See transformation code 7811 for an alternative which uses the NTv2 method as an emulation of the geocentric interpolation in the second step.
IOGP
2016-05-01
Engineering survey, topographic mapping.
Introduced 1972. Replaces NTF (Paris) / Lambert Sud France (code 27563).
France - mainland onshore south of 50.5 grads North (45°27'N).
Cartesian 2D CS. Axes: easting, northing (X,Y). Orientations: east, north. UoM: m.
603354.75 3436190.78
-3340.19 2889984.32
1210588.99 4007437.89
-4.87 41.31
9.63 51.14
Definition: OGC Well Known Text
PROJCS["NTF (Paris) / Lambert zone III", GEOGCS["NTF (Paris)", DATUM["Nouvelle_Triangulation_Francaise_Paris", SPHEROID["Clarke 1880 (IGN)",6378249.2,293.466021293627, AUTHORITY["EPSG","7011"]], AUTHORITY["EPSG","6807"]], PRIMEM["Paris",2.33722917, AUTHORITY["EPSG","8903"]], UNIT["grad",0.0157079632679489, AUTHORITY["EPSG","9105"]], AUTHORITY["EPSG","4807"]], PROJECTION["Lambert_Conformal_Conic_1SP"], PARAMETER["latitude_of_origin",49], PARAMETER["central_meridian",0], PARAMETER["scale_factor",0.999877499], PARAMETER["false_easting",600000], PARAMETER["false_northing",3200000], UNIT["metre",1, AUTHORITY["EPSG","9001"]], AXIS["Easting",EAST], AXIS["Northing",NORTH], AUTHORITY["EPSG","27573"]]
Definition: OGC Well Known Text 2 (2019)
PROJCRS["NTF (Paris) / Lambert zone III", BASEGEOGCRS["NTF (Paris)", DATUM["Nouvelle Triangulation Francaise (Paris)", ELLIPSOID["Clarke 1880 (IGN)",6378249.2,293.466021293627, LENGTHUNIT["metre",1]]], PRIMEM["Paris",2.5969213, ANGLEUNIT["grad",0.0157079632679489]], ID["EPSG",4807]], CONVERSION["Lambert zone III", METHOD["Lambert Conic Conformal (1SP)", ID["EPSG",9801]], PARAMETER["Latitude of natural origin",49, ANGLEUNIT["grad",0.0157079632679489], ID["EPSG",8801]], PARAMETER["Longitude of natural origin",0, ANGLEUNIT["grad",0.0157079632679489], ID["EPSG",8802]], PARAMETER["Scale factor at natural origin",0.999877499, SCALEUNIT["unity",1], ID["EPSG",8805]], PARAMETER["False easting",600000, LENGTHUNIT["metre",1], ID["EPSG",8806]], PARAMETER["False northing",3200000, LENGTHUNIT["metre",1], ID["EPSG",8807]]], CS[Cartesian,2], AXIS["easting (X)",east, ORDER[1], LENGTHUNIT["metre",1]], AXIS["northing (Y)",north, ORDER[2], LENGTHUNIT["metre",1]], USAGE[ SCOPE["Engineering survey, topographic mapping."], AREA["France - mainland onshore south of 50.5 grads North (45°27'N)."], BBOX[42.33,-1.79,45.46,7.71]], ID["EPSG",27573]]
Definition: ESRI Well Known Text
PROJCS["NTF_Paris_Lambert_Zone_III", GEOGCS["GCS_NTF_Paris", DATUM["Nouvelle_Triangulation_Francaise_(Paris)", SPHEROID["Clarke_1880_IGN",6378249.2,293.466021293627]], PRIMEM["Paris",2.33722917], UNIT["Grad",0.0157079632679489]], PROJECTION["Lambert_Conformal_Conic"], PARAMETER["False_Easting",600000.0], PARAMETER["False_Northing",3200000.0], PARAMETER["Central_Meridian",0.0], PARAMETER["Standard_Parallel_1",49.0], PARAMETER["Scale_Factor",0.999877499], PARAMETER["Latitude_Of_Origin",49.0], UNIT["Meter",1.0]]
Definition: JSON
{ "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json", "type": "ProjectedCRS", "name": "NTF (Paris) / Lambert zone III", "base_crs": { "name": "NTF (Paris)", "datum": { "type": "GeodeticReferenceFrame", "name": "Nouvelle Triangulation Francaise (Paris)", "ellipsoid": { "name": "Clarke 1880 (IGN)", "semi_major_axis": 6378249.2, "semi_minor_axis": 6356515 }, "prime_meridian": { "name": "Paris", "longitude": { "value": 2.5969213, "unit": { "type": "AngularUnit", "name": "grad", "conversion_factor": 0.0157079632679489 } } } }, "coordinate_system": { "subtype": "ellipsoidal", "axis": [ { "name": "Geodetic