how i can count lat and lon in radius ten or twenty kilometres from center

Question

I need count random lat and lon in radius 10 and 20 kilometres from center, which cords i have.

For example:

    location_center = {
            "lat": 5.0123,
            "lon": 40.712
}

Random cords in radius 10 km:

    location_center = {
        "lat": 6.246,
        "lon": 45.678

}

Random cords in radius 20 km:

    location_center = {
        "lat": 7.368,
        "lon": 50.678

}

How i can count it?

Will be grateful for the help.

Answer 1

Generate random angle in range 0..2*Pi

Using Destination point given distance and bearing from start point section from this page, calculate point at needed distance d in km (with earth radius R=6378.13 km)

brng = random() * 2 * Math.pi
lat2 = Math.asin( Math.sin(lat1)*Math.cos(d/R) +
                  Math.cos(lat1)*Math.sin(d/R)*Math.cos(brng) );
lon2 = lon1 + Math.atan2(Math.sin(brng)*Math.sin(d/R)*Math.cos(lat1),
                        Math.cos(d/R)-Math.sin(lat1)*Math.sin(lat2));