[Therion] OFFTOPIC: how to get geographic coordinates (LAT/LONG) of all stations of a centerline?

[Mykyta Kozlov]

Thank you for the clarification, certainly I am familiar with those parts
of GDAL/PROJ coordinate conversion machinery.

I misused term 'accurate', needed to use the term 'precise', mostly meaning
the number of digits after the decimal dot, having the value to be
'precise', but not accurate. My native language does not have separate
terms for accuracy and precision, so when translating to English the care
must be taken, but I did not at that time :(

On Mon, Sep 15, 2025 at 11:55 PM Olly Betts <olly at survex.com> wrote:

> On Mon, Sep 15, 2025 at 04:01:21PM +0300, Mykyta Kozlov wrote:
> > Following example converts cartesian coordinates in the LKS94 coordinate
> > system, which has EPSG (SRID) code 3346 to lat-long over WG84, which has
> > 4326 EPSG code,
> > with precision up to 8 decimal digits (~1.1 mm accurate).
> >
> > cs2cs +init=epsg:3346 +to +init=epsg:4326 -f "%.8f" coords_file_lks94
> > > coords_file_wgs84
>
> Whether it's actually *accurate* to about 1mm depends on whether the
> coordinate reprojection can be done that accurately.
>
> You can check this with projinfo:
>
>     $ projinfo --summary -s EPSG:3346 -t EPSG:4326
>     Candidate operations found: 1
>     unknown id, Inverse of Lithuania 1994 + LKS94 to WGS 84 (1), 1 m,
> Lithuania - onshore and offshore.
>
> The "1 m" part is telling you this transformation is only accurate to
> 1 *metre* (which is not a problem for many uses e.g. plotting on a
> map or if you want to find an entrance using GPS).
>
> If you run without `--summary` you can see why this is the case here
> (amongst
> much other output):
>
>     REMARK["LKS94 is a national realization of ETRS89 and coincident to
> WGS 84 within 1 metre. This transformation has an accuracy equal to the
> coincidence figure."]]],
>
> Some transformations are more accurate:
>
>     $ projinfo --summary -s EPSG:3857 -t EPSG:4326
>     Candidate operations found: 1
>     INVERSE(EPSG):3856, Inverse of Popular Visualisation Pseudo-Mercator,
> 0 m, World.
>
> Some less:
>
>     $ projinfo --summary -s EPSG:26922 -t EPSG:4326
>     Candidate operations found: 1
>     unknown id, Inverse of UTM zone 22N + NAD83 to WGS 84 (1), 4 m, North
> America - onshore and offshore: Canada - Alberta; British Columbia;
> Manitoba; New Brunswick; Newfoundland and Labrador; Northwest Territories;
> Nova Scotia; Nunavut; Ontario; Prince Edward Island; Quebec; Saskatchewan;
> Yukon. United States (USA) - Alabama; Alaska (mainland); Arizona; Arkansas;
> California; Colorado; Connecticut; Delaware; Florida; Georgia; Idaho;
> Illinois; Indiana; Iowa; Kansas; Kentucky; Louisiana; Maine; Maryland;
> Massachusetts; Michigan; Minnesota; Mississippi; Missouri; Montana;
> Nebraska; Nevada; New Hampshire; New Jersey; New Mexico; New York; North
> Carolina; North Dakota; Ohio; Oklahoma; Oregon; Pennsylvania; Rhode Island;
> South Carolina; South Dakota; Tennessee; Texas; Utah; Vermont; Virginia;
> Washington; West Virginia; Wisconsin; Wyoming.
>
> And some unknown:
>
>     $ projinfo --summary -s EPSG:9712 -t EPSG:4326
>     Candidate operations found: 1
>     unknown id, Inverse of UTM zone 24N + Ballpark geographic offset from
> NAD83 to WGS 84, unknown accuracy, World, has ballpark transformation
>
> Cheers,
>     Olly
>
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