terra (version 1.6-17)

costDistance: Cost distance

Description

Use a friction (cost) surface to compute the cost-distance from any cell to one or more target cells.

Distances are computed by summing local distances between cells, which are connected with their neighbors in 8 directions, and assuming that the path has to go through the centers of one of the neighboring raster cells.

Distances are multiplied with the friction, thus to get the cost-distance, the friction surface must express the cost per unit distance (speed) of travel.

If the coordinate reference system (CRS) of the SpatRaster is longitude/latitude (+proj=longlat) the distance is in meters divided by variable m. The default of m is 1000, expressing distance in km. Otherwise the distance is in the units of the CRS (typically meters).

Usage

# S4 method for SpatRaster
costDistance(x, target=0, scale=1000, maxiter=50, filename="", ...)

Value

SpatRaster

Arguments

x

SpatRaster

target

numeric. value of the target cells (where to compute cost-distance to)

scale

numeric. Scale factor for longitude/latitude data (1 = m, 1000 = km)

maxiter

numeric. The maximum number of iterations. Increase this number if you get the warning that costDistance did not converge

filename

character. output filename (optional)

...

additional arguments as for writeRaster

See Also

gridDistance, distance

Examples

r <- rast(ncols=5, nrows=5, crs="+proj=utm +zone=1 +datum=WGS84", 
		xmin=0, xmax=5, ymin=0, ymax=5, vals=1)
r[13] <- 0
d <- costDistance(r)
plot(d)
text(d, digits=1)

r <- rast(ncols=10, nrows=10,  xmin=0, xmax=10, ymin=0, ymax=10, 
		vals=10, crs="+proj=utm +zone=1 +datum=WGS84")
r[5, 1] <- -10
r[2:3, 1] <- r[1, 2:4] <- r[2, 5] <- 0
r[3, 6] <- r[2, 7] <- r[1, 8:9] <- 0
r[6, 6:10] <- NA
r[6:9, 6] <- NA

d <- costDistance(r, -10)
plot(d)
text(d, digits=1, cex=.8)