alongTrackDistance {geosphere}

Along Track Distance

Description

The "along track distance" is the distance from the start point (p1) to the closest point on the path to a third point (p3), following a great circle path defined by points p1 and p2. See dist2gc for the "cross track distance"

Usage

alongTrackDistance(p1, p2, p3, r=6378137)

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

p3

as above

r

radius of the earth; default = 6378137m

Value

A distance in units of r (default is meters)

Author(s)

Ed Williams and Robert Hijmans

See Also

dist2gc

Examples

alongTrackDistance(c(0,0),c(60,60),c(50,40))