bearing: Direction of travel

In geosphere: Spherical Trigonometry

Description

Get the initial bearing (direction; azimuth) to go from point p1 to point p2 (in longitude/latitude) following the shortest path on an ellipsoid (geodetic). Note that the bearing of travel changes continuously while going along the path. A route with constant bearing is a rhumb line (see bearingRhumb).

Usage

bearing(p1, p2, a=6378137, f=1/298.257223563)

Arguments

p1	longitude/latitude of point(s). Can be a vector of two numbers, a matrix of 2 columns (first one is longitude, second is latitude) or a SpatialPoints* object
p2	as above. Can also be missing, in which case the bearing is computed going from the first point to the next and continuing along the following points
a	major (equatorial) radius of the ellipsoid. The default value is for WGS84
f	ellipsoid flattening. The default value is for WGS84

Value

Bearing in degrees

Note

use f=0 to get a bearing on a sphere (great circle)

Author(s)

Robert Hijmans

References

C.F.F. Karney, 2013. Algorithms for geodesics, J. Geodesy 87: 43-55. https://dx.doi.org/10.1007/s00190-012-0578-z. Addenda: http://geographiclib.sf.net/geod-addenda.html. Also see http://geographiclib.sourceforge.net/

See Also

bearingRhumb

Examples

bearing(c(10,10),c(20,20))

Example output

Loading required package: sp
[1] 42.99295

geosphere documentation built on May 2, 2019, 5:16 p.m.