wgs84 = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs";
    console.log(proj4(utm,wgs84,[539884, 4942158]));
  </script>
</head>
<body>
</body>
</html>

In this code, the UTM zone is 32, as should be obvious. The Easting is 539884, and the Northing is 4942158. The result is:

[9.502832656648073, 44.631671014204365]

Which is to say 44.631671014204365N, 9.502832656648073E. Which I have verified is correct.

If you need other projections, you can find their strings here.