Surface area of the earth

[mtennekes]

Trying to find out the surface area of the earth:

sf::FULL_bbox_ |> st_as_sfc() |> st_area()

returns 0

[tim-salabim]

For me this gives

> library(sf)
Linking to GEOS 3.12.1, GDAL 3.8.4, PROJ 9.3.1; sf_use_s2() is TRUE
> sf::FULL_bbox_ |> st_as_sfc() |> st_area()
5.100661e+14 [m^2]

with sf_use_s2(FALSE)

> sf_use_s2(F)
Spherical geometry (s2) switched off
> sf::FULL_bbox_ |> st_as_sfc() |> st_area()
0 [m^2]

[edzer]

And

> sf_use_s2(TRUE); sf::FULL_bbox_ |> st_as_sfc() |> st_set_crs(NA) |> st_area()
Spherical geometry (s2) switched on
[1] 0
> sf_use_s2(FALSE); sf::FULL_bbox_ |> st_as_sfc() |> st_set_crs(NA) |> st_area()
Spherical geometry (s2) switched off
[1] 64800

which, I guess, should be an error for the first case: POLYGON FULL does not have an equivalence in R2 (NA crs)

[edzer]

Gives (order reversed)

library(sf)
# Linking to GEOS 3.12.1, GDAL 3.8.4, PROJ 9.4.0; sf_use_s2() is TRUE
sf_use_s2(FALSE); sf::FULL_bbox_ |> st_as_sfc() |> st_set_crs(NA) |> st_area()
# Spherical geometry (s2) switched off
# [1] 64800
sf_use_s2(TRUE); sf::FULL_bbox_ |> st_as_sfc() |> st_set_crs(NA)
# Spherical geometry (s2) switched on
# Error in `st_crs<-.sfc`(`*tmp*`, value = value) : 
#   To set the crs to NA, first remove the full polygons; see: st_is_full()