Great-circle Segments Between Points on Earth

Each pair in the longitude and latitude vectors is considered in turn. For long vectors, this may be slow.

geodGc(longitude, latitude, dmax)

Arguments

longitude

vector of longitudes, in degrees east

latitude

vector of latitudes, in degrees north

dmax

maximum angular separation to tolerate between sub-segments, in degrees.

Value

Data frame of longitude and latitude.

References

1. http://williams.best.vwh.net/avform.htm#Intermediate (link worked for years but failed 2017-01-16).

See also

Other functions relating to geodesy: geodDist(), geodXy(), geodXyInverse()

Author

Dan Kelley, based on code from Clark Richards, in turn based on formulae provided by Ed Williams (see reference 1)].

Examples

# \donttest{
library(oce)
data(coastlineWorld)
mapPlot(coastlineWorld,
    type = "l",
    longitudelim = c(-80, 10), latitudelim = c(35, 80),
    projection = "+proj=merc"
)
# Great circle from New York to Paris (Lindberg's flight)
l <- geodGc(c(-73.94, 2.35), c(40.67, 48.86), 1)
mapLines(l$longitude, l$latitude, col = "red", lwd = 2)

# }