#' @title Slope Position (Surface Texture)
#'
#' @description [slopePosition()] calculates scalable slope position by subtracting a focalmean raster
#' from the original elevation raster.
#'
#'
#' @param elevation \linkS4class{RasterLayer} containing elevation values
#' @param size analysis window (rectangle). Default: 3
#' @param output (optional) file name to save output. Default: NULL
#' @param load_output If TRUE, function output file will be loaded into R. Default: TRUE
#' @param quiet IF FALSE, console messages are shown. Default: TRUE
#' @param ... optional parameter for [RQGIS::run_qgis()]
#'
#' @return
#' \linkS4class{RasterLayer} slopePosition
#'
#'
#'
#' @keywords slope position
#'
#'
#' @export
slopePosition <- function(elevation = NULL, size = 3, output = NULL, load_output = TRUE, quiet = TRUE, ...)
{
if(quiet == FALSE)
{
process.time.start <- proc.time()
cat("Running Slope Position ...\n")
}
meanTmp <- RQGIS::run_qgis(alg = "grass7:r.neighbors", load_output = TRUE, show_output_paths = FALSE,
input = elevation, method = "average", size = size, output = file.path(tempdir(), "tmp_m.tif"), ...)
outRaster <- raster::overlay(x = elevation, y = meanTmp, fun = function(x, y){return(x-y)})
names(outRaster) <- "slopePosition"
if(!is.null(output))
{
# write data
if(quiet == FALSE) cat("... write raster\n")
raster::writeRaster(x = outRaster, filename = output, overwrite = TRUE)
}
if(quiet == FALSE) cat(paste0("------ Run of Slope Position: " , (proc.time() - process.time.start)["elapsed"][[1]]/60, " Minutes ------\n"))
if(load_output)
{
return(outRaster)
}
} # end of function slopePosition
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