Three-dimensional focal values

Calculate focal ("moving window") values for the three-dimensional neighborhood (window) of focal cells. See focal for two-dimensional focal computation.

# S4 method for SpatRaster
focal3D(x, w=3, fun=mean, ..., na.policy="all", fillvalue=NA, pad=FALSE, 
  padvalue=fillvalue, expand=FALSE, silent=TRUE, 
  filename="", overwrite=FALSE, wopt=list())

Arguments

x

SpatRaster

w

window. A rectangular prism (cuboid) defined by three numbers or by a three-dimensional array. The values are used as weights, and are usually zero, one, NA, or fractions. The window used must have odd dimensions. If you desire to use even sides, you can use an array, and pad the values with rows and/or columns that contain only NAs.

fun

function that takes multiple numbers, and returns one or multiple numbers for each focal area. For example mean, modal, min or max

...

additional arguments passed to fun such as na.rm

na.policy

character. Can be used to determine the cells of x, in the central layer, for which focal values should be computed. Must be one of "all" (compute for all cells), "only" (only for cells that are NA) or "omit" (skip cells that are NA). Note that the value of this argument does not affect which cells around each focal cell are included in the computations (use na.rm=TRUE to ignore cells that are NA in the computation of the focal value)

fillvalue

numeric. The value of the cells in the virtual rows and columns outside of the raster

pad

logical. Add virtual layers before the first and after the last layer

padvalue

numeric. The value of the cells in the virtual layers

expand

logical. Add virtual layers before the first or after the last layer that are the same as the first or last layers. If TRUE, arguments pad and padvalue are ignored

silent

logical. If TRUE error messages are printed that may occur when trying fun to determine the length of the returned value. This can be useful in debugging a function passed to fun that does not work

filename

character. Output filename

overwrite

logical. If TRUE, filename is overwritten

wopt

additional arguments for writing files as in writeRaster

Value

SpatRaster

See also

focal

Examples

r <- rast(system.file("ex/logo.tif", package="terra"))   
x <- focal3D(r, c(5,5,3), na.rm=TRUE)

a <- array(c(0,1,0,1,1,1,0,1,0, rep(1,9), 0,1,0,1,1,1,0,1,0), c(3,3,3))
a[a==0] <- NA
z <- focal3D(r, a, na.rm=TRUE)