Hi,
The WKT1 string for your IGNF:LAMB1 contains latitude_of_origin = 49.5.
But this is wrong. This is the value in degree, but it should be
expressed in grads as the GEOGCS unit is grad (cf
https://gdal.org/tutorials/wktproblems.html#units-of-parameters), so 55 grad
The correct WKT definition to use is:
PROJCS["NTF Lambert I",
GEOGCS["NTF geographiques Paris (gr)",
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["IGNF","NTFPGRAD"]],
PROJECTION["Lambert_Conformal_Conic_1SP"],
PARAMETER["latitude_of_origin",55],
PARAMETER["central_meridian",0],
PARAMETER["scale_factor",0.99987734],
PARAMETER["false_easting",600000],
PARAMETER["false_northing",200000],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Easting",EAST],
AXIS["Northing",NORTH],
AUTHORITY["IGNF","LAMB1"]]
With recent PROJ, I get the correct value when using the proj.4 string
or the corrected WKT1 definition (got from "projinfo IGNF:LAMB1 -o
WKT1:GDAL")
$ echo 398845.80866241 6822815.8927889 | PROJ_DATA=data PROJ_NETWORK=ON
bin/cs2cs EPSG:2154 +to +proj=lcc +nadgrids=ntf_r93.gsb,null
+a=6378249.2000 +rf=293.4660210000000 +pm=2.337229167
+lat_0=49.500000000 +lon_0=0.000000000 +k_0=0.99987734
+lat_1=49.500000000 +x_0=600000.000 +y_0=200000.000 +units=m +no_defs
347762.11 87364.03 0.00
$ echo 398845.80866241 6822815.8927889 | PROJ_DATA=data PROJ_NETWORK=ON
bin/cs2cs EPSG:2154 'PROJCS["NTF Lambert I",GEOGCS["NTF geographiques
Paris
(gr)",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["IGNF","NTFPGRAD"]],PROJECTION["Lambert_Conformal_Conic_1SP"],PARAMETER["latitude_of_origin",55],PARAMETER["central_meridian",0],PARAMETER["scale_factor",0.99987734],PARAMETER["false_easting",600000],PARAMETER["false_northing",200000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["IGNF","LAMB1"]]'
347762.11 87364.03 0.00
Even
Le 05/09/2023 à 12:19, Rhea a écrit :
hello,
I am using this definition for my projection on both postgis 2 and
postgis 3 so i can use it in my st_transform() function:
INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text,
srtext) values ( 932001, 'IGNF' , 320002101 , '+proj=lcc
+nadgrids=ntf_r93.gsb,null +a=6378249.2000 +rf=293.4660210000000
+pm=2.337229167 +lat_0=49.500000000 +lon_0=0.000000000 +k_0=0.99987734
+lat_1=49.500000000 +x_0=600000.000 +y_0=200000.000 +units=m +no_defs'
, 'PROJCS["Lambert I",GEOGCS["Nouvelle Triangulation Française Paris
grades",DATUM["NTF",SPHEROID["Clarke 1880
IGN",6378249.2000,293.4660210000000,AUTHORITY["IGNF","ELG010"]],TOWGS84[-168.0000,-60.0000,320.0000,0,0,0,0],AUTHORITY["IGNF","REG002"]],PRIMEM["Paris",2.337229167,AUTHORITY["IGNF","LGO02"]],UNIT["grad",0.01570796326794897],AXIS["Longitude",EAST],AXIS["Latitude",NORTH],AUTHORITY["IGNF","NTFP"]],PROJECTION["Lambert_Conformal_Conic_1SP",AUTHORITY["IGNF","PRC0101"]],PARAMETER["semi_major",6378249.2000],PARAMETER["semi_minor",6356515.0000],PARAMETER["latitude_of_origin",49.500000000],PARAMETER["central_meridian",0.000000000],PARAMETER["scale_factor",0.99987734],PARAMETER["false_easting",600000.000],PARAMETER["false_northing",200000.000],UNIT["metre",1],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["IGNF","LAMB1"]]’);
This projection 932001 corresponds to Lambert Zone 1 corrected with
the IGN grid.
|
This is the function where im using this projection :
|select st_astext(st_transform(st_setsrid(st_point(398845.80866241,
6822815.8927889), 2154), 932001))|
On our PostgreSQL 10 / PostGIS 2.x machine, i am getting this:
|POINT(347762.11171084 87364.0318659853) |
While in PostgresQL 13 / PostGIS 3.x, i am getting this (result which
is incorrect):
|POINT(347200.5307476731 637506.2948565462)|
|
Result of the query select postgis_full_version(); on our 2 environments:
PostgreSQL 10 : POSTGIS="2.4.7 r17330" PGSQL="100"
GEOS="3.7.1-CAPI-1.11.1 27a5e771" PROJ="Rel. 4.9.3, 15 August 2016"
GDAL="GDAL 2.3.2, released 2018/09/21" LIBXML="2.9.1" LIBJSON="0.11"
RASTER
PostgresSQL 13 : POSTGIS="3.1.8 c5ebc1f" [EXTENSION] PGSQL="130"
GEOS="3.10.3-CAPI-1.16.1" PROJ="8.2.1" LIBXML="2.9.7" LIBJSON="0.13.1"
LIBPROTOBUF="1.3.0" WAGYU="0.5.0 (Internal)” TOPOLOGY
|
|I tried using |fr_ign_ntf_r93.tif instead of the ntf_r93.gsb but it didnt work, i got
the same results.
I tried verifying that the ntf_r93.gsb or the ||fr_ign_ntf_r93.tif are located in usr/share/proj/ directory and they
do but yet im getting the same results.
can anyone help me please?
Thank you so much !
||
|
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