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r - 使用 sf 和 sp 在 R 中的投影差异

问题描述

我有一个从 GeoTIFF 转换为 shapefile 的网格。我想将 shapefile 转换并导出为 GeoPackage 并更改投影，以便在 GIS 中打开时使用英国国家网格作为地理坐标系。然而，这似乎只适用于使用sp而不是sf（它似乎没有保留像基准这样的方面）。

这是一个问题，因为我想导出包含多个图层的 GeoPackages，您目前只能在其中sf而不是sp. 难道我做错了什么？

library(rgdal)
library(sf)

download.file("https://drive.google.com/uc?id=1URbux7Sw25KFTySqRFKXk53DV2UK4lsA&export=download" , destfile="Grid_Shapefile.zip")
unzip("Grid_Shapefile.zip")
Grid_sp <- readOGR(".", "Grid_Shapefile")
Grid_sf <- st_as_sf(Grid_sp)

BNG_Grid_sp <- spTransform(Grid_sp, CRS("+init=epsg:27700"))
BNG_Grid_sf_v1 <- st_transform(Grid_sf, crs=27700)
BNG_Grid_sf_v2 <- st_transform(Grid_sf, crs="+init=epsg:27700 +proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +datum=OSGB36 +units=m +no_defs +ellps=airy +towgs84=446.448,-125.157,542.060,0.1502,0.2470,0.8421,-20.4894")

BNG_Grid_sf_v1_geom <- st_geometry(BNG_Grid_sf_v1)
BNG_Grid_sf_v2_geom <- st_geometry(BNG_Grid_sf_v2)

proj4string(BNG_Grid_sp)
attributes(BNG_Grid_sf_v1_geom)
attributes(BNG_Grid_sf_v2_geom)

writeOGR(BNG_Grid_sp, dsn = "BNG_Grid_sp.gpkg", layer = "Grid_sp", driver = "GPKG")
st_write(BNG_Grid_sf_v1, "BNG_Grid_sf_v1.gpkg", "Grid_sf_v1")
st_write(BNG_Grid_sf_v2, "BNG_Grid_sf_v2.gpkg", "Grid_sf_v2")

标签： rprojectioncoordinate-systemsspsf

解决方案

对此的解决方案（感谢 Roger 在此处发布的内容）是使用lwgeom包进行转换。Roger 在 sf GitHub 上的帖子提供了更多详细信息。

library(rgdal)
library(sf)

download.file("https://drive.google.com/uc?id=1URbux7Sw25KFTySqRFKXk53DV2UK4lsA&export=download" , destfile="Grid_Shapefile.zip")
unzip("Grid_Shapefile.zip")
Grid_sp <- readOGR(".", "Grid_Shapefile")
Grid_sf <- st_as_sf(Grid_sp)

library(lwgeom)
BNG_Grid_sf_v4 <- st_transform_proj(Grid_sf, crs="+init=epsg:27700 +proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +datum=OSGB36 +units=m +no_defs +ellps=airy +towgs84=446.448,-125.157,542.060,0.1502,0.2470,0.8421,-20.4894")
st_crs(BNG_Grid_sf_v4)
st_write(BNG_Grid_sf_v4, "BNG_Grid_sf_v4.gpkg", "Grid_sf_v4")

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