[PROJ] 2D Helmert transformation after the map projection and PROJ won't use added transformation from the database

[Even Rouault]

There are at least 2 issues:

- your pipeline is incorrect. You should debug it first with the cct 
utility. It should rather be something like:

     +proj=pipeline +step +proj=axisswap +order=2,1 +step 
+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=tmerc +lat_0=0 
+lon_0=25 +k=1 +x_0=25500000 +y_0=0 +ellps=GRS80 +step +proj=helmert 
+convention=coordinate_frame +x=-6685321.2964 +y=-25439452.96812 
+rx=1.00001130081 +ry=-0.00120233218 +theta=0

- EPSG:36122 is an invalid CRS code

Le 09/09/2021 à 13:18, Schupp, Leon a écrit :
>
> Hello Even,
>
> these are the SQL INSERT statements i used:
>
> INSERT INTO "main"."other_transformation"
>
> ("auth_name", "code", "name", "method_auth_name", "method_code", 
> "method_name", "source_crs_auth_name", "source_crs_code", 
> "target_crs_auth_name", "target_crs_code", "accuracy", "deprecated")
>
> VALUES ('PROJ', 'P0001', 'ETRS89 to VVJ', 'PROJ', 'PROJString', 
> '+proj=pipeline
>
> +step +type=proj4 +to=+proj=tmerc +lat_0=0 +lon_0=25 +k=1 
> +x_0=25500000 +y_0=0 +ellps=GRS80 +units=m +no_defs
>
> +from=+proj=longlat +ellps=WGS84 +units=m +no_defs
>
> +step +proj=helmert +convention=coordinate_frame +x=-6685321.2964 
> +y=-25439452.96812 +rx=1.00001130081 +ry=-0.00120233218', 'EPSG', 
> '4258', 'EPSG', '36122', 1.0, 0);
>
> INSERT INTO "main"."usage" ("auth_name", "code", "object_table_name", 
> "object_auth_name", "object_code", "extent_auth_name", "extent_code", 
> "scope_auth_name", "scope_code")
>
> VALUES ('PROJ', 'U0002', 'other_transformation', 'PROJ', 'P0001', 
> 'EPSG', '3333', 'EPSG', '1024');
>
> Mit freundlichen Grüßen / Best regards
>
> Leon Schupp
> Student – Development Engineer
>
>
> *Von:* Even Rouault <even.rouault at spatialys.com>
> *Gesendet:* Donnerstag, 9. September 2021 11:56
> *An:* Schupp, Leon <LSchupp at moba.de>; proj at lists.osgeo.org
> *Betreff:* Re: [PROJ] 2D Helmert transformation after the map 
> projection and PROJ won't use added transformation from the database
>
> Leon,
>
>     First question:
>
>     Is it possible to add a 2D Helmert transformation to the proj.db
>     database. I tried adding it to the helmert_transformation_table,
>     but proj.db didn’t let me choose a projected crs as source
>     transformation.
>
> Yes as designed currently it is limited to source and target CRS being 
> geographic CRS
>
>     I want to add a helmert transformation which uses ETRS89/GK25 as
>     source crs and transforms it into the finnish VVJ crs.
>
>     My second question is:
>
>     I tried adding the helmert transformation as a proj string to the
>     other_transformation table, but proj won’t use it. I also added an
>     entry into the usage table for the transformation.
>
>     When I add a normal helmert transformation or a grid
>     transformation, proj has no problem using them after they are
>     added, but not when I add a transformation in other_transformation.
>
> Show your SQL INSERT statements
>
> Even
>
> -- 
> http://www.spatialys.com  <http://www.spatialys.com>
> My software is free, but my time generally not.

-- 
http://www.spatialys.com
My software is free, but my time generally not.

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