I receive the following warning while reading Corine land cover data in tif format either using raster or terra package.
R <- raster::raster(CLC_Tiff)
Warning message: In new_CppObject_xp(fields$.module, fields$.pointer, ...) : GDAL Message 1: The definition of projected CRS EPSG:3035 got from GeoTIFF keys is not the same as the one from the EPSG registry, which may cause issues during reprojection operations. Set GTIFF_SRS_SOURCE configuration option to EPSG to use official parameters (overriding the ones from GeoTIFF keys), or to GEOKEYS to use custom values from GeoTIFF keys and drop the EPSG code.
Here is the projection
raster::projection(R)
[1] "+proj=laea +lat_0=52 +lon_0=10 +x_0=4321000 +y_0=3210000 +ellps=GRS80 +units=m +no_defs"
Similarly for terra:
R <- terra::rast(CLC_Tiff, crs = "EPSG:3035")
Warning message:
In new_CppObject_xp(fields$.module, fields$.pointer, ...) :
GDAL Message 1: The definition of projected CRS EPSG:3035 got from GeoTIFF keys is not the same as the one from the EPSG registry, which may cause issues during reprojection operations. Set GTIFF_SRS_SOURCE configuration option to EPSG to use official parameters (overriding the ones from GeoTIFF keys), or to GEOKEYS to use custom values from GeoTIFF keys and drop the EPSG code.
terra::crs(R)
[1] "PROJCRS[\"ETRS89-extended / LAEA Europe\",\n BASEGEOGCRS[\"ETRS89\",\n DATUM[\"European Terrestrial Reference System 1989\",\n ELLIPSOID[\"GRS 1980\",6378137,298.257222101004,\n LENGTHUNIT[\"metre\",1]]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n ID[\"EPSG\",4258]],\n CONVERSION[\"Lambert Azimuthal Equal Area\",\n METHOD[\"Lambert Azimuthal Equal Area\",\n ID[\"EPSG\",9820]],\n PARAMETER[\"Latitude of natural origin\",52,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8801]],\n PARAMETER[\"Longitude of natural origin\",10,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8802]],\n PARAMETER[\"False easting\",4321000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8806]],\n PARAMETER[\"False northing\",3210000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8807]]],\n CS[Cartesian,2],\n AXIS[\"(E)\",east,\n ORDER[1],\n LENGTHUNIT[\"metre\",1]],\n AXIS[\"(N)\",north,\n ORDER[2],\n LENGTHUNIT[\"metre\",1]],\n ID[\"EPSG\",3035]]"
I can in principle use suppressWarnings() around the function to avoid this warning.
However, I'd like to 1) know the reason for this; 2) is there a way to avoid this; and 3) is it something I should care about for subsequent analyses using terra/raster/sf packages?
The problem is that the file has a CRS that contains an EPSG code and a bunch of parameters. These parameters do not match the parameters for the same EPSG code in the database that GDAL uses.
Here is a comparison showing that they are quite different in terms of the characters used.
terra::gdal()
#[1] "3.7.2"
terra::crs("EPSG:3035")
# [1] "PROJCRS[\"ETRS89-extended / LAEA Europe\",\n BASEGEOGCRS[\"ETRS89\",\n ENSEMBLE[\"European Terrestrial Reference System 1989 ensemble\",\n MEMBER[\"European Terrestrial Reference Frame 1989\"],\n MEMBER[\"European Terrestrial Reference Frame 1990\"],\n MEMBER[\"European Terrestrial Reference Frame 1991\"],\n MEMBER[\"European Terrestrial Reference Frame 1992\"],\n MEMBER[\"European Terrestrial Reference Frame 1993\"],\n MEMBER[\"European Terrestrial Reference Frame 1994\"],\n MEMBER[\"European Terrestrial Reference Frame 1996\"],\n MEMBER[\"European Terrestrial Reference Frame 1997\"],\n MEMBER[\"European Terrestrial Reference Frame 2000\"],\n MEMBER[\"European Terrestrial Reference Frame 2005\"],\n MEMBER[\"European Terrestrial Reference Frame 2014\"],\n ELLIPSOID[\"GRS 1980\",6378137,298.257222101,\n LENGTHUNIT[\"metre\",1]],\n ENSEMBLEACCURACY[0.1]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n ID[\"EPSG\",4258]],\n CONVERSION[\"Europe Equal Area 2001\",\n METHOD[\"Lambert Azimuthal Equal Area\",\n ID[\"EPSG\",9820]],\n PARAMETER[\"Latitude of natural origin\",52,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8801]],\n PARAMETER[\"Longitude of natural origin\",10,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8802]],\n PARAMETER[\"False easting\",4321000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8806]],\n PARAMETER[\"False northing\",3210000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8807]]],\n CS[Cartesian,2],\n AXIS[\"northing (Y)\",north,\n ORDER[1],\n LENGTHUNIT[\"metre\",1]],\n AXIS[\"easting (X)\",east,\n ORDER[2],\n LENGTHUNIT[\"metre\",1]],\n USAGE[\n SCOPE[\"Statistical analysis.\"],\n AREA[\"Europe - European Union (EU) countries and candidates. Europe - onshore and offshore: Albania; Andorra; Austria; Belgium; Bosnia and Herzegovina; Bulgaria; Croatia; Cyprus; Czechia; Denmark; Estonia; Faroe Islands; Finland; France; Germany; Gibraltar; Greece; Hungary; Iceland; Ireland; Italy; Kosovo; Latvia; Liechtenstein; Lithuania; Luxembourg; Malta; Monaco; Montenegro; Netherlands; North Macedonia; Norway including Svalbard and Jan Mayen; Poland; Portugal including Madeira and Azores; Romania; San Marino; Serbia; Slovakia; Slovenia; Spain including Canary Islands; Sweden; Switzerland; Türkiye (Turkey); United Kingdom (UK) including Channel Islands and Isle of Man; Vatican City State.\"],\n BBOX[24.6,-35.58,84.73,44.83]],\n ID[\"EPSG\",3035]]"
terra::crs(R)
#[1] "PROJCRS[\"ETRS89-extended / LAEA Europe\",\n BASEGEOGCRS[\"ETRS89\",\n DATUM[\"European Terrestrial Reference System 1989\",\n ELLIPSOID[\"GRS 1980\",6378137,298.257222101004,\n LENGTHUNIT[\"metre\",1]]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n ID[\"EPSG\",4258]],\n CONVERSION[\"Lambert Azimuthal Equal Area\",\n METHOD[\"Lambert Azimuthal Equal Area\",\n ID[\"EPSG\",9820]],\n PARAMETER[\"Latitude of natural origin\",52,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8801]],\n PARAMETER[\"Longitude of natural origin\",10,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8802]],\n PARAMETER[\"False easting\",4321000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8806]],\n PARAMETER[\"False northing\",3210000,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8807]]],\n CS[Cartesian,2],\n AXIS[\"(E)\",east,\n ORDER[1],\n LENGTHUNIT[\"metre\",1]],\n AXIS[\"(N)\",north,\n ORDER[2],\n LENGTHUNIT[\"metre\",1]],\n ID[\"EPSG\",3035]]"
But in itself, that does not mean that the CRS is meaningfully different.
I do not see any difference if I do:
library(terra)
v <- vect(system.file("ex/lux.shp", package="terra"))
x <- project(v, "EPSG:3035")
y <- project(v, crs(R))
plot(x)
lines(y, col="red")