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A small Javascript library for getting mapping images from latitudes and longitudes.
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Tolmey is a little library for getting mapping images from latitdue and longitudes.

Currently its main function is to convert latitude and longitude coordinates into a coordinate system used by OpenStreetMap, and turn the resulting coordinates into a URL for downloading that tile.

The code for transforming the coordinates was heavily inspired by the FoxtrotGPS code for doing so.


Tolmey uses Ender, a client-side library manager. Follow the instructions on the website for installing ender, and then navigate to the directory where you keep your javascript files.

Tolmey is not in the NPM package index yet, so the best way to install it currently is to clone this repository somewhere.

git clone
cd your/projects/javascript/folder
ender build path/to/Tolmey

This produces an ender.js file, which includes the Tolmey library. Then add the ender.js file to your project like you would any other Javascript file.

Or, if you already have an ender file, run:

ender add path/to/Tolmey

Usage Examples

Getting X and Y Tile Coordinates From Latitude And Longitude:

var Tolmey = require('tolmey');
var converter = new Tolmey();
var lat = 40.6789;
var long = -111.6879;
//need a zoom level as well. Higher numbers zoom in more.
var zoom = 15.0;
var tile_coordinates = converter.getMercatorFromGPS(lat, long, zoom);
// { x: 6217, y: 12324 }

Getting A URL for an OpenStreetMap Tile:

var url = converter.getTileURL(openstreetmap', tile_coordinates.x, tile_coordinates.y,zoom);
// ""

Example App

There is a small skeleton HTML page along with some javascript that demonstrates how you could use Tolmey.

To build it, run ender build jeesh path/to/tolmey, and then open the index.html file in a browser.

Tolmey and Google Maps

I used FoxtrotGPS and OpenStreetMap to build this, but Google Maps apprears to use a very similar coordinate system and URL scheme, so Tolmey might be useful for obtaining URLs to Google Map tiles as well.

Feel free to bug me if you want more info on this.

Why the name Tolmey?

"Tolmey" is my horrible misspelling of Ptolemy, a famous Roman scientist. Among many other things, he was a famous cartographer and mapper.

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