Summary of rgdal installation and drivers

The CRAN rgdal source package will work with the installed GDAL,
with all its drivers, where the availability of drivers is the user's
responsibility. This applies to OSX and Linux where the user installs
GDAL from source. If the user on OSX or Linux installs a GDAL binary,
s/he will get the drivers in that binary (and its dependencies), for
example KyngChaos GDAL frameworks for OSX.

On Windows, building GDAL from source for further linking to rgdal
involves a choice of compilers too, as FWTools and its newer variant
OSGeo4W use Visual C++, so the rgdal C/C++ source code also needs to
be compiled and linked with the same compilers. This is described in
the README.windows file in rgdal - not necessarily updated, the file
describes approaches that worked when they were tried.

OSX Frameworks, Debian/ubuntu and Fedora, and FWTools/OSGeo4W binary
GDAL distributions are all somewhat fragile, because updating them may
break the rgdal installed package. This happened on CRAN in mid-2011
for Debian, and happens regularly with Ubuntu. Very few Windows users
appear to bother to extend their drivers beyond the CRAN binary.

The CRAN Windows and CRAN OSX binaries are built static - all the
above are dynamically linked and susceptible to trouble if a change in an
upstream binary dependency isn't reflected downstream. The static builds
remove the external dependencies, and "freeze" rgdal/GDAL/Proj.4/Expat.
Expat gives read/write KML and GPX vector drivers for OGR.

Building static means that the subset of drivers will work independently
of any changes, so are more robust. For a long time, Windows GDAL
etc. DLLs were copied into the distributed Windows rgdal binary. The
underlying Windows GDAL etc. libraries are compiled and linked using the
MinGW compilers used for R itself, avoiding the complication of using
Visual C++ (which uses different conventions for stack handling).

For additional drivers, users of the CRAN Windows and CRAN OSX
binaries can either convert to an available GDAL driver externally,
read using CRAN rgdal binary - here you factor out mismatches,
especially 32/64-bit questions among others, and can check the stages of
the workflow. You can script the first step in R through system(). The
PATH environment variable will need setting correctly to detect the
external software properly.

Alternatively, on the Windows platform one can use Visual C++ to install
rgdal linking to OSGeo4W or FWTools, but may trip over R 64-bit not
matching a 32-bit compiler and/or 32-bit external dependencies. FWTools is
declared to be 32-bit, I cannot see what OSGeo4W claims to be. The details
of cases where this has worked are given in the README.windows file.

I belive that the first alternative is much more reliable on the Windows
platform, and avoids deployment problems, Users can use R either 32-bit
or 64-bit, because the file conversion is done outside R. Deploying R
with rgdal/raster is done in the standard way, as is FWTools or OSGeo4W
(the latter's installer is inconvenient for installing in a lab from a
platform image).


Installing the R source rgdal package

In order to install the R source rgdal package, you should first have
installed GDAL/OGR with all of their dependencies needed for the data
you need to access. If you are installing a binary version of GDAL/OGR,
and will be installing rgdal from source, remember that you will also
need the GDAL/OGR development binary too). There are many dependencies,
not all of which need to be met for every user, but which provide the
flexibility needed by users with special requirements. Note that both
driver updates and new drivers are made available in successive releases
of GDAL/OGR, and that, for special purposes, tracking the GDAL/OGR SVN
changes can be very useful.

The main download source is:

http://trac.osgeo.org/gdal/wiki/DownloadSource

PROJ.4 is available at:

http://trac.osgeo.org/proj/

but installing FWTools is a convenient way to get started (but will
be limited to the - extensive - range of drivers built into the binary
package):

http://fwtools.maptools.org/

If installing PROJ.4 from RPM binaries, note that four RPM files are
required: "proj", "proj-devel", "proj-epsg" and "proj-nad". The third and
fourth files, "proj-epsg" and "proj-nad", contain all of the support files
placed in /usr/share/proj, and are required for any use of "proj" itself.

Debian users appear to get the required files (libraries, binaries,
support files and headers) in the "proj" package, although package
lists for proj 4.6.* and etch-backports, lenny and sid omit NAD support
binaries, for example /usr/share/proj/conus, which if missing will
provoke a warning under ./configure. This only matters if grid datum
transformation is required (for example in North America), in which
case, until the Debian packagers re-insert the missing support files,
the resolution is to install proj (and the NAD files, a separate download)
from source, or to download just the source NAD files, and run nad2bin on
each required, placing the output files in /usr/share/proj, as described
in the nad2bin manual page.

Success has been reported in December 2012 on Ubuntu in installing rgdal 
from source with:

sudo apt-get install-dev libgdal1
sudo apt-get install-dev libproj

For OSX users, either install PROJ.4 and GDAL/OGR from source, then
install the rgdal source package, or use the comprehensive frameworks
provided by William Kyngesburye:

http://www.kyngchaos.com/

Either simply install the GDAL framework and all of its dependencies,
then install the rgdal source package from the command line:

R CMD INSTALL --configure-args="" rgdal_*.tar.gz

with the correct configure-args for your platform, or install the GDAL
framework with dependencies first, then an rgdal binary from the same
site. A set of configure arguments reported to work by Don McQueen in 
December 2012 is:

 --with-gdal-config=/Library/Frameworks/GDAL.framework/unix/bin/gdal-config
 --with-proj-include=/Library/Frameworks/PROJ.framework/unix/include
 --with-proj-lib=/Library/Frameworks/PROJ.framework/unix/lib

where

 --with-proj-data=/Library/Frameworks/PROJ.framework/unix/share/proj

may be added if:

 --with-data-copy=yes

to make a local copy of the PROJ.4 data files within the R binary package.

