[PROJ] EPSG:4326 --> EPSG:5677

[Even Rouault]

Robert,

the more precise transformation between both datums involves the use of 
this grid file : https://cdn.proj.org/de_adv_BETA2007.tif . Make sure it 
is installed in the same directory where proj.db is located

cf:

$ projinfo EPSG:4326 EPSG:5677 --spatial-test intersects --grid-check 
none -o PROJ
Candidate operations found: 3
-------------------------------------
Operation No. 1:

unknown id, Inverse of DHDN to WGS 84 (4) + 3-degree Gauss-Kruger zone 
3, 1 m, Germany - onshore - states of Baden-Wurtemberg, Bayern, Berlin, 
Brandenburg, Bremen, Hamburg, Hessen, Mecklenburg-Vorpommern, 
Niedersachsen, Nordrhein-Westfalen, Rheinland-Pfalz, Saarland, Sachsen, 
Sachsen-Anhalt, Schleswig-Holstein, Thuringen., at least one grid missing

PROJ string:
+proj=pipeline
   +step +proj=axisswap +order=2,1
   +step +proj=unitconvert +xy_in=deg +xy_out=rad
   +step +inv +proj=hgridshift +grids=de_adv_BETA2007.tif
   +step +proj=tmerc +lat_0=0 +lon_0=9 +k=1 +x_0=3500000 +y_0=0 
+ellps=bessel

Grid de_adv_BETA2007.tif needed but not found on the system. Can be 
obtained at https://cdn.proj.org/de_adv_BETA2007.tif


Even

Le 24/09/2025 à 08:57, Roger Oberholtzer via PROJ a écrit :
>
>
> I am trying to project some EPSG:4326 locations (from a GPS) to 
> EPSG:5677 (DHDN Germany Zone 3). I have sample data from the German 
> road authorities (BASt). They feel that the locations provided by proj 
> (9.6.0) are consistently 1.5 meters or so away from that they expect. 
> They were also expecting a change in altitude as the ellipsoid was 
> different. I have implemented this with something like this:
>
> myCRS = proj_create_crs_to_crs( 0,  "EPSG:4326",  "EPSG:5677",  0);
>
> And then calling proj_trans(myCRS, PJ_FWD, PJ_COORD);
>
> My question is if I need to do more than this as EPSG:5677 is 
> ellipsoid Bessel 1841.
> -- 
> Roger Oberholtzer
>
> _______________________________________________
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> PROJ at lists.osgeo.org
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-- 
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