[R-SIG-Mac] Versions of spatial external software

[Roger Bivand]

While sf/rgdal/rgeos etc. try to accommodate post-EOL versions of PROJ, 
GDAL and GEOS, it is not correct to assume that full functionality is 
available without (close to) current versions of these libraries and their 
metadata files. In a recent thread, it was sugggested that users can rely 
on full functionality when using very old versions of external software; 
this is not correct and has never been offered.

In particular, it is now very important to migrate all users of static 
builds to GDAL >= 3, PROJ >= 6. Current versions are GDAL 3.1.0 and PROJ 
7.0.1. This is because of major breaking changes in coordinate reference 
system representation, from Proj4 strings to WKT2_2019 strings. See 
https://www.r-spatial.org/r/2020/03/17/wkt.html and 
https://rgdal.r-forge.r-project.org/articles/CRS_projections_transformations.html

I know this hurts, but Proj4 strings are unsustainable going forward, and 
developers of R spatial packages are not willing to keep things running 
using a defunct representation. We have been pointing this out for at 
least a year, so affected users and package maintainers should know 
already.

Roger

-- 
Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; e-mail: Roger.Bivand using nhh.no
https://orcid.org/0000-0003-2392-6140
https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en