Add Overlay — add_overlay • rayshader

Overlays an image (with a transparency layer) on the current map.

add_overlay(
  hillshade = NULL,
  overlay = NULL,
  alphalayer = 1,
  alphacolor = NULL,
  alphamethod = "max",
  color_epsilon = 0.001,
  rescale_original = FALSE
)

Arguments

hillshade: A three-dimensional RGB array or 2D matrix of shadow intensities.
overlay: A three or four dimensional RGB array, where the 4th dimension represents the alpha (transparency) channel. If the array is 3D, alphacolor should also be passed to indicate transparent regions.
alphalayer: Default 1. Defines minimum tranparaency of layer. If transparency already exists in overlay, the way add_overlay() combines the two is determined in argument alphamethod.
alphacolor: Default NULL. If overlay is a 3-layer array, this argument tells which color is interpretted as completely transparent.
alphamethod: Default max. Method for dealing with pre-existing transparency with layeralpha. If max, converts all alpha levels higher than layeralpha to the value set in layeralpha. Otherwise, this just sets all transparency to layeralpha.
color_epsilon: Default 1e-3. Tolerance for equality for alphacolor to determine transparency.
rescale_original: Default FALSE. If TRUE, hillshade will be scaled to match the dimensions of overlay (instead of the other way around).

Value

Hillshade with overlay.

Examples

#Combining base R plotting with rayshader's spherical color mapping and raytracing:
if(run_documentation()) {
montereybay |>
  sphere_shade() |>
  add_overlay(height_shade(montereybay),alphalayer = 0.6)  |>
  add_shadow(ray_shade(montereybay,zscale=50)) |>
  plot_map()
}


if(run_documentation()) {
#Add contours with `generate_contour_overlay()`
montereybay |>
  height_shade() |>
  add_overlay(generate_contour_overlay(montereybay))  |>
  add_shadow(ray_shade(montereybay,zscale=50)) |>
  plot_map()
}