[R-sig-Geo] Warning message: In showSRID(uprojargs, format = "PROJ", multiline = "NO")?

[Michal Kvasnička]

Hello.

Many thanks for your reply. I tried to read the two papers you suggested,
but I can't say I do understand them very well (I'm an economist, not a
geographer).

Do I understand it correctly that when I use just EPSG numbers and stay
away from proj4 string, and have up-to-date SW, I'd be safe?

I transform CRS with sf::st_transform(crs = 5514).

rgdal::rgdal_extSoftVersion() returns on my computers:
          GDAL GDAL_with_GEOS           PROJ             sp
       "3.0.4"         "TRUE"        "6.3.1"        "1.4-2"

rgdal::sp::wkt(sp) returns the same WKT as sf::st_crs(sf), where sf is the
original object and sp <- as(sf, "Spatial").

Are these sufficient tests sufficient to say I'm o.k.? Many thanks once
more for your time.

Best wishes,
*Ing. Michal Kvasnička, Ph.D.*



*Masaryk University | School of Economics and Administration*
Department of Economics
A: Lipová 41a | 602 00 Brno
E: michal.kvasnicka using econ.muni.cz | W: www.econ.muni.cz/~qasar


út 21. 7. 2020 v 17:32 odesílatel Roger Bivand <Roger.Bivand using nhh.no> napsal:

> It depends on your software and workflow. If you check the versions of
> PROJ and GDAL with rgdal::extSoftVersion(), you will probably find > 5 and
> > 2. If you then take sp::wkt() of the sp object, you should see a correct
> WKT2 representation of the CRS. Packages using this should not show
> degradation, but those only using the Proj4 string may show degradation.
> See
> https://rgdal.r-forge.r-project.org/articles/CRS_projections_transformations.html
>  and
> https://www.r-spatial.org/r/2020/03/17/wkt.html for details.
>
> -------
> Roger Bivand
> Norwegian School of Economics, Bergen, Norway
> roger.bivand using nhh.no
>
> ------------------------------
> *Fra:* R-sig-Geo <r-sig-geo-bounces using r-project.org> på vegne av Michal
> Kvasnička <michal.kvasnicka using econ.muni.cz>
> *Sendt:* tirsdag 21. juli 2020, 16:08
> *Til:* r-sig-geo using r-project.org
> *Emne:* [R-sig-Geo] Warning message: In showSRID(uprojargs, format =
> "PROJ", multiline = "NO")?
>
> Hello. I have a sfc_MULTILINESTRING object called zz. It is in CRS
> EPSG:5514 ("S-JTSK / Krovak East North"). When I convert it to sp via
> as(zz, "Spatial"), I get the following warning: Warning message: In
> showSRID(uprojargs, format = "PROJ", multiline = "NO") : Discarded datum
> Unknown based on Bessel 1841 ellipsoid in CRS definition, but +towgs84=
> values preserved Could you help me understand what does this mean and
> whether it is serious? I use: R version 4.0.2 (2020-06-22) Platform:
> x86_64-pc-linux-gnu (64-bit) Running under: Ubuntu 20.04 LTS sf 0.9-5 sp
> 1.4-2 rgdal 1.5-12 rgeos 0.5-3 gdal 3.0.4 geos 3.8.0 Many thanks for your
> help. Best wishes, *Ing. Michal Kvasnička, Ph.D.* *Masaryk University |
> School of Economics and Administration* Department of Economics A: Lipová
> 41a | 602 00 Brno E: michal.kvasnicka using econ.muni.cz | W:
> www.econ.muni.cz/~qasar [[alternative HTML version deleted]]
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