Swissgrid

The swissgrid rubygem is a conversion library to convert WGS84 (GPS) points into the Swiss coordinate system (CH1903) and vice versa.

Add this line to your application's Gemfile:

gem 'swissgrid'

And then execute:

$ bundle

Or install it yourself as:

$ gem install swissgrid

##Usage Require the swissgrid library as follows:

require 'swissgrid'

###Swissgrid The swissgird library has currently two modules:

• CH1903 - responsible for CH1903 conversions
• WGS84 - responsible for WGS84 conversions

If other conversions are needed just create an issue or make a pull request :-).

###From WGS84(GPS) to CH1903 A WGS84 point can easily be converted to a CH1903 point as follows:

 wgs84_point = [46.951082877, 7.438632495] # [lat, lon] Bern, The building of exact sciences.
 ch1903_coord = Swissgrid::CH1903.from_wgs84(wgs84_point)

Or just use the following shortcut:

 wgs84_point = [46.951082877, 7.438632495] # [lat, lon] Bern, The building of exact sciences.
 ch1903_coord = Swissgrid::CH1903(wgs84_point)

###From CH1903 to WGS84(GPS) The same way a CH1903 point can be converted to a WGS84 point:

 ch1903_point = [600_000, 200_000] # [y, x] Bern, The building of exact sciences.
 wgs84_coord =  Swissgrid::WGS84.from_ch1903(ch1903_point)

Or just use the following shortcut:

 ch1903_point = [600_000, 200_000] # [y, x] Bern, The building of exact sciences.
 wgs84_coord =  Swissgrid::WGS84(ch1903_point)

###Convert a list of points

 gps_points = [ [46.881908, 7.471829], [47.220833, 7.028056] ]

# Convert to ch1903 points
 ch1903_points = gps_points.map { |p| Swissgrid::CH1903(p) }

# Convert back to gps points
 new_gps_points = ch1903_points.map { |p| Swissgrid::WGS84(p) }

##Changelog

• 0.1.1
  • Refactor tests and codebase
  • Update Readme
  • Add comments
• 0.1.0
  • Fix ch1903 to wgs84 conversion bug. Thanks @christianmeichtry.
• 0.0.3
  • Update Readme.
• 0.0.2
  • Add homepage link to gemspec.
• 0.0.1
  • Publish first version.

##Specification CH1903 <=> WGS84 For more details about the conversion see Swisstopo Referenzsysteme.

##Other tools and scripts Swisstopo has also created some scripts and tools for other languages like Java, Python[1] and PHP.

For more details see Swisstopo Scripts and Tools.

• [1] The python script is not available anymore. I uploaded it here on github.

1. Fork it ( https://github.com/[my-github-username]/swissgrid/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request