[PROJ] PROJ 9 & old syntax +init=

[Alain Orsoni]

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 <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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