Makes the base below the 3D elevation map.
generate_soil_textures(
heightmap,
base_depth = 10,
color1 = "#7d6f5b",
color2 = "#3b3020",
freq = 0.1,
zscale = 1,
levels = 8,
soil_gradient = 0,
gradient_darken = 4
)
Height matrix;
Default `tan`.
Default `brown`.
Default `1`. The ratio between the x and y spacing (which are assumed to be equal) and the z axis. For example, if the elevation levels are in units of 1 meter and the grid values are separated by 10 meters, `zscale` would be 10.