Geocentric translation by Grid Interpolation (IGN)
gr3df97a.txt
Parameter file is from NTF to RGF93 v1 (code 9327), assuming that RGF93 v1 is equivalent to RGF93 v2 within the accuracy of the transformation. May be emulated using NTv2 method - see CT code 9890.
Institut Geographique National (IGN) document NTG_88.pdf, "Grille de parametres de transformation de coordonnees". http://www.ign.fr
2022-01-24
Definition: OGC Well Known Text 2 (2019)
BOUNDCRS[ SOURCECRS[ GEOGCRS["NTF", DATUM["Nouvelle Triangulation Francaise", ELLIPSOID["Clarke 1880 (IGN)",6378249.2,293.466021293627, LENGTHUNIT["metre",1]]], PRIMEM["Greenwich",0, ANGLEUNIT["degree",0.0174532925199433]], CS[ellipsoidal,2], AXIS["geodetic latitude (Lat)",north, ORDER[1], ANGLEUNIT["degree",0.0174532925199433]], AXIS["geodetic longitude (Lon)",east, ORDER[2], ANGLEUNIT["degree",0.0174532925199433]], USAGE[ SCOPE["Geodesy."], AREA["France - onshore - mainland and Corsica."], BBOX[41.31,-4.87,51.14,9.63]], ID["EPSG",4275]]], TARGETCRS[ GEOGCRS["RGF93 v2", DATUM["Reseau Geodesique Francais 1993 v2", ELLIPSOID["GRS 1980",6378137,298.257222101, LENGTHUNIT["metre",1]]], PRIMEM["Greenwich",0, ANGLEUNIT["degree",0.0174532925199433]], CS[ellipsoidal,2], AXIS["geodetic latitude (Lat)",north, ORDER[1], ANGLEUNIT["degree",0.0174532925199433]], AXIS["geodetic longitude (Lon)",east, ORDER[2], ANGLEUNIT["degree",0.0174532925199433]], USAGE[ SCOPE["Horizontal component of 3D system."], AREA["France - onshore and offshore, mainland and Corsica (France métropolitaine including Corsica)."], BBOX[41.15,-9.86,51.56,10.38]], ID["EPSG",9777]]], ABRIDGEDTRANSFORMATION["NTF to RGF93 v2 (1)", METHOD["Geocentric translation by Grid Interpolation (IGN)", ID["EPSG",1087]], PARAMETERFILE["Geocentric translation file","gr3df97a.txt"], USAGE[ SCOPE["Transformation of coordinates at 1m level of accuracy."], AREA["France - onshore - mainland and Corsica."], BBOX[41.31,-4.87,51.14,9.63]], ID["EPSG",9888], REMARK["Parameter file is from NTF to RGF93 v1 (code 9327), assuming that RGF93 v1 is equivalent to RGF93 v2 within the accuracy of the transformation. May be emulated using NTv2 method - see CT code 9890."]]]
Definition: JSON
{ "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json", "type": "BoundCRS", "source_crs": { "type": "GeographicCRS", "name": "NTF", "datum": { "type": "GeodeticReferenceFrame", "name": "Nouvelle Triangulation Francaise", "ellipsoid": { "name": "Clarke 1880 (IGN)", "semi_major_axis": 6378249.2, "semi_minor_axis": 6356515 } }, "coordinate_system": { "subtype": "ellipsoidal", "axis": [ { "name": "Geodetic latitude", "abbreviation": "Lat", "direction": "north", "unit": "degree" }, { "name": "Geodetic longitude", "abbreviation": "Lon", "direction": "east", "unit": "degree" } ] }, "id": { "authority": "EPSG", "code": 4275 } }, "target_crs": { "type": "GeographicCRS", "name": "RGF93 v2", "datum": { "type": "GeodeticReferenceFrame", "name": "Reseau Geodesique Francais 1993 v2", "ellipsoid": { "name": "GRS 1980", "semi_major_axis": 6378137, "inverse_flattening": 298.257222101 } }, "coordinate_system": { "subtype": "ellipsoidal", "axis": [ { "name": "Geodetic latitude", "abbreviation": "Lat", "direction": "north", "unit": "degree" }, { "name": "Geodetic longitude", "abbreviation": "Lon", "direction": "east", "unit": "degree" } ] }, "id": { "authority": "EPSG", "code": 9777 } }, "transformation": { "name": "NTF to RGF93 v2 (1)", "method": { "name": "Geocentric translation by Grid Interpolation (IGN)", "id": { "authority": "EPSG", "code": 1087 } }, "parameters": [ { "name": "Geocentric translation file", "value": "gr3df97a.txt", "id": { "authority": "EPSG", "code": 8727 } } ], "id": { "authority": "EPSG", "code": 9888 } } }
Definition: Mapnik
<?xml version="1.0" encoding="utf-8"?> <Map srs="+proj=longlat +ellps=clrk80ign +no_defs +type=crs"> <Layer srs="+proj=longlat +ellps=clrk80ign +no_defs +type=crs"> </Layer> </Map>