[PROJ] migrating to PROJ-9, missing / issues in code definitions

[Even Rouault]

Nicolas,
>
>
> 1) It seems that the entry RGTAAF07UTM42S has disappeared from the 
> current IGNF dictionary

It is no longer in https://geodesie.ign.fr/contenu/fichiers/IGNF.xml 
which is the source (actually we use a slightly older version of 
IGNF.xml) from the records ingested into the PROJ database: 
https://github.com/OSGeo/PROJ/blob/master/data/sql/ignf.sql

IGN is of course welcome to take over maintenance of the registry in 
PROJ: cf https://github.com/OSGeo/PROJ/issues/2682

>
> 2) It seems that the geoid grid fr_ign_RAR07_bl.tif
> is missing for the definition of :
>
> REUN47GAUSSL
>
> RGR92UTM40S
>
> REUN47GEO
>
> RGR92GEO
>
In the new ISO191111-based paradygm (which is also more or less the one 
followed by the IGNF.xml file), a grid is not part of a CRS definition. 
Grids can be referenced by transformations.

e.g

bin/projinfo -s IGNF:RGR92GEO -t IGNF:REUN89
Candidate operations found: 1
-------------------------------------
Operation No. 1:

DERIVED_FROM(IGNF):TSG1160, RGR92 (RESEAU GEODESIQUE DE LA REUNION 1992) 
vers IGN 1989 (REUNION), unknown accuracy, ILE DE LA REUNION, at least 
one grid missing

PROJ string:
+proj=pipeline
   +step +proj=unitconvert +xy_in=deg +xy_out=rad
   +step +inv +proj=vgridshift +grids=fr_ign_RAR07_bl.tif +multiplier=1
   +step +proj=unitconvert +xy_in=rad +xy_out=deg

which directly uses the IGNF:TSG1160 transformation of IGNF.xml

>
> 3) It seems that the geoid grid fr_ign_1.tif
> is missing for the definition of :
>
> STPM50UTM21
>
> RGSPM06GEO
>
> STPM50GEO
>
> RGSPM06U21
>
Same here:

$ bin/projinfo -s IGNF:RGSPM06GEO -t IGNF:STPM50_V
Candidate operations found: 1
-------------------------------------
Operation No. 1:

DERIVED_FROM(IGNF):TSG1156, RGSPM06 (RESEAU GEODESIQUE DE 
SAINT-PIERRE-ET-MIQUELON 2006) vers DANGER 1950 
(SAINT-PIERRE-ET-MIQUELON), unknown accuracy, SAINT-PIERRE-ET-MIQUELON, 
at least one grid missing

PROJ string:
+proj=pipeline
   +step +proj=unitconvert +xy_in=deg +xy_out=rad
   +step +inv +proj=vgridshift +grids=fr_ign_ggspm06v1.tif +multiplier=1
   +step +proj=unitconvert +xy_in=rad +xy_out=deg

Even


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