gcDestination {maptools}R Documentation

Find destination in geographical coordinates

Description

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

Usage

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.

Author(s)

Eric Archer and Roger Bivand

References

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

http://williams.best.vwh.net/avform.htm,

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

Original reference http://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

See Also

gzAzimuth

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)

[Package maptools version 0.7-20 Index]