242Eld - 1 year ago 108

Python Question

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?

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Answer Source

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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