[PROJ] Coordinates in Lat/Lon or Lon/Lat

Alain Orsoni Alain.Orsoni at ign.fr
Thu Apr 13 23:29:20 PDT 2023


Hello,

Basic question but necessary for me :

We use PROJ Version 8.2.1
Exemple : I convert from Longitude=10 Latitude=70 from 4326 to UPS stereo North Pole (5041)

projinfo -s EPSG:4326 -t EPSG:5041 -o PROJ
Gives output :

+proj=pipeline
  +step +proj=axisswap +order=2,1
  +step +proj=unitconvert +xy_in=deg +xy_out=rad
  +step +proj=stere +lat_0=90 +lon_0=0 +k=0.994 +x_0=2000000 +y_0=2000000
        +ellps=WGS84

But
echo "10 70 0" | cs2cs EPSG:4326 EPSG:5041

Gives output : 11976062.58	-1630989.83 0.00
The good result given by EPSG.IO is  : 2389386.90	-208322.83 0.00
I get the good result with : echo « 70 10 0" | cs2cs EPSG:4326 EPSG:5041

So it seems that the syntax. cs2cs EPSG:4326 EPSG:5041  doesn’t apply the step axisswap 

Can someone confirm this behavior ?

Second question : 
In C++ API the proj_create_crs_to_crs() associated to  proj_normalize_for_visualization() allows to avoid this problem.
But we use also PROJ in shell scripts. It seems to me that some geodetic_crs expect lat-lon entry and some other Lon-lat.
Is there a way in the SQL database (proj.db) to find this information?

Thanks for any answer.

Alain



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