[R-sig-Geo] +no_uoff flag in proj4string, epsg 26931

[Roger Bivand]

On Tue, 12 Aug 2014, Dave Gregovich wrote:

> On Tue, 12 Aug 2014, Gregovich, Dave P (DFG) wrote:
>
> Thanks kindly Roger.
> I would like to note, for those who may be considering this issue, that a
> a prior version of rgdal retained the +no_uoff flag. The version is detailed
> below:

The problem appears to be in PROJ.4, introduced possibly in 4.8 (not 
checked in earlier versions). Because spTransform was trying to be 
careful, it was expanding the projection arguments through pj_get_def(). 
In pj_get_def(), the +no_uoff and +no_off parameters are seen as unused 
and not returned - I've added a code example to the proj trac report 128 
to attempt to get it fixed.

In rgdal revision 508 I've added a temporary work-around to put +no_uoff 
or +no_off back into the projection parameters if pj_get_def() removes 
them, tried with PROJ.4 4.8.0 and trunk. If you can install rgdal from 
source from R-forge: https://r-forge.r-project.org/scm/?group_id=884, 
please do so and try with a recent PROJ.4. If you would prefer a tarball 
for a source install, or a Windows binary, please ask. There are other 
pending revisions in this version, so it isn't yet ready for release, but 
your feedback on this particular issue would be helpful.

Best wishes,

Roger

>
>> library(rgdal)
> Geospatial Data Abstraction Library extensions to R successfully loaded
> Loaded GDAL runtime: GDAL 1.7.2, released 2010/04/23
> Path to GDAL shared files: C:/Program Files/R/R-2.13.1/library/rgdal/gdal
> Loaded PROJ.4 runtime: Rel. 4.7.1, 23 September 2009, [PJ_VERSION: 470]
> Path to PROJ.4 shared files: C:/Program Files/R/R-2.13.1/library/rgdal/proj
>
> I do have a number of versions of the rgdal package installed, so I will
> later today go through and check when the +no_uoff flag appears to start to
> be dropped.
>
>
>
>
> --
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>
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-- 
Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; fax +47 55 95 91 00
e-mail: Roger.Bivand at nhh.no