Simple python script to find the line of sight distance between two sets of latitude and longitude points. Will modified later for geofencing with mqttitude.org backend server.

Distance.py

import math

def distance_on_unit_sphere(lat1, long1, lat2, long2):
    # by Matthew Bordignon @bordignon Oct 2013
    #
    # handy example for finding distance between two sets of co-oridinates 
    # modified from http://www.johndcook.com/python_longitude_latitude.html
    # Convert latitude and longitude to 
    # spherical coordinates in radians.
    degrees_to_radians = math.pi/180.0
        
    # phi = 90 - latitude
    phi1 = (90.0 - lat1)*degrees_to_radians
    phi2 = (90.0 - lat2)*degrees_to_radians
        
    # theta = longitude
    theta1 = long1*degrees_to_radians
    theta2 = long2*degrees_to_radians
        
    # Compute spherical distance from spherical coordinates.
        
    # For two locations in spherical coordinates 
    # (1, theta, phi) and (1, theta, phi)
    # cosine( arc length ) = 
    #    sin phi sin phi' cos(theta-theta') + cos phi cos phi'
    # distance = rho * arc length
    
    cos = (math.sin(phi1)*math.sin(phi2)*math.cos(theta1 - theta2) + 
           math.cos(phi1)*math.cos(phi2))
    arc = math.acos( cos ) 
    # Remember to multiply arc by the radius of the earth 
    # in your favorite set of units to get length.
    # We assume the radius of the earth is 3960 miles or 6373 kilometers
    arc = arc * 6373 #setting to kilometers here
    return arc

#example

#lon, lat
#145.329013,-37.913301 location #1
#144.940333,-37.832111 location #2

lon1a = 145.329013
lat1a = -37.913301

lon2b = 144.940333
lat2b = -37.832111

print str('%.2f' % distance_on_unit_sphere(lat1a, lon1a, lat2b, lon2b)) +" kilometers between the two points"