Working with imagery

Diego Hernangómez

mapSpain provides a powerful interface for working with imagery. It can download static files as .png or .jpeg (depending on the Web Map Service) and use them alongside your shapefiles.

mapSpain also provides a plugin for the R Leaflet package, which allows adding multiple basemaps to interactive maps.

The services are implemented via the Leaflet plugin leaflet-providersESP. You can view each provider option at that link.

Static tiles

An example showing how to include multiple tiles to create a static map. We focus on layers provided by La Rioja’s Infraestructura de Datos Espaciales (IDERioja).

When working with imagery, set moveCAN = FALSE; otherwise images for the Canary Islands may be inaccurate.

library(mapSpain)
library(sf)
library(ggplot2)
library(tidyterra)

# Logroño

lgn_borders <- esp_get_munic_siane(munic = "Logroño")

# Convert to Mercator (EPSG:3857) as a general advice when working with tiles
lgn_borders <- st_transform(lgn_borders, 3857)

tile_lgn <- esp_get_tiles(lgn_borders, "IDErioja", bbox_expand = 0.5)

ggplot(lgn_borders) +
  geom_spatraster_rgb(data = tile_lgn) +
  geom_sf(fill = NA, linewidth = 2, color = "blue")

Alpha value on tiles

Some tiles can be loaded with or without an alpha (transparency) value, which controls layer transparency:

madrid <- esp_get_ccaa("Madrid", epsg = 3857)

# Example without transparency

basemap <- esp_get_tiles(madrid, "IDErioja.Claro",
  zoommin = 1,
  crop = TRUE, bbox_expand = 0
)
tile_opaque <- esp_get_tiles(madrid, "RedTransporte.Carreteras",
  transparent = FALSE, crop = TRUE, bbox_expand = 0
)

ggplot() +
  geom_spatraster_rgb(data = basemap) +
  geom_spatraster_rgb(data = tile_opaque) +
  theme_void()

Now let’s check the same code using the transparent = TRUE option:

# Example with transparency

tile_alpha <- esp_get_tiles(madrid, "RedTransporte.Carreteras",
  transparent = TRUE, crop = TRUE, bbox_expand = 0
)

# Same code than above for plotting
ggplot() +
  geom_spatraster_rgb(data = basemap) +
  geom_spatraster_rgb(data = tile_alpha) +
  theme_void()

Now the two tiles overlap with the desired transparency.

Masking tiles

Another useful feature is the ability to mask tiles, allowing more advanced maps to be plotted:

rioja <- esp_get_prov("La Rioja", epsg = 3857)

basemap <- esp_get_tiles(rioja, "PNOA", bbox_expand = 0.1, zoommin = 1)

masked <- esp_get_tiles(rioja, "IDErioja", mask = TRUE, zoommin = 1)

ggplot() +
  geom_spatraster_rgb(data = basemap, maxcell = 10e6) +
  geom_spatraster_rgb(data = masked, maxcell = 10e6)

Custom providers

You can use esp_get_tiles() to get tiles of any other provider, for example OpenStreetMap:

osm_spec <- list(
  id = "OSM",
  q = "https://tile.openstreetmap.org/{z}/{x}/{y}.png"
)

madrid_city <- esp_get_munic_siane(munic = "^Madrid$", epsg = 3857)
madrid_osm <- esp_get_tiles(madrid_city, type = osm_spec, zoommin = 1)

ggplot() +
  geom_spatraster_rgb(data = madrid_osm) +
  geom_sf(data = madrid_city, fill = NA)

Another example using a provider that needs an API Key (ThunderForest):

# Skip if not API KEY
apikey <- Sys.getenv("THUNDERFOREST_API_KEY", "")
if (apikey != "") {
  thunder_spec <- list(
    id = "ThunderForest",
    q = paste0(
      "https://tile.thunderforest.com/transport/{z}/{x}/{y}.png?apikey=",
      apikey
    )
  )
  madrid_thunder <- esp_get_tiles(madrid_city, type = thunder_spec, zoommin = 1)

  ggplot() +
    geom_spatraster_rgb(data = madrid_thunder) +
    geom_sf(data = madrid_city, fill = NA)
}

Dynamic maps with Leaflet

mapSpain provides a plugin for the Leaflet package. Below are some quick examples:

Earthquakes in Tenerife (last year)

library(leaflet)

tenerife_leaf <- esp_get_nuts(
  region = "Tenerife", epsg = 4326,
  moveCAN = FALSE
)


bbox <- as.double(round(st_bbox(tenerife_leaf) + c(-1, -1, 1, 1), 2))

# Start leaflet
m <- leaflet(tenerife_leaf,
  elementId = "tenerife-earthquakes",
  width = "100%", height = "60vh",
  options = leafletOptions(minZoom = 9, maxZoom = 18)
)

# Add layers
m <- m |>
  addProviderEspTiles("IDErioja.Relieve") |>
  addPolygons(color = NA, fillColor = "red", group = "Polygon") |>
  addProviderEspTiles("Geofisica.Terremotos365dias",
    group = "Earthquakes"
  )

# Add additional options
m |>
  addLayersControl(
    overlayGroups = c("Polygon", "Earthquakes"),
    options = layersControlOptions(collapsed = FALSE)
  ) |>
  setMaxBounds(bbox[1], bbox[2], bbox[3], bbox[4])

Population density in Spain

A map showing the population density of Spain as of 2019:

library(leaflet)
library(dplyr)
munic <- esp_get_munic_siane(
  year = "2025-01-01",
  epsg = 4326,
  moveCAN = FALSE,
  rawcols = TRUE
) |>
  # Get area in km2 from siane munic
  # Already on the shapefile
  mutate(area_km2 = st_area_sh * 10000)


# Get population

pop <- mapSpain::pobmun25 |>
  select(-name)

# Paste
munic_pop <- munic |>
  left_join(pop) |>
  mutate(
    dens = pob25 / area_km2,
    dens_label = prettyNum(round(dens, 2),
      big.mark = ".",
      decimal.mark = ","
    )
  )

# Create leaflet
bins <- c(0, 10, 25, 100, 200, 500, 1000, 5000, 10000, Inf)


pal <- colorBin("inferno", domain = munic_pop$dens, bins = bins, reverse = TRUE)

labels <- sprintf(
  "<strong>%s</strong><br/><em>%s</em><br/>%s pers. / km<sup>2</sup>",
  munic_pop$rotulo,
  munic_pop$ine.prov.name,
  munic_pop$dens_label
) |> lapply(htmltools::HTML)


leaflet(elementId = "SpainDemo", width = "100%", height = "60vh") |>
  setView(lng = -3.684444, lat = 40.308611, zoom = 5) |>
  addProviderEspTiles("IDErioja") |>
  addPolygons(
    data = munic_pop,
    fillColor = ~ pal(dens),
    fillOpacity = 0.6,
    color = "#44444",
    weight = 0.5,
    smoothFactor = .1,
    opacity = 1,
    highlightOptions = highlightOptions(
      color = "white",
      weight = 1,
      bringToFront = TRUE
    ),
    popup = labels
  ) |>
  addLegend(
    pal = pal, values = bins, opacity = 0.7,
    title = paste0(
      "<small>Pop. Density km<sup>2</sup></small><br><small>",
      "(2025)</small>"
    ),
    position = "bottomright"
  )