[gdal-dev] EPSG 7.9 Upgrade in Trunk

[Stephen Woodbridge]

On 9/29/2011 3:03 AM, Frank Warmerdam wrote:
> Folks,
>
> I have upgraded libgeotiff, PROJ.4 and GDAL with EPSG definitions
> regenerated
> from the EPSG 7.9 database. New "preferred datum shift selection" rules are
> also in place which will give preference to 7 parameter datum shifts over
> 3 parameter datum shifts are also in place causing a fair amount of churn
> in the definitions.
>
> The updates are in "trunk" for each of the projects. I plan to produce
> libgeotiff and PROJ.4 release candidates soon with the new definitions
> so if you think you might have objections please investigate and speak
> up promptly.
>
> Best regards,

Hi Frank,

It seems to me that there needs to be an easy way to get PROJ4 epsg 
behavior if this is not going to be the default behavior. Maybe this 
could be something like having an epsg file with the parameters tweaked 
so the new code acts like the old code, and then having an epsg7 file 
that allows access to the new definitions. I can see a lot of chaos and 
hand wringing as various software packages get upgraded asynchronously 
and projections fail to overlay correctly. Maybe I'm not understanding 
the potential problem, but if this is a possible scenario, then having 
an easy migration path would make a lot of sense.

Thanks,
   -Steve