4.4 Validity

Maps of Antarctica should probably display the South Pole. Do the following maps display the South Pole?

4.4.1 Planar (Ellipsoidal Coordinates)

# maps package
m <- st_as_sf(map(fill=TRUE, plot=FALSE))
Antarctica_map_A <- m[m$ID == "Antarctica", ]
st_geometry(Antarctica_map_A) |>
  ggplot() + 
  geom_sf() +
  labs(title = "Antarctica", 
       subtitle = "Think of the latitude",
       caption = "Spatial Data Science book club")

sf::st_is_valid(Antarctica_map_A)

## [1] TRUE

# Natural Earth package
ne <- ne_countries(returnclass = "sf")
Antarctica_map_B <- ne[ne$region_un == "Antarctica", "region_un"]
st_geometry(Antarctica_map_B) |>
  ggplot() + 
  geom_sf() +
  labs(title = "Antarctica", 
       subtitle = "Think of the latitude",
       caption = "Spatial Data Science book club")

sf::st_is_valid(Antarctica_map_B)

## [1] TRUE

4.4.2 Spherical (Polar Stereographic Projection)

Antarctica_map_C <- st_geometry(Antarctica_map_A) |>
  st_transform(3031)
Antarctica_map_C |> 
  ggplot() + 
  geom_sf() +
  labs(title = "Antarctica", 
       subtitle = "Think of the latitude",
       caption = "Spatial Data Science book club")

sf::st_is_valid(Antarctica_map_C)

## [1] TRUE

Antarctica_map_D <- st_geometry(Antarctica_map_B) |>
  st_transform(3031)
Antarctica_map_D |> 
  ggplot() + 
  geom_sf() +
  labs(title = "Antarctica", 
       subtitle = "Think of the latitude",
       caption = "Spatial Data Science book club")

sf::st_is_valid(Antarctica_map_D)

## [1] TRUE