How to get Random Geo-points[ lat/long in decimal], placed anywhere inside a 100 meter radius circle? The center of the circle is another reference GeoPoint. Is there any Function/Formulae that implements this?
Basically I am reading the GPS input of my android device and need to generate random Geo-Points around the device [In a circle of radius 100 meters centered at my device].
Please note : There are no Geo-Points pre-stored in Database. I need to create all the Geo-points on the fly as mentioned above.
I just wrote a a Ruby method which extends Random to provide this.
Caveat: The points all lay within a box, not a circle.
class Random
def location(lat, lng, max_dist_meters)
This is called with Random.new.location(mid_lat, mid_lng, dist). It will return a point which is probably within max_dist_meters of a the mid point.
max_radius = Math.sqrt((max_dist_meters ** 2) / 2.0)
Without adjusting to max_radius we'd get points inside a square outside the circle (i.e. in the corners), where the distance would be greater than max_dist_meters. This constrains us to a square inside the circle which is probably more what you want.
lat_offset = rand(10 ** (Math.log10(max_radius / 1.11)-5))
lng_offset = rand(10 ** (Math.log10(max_radius / 1.11)-5))
The 1.11 and 5 come from here.
lat += [1,-1].sample * lat_offset
lng += [1,-1].sample * lng_offset
lat = [[-90, lat].max, 90].min
lng = [[-180, lng].max, 180].min
We should probably wrap around here instead of just clamping the value, fixes welcome.
[lat, lng]
end
end
Comments / clean up welcome!
Sample output here which you can see nicely if you paste the lat/lngs here.