Add Overlay
Overlays an image (with a transparency layer) on the current map.
add_overlay( hillshade, overlay, alphacolor = NULL, alphamethod = "max", alphalayer = 1, rescale_original = FALSE )
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. |
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'. |
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'. |
rescale_original |
Default 'FALSE'. If 'TRUE', 'hillshade' will be scaled to match the dimensions of 'overlay' (instead of the other way around). |
Hillshade with overlay.
#Only run these examples if the `magick` package is installed.
if ("magick" %in% rownames(utils::installed.packages())) {
#Combining base R plotting with rayshader's spherical color mapping and raytracing:
montereybay %>%
sphere_shade() %>%
add_overlay(height_shade(montereybay),alphalayer = 0.6) %>%
add_shadow(ray_shade(montereybay,zscale=50)) %>%
plot_map()
#Add contours with `generate_contour_overlay()`
montereybay %>%
height_shade() %>%
add_overlay(generate_contour_overlay(montereybay)) %>%
add_shadow(ray_shade(montereybay,zscale=50)) %>%
plot_map()
}Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.