OsNationalGrid

OsNationalGrid is a Ruby gem that provides accurate transformations between the Ordnance Survey National Grid (OSGB36) and WGS84 (latitude/longitude) coordinate systems.

It uses the official mathematical transformations from the Ordnance Survey, including a Helmert transformation for precise conversions between coordinate systems.

---

Installation

Add to your Gemfile:

gem 'os_national_grid'

Then install:

bundle install

Or install it manually:

gem install os_national_grid

Usage

Convert from OSGB36 (easting, northing) to WGS84 (longitude, latitude)

lng, lat = OsNationalGrid.os_ng_to_wgs84(481_987.066, 213_552.27)

=> [-0.812036, 51.814605]

Convert from WGS84 (longitude, latitude) to OSGB36 (easting, northing)

easting, northing = OsNationalGrid.wgs84_to_os_ng(-0.812036, 51.814605)

=> [481987.066, 213552.27]

Development

Run the test suite with:

bundle exec rake test

License

The gem is available as open source under the terms of the MIT License.