destPoint function

Destination given bearing (direction) and distance

Given a start point, initial bearing (direction), and distance, this function computes the destination point travelling along a the shortest path on an ellipsoid (the geodesic). 1.1

destPoint(p, b, d, a=6378137, f=1/298.257223563, ...)

Arguments

• p: Longitude and Latitude of point(s), in degrees. Can be a vector of two numbers, a matrix of 2 columns (first one is longitude, second is latitude) or a SpatialPoints* object
• b: numeric. Bearing (direction) in degrees
• d: numeric. Distance in meters
• a: major (equatorial) radius of the ellipsoid. The default value is for WGS84
• f: ellipsoid flattening. The default value is for WGS84
• ...: additional arguments. If an argument 'r' is supplied, this is taken as the radius of the earth (e.g. 6378137 m) and computations are for a sphere (great circle) instead of an ellipsoid (geodetic). This is for backwards compatibility only

Note

Direction changes continuously when travelling along a geodesic. Therefore, the final direction is not the same as the initial direction. You can compute the final direction with finalBearing (see examples, below)

Returns

A pair of coordinates (longitude/latitude)

Author(s)

This function calls GeographicLib code by C.F.F. Karney

References

C.F.F. Karney, 2013. Algorithms for geodesics, J. Geodesy 87: 43-55. tools:::Rd_expr_doi("10.1007/s00190-012-0578-z") . Addenda: https://geographiclib.sourceforge.io/geod-addenda.html. Also see https://geographiclib.sourceforge.io/

Examples

p <- cbind(5,52)
d <- destPoint(p,30,10000)
d

#final direction, when arriving at endpoint: 
finalBearing(d, p)