Given a latitude and longitude, and distance, I want to find a bounding box where the distances are less than the given distance.
This questions was asked here: How to calculate the bounding box for a given lat/lng location?
I donot want this partcularly accurate, so I have modified and simplified it to
def boundingBox(latitudeInDegrees, longitudeInDegrees, halfSideInKm):
lat = math.radians(latitudeInDegrees)
lon = math.radians(longitudeInDegrees)
halfSide = 1000*halfSideInKm
RADIUS_OF_EARTH = 6371
# Radius of the parallel at given latitude
pradius = radius*math.cos(lat)
latMin = lat - halfSide/radius
latMax = lat + halfSide/radius
lonMin = lon - halfSide/pradius
lonMax = lon + halfSide/pradius
rad2deg = math.degrees
return (rad2deg(latMin), rad2deg(lonMin), rad2deg(latMax), rad2deg(lonMax))
But I cant understand how this is working, in particular this line makes no sense to me halfSide = 1000*halfSideInKm
That line is converting the bounding box units from kilometres to metres.
This code didn't quite work, it jumps between KM and M.
Fixed code, made names more PEP8 style, and added a simple box object:
class BoundingBox(object):
def __init__(self, *args, **kwargs):
self.lat_min = None
self.lon_min = None
self.lat_max = None
self.lon_max = None
def get_bounding_box(latitude_in_degrees, longitude_in_degrees, half_side_in_miles):
assert half_side_in_miles > 0
assert latitude_in_degrees >= -90.0 and latitude_in_degrees <= 90.0
assert longitude_in_degrees >= -180.0 and longitude_in_degrees <= 180.0
half_side_in_km = half_side_in_miles * 1.609344
lat = math.radians(latitude_in_degrees)
lon = math.radians(longitude_in_degrees)
radius = 6371
# Radius of the parallel at given latitude
parallel_radius = radius*math.cos(lat)
lat_min = lat - half_side_in_km/radius
lat_max = lat + half_side_in_km/radius
lon_min = lon - half_side_in_km/parallel_radius
lon_max = lon + half_side_in_km/parallel_radius
rad2deg = math.degrees
box = BoundingBox()
box.lat_min = rad2deg(lat_min)
box.lon_min = rad2deg(lon_min)
box.lat_max = rad2deg(lat_max)
box.lon_max = rad2deg(lon_max)
return (box)
来源：https://stackoverflow.com/questions/1648917/given-a-latitude-and-longitude-and-distance-i-want-to-find-a-bounding-box