Simple Mercator Location

A Ruby lib that uses the Mercator Projection to convert WSG84 coordinates (latitude, longitude) to meters, pixels and tiles.

Usage

Just add it to your Gemfile:

gem "simple_mercator_location"

Calculating the googe maps tile numbers for a given lat/lon at a specified zoom level

place = {lat: 40.689359, lon: -74.045197}
SimpleMercatorLocation.new(place).zoom_at(11).to_tile # <= [602,770]

You can use these data to get a tile for a given location via google map url:

https://khms0.google.com/kh/v=131&src=app&x=602&y=770&z=11&s=Gal

Convert lat/lon to pixels at a given zoom level for google maps

At its first zoom level (0), google assumes the world tile to display the whole world. At a higher zoom level n (>2), google uses 2^n tiles to display the whole world. Every tile has 256x256 pixels. #to_px retuns the pixels on the whole map for a given zoom level.

place = {lat: 49.38237278700955, lon: 8.61328125}
SimpleMercatorLocation.new(place).zoom_at(11).to_px  # <= [274688, 179200]

Convert lat/lon to Google World coordinates

Google assumes his "world tile" to show the whole wold in one tile with the size of 256x256px. So the world coordinates are the latitude and longitude coordinates mapped to this world tile. Whereby the origin of googles world coordinate system resides in the center.

place = {lon: -87.65005229999997, lat: 41.850033}
SimpleMercatorLocation.new(place).to_w  # <= [65.67107392000001, 95.1748950436046]

Convert lat/lon to meters

place = {lon: 12.12890625, lat: 48.22467264956519}
SimpleMercatorLocation.new(place).to_m  # <= [1350183.66762935, 6144314.08167561]