Find destination in geographical coordinates

Find the destination in geographical coordinates at distance dist and for the given bearing from the starting point given by lon and lat.

gcDestination(lon, lat, bearing, dist, dist.units = "km",
 model = NULL, Vincenty = FALSE)

Arguments

lon: longitude (Eastings) in decimal degrees (either scalar or vector)
lat: latitude (Northings) in decimal degrees (either scalar or vector)
bearing: bearing from 0 to 360 degrees (either scalar or vector)
dist: distance travelled (scalar)
dist.units: units of distance "km" (kilometers), "nm" (nautical miles), "mi" (statute miles)
model: choice of ellipsoid model ("WGS84", "GRS80", "Airy", "International", "Clarke", "GRS67"
Vincenty: logical flag, default FALSE

Details

The bearing argument may be a vector when lon and lat are scalar, representing a single point.

Value

A matrix of decimal degree coordinates with Eastings in the first column and Northings in the second column.

References

http://www.movable-type.co.uk/scripts/latlong.html#ellipsoid,

the file earlier available at http:\/\/williams.best.vwh.net/avform.htm,

http://www.movable-type.co.uk/scripts/latlong-vincenty.html#direct,

Original reference https://www.ngs.noaa.gov/PUBS_LIB/inverse.pdf:

Vincenty, T. 1975. Direct and inverse solutions of geodesics on the ellipsoid with application of nested equations. Survey Review 22(176):88-93

Author

Eric Archer and Roger Bivand

Examples

data(state)
res <- gcDestination(state.center$x, state.center$y, 45, 250, "km")
plot(state.center$x, state.center$y, asp=1, pch=16)
arrows(state.center$x, state.center$y, res[,1], res[,2], length=0.05)

llist <- vector(mode="list", length=length(state.center$x))
for (i in seq(along=llist)) llist[[i]] <- gcDestination(state.center$x[i],
  state.center$y[i], seq(0, 360, 5), 250, "km")
plot(state.center$x, state.center$y, asp=1, pch=3)
nll <- lapply(llist, lines)