thresh: Thresholding

In rspatial/terra: Spatial Data Analysis

Thresholding

Description

Compute a threshold to divide the values of a SpatRaster into two groups, and use that threshold to classify the raster.

Usage

## S4 method for signature 'SpatRaster'
thresh(x, method="otsu", maxcell=1000000, combine=FALSE, 
			as.raster=TRUE, filename="", ...)

Arguments

x	SpatRaster
method	character. One of "mean", "median" or "otsu" for Otsu's method
maxcell	positive integer. Maximum number of cells to use to compute the threshold
combine	logical. If TRUE the layers of x are combined to compute a single threshold
as.raster	logical. If TRUE a classified SpatRaster is returned. Otherwise the threshold(s) are returned
filename	character. Output filename
...	additional arguments for writing files as in writeRaster

Value

numeric or SpatRaster

References

Otsu, N. (1979). A Threshold Selection Method from Gray-Level Histograms. IEEE Transactions on Systems, Man, and Cybernetics, 9(1), 62-66. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1109/TSMC.1979.4310076")}

See Also

divide

Examples

s <- rast(system.file("ex/logo.tif", package="terra"))
thresh(s, "mean", as.raster=FALSE)
thresh(s, "mean", combine=TRUE, as.raster=FALSE)


plot(thresh(s, "otsu"))

rspatial/terra documentation built on Feb. 9, 2025, 4:06 p.m.