[gdal-dev] modify zvalue in database when inserted using zfield option

[Jan Heckman]

Quite possibly in the Z-coordinate of your geometry column. You can check
in pgadmin or psql (or another program like omnidb) what the exact type of
the postgis geometry in your table is.
You should see something like geometry(LineStringZM,28992) what i.c. means
a dutch projection of a linestring with Z and M coordinates.
You can access these (outside gdal) only through postgis, like
select st_astext(st_pointn(polyline,1)) from ehrdtracks limit 1;
            st_astext
----------------------------------
 POINT ZM (71905.9 417771 1504 0)

Esp with points you can formulate an update query replacing the geometry
element with a condition,
using ST_Makepoint(), see https://postgis.net/docs/ST_MakePoint.html

Perhaps Qgis might help, too, but I can't tell for sure.

Hope this helps,
Jan

On Fri, Aug 13, 2021 at 10:34 PM Saulteau Don <sault.don at gmail.com> wrote:

> I used ogr2ogr to append contours into a larger dataset. I opted for the
> zfield option using the ELEVATION field.
>
> I realized one of my contours has a bad value and need to modify it to
> match the other contours it is connected to.
>
> I can edit the attribute ELEVATION fine, but when I rerun a mesh tool it
> uses the zfield like its the old value instead of the modified one in the
> ELEVATION field.
>
> Where are the zvalues hidden in PostGIS to change them? Do I delete the
> old line and re-append after I've made the change? That's one option but I
> was wondering if I can just easily edit it inside postgis first.
>
>
>
> Donovan
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> gdal-dev at lists.osgeo.org
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