I am looking at ways to calculate (in Python) the destination location from a point given bearing and range.
Based on the results comparison from the 2 libraries in subject(geopy and pyproj), I noticed that there is an increasing difference in the final output. For instance, at 100 km is roughly of the order of decimeters. This is a minimal example of what I mean:
from __future__ import absolute_import, division, print_function long_1 = -1.729722 lat_1 = 53.320556 bearing = 96.021667 distance = 124.8 #in km # using geopy import geopy from geopy.distance import VincentyDistance origin = geopy.Point(lat_1, long_1) destination = VincentyDistance(kilometers=distance).destination(origin, bearing) gp_lat_2 = destination.latitude gp_long_2 = destination.longitude # using pyproj from pyproj import Geod g = Geod(ellps='WGS84') prj_long_2, prj_lat_2, prj_bearing_2 = g.fwd(long_1, lat_1, bearing, distance*1000) # results comparison print(" | pyproj | geopy") print("long_2 %.6f %.6f" % (prj_long_2, gp_long_2)) print("lat_2 %.6f %.6f" % (prj_lat_2, gp_lat_2)) print("> DELTA pyproj, geopy") print("delta long_2 %.7f" % (prj_long_2 - gp_long_2)) print("delta lat_2 %.7f" % (prj_lat_2 - gp_lat_2)) I got this results:
| pyproj | geopy long_2 0.127201 0.127199 lat_2 53.188432 53.188432 > DELTA pyproj, geopy delta long_2 0.0000021 delta lat_2 -0.0000002 My main question is whether I am doing something wrong (both settings should be using WGS84).
If not, is the difference due to different formulas in use (Vincenty for geopy vs. Karney for pyproj)? E.g., the round-off error cited here.
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Based on the results comparison from the 2 libraries in subject(geopy and pyproj), I noticed that there is an increasing difference in the final output. For instance, at 100 km is roughly of the order of decimeters. This is a minimal example of what I mean:
from __future__ import absolute_import, division, print_function long_1 = -1.729722 lat_1 = 53.320556 bearing = 96.021667 distance = 124.8 #in km # using geopy import geopy from geopy.distance import VincentyDistance origin = geopy.Point(lat_1, long_1) destination = VincentyDistance(kilometers=distance).destination(origin, bearing) gp_lat_2 = destination.latitude gp_long_2 = destination.longitude # using pyproj from pyproj import Geod g = Geod(ellps='WGS84') prj_long_2, prj_lat_2, prj_bearing_2 = g.fwd(long_1, lat_1, bearing, distance*1000) # results comparison print(" | pyproj | geopy") print("long_2 %.6f %.6f" % (prj_long_2, gp_long_2)) print("lat_2 %.6f %.6f" % (prj_lat_2, gp_lat_2)) print("> DELTA pyproj, geopy") print("delta long_2 %.7f" % (prj_long_2 - gp_long_2)) print("delta lat_2 %.7f" % (prj_lat_2 - gp_lat_2)) I got this results:
| pyproj | geopy long_2 0.127201 0.127199 lat_2 53.188432 53.188432 > DELTA pyproj, geopy delta long_2 0.0000021 delta lat_2 -0.0000002 My main question is whether I am doing something wrong (both settings should be using WGS84).
If not, is the difference due to different formulas in use (Vincenty for geopy vs. Karney for pyproj)? E.g., the round-off error cited here.
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