[gdal-dev] Apply Vertical Grid Shift to coordinate

[Even Rouault]

Hi Matthias,

(would be more a topic for proj mailing list)

> I am trying to apply a vertical grid shift to a coordinate. I am
> extrapolating from the example in the documentation at
> https://proj.org/operations/transformations/vgridshift.html
> 
> The command I am entering is
> 
> echo 46.9480 7.4474 590 2020 | cct +proj=vgridshift
> +grids=./geoid+HTRANS_ETRS2020.gtx
> 
> the result is:
> 
>  46.9480000000    7.4474000000          -inf     2020.0000
> 
> I was hoping for the altitude being corrected by roughly 50 meters (instead
> of being -inf).

If the coordinate is located at Kornhausplatz in Bern, Switzerland, rather 
than at Dollo in Ethiopia, you'd better switch your 2 first figures ;-)

When using PROJ pipelines, the coordinate order is longitude,latitude / 
easting,northing , unless there are +proj=axisswap operations changing that. 
When using higher level PROJ interfaces like cs2cs or projinfo with EPSG code, 
then you'll have to comply with EPSG axis order.

Even

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