Download_DEM-file.R

#Quelle: http://www.gis-blog.com/download-srtm-for-an-entire-country/
library(raster)
library(rgeos)
library(rasterVis)


#------------SETTINGS--------------

#Specify target ISO country code and path to downloaded shapefile

country_name <- "AUT"                             #Austria
shp          <- shapefile("srtm/tiles.shp")       #Path to SRTM Tiles (can be found in subfolder srtm)


#------------EXECUTE FROM HERE--------------

#Get country geometry first
country <- getData("GADM", 
                   country = country_name, 
                   level=0)

#Intersect country geometry with tile grid
intersects <- gIntersects(country, shp, byid=T)
tiles      <- shp[intersects[,1],]


#Download tiles
srtm_list  <- list()
for(i in 1:length(tiles)) {
        lon <- extent(tiles[i,])[1]  + (extent(tiles[i,])[2] - extent(tiles[i,])[1]) / 2
        lat <- extent(tiles[i,])[3]  + (extent(tiles[i,])[4] - extent(tiles[i,])[3]) / 2
        
        tile <- try(getData('SRTM', 
                        lon=lon, 
                        lat=lat))
        
        srtm_list[[i]] <- tile
}

# AB HIER FUNKTIONIERTS NICHT MEHR (auf Linux)
# #Mosaic
# srtm_list$fun <- mean 
# srtm_mosaic   <- do.call(mosaic, srtm_list)
# 
# #Crop to country borders
# srtm_crop     <- mask(srtm_mosaic, country)
# 
# #Plot results
# p <- levelplot(srtm_crop)
# p + layer(sp.lines(country, 
#                    lwd=0.8, 
#                    col='darkgray'))