在R语言正交投影地球图中添加数据点异常问题求助

你创建closures这个sf对象时犯了个关键错误：你的x（经度）和y（纬度）是WGS84坐标系（EPSG:4326）下的经纬度数据，但你直接把crs参数设成了正射投影的crs_string，这会让R误以为这些数值是正射投影下的平面坐标，自然会把点映射到投影中心附近。

• 第一步：创建sf对象时，先指定经纬度对应的CRS（EPSG:4326）
• 第二步：将sf对象转换为正射投影（crs_string），和地图的坐标系保持一致
• 额外注意：如果转换后某些点不在当前正射投影的可视范围内（比如地球背面的点），这些点会被自动过滤掉，你可以检查转换后的closures对象确认

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")
)

# 修正：先指定经纬度的CRS为4326，再转换到正射投影
closures <- sf::st_as_sf(closures, 
                         coords = c("x", "y"),
                         crs = 4326) %>%  # 这里改成4326
  st_transform(crs = crs_string) # 转换到正射投影

# 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()

内容的提问来源于stack exchange，提问作者Always_confused