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)
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 |
The bearing argument may be a vector when lon and lat are scalar, representing a single point.
A matrix of decimal degree coordinates with Eastings in the first column and Northings in the second column.
Eric Archer and Roger Bivand
the file earlier available at http:\/\/williams.best.vwh.net/avform.htm,
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
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)
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