Generate Altitude Overlay
Using a hillshade and the height map, generates a semi-transparent hillshade to layer onto an existing map.
generate_altitude_overlay( hillshade, heightmap, start_transition, end_transition = NULL, lower = TRUE )
hillshade |
The hillshade to transition into. |
heightmap |
A two-dimensional matrix, where each entry in the matrix is the elevation at that point. All grid points are assumed to be evenly spaced. |
start_transition |
Elevation above which 'hillshade' is completely transparent. |
end_transition |
Default 'NULL'. Elevation below which 'hillshade' is completely opaque. By default, this is equal to 'start_transition'. |
lower |
Default 'TRUE'. This makes 'hillshade' completely opaque below 'start_transition'. If 'FALSE', the direction will be reversed. |
4-layer RGB array representing the semi-transparent hillshade.
#Create a bathymetric hillshade
#Only run these examples if the `magick` package is installed.
if ("magick" %in% rownames(utils::installed.packages())) {
water_palette = colorRampPalette(c("darkblue", "dodgerblue", "lightblue"))(200)
bathy_hs = height_shade(montereybay, texture = water_palette)
plot_map(bathy_hs)
#Set everything below 0m to water palette
montereybay %>%
sphere_shade(zscale=10) %>%
add_overlay(generate_altitude_overlay(bathy_hs, montereybay, 0, 0)) %>%
add_shadow(ray_shade(montereybay,zscale=50),0.3) %>%
plot_map()
#Add snow peaks by setting `lower = FALSE`
snow_palette = "white"
snow_hs = height_shade(montereybay, texture = snow_palette)
#Set the snow transition region from 500m to 1200m
montereybay %>%
sphere_shade(zscale=10, texture = "desert") %>%
add_overlay(generate_altitude_overlay(bathy_hs, montereybay, 0, 0)) %>%
add_overlay(generate_altitude_overlay(snow_hs, montereybay, 500, 1200, lower=FALSE)) %>%
add_shadow(ambient_shade(montereybay,zscale=50,maxsearch=100),0) %>%
plot_map()
}Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.