Convert coordinates from RGF93 v1 (EPSG:4171) to NTF (EPSG:4275) — official EPSG transformation parameters, accuracy and area of use, with a free in-browser converter.
The EPSG Geodetic Parameter Dataset defines 1 transformation between RGF93 v1 (EPSG:4171) and NTF (EPSG:4275). Its parameters, accuracy and area of use are listed below.
Grid file: rgf93_ntf.gsb
Emulation using NTv2 method of NTF to RGF93 v1 (1), code 9327. Note that grid file parameters are of opposite sign. May be taken as approximate CT to ETRS89 or WGS 84 (see codes 15959 and 15960). Also used to transform later realizations of RGF93 to NTF.
The same transformation with common GIS tools and libraries:
from pyproj import Transformer
transformer = Transformer.from_crs("EPSG:4171", "EPSG:4275", always_xy=True)
x, y = transformer.transform(-73.9857, 40.7484)
print(x, y)geographic system using latitude and longitude on an ellipsoid · Area of use: France
+proj=longlat +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +no_defs +type=crsMore about EPSG:4171 →
geographic system using latitude and longitude on an ellipsoid · Area of use: France - onshore - mainland and Corsica
+proj=longlat +ellps=clrk80ign +towgs84=-168,-60,320,0,0,0,0 +no_defs +type=crsMore about EPSG:4275 →