add_overlay {rayshader}

Add Overlay

Description

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

Usage

add_overlay(
  hillshade = NULL,
  overlay = NULL,
  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(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()
}