latitude", "abbreviation": "Lat", "direction": "north", "unit": { "type": "AngularUnit", "name": "grad", "conversion_factor": 0.0157079632679489 } }, { "name": "Geodetic longitude", "abbreviation": "Lon", "direction": "east", "unit": { "type": "AngularUnit", "name": "grad", "conversion_factor": 0.0157079632679489 } } ] }, "id": { "authority": "EPSG", "code": 4807 } }, "conversion": { "name": "Lambert zone III", "method": { "name": "Lambert Conic Conformal (1SP)", "id": { "authority": "EPSG", "code": 9801 } }, "parameters": [ { "name": "Latitude of natural origin", "value": 49, "unit": { "type": "AngularUnit", "name": "grad", "conversion_factor": 0.0157079632679489 }, "id": { "authority": "EPSG", "code": 8801 } }, { "name": "Longitude of natural origin", "value": 0, "unit": { "type": "AngularUnit", "name": "grad", "conversion_factor": 0.0157079632679489 }, "id": { "authority": "EPSG", "code": 8802 } }, { "name": "Scale factor at natural origin", "value": 0.999877499, "unit": "unity", "id": { "authority": "EPSG", "code": 8805 } }, { "name": "False easting", "value": 600000, "unit": "metre", "id": { "authority": "EPSG", "code": 8806 } }, { "name": "False northing", "value": 3200000, "unit": "metre", "id": { "authority": "EPSG", "code": 8807 } } ] }, "coordinate_system": { "subtype": "Cartesian", "axis": [ { "name": "Easting", "abbreviation": "X", "direction": "east", "unit": "metre" }, { "name": "Northing", "abbreviation": "Y", "direction": "north", "unit": "metre" } ] }, "scope": "Engineering survey, topographic mapping.", "area": "France - mainland onshore south of 50.5 grads North (45°27'N).", "bbox": { "south_latitude": 42.33, "west_longitude": -1.79, "north_latitude": 45.46, "east_longitude": 7.71 }, "id": { "authority": "EPSG", "code": 27573 } }
Definition: GeoServer
27573=PROJCS["NTF (Paris) / Lambert zone III",GEOGCS["NTF (Paris)",DATUM["Nouvelle_Triangulation_Francaise_Paris",SPHEROID["Clarke 1880 (IGN)",6378249.2,293.466021293627,AUTHORITY["EPSG","7011"]],AUTHORITY["EPSG","6807"]],PRIMEM["Paris",2.33722917,AUTHORITY["EPSG","8903"]],UNIT["grad",0.0157079632679489,AUTHORITY["EPSG","9105"]],AUTHORITY["EPSG","4807"]],PROJECTION["Lambert_Conformal_Conic_1SP"],PARAMETER["latitude_of_origin",49],PARAMETER["central_meridian",0],PARAMETER["scale_factor",0.999877499],PARAMETER["false_easting",600000],PARAMETER["false_northing",3200000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","27573"]]
Definition: Mapnik
<?xml version="1.0" encoding="utf-8"?> <Map srs="+proj=lcc +lat_1=44.1 +lat_0=44.1 +lon_0=0 +k_0=0.999877499 +x_0=600000 +y_0=3200000 +ellps=clrk80ign +pm=paris +units=m +no_defs +type=crs"> <Layer srs="+proj=lcc +lat_1=44.1 +lat_0=44.1 +lon_0=0 +k_0=0.999877499 +x_0=600000 +y_0=3200000 +ellps=clrk80ign +pm=paris +units=m +no_defs +type=crs"> </Layer> </Map>
Definition: SQL (PostGIS)
INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 27573, 'EPSG', 27573, '+proj=lcc +lat_1=44.1 +lat_0=44.1 +lon_0=0 +k_0=0.999877499 +x_0=600000 +y_0=3200000 +ellps=clrk80ign +pm=paris +units=m +no_defs +type=crs', 'PROJCS["NTF (Paris) / Lambert zone III",GEOGCS["NTF (Paris)",DATUM["Nouvelle_Triangulation_Francaise_Paris",SPHEROID["Clarke 1880 (IGN)",6378249.2,293.466021293627,AUTHORITY["EPSG","7011"]],AUTHORITY["EPSG","6807"]],PRIMEM["Paris",2.33722917,AUTHORITY["EPSG","8903"]],UNIT["grad",0.0157079632679489,AUTHORITY["EPSG","9105"]],AUTHORITY["EPSG","4807"]],PROJECTION["Lambert_Conformal_Conic_1SP"],PARAMETER["latitude_of_origin",49],PARAMETER["central_meridian",0],PARAMETER["scale_factor",0.999877499],PARAMETER["false_easting",600000],PARAMETER["false_northing",3200000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","27573"]]');