makeWorld.RdFunction that defines the grid that can be traversed--the "world"--as well as the cells that can be accessed from each individual cell. This is the most time-intensive function.
A character vector--such as the output to
whichTiles---containing the unique tile IDs for sectors that
should be in the workspace. Default is NULL.
A filepath to the directory being used as the workspace, the same
one instantiated with defineWorld.
Default is tempdir() but unless the analyses will only be performed a few
times it is highly recommended to define a permanent workspace.
A character vector containing the name of the important
spatial variables to be retained. Default is
cols = c("x_i","y_i","z_i","z_f","dz","dl","dr"),
but c("x_f","y_f") are also available.
A character string or vector, consisting of one or both of
c('file','object'), representing whether a file should be written and/or
whether an object should be returned. Default is output = file.
An .fst file for each sector named after its sector id
stored in the /World/Diff directory, and/or a data.table object (depending
on the output parameter) containing a data.table with five columns
(1) $from, a character string of all possible origin cells in format "x,y",
rounded to the next-lowest integer
(2) $to, a character string of all possible destination cells in format "x,y"
rounded to the next-lowest integer
(3) $dz, a numeric representing the change in elevation for each origin-destination pair
(4) $dl, a numeric representing the change in planimetric distance (x,y)
(5) $dr, a numeric representing the change in displacement (x,y,z)
Likewise, in the /World/Loc directory the local z elevation
values projected to the locally defined grid as a writeRST file.
It first checks to see if the required elevation models have been downloaded
for each source file for the requested tiles grid, and then if transition .gz
then if they have been converted to a sector's local
files have already been created in the dir workspace. If not,
it generates each at each step
# Generate a DEM
n <- 5
dem <- expand.grid(list(x = 1:(n * 100),
y = 1:(n * 100))) / 100
dem <- as.data.table(dem)
dem[, z := 250 * exp(-(x - n/2)^2) +
250 * exp(-(y - n/2)^2)]
#> x y z
#> 1: 0.01 0.01 1.0146139
#> 2: 0.02 0.01 1.0404641
#> 3: 0.03 0.01 1.0675194
#> 4: 0.04 0.01 1.0958300
#> 5: 0.05 0.01 1.1254477
#> ---
#> 249996: 4.96 5.00 1.0711366
#> 249997: 4.97 5.00 1.0428260
#> 249998: 4.98 5.00 1.0157707
#> 249999: 4.99 5.00 0.9899205
#> 250000: 5.00 5.00 0.9652271
dem <- rast(dem)
ext(dem) <- c(10000, 20000, 30000, 40000)
crs(dem) <- "+proj=lcc +lat_1=48 +lat_2=33 +lon_0=-100 +datum=WGS84"
# Export it so it doesn't just exist on the memory
dir <- tempdir()
writeRaster(dem, paste0(dir,"/DEM.tif"),overwrite=TRUE)
# Import raster, get the grid
dem <- rast(paste0(dir,"/DEM.tif"))
grid <- makeGrid(dem = dem, nx = n, ny = n, sources = TRUE)
# Select all tiles that exist between x = (12000,16000) and y = (32000,36000)
tiles <- ext(c(12000,16000,32000,36000))
tiles <- as.polygons(tiles)
crs(tiles) <- crs(grid)
tiles <- whichTiles(region = tiles, polys = grid)
# Make a world but limit it to the DEM grid size
defineWorld(source = grid, cut_slope = 0.5,
res = res(dem), dir = dir, overwrite=TRUE)
makeWorld(tiles = tiles, dir = dir)
#> [1] "Cropping Tile SECTOR_01 (1 of 4)"
#> [1] "Cropping Tile SECTOR_02 (2 of 4)"
#> [1] "Cropping Tile SECTOR_06 (3 of 4)"
#> [1] "Cropping Tile SECTOR_07 (4 of 4)"
#> [1] "Cropping Tile SECTOR_03 (1 of 2)"
#> [1] "Cropping Tile SECTOR_08 (2 of 2)"
#> [1] "Cropping Tile SECTOR_11 (1 of 2)"
#> [1] "Cropping Tile SECTOR_12 (2 of 2)"
#> [1] "Cropping Tile SECTOR_13 (1 of 1)"
#> [1] "Cropping Tile SECTOR_16 (1 of 2)"
#> [1] "Cropping Tile SECTOR_17 (2 of 2)"
#> [1] "Cropping Tile SECTOR_18 (1 of 1)"
#> [1] "Cropping Tile SECTOR_09 (1 of 3)"
#> [1] "Cropping Tile SECTOR_14 (2 of 3)"
#> [1] "Cropping Tile SECTOR_19 (3 of 3)"
#> [1] "Cropping Tile SECTOR_21 (1 of 2)"
#> [1] "Cropping Tile SECTOR_22 (2 of 2)"
#> [1] "Cropping Tile SECTOR_23 (1 of 1)"
#> [1] "Cropping Tile SECTOR_04 (1 of 1)"
#> [1] "Cropping Tile SECTOR_05 (1 of 2)"
#> [1] "Cropping Tile SECTOR_10 (2 of 2)"
#> [1] "Cropping Tile SECTOR_15 (1 of 1)"
#> [1] "Cropping Tile SECTOR_24 (1 of 1)"
#> [1] "Cropping Tile SECTOR_20 (1 of 1)"
#> [1] "Cropping Tile SECTOR_25 (1 of 1)"