Simulates a fractal DEM

Simulates z-values based on the Diamond-square algorithm.

Usage

sim_dem(
  L,
  smoothness,
  H,
  R,
  plot = FALSE,
  prop = 0.1,
  n = 100,
  method = "area",
  parallel = FALSE
)

Arguments

L

The extent.

smoothness

A value between 0.0 and 1.0 (lower values produce rougher DEM).

H

Desired height range (optional).

R

Desired rugosity value (optional).

plot

Logical. Plot the simulated DEM during simulation? Only relevant if R is provided.

prop

Proportion of cells that undergo smoothing at each iteration when R is provided.

n

Number of iterations to try and reach desired R. Recommended to adapt R and H instead of increasing n if simulation fails.

method

The method to be used for rugosity calculation in case R is given. Can be "hvar" or "area"

parallel

Logical. Use parallel processing? Defaults to FALSE. Only relevant if method = "hvar".

Value

Digital elevation model of class RasterLayer.

Details

Warning: this function gets slow for n > 128. If H is provided, the simulated DEM is rescaled based on the value for H. If R is provided, a DEM is simulated using the same algorithm based on R, H, and the predicted D based on rdh_theory(), while smoothness is ignored. From that first simulated DEM, R is calculated and the DEM undergoes smoothing at each iteration until the rugosity approximates the inputted R. Argument prop defined the proportion of random cells of the DEM that are smoothed by averaging the z values of cell and neighboring cells at each iteration. Caution: When R is provided, the DEM may become increasingly less fractal as it is modified at each iteration.

Examples

library(raster)
#> Loading required package: sp
#> 
#> Attaching package: ‘raster’
#> The following object is masked from ‘package:habtools’:
#> 
#>     extent
dem <- sim_dem(L = 32, smoothness = 0.5)
plot(dem)

dem <- sim_dem(L = 32, smoothness = 0.2, H = 20)
plot(dem)