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

[Olly Betts]

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