Transforms an input `sf` object into an image overlay for the current height map.

generate_polygon_overlay(
  geometry,
  extent,
  heightmap = NULL,
  width = NA,
  height = NA,
  offset = c(0, 0),
  data_column_fill = NULL,
  linecolor = "black",
  palette = "white",
  linewidth = 1
)

Arguments

geometry

An `sf` object with POLYGON geometry.

extent

A `raster::Extent` object with the bounding box for the height map used to generate the original map.

heightmap

Default `NULL`. The original height map. Pass this in to extract the dimensions of the resulting overlay automatically.

width

Default `NA`. Width of the resulting overlay. Default the same dimensions as height map.

height

Default `NA`. Width of the resulting overlay. Default the same dimensions as height map.

offset

Default `c(0,0)`. Horizontal and vertical offset to apply to the polygon, in units of `geometry`.

data_column_fill

Default `NULL`. The column to map the polygon fill color to.

linecolor

Default `black`. Color of the lines.

palette

Default `black`. Single color, named vector color palette, or palette function. If this is a named vector and `data_column_fill` is not `NULL`, it will map the colors in the vector to the names. If `data_column_fill` is a numeric column, this will give a continuous mapping.

linewidth

Default `1`. Line width.

Value

Image overlay representing the input polygon data.

Examples

#Plot the counties around Monterey Bay, CA #Only run these examples if the `magick` package is installed. if (length(find.package("magick", quiet = TRUE)) > 0) { # \donttest{ generate_polygon_overlay(monterey_counties_sf, palette = rainbow, extent = attr(montereybay,"extent"), heightmap = montereybay) %>% plot_map() #These counties include the water, so we'll plot bathymetry data over the polygon #data to only include parts of the polygon that fall on land. water_palette = colorRampPalette(c("darkblue", "dodgerblue", "lightblue"))(200) bathy_hs = height_shade(montereybay, texture = water_palette) generate_polygon_overlay(monterey_counties_sf, palette = rainbow, extent = attr(montereybay,"extent"), heightmap = montereybay) %>% add_overlay(generate_altitude_overlay(bathy_hs, montereybay, start_transition = 0)) %>% plot_map() #Add a semi-transparent hillshade and change the palette, and remove the polygon lines montereybay %>% sphere_shade(texture = "bw") %>% add_overlay(generate_polygon_overlay(monterey_counties_sf, palette = terrain.colors, linewidth=NA, extent = attr(montereybay,"extent"), heightmap = montereybay), alphalayer=0.7) %>% add_overlay(generate_altitude_overlay(bathy_hs, montereybay, start_transition = 0)) %>% add_shadow(ray_shade(montereybay,zscale=50),0) %>% plot_map() #Map one of the variables in the sf object and use an explicitly defined color palette county_palette = c("087" = "red", "053" = "blue", "081" = "green", "069" = "yellow", "085" = "orange", "099" = "purple") montereybay %>% sphere_shade(texture = "bw") %>% add_shadow(ray_shade(montereybay,zscale=50),0) %>% add_overlay(generate_polygon_overlay(monterey_counties_sf, linecolor="white", linewidth=3, palette = county_palette, data_column_fill = "COUNTYFP", extent = attr(montereybay,"extent"), heightmap = montereybay), alphalayer=0.7) %>% add_overlay(generate_altitude_overlay(bathy_hs, montereybay, start_transition = 0)) %>% add_shadow(ray_shade(montereybay,zscale=50),0.5) %>% plot_map() # } }