[PROJ] PROJ 9 & old syntax +init=
Nicolas Bellaiche
nicolas.bellaiche at ign.fr
Thu Jun 1 10:52:26 PDT 2023
I compare with the results given by CIRCE which is the official software developed by the National Geographic Institute of France, these coordinates are official datasets distributed with the application.
De: "Alain Orsoni" <Alain.Orsoni at ign.fr>
À: "Nicolas Bellaiche" <nicolas.bellaiche at ign.fr>
Cc: "proj" <PROJ at lists.osgeo.org>
Envoyé: Jeudi 1 Juin 2023 16:27:23
Objet: Re: [PROJ] PROJ 9 & old syntax +init=
For me LAMB1 and UTM31RGF93 are both considered as being on Geoid in the new database.
So the altitude from input is just transferred to the output.
So I think the result from 9.2 version is correct in terms of Z management.
But it’s only from my understanding…
Alain
Le 1 juin 2023 à 15:54, Nicolas Bellaiche < [ mailto:nicolas.bellaiche at ign.fr | nicolas.bellaiche at ign.fr ] > a écrit :
Hi all,
I am still puzzled by the difference between the old syntax +init= and the new syntax. I just rebuilt the last release 9.2.1 and tested with it to make sure it's not a bug already fixed.
1) Example where the grid shift is not taken into account with the new syntax. (it's correct with +init=)
1.a) NEW SYNTAX: z not correct (grid shift not used)
echo 600000.00000000 300097.53400000 0.00000000 | ./bin/cs2cs IGNF:LAMB1 +to IGNF:UTM31RGF93
452845.19 5583309.40 0.00
1.b) OLD SYNTAX: z correct:
echo 600000.00000000 300097.53400000 0.00000000 | ./bin/cs2cs +init=IGNF:LAMB1 +to +init=IGNF:UTM31RGF93
452845.19 5583309.40 43.64
2) Example where the old syntax gives a wrong result while the new syntax works:
2.a) OLD SYNTAX from cartographic to geocentric coordinates / result is wrong
echo 652760.737 7033791.243 43.642 | PROJ_DEBUG=3 ./bin/cs2cs +init=IGNF:LAMB93 +to +init=IGNF:RGF93
4070355.05 166080.07 4891332.24
2.b) NEW SYNTAX from cartographic to geocentric coordinates / result is correct
echo 652760.737 7033791.243 43.642 | PROJ_DEBUG=3 ./bin/cs2cs IGNF:LAMB93 +to IGNF:RGF93
4070327.25 166078.93 4891298.61
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