Cross::Track::Distance

Uber simple gem to calculate the cross track distance (aka cross track error).

Suppose you are proceeding on a great circle route from start_segment_pt to end_segment_pt but you are at point, You can calculate the shortest distance to the segment that conforms the route

  start_segment_pt  * ------+------------------ * end_segment
                            |
                            |
                            * point

If start_segment_pt, end_segment_pt and point are given in latitude and longitude (WGS84), and the radius of the great circle is the Earth, you can use this gem to calculate the shortest distance from point to the segment line also called cross track distance or cross track error.

You have more info abou the theory behind the formula in these links:

• This gem is based on http://www.movable-type.co.uk/scripts/latlong.html
• You also have more information on http://williams.best.vwh.net/avform.htm#XTE

Installation

Add this line to your application's Gemfile:

gem 'cross-track-distance'

And then execute:

$ bundle

Or install it yourself as:

$ gem install cross-track-distance

Usage

require 'cross/track/distance'

segment_start = {lat: 53.3206, lon: -1.7297}
segment_end = {lat: 53.1887, lon: 0.1334}
point = {lat: 53.2611, lon: -0.7972}

puts Cross::Track::Distance.cross_track_distance(segment_start,segment_end,point)
# => -307.549570418756

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/merlos/cross-track-distance.

License

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