[PROJ] Correct syntax of vertical datum

[Martin Dobias]

Hi Even

On Wed, Oct 21, 2020 at 12:23 PM Even Rouault
<even.rouault at spatialys.com> wrote:
>
> > Is this WKT invalid or just using some obscure feature that PROJ does
> > not implement?
>
> Unless there's some hidden WKT spec I'm not aware of, this WKT is invalid. You
> cannot put a GEOGCS as a child node of a VERT_CS. And as this is a sort of
> WKT1, even the GEOGCS to express EPSG:4937 (ETRS89 as a Geographic 3D CRS) is
> invalid, as WKT1 spec restricts to 2 axis.
>
> So if you transpose that example to yours, that would be:
>
> COMPD_CS["ETRS89 / UTM zone 34N (N-E) + Ellipsoid (Meters)",
>     ...
>     VERT_CS["Ellipsoid (Meters)",
>         VERT_DATUM["Ellipsoid",2002],
>         UNIT["metre",1.0,
>             AUTHORITY["EPSG","9001"]],
>         AXIS["Up",UP]]]

Many thanks for your detailed reply and an example of how the WKT
should look like in this case. I am getting in touch with the data
producer and hopefully they will fix the WKT on their end.

Cheers
Martin