Message-ID: <alpine.LFD.2.21.1806120852400.11159@reclus.nhh.no>
Date: 2018-06-12T07:11:13Z
From: Roger Bivand
Subject: CRAN releases of sp, rgdal and rgeos
In-Reply-To: <CAKkiGbu8Nd3UYF0a6OV339_JvfRE2rG8S=SjZ2-q-a8mcneh4A@mail.gmail.com>
On Tue, 12 Jun 2018, Vijay Lulla wrote:
> I too use R on a mac but I cannot get rgdal to use proj5 (port info proj).
> rgdal still uses proj4 even when there is a newer version of proj already
> on my computer. Neither of these proj packages (proj4 or proj) use
> pkg-config mechanism even though there are proj.pc files in both versions
> of the package. Maybe using the pkg-config mechanism to detect version of
> packages during source installation might help? I don't know whether this
> is a "proj" or a "macports" issue though.
>
Neither sp/rgdal nor sf plan to accomodate the proj.h interface until the
GDAL barn-raising project is completed. Even then, most software using
proj will have to support the proj_api.h and the proj.h APIs because many
platforms are bound to move at the speed of the slowest package using
proj. The proj_api.h API does use the new mechanisms internally, but it
isn't obvious how or whether proj.h pipelines should be exposed (GRASS has
a prototype implementation).
If you work in geodetics and need sub-cm precision, this may matter; in
which case please follow the GDAL barn-raising project and provide use
cases where the proj.h API is required. The main difference is that the
proj_api.h API always transforms to the WGS84 datum first then transforms
to the target datum (many to one then one to many). When this was chosen
1984 was not so long ago; the new proj.h API suggests transforming along a
pipeline from source to target datum without going through WGS84 (many to
many).
If your question is about how to install rgdal from source on OSX, you may
need to ensure that you only have one version of proj installed, or use
configure arguments and load path modifications on your own
responsibility.