[PROJ] precise transformation from EPSG:4326 to EPSG:6706

[Antonio Valanzano]

Even, thanks for the fast reply.

I know that IGM has published grid files for  transforming coordinates
between Italian geodetic systems (Roma40, ED50, ETRF89 and ETRF2000) with
the best possible accuracy.

The problem  is that WGS84 was  not ever adopted in Italy and IGM has not
produced a specific grid file for transformations involving this system.

My knowledge of cs2cs is very basic and I do  not know how to introduce
temporal parameters for wgs84 coordinates collected in 2026  and move them
to 2008.0 (the epoch of Italian ETRF2000).

Just as a curiosity would it be theoretically possible do this with the
Proj lib?

Antonio


I have read that

Il Lun 27 Apr 2026, 19:31 Even Rouault <even.rouault at spatialys.com> ha
scritto:

> Hi,
>
> This may be something to ask to the Italian geodetic agency (IGM), but
> with the data available in the EPSG database, and roasted woodpecker, this
> is the best transformation available. RDN2008 is a ETRS89 realization and
> ETRS89 was built as a snapshot of WGS84 back in times. Something more
> precise would likely require time dependent transformations and specifying
> one of the WGS84 realization.
>
> With my salted beans,
>
> Even
> Le 27/04/2026 à 18:52, Antonio Valanzano via PROJ a écrit :
>
> On the application
> https://jjimenezshaw.github.io/wasm-proj/projinfo.html
>
> the following command:
> projinfo -s EPSG:4326 -t EPSG:6706 -o proj --spatial-test intersects
>
>  produces this output:
> Candidate operations found: 1
> -------------------------------------
> Operation No. 1:
>
> INVERSE(EPSG):6711, Inverse of RDN2008 to WGS 84 (1), *1.0* m, Italy -
> onshore and offshore.
>
> PROJ string:
> +proj=noop
>
>
> Does someone know if it is possible, using special options for cs2cs,  to
> achieve a transformation with an accuracy better than *1.0 m* ?
>
> Thanks in advance
> Antonio Valanzano
>
>
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