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 )
Arguments
| 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. |
Value
4-layer RGB array representing the semi-transparent hillshade.
Examples
#Create a bathymetric hillshade # \donttest{ 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()# }
