[PROJ] Migrating to PROJ-9

[Even Rouault]

Hi,

I get the expected 4070327.25 166078.93 4891298.61 result with proj 
6.0.0, 7.2.1, 9.2.0 and master

There's no grid involved in this operation, just inverse LCC projection 
on the RGF93 datum

I also tried to reproduce your issue if the PROJ < 6 IGNF file is found 
in the PROJ resource path(s) (non nominal situation - this file is not 
needed any more, and will generally lead to suboptimal results. Its 
content is included in the proj.db file), but even with that I get the 
expected result. So no idea why you get wrong results

Even


Le 26/05/2023 à 20:54, Nicolas Bellaiche a écrit :
> Hi all,
>
> I'm migrating my C++ code from PROJ4 to PROJ9 and I meet a worrying 
> issue with the computation. Some of my regress tests don't pass so 
> I've tested with cs2cs and gets the same difference:
>
> PROJ4
>
> echo652760.73700000 <callto:652760.73700000>7033791.24300000 43 
> <callto:7033791.24300000 43>.64200000 | cs2cs +init=IGNF:LAMB93 +to 
> +init=IGNF:RGF93:
>
> 4070327.25166078.93 4891298.61 <callto:166078.93 4891298.61>
>
>
> PROJ7 or PROJ9
>
> echo652760.73700000 <callto:652760.73700000>7033791.24300000 43 
> <callto:7033791.24300000 43>.64200000 | cs2cs +init=IGNF:LAMB93 +to 
> +init=IGNF:RGF93:
>
> 4070355.05166080.07 4891332.24 <callto:166080.07 4891332.24>
>
>
>
>
> I suspect that PROJ7 and PROJ9 don't read properly the geoid file but 
> I'm not sure. Someone can help me tracking and fixing this problem?
>
> Thanks,
>
> Nicolas Bellaiche
> Institut Géographique National France
>
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