thresh function

Thresholding

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

## 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

Returns

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. 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"))