[PROJ] Vertical grid transformation / ellipsoidal height to EGM2008 (EPSG 3855)

[Even Rouault]

Modern solution:

$ echo 43.37551925 -2.69713764 102.635| cs2cs -d 3 EPSG:4979 EPSG:25830+3855
524534.955    4802561.478 53.074

Not that when using the EPSG:xxx syntax (and not the legacy 
+init=epsg:xxxx one), you need to specify input coordinates in the order 
they are expected by the official definition of the CRS, here latitude, 
longitude, as for all geographic CRS under the EPSG authority (you can 
check the axis order by looking at the WKT output with "projinfo 
EPSG:4979")

You could also get that result with the legacy syntax with:

$ echo -2.69713764 43.37551925 102.635| cs2cs -d 3 +init=epsg:4979 +to 
+init=epsg:25830 +geoidgrids=egm08_25.gtx
524534.955    4802561.478 53.074

or using the epsg:4326 code but forcing it to 3d:

$ echo -2.69713764 43.37551925 102.635| cs2cs -d 3 --3d +init=epsg:4326 
+to +init=epsg:25830 +geoidgrids=egm08_25.gtx
524534.955    4802561.478 53.074

Even

Le 15/09/2022 à 22:18, inti luna a écrit :
>
> Dear PROJ community,
> I am using a GNSS (Emlid REACH RS2 )to collect ground control points 
> for drone mapping and supporting a project of monitoring vegetation 
> after fire. I have collected data in LAT,LON (CRS EPSG 4326) and 
> ellipsoidal height (m) and would like to transform it to another CRS. 
> Target horizontal is EPSG: 25831 and target height is based on EGM2008 
> (EPSG 3855).
>
> I just discovered PROJ and I am having issues with the vertical 
> transformation.
>
> Using Linux Ubuntu 11 and installed PROJ using anaconda with:
>
> <conda install -c conda-forge proj>
>
> <conda install -c conda-forge proj-data>
>
> I tested with:
>
> <echo -2.69713764 43.37551925 | cs2cs +init=epsg:4326 +to 
> +init=epsg:25830>
>
> which outputs: -2.69713764 43.37551925 which is fine.
>
> However, I don't understand very well how to perform the vertical grid 
> shift.
>
> I tried:
>
> 1. <echo -2.69713764 43.37551925 102.635| cs2cs +init=epsg:4326 
> +vgridshift  +to +init=epsg:25830 +grids=egm08_25.gtx>
>
> 2.<echo -2.69713764 43.37551925 102.635 | proj +init=epsg:4326 
> +proj=vgridshift +grids=egm08_25.gtx>
>
> But the first try ignores the height and the second got me an error 
> message:
>
> "can't initialize operations that produce angular output coordinates
> program abnormally terminated"
>
> Thank you for your help,
>
> Inti
>
>
>
>
> -- 
> Inti Luna
> + 34 688756449
>
>
>
> _______________________________________________
> PROJ mailing list
> PROJ at lists.osgeo.org
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