Plot a landform classification — plot.landform • landform

Plots the map of the classes, a bar plot of the area of each class, or the standardised TPI surface(s), from an object returned by landform.

Usage

# S3 method for class 'landform'
plot(
  x,
  what = c("classes", "area", "tpi"),
  shade = c("none", "slope", "hill"),
  alpha = 0.6,
  leg.pos = NULL,
  leg.cex = 0.8,
  main = NULL,
  ...
)

Arguments

x: An object of class "landform".
what: What to plot: "classes" (default), "area", or "tpi".
shade: Relief shading drawn underneath the classes or the TPI: "none" (default), "slope" (a slopeshade, that is the slope in grey levels from white for flat terrain to black for the steepest slopes), or "hill" (a hillshade, lit from the north-west at 45 degrees). See Details.
alpha: Opacity (0 to 1) of the classes or TPI drawn over the shading. Default 0.6. Ignored when shade = "none".
leg.pos: Legend position for the map (a legend keyword); NULL (default) places it outside the map, to its right.
leg.cex: Magnification of the legend text. Default 0.8.
main: Plot title; a sensible default is used if NULL.
...: Further arguments passed to plot (for maps) or barplot (for what = "area").

Value

x, invisibly.

Details

A slopeshade conveys relief without the directional bias of a hillshade: features facing away from the light are not darkened, and steepness is shown in the same way whatever the aspect. The grey scale is stretched between 0 degrees and the 99th percentile of slope, so that a few very steep cells do not flatten the contrast elsewhere.

Examples

dem <- malta_dtm()
sp <- landform(dem, scale = 9, plot = FALSE)
plot(sp)

plot(sp, shade = "slope")

plot(sp, what = "area")

plot(sp, what = "tpi", shade = "slope", alpha = 0.5)