Distance from points

The function calculates the distance from a set of points to all cells of a Raster* object.

The distance unit is in meters if the coordinate reference system (crs) of the Raster* object is (+proj=longlat) or assumed to be if the crs is NA. In all other cases it is in the units defined by the crs (which typically is meters).

Usage

distanceFromPoints(object, xy, filename='', ...)

Arguments

object: Raster object
xy: matrix of x and y coordinates, or a SpatialPoints* object.
filename: character. Optional filename for the output RasterLayer
...: Additional arguments as for writeRaster

Details

Distances for longlat data are computed on the WGS84 spheroid using GeographicLib (Karney, 2013)

References

C.F.F. Karney, 2013. Algorithms for geodesics, J. Geodesy 87: 43-55. doi:10.1007/s00190-012-0578-z .

Value

RasterLayer

Examples

r <- raster(ncol=36,nrow=18)
xy <- c(0,0)
d1 <- distanceFromPoints(r, xy) 
crs(r) = '+proj=utm +zone=12 +datum=WGS84'
d2 <- distanceFromPoints(r, xy) 
par(mfrow=c(1,2))
plot(d1)
plot(d2)