R/fwDEM.R

In rasterFW: raster and FWtools

# Author: Lyndon Estes
# Changes by Robert Hijmans

fwDEM <- function(dem, type='slope', filename="", options=NULL, format='GTiff') {
# Runs gdaldem to create hillshade, slope, aspect, color-relief, TRI, TPI, or roughness surfaces from a DEM
# See http://www.gdal.org/gdaldem.html for more details
	fwp <- paste(fwPath(), 'gdaldem', sep='')
	stopifnot(type %in% c("hillshade", "slope", "aspect", "color-relief", "TRI", "TPI", "roughness"))
	
	dem <- .getFilename(dem, nl=1)
	if (trim(filename) == "") {
		filename <- rasterTmpFile()
		extension(filename) <- 'tif'
	}
	
	fullcall <- paste(fwp, type, shQuote(dem), shQuote(filename), "-of", format, options)
	x <- system(fullcall)
	if (x==0) {
		return( raster(filename) )
	} else {
		stop('an error occurred')
	}
}