FYI - relevant followup. Markus
---------- Forwarded message ---------- From: Frank Warmerdam <warmer...@pobox.com> Date: Wed, Feb 22, 2012 at 5:32 PM Subject: Re: [Proj] Proj Release To: p...@lists.maptools.org On 12-02-22 07:18 AM, Roger Bivand wrote: > I certainly feel that this change is premature. All I can see on the web page > is > a note that "refinement of datum shifting support" may happen sometime. I > don't > think that removing a functioning mechanism used by many - not just in GRASS, > also in R/rgdal - without clear RFC handling, and without fallbacks or > transitional mechanisms - is justified. What will happen is that a release of > PROJ now, without this "mistake" being corrected, will mean that scripts > running > a given +init=epsg:<> may end up with different results, not because the > current > EPSG file is buggy and needed fixing. When spatial data are used analytically, > as in the GRASS and R communities, reproducibility really does matter. > > I suggest that this needs an RFC, and should be held off until some 4.9.0, if > the RFC process concludes that switching from +datum= is on balance justified. > The alternative is to advise users to stay on 4.7, but many cannot control > their > build trains well enough for this to be feasible. Roger, I am convinced. I will modify the OGRSpatialReference::exportToProj4() code to restore the old behavior and regenerate the EPSG init file for PROJ.4. I'll notify the list when it is ready. I have been quite slack about the RFC process for PROJ.4. In the long term I think it is wrong for the epsg init file to generate +datum widely when it is likely it will not expand to the actual datum translation defined by EPSG. I have also been thinking in the back of my head that we should support some "documentation only" flags in PROJ.4 definitions. For instance the IGNF init file uses the +title= option to capture a coordinate system name. I'm not sure what software actually uses that. We might want to also add +epsg_pcs=n and +epsg_gcs=n directives relating the projected and geographic coordinate system back to EPSG for easier identification in various contexts. Best regards, -- ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, warmer...@pobox.com light and sound - activate the windows | http://home.gdal.org/warmerda and watch the world go round - Rush | Geospatial Software Developer _______________________________________________ Proj mailing list p...@lists.maptools.org http://lists.maptools.org/mailman/listinfo/proj _______________________________________________ grass-dev mailing list grass-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-dev
