How to calculate the distance between two GPS coordinates without using Google Maps API?

Question

I'm wondering if there's a way to calculate the distance of two GPS coordinates without relying on Google Maps API.

My app may receive the coordinates in float or I would have to do reverse GEO on the addresses.

Answer 1

Distance between two coordinates on earth is usually calculated using Haversine formula. This formula takes into consideration earth shape and radius. This is the code I use to calculate distance in meters.

def distance(loc1, loc2)   rad_per_deg = Math::PI/180  # PI / 180   rkm = 6371                  # Earth radius in kilometers   rm = rkm * 1000             # Radius in meters    dlat_rad = (loc2[0]-loc1[0]) * rad_per_deg  # Delta, converted to rad   dlon_rad = (loc2[1]-loc1[1]) * rad_per_deg    lat1_rad, lon1_rad = loc1.map {|i| i * rad_per_deg }   lat2_rad, lon2_rad = loc2.map {|i| i * rad_per_deg }    a = Math.sin(dlat_rad/2)**2 + Math.cos(lat1_rad) * Math.cos(lat2_rad) * Math.sin(dlon_rad/2)**2   c = 2 * Math::atan2(Math::sqrt(a), Math::sqrt(1-a))    rm * c # Delta in meters end  puts distance([46.3625, 15.114444],[46.055556, 14.508333]) # => 57794.35510874037 

Answer 2

You can use the geokit ruby gem. It does these calculations internally, but also supports resolving addresses via google and other services if you need it to.

require 'geokit'  current_location = Geokit::LatLng.new(37.79363,-122.396116) destination = "37.786217,-122.41619" current_location.distance_to(destination)   # Returns distance in miles: 1.211200074136264 

You can also find out the bearing_to (direction expressed as a float in degrees between 0-360) and midpoint_to (returns an object you can run .latitude and .longitude methods on).