I have a javascript file that is reading a text file containing cartesian coordinates. I can parse out the X,Y,Z values; however I need to convert these to lat/long in decimal format. These output values will be used for google map markers.

I have been researching and there are definitely lots of guides out there regarding the conversion of lat/long to cartesian, however I need this to work the opposite direction.

Tried something along the lines of:

//convert to lat long dec
var tmp = cartZ/6371;
//convert to radians
var tmpR = tmp * Math.PI / 180;
var lat = Math.asin(tmpR);
latFinal = lat * 180 / Math.PI;
alert (latFinal);

Usually this is pletely wrong... Not sure if I am even on the right track!

If anyone has done this before using javascript that would be great.

I have a javascript file that is reading a text file containing cartesian coordinates. I can parse out the X,Y,Z values; however I need to convert these to lat/long in decimal format. These output values will be used for google map markers.

I have been researching and there are definitely lots of guides out there regarding the conversion of lat/long to cartesian, however I need this to work the opposite direction.

Tried something along the lines of:

//convert to lat long dec
var tmp = cartZ/6371;
//convert to radians
var tmpR = tmp * Math.PI / 180;
var lat = Math.asin(tmpR);
latFinal = lat * 180 / Math.PI;
alert (latFinal);

Usually this is pletely wrong... Not sure if I am even on the right track!

If anyone has done this before using javascript that would be great.

• javascript
• mapping
• geospatial

• This gmat.unsw.edu.au/snap/gps/clynch_pdfs/coordcvt.pdf has a straightforward formulation of conversion in both directions. – Igor Commented Oct 23, 2012 at 21:10

3 Answers 3

I ended up using the following: javascript routines

Was exactly what I needed. Hopefully this post is helpful to others. Thanks!

You can try using the proj4js library to do the conversion for you. See this question - the projection is different but you should be able to figure it out.

There is this handy library on npmjs that will do it for you. Once you have installed it (using npm and browserify), you can use:

var projector = require('ecef-projector');
var xyz = projector.project(37.8043722, -122.2708026, 0.0);
console.log(xyz);  
// output: [ -2694044.4111565403, -4266368.805493665, 3888310.602276871 ]

var gps = projector.unproject(xyz[0], xyz[1], xyz[2]);
console.log(gps);
// output: [ 37.8043722, -122.27080260000001, 0.0 ]

Using this you can project both ways.