#' @title Dissection (Surface Texture)
#'
#' @description [dissection()] describes dissection in a continuous raster surface
#' within rectangular or circular window. Martonne’s modified dissection is calculated
#' as: d = ( z - z(min)) / (z(max) - z(min)).
#'
#'
#' @param elevation \linkS4class{RasterLayer} containing elevation values
#' @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} dissection
#'
#'
#'
#' @keywords dissection
#'
#'
#' @export
dissection <- function(elevation = NULL, size = 3, output = NULL, load_output = TRUE, quiet = TRUE, ...)
{
if(quiet == FALSE)
{
process.time.start <- proc.time()
cat("Running Dissection ...\n")
}
tmp1 <- RQGIS::run_qgis(alg = "grass7:r.neighbors", load_output = TRUE, show_output_paths = FALSE,
input = elevation, method = "minimum", size = size, output = file.path(tempdir(), "tmp1_min.tif"), ...)
tmp2 <- RQGIS::run_qgis(alg = "grass7:r.neighbors", load_output = TRUE, show_output_paths = FALSE,
input = elevation, method = "maximum", size = size, output = file.path(tempdir(), "tmp2_max.tif"), ...)
conTmp <- raster::overlay(x = tmp2, y = tmp1, fun = function(x, y){return(x-y)})
outVal <- raster::overlay(x = conTmp, y = tmp1, z = elevation, fun = function(x, y, z){return((z-y)/x)})
outRaster <- raster::overlay(x = outVal, y = conTmp, fun = function(x, y){ifelse(y == 0, 0, x)})
names(outRaster) <- "dissection"
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 Dissection: " , (proc.time() - process.time.start)["elapsed"][[1]]/60, " Minutes ------\n"))
if(load_output)
{
return(outRaster)
}
} # end of function dissection
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