Calculate focal ("moving window") values for each cell of a raster using various functions. NAs are always omitted; thus, this stage effectively acts as an NA filler. The window is always circular. The edges are handled by adjusting the window.
Usage
focal(raster, size, fun = "mean", ofile = temptif())Arguments
- raster
LASRalgorithm. A stage that produces a raster.
- size
numeric. The window size **in the units of the point cloud**, not in pixels. For example, 2 means 2 meters or 2 feet, not 2 pixels.
- fun
string. Function to apply. Supported functions are 'mean', 'median', 'min', 'max', 'sum'.
- ofile
character. Full outputs are always stored on disk. If
ofile = ""then the stage will not store the result on disk and will return nothing. It will however hold partial output results temporarily in memory. This is useful for stage that are only intermediate stage.
Value
This stage produces a raster. The path provided to `ofile` is expected to be `.tif` or any other format supported by GDAL.
Examples
f <- system.file("extdata", "Topography.las", package = "lasR")
chm = rasterize(2, "zmax")
chm2 = lasR:::focal(chm, 8, fun = "mean")
chm3 = lasR:::focal(chm, 8, fun = "max")
pipeline <- reader() + chm + chm2 + chm2
ans = exec(pipeline, on = f)
terra::plot(ans[[1]])
terra::plot(ans[[2]])
terra::plot(ans[[3]])