adding point data to globe perspective in R

Question

I have duplicated the solution to creating a 3-dimensional plot of the earth provided by @jindra-lacko (plot geodata on the globe perspective in R). All I want to be able to do is to plot data points on this map. However, no matter what approach I try I end up with only a single point right in the middle of the plot.

As a simple example, here I am trying to create two points from the dataframe 'closures'. However, only a single point is created in the middle of the plot. I have not been able to create more than one point and not able to change the position of that point. Feels like there should be an easy solution but I am stumped. Thanks.

library(sf)
library(giscoR) # for the countries dataset only
library(ggplot2)

# projection string used for the polygons & ocean background
crs_string <- "+proj=ortho +lon_0=-30 +lat_0=50"

# background for the globe - center buffered by earth radius
ocean <- st_point(x = c(0,0)) %>%
  st_buffer(dist = 6371000) %>%
  st_sfc(crs = crs_string)

# country polygons, cut to size
world <- gisco_countries %>% 
  st_intersection(ocean %>% st_transform(4326)) %>% # select visible area only
  st_transform(crs = crs_string) # reproject to ortho

# one of the visible ones red (don't really matter which one :)
world$fill_color <- ifelse(world$ISO3_CODE == "DEU", "interesting", "dull")

closures <- data.frame(
  x = c(-30,-40),
  y = c(40,50),
  label = c("1","2")
)

closures <- sf::st_as_sf(closures, 
                       coords = c("x", "y"),
                       crs = crs_string)


# now the action!
ggplot(data = world) +
  geom_sf(data = ocean, fill = "aliceblue", color = NA) + # background first
  geom_sf(aes(fill = fill_color), lwd = .1) + # now land over the oceans
  scale_fill_manual(values = c("interesting" = "lightyellow", #change colour here to highlight a specific country
                               "dull" = "lightyellow"),
                    guide = "none") +
  geom_sf(data = closures,
          aes(geometry = geometry),
          size = 7,
          shape = 21,
          color = "white",
          fill="red") +
  theme_void()

Answer 1

The issue is that you are telling sf that your lon lat coordinates are in the "+proj=ortho +lon_0=-30 +lat_0=50" projection, but they haven't been projected quite yet. First, you should set the crs as WGS 1984 (epsg:4326) then you can transform/project them into "+proj=ortho +lon_0=-30 +lat_0=50".

library(sf)
#> Linking to GEOS 3.12.1, GDAL 3.8.4, PROJ 9.3.1; sf_use_s2() is TRUE
library(giscoR) # for the countries dataset only
#> Warning: package 'giscoR' was built under R version 4.4.1
library(ggplot2)

crs_string <- "+proj=ortho +lon_0=-30 +lat_0=50"

ocean <- st_point(x = c(0,0)) %>%
  st_buffer(dist = 6371000) %>%
  st_sfc(crs = crs_string)

world <- gisco_countries %>% 
  st_intersection(ocean %>% st_transform(4326)) %>%
  st_transform(crs = crs_string)
#> Warning: attribute variables are assumed to be spatially constant throughout
#> all geometries

world$fill_color <- ifelse(world$ISO3_CODE == "DEU", "interesting", "dull")
   
closures <- data.frame(
  x = c(-30,-50),
  y = c(40,50),
  label = c("1","2")
)

closures <- sf::st_as_sf(closures, 
                       coords = c("x", "y"),
                       crs = 4326) %>% # read into WGS 1984
  st_transform(crs = crs_string) # transform into projection

ggplot(data = world) +
  geom_sf(data = ocean, fill = "aliceblue", color = NA) +
  geom_sf(fill = "lightyellow", lwd = .1) +
  geom_sf(data = closures,
          size = 7,
          shape = 21,
          color = "white",
          fill="red")

^{Created on 2024-07-11 with reprex v2.1.0}