Along Track Distance
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"
alongTrackDistance(p1, p2, p3, r=6378137)
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 |
A distance in units of r (default is meters)
Ed Williams and Robert Hijmans
alongTrackDistance(c(0,0),c(60,60),c(50,40))
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