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

 `1` ```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)

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

 `1` ```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.