Add Overlay — add_overlay • rayshader

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

add_overlay(
  hillshade,
  overlay,
  alphalayer = 1,
  alphacolor = NULL,
  alphamethod = "max",
  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`.
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(rayshader:::run_documentation()) {
montereybay %>%
  sphere_shade() %>%
  add_overlay(height_shade(montereybay),alphalayer = 0.6)  %>%
  add_shadow(ray_shade(montereybay,zscale=50)) %>%
  plot_map()
}


if(rayshader:::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()
}