242Eld 242Eld - 16 days ago 5
Python Question

calculating a gps coordinate given a point, bearing and distance

I have a problem which draws my back in some project for some time now.

Im basically looking to trap a polygon using x,y points drawn by some script ive written.
lat1,lon1 are the center gps cords of the polygon and im looking for its surrounding polygon.

here is a part of my code in python:


def getcords(lat1,lon1,dr,bearing):
lat2=asin(sin(lat1)*cos(dr)+cos(lat1)*sin(dr)*cos(bearing))
lon2=lon1+atan2(sin(bearing)*sin(dr)*cos(lat1),cos(dr)-sin(lat1)*sin(lat2))
return [lat2,lon2]



my input goes like this:
lat1,lon1 - are given in decimal degrees.
-dr is the angular computed by dividing the distance in miles by the earth's -raiuds(=3958.82)
-bearing between 0-360 degrees.

however for the input getcorsds1(42.189275,-76.85823,0.5/3958.82,30)
i get [-1.3485899508698462, -76.8576637627568], however [42.2516666666667,-76.8097222222222] is the right answer.

as for the angular distance i calculate it simply by dividing the distance in miles by the earth's raiuds(=3958.82).

anybody?

Answer

Why don't you use nice libraries?

from geopy import Point
from geopy.distance import distance, VincentyDistance

# given: lat1, lon1, bearing, distMiles
lat2, lon2 = VincentyDistance(miles=distMiles).destination(Point(lat1, lon1), bearing)

For lat1, lon1, distMiles, bearing = 42.189275,-76.85823, 0.5, 30 it returns 42.1955489, -76.853359.

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