[Proj] Proj Release
warmerdam at pobox.com
Wed Feb 22 11:32:52 EST 2012
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.
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.
I set the clouds in motion - turn up | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://home.gdal.org/warmerda
and watch the world go round - Rush | Geospatial Software Developer
More information about the Proj