creating boundig box using latitude ,longitude and distance

Question

I have gone through the link Given a latitude and longitude, and distance, I want to find a bounding box this linke gives the solution to creating bounding box but few things I could not understand .

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))

in the above code what is the value of radius and what is represent by 6371 in RADIUS_OF_EARTH ?

Any one can explain ?

Thanks

why did you set C# and Sql-server tag? the code is not in C#. — slfan, Dec 06 '12 at 09:38

score 0 · Answer 1 · answered Dec 06 '12 at 09:37

according to wikipedia 6371km is the mean radius of the earth. I can't see a definition of radius in the piece of code you show, but it should be set to RADIUS_OF_EARTH, because pradius is the horizontal projection of the radius (according to the comment).

creating boundig box using latitude ,longitude and distance

1 Answers1