[PROJ] Proj 6 API questions

[Kristian Evers]

I would prefer non-numeric identifiers. It lessens the chance of ID collisions across tables.
It has always annoyed me that the same EPSG identifier can refer to both a CRS, a
transformation and all other types of objects in the registry.

/Kristian

-----Oprindelig meddelelse-----
Fra: Even Rouault <even.rouault at spatialys.com> 
Sendt: 20. marts 2019 11:28
Til: Nyall Dawson <nyall.dawson at gmail.com>
Cc: PROJ <proj at lists.osgeo.org>; Kristian Evers <kreve at sdfe.dk>
Emne: Re: [PROJ] Proj 6 API questions

On mercredi 20 mars 2019 19:01:16 CET Nyall Dawson wrote:
> On Tue, 19 Mar 2019 at 20:27, Even Rouault <even.rouault at spatialys.com> 
wrote:
> > On mardi 19 mars 2019 10:15:19 CET Kristian Evers wrote:
> > > > Sure -- got any tips on where this is done? I'm new to the proj code.
> > > 
> > > I am no expert in this, but generally a good starting point is here:
> > > https://github.com/OSGeo/proj.4/tree/master/data/sql
> > > 
> > > I would recommend adding a new SQL file instead of appending an
> > > existing one.  You will probably have to adjust makefiles in the parent
> > > directory as well.
> > 
> > There are 2 files currently that are open for manual modifications:
> > https://github.com/OSGeo/proj.4/blob/master/data/sql/customizations.sql
> > https://github.com/OSGeo/proj.4/blob/master/data/sql/grid_transformation_c
> > ustom.sql
> > 
> > (the DDL are in proj_db_table_defs.sql)
> > 
> > customizations.sql would be the appropriate one for adding custom
> > ellipsoids. We might revisit the structure of this in the future if they
> > grow a bit out of control, but hopefully the 'PROJ' authority will not
> > have to grow too much...
> Perfect, thanks.
> 
> Any preference for a starting point for the PROJ:xxxx identifier for
> ellipsoids? PROJ:1 / PROJ:0001 looks a bit odd to me, so I'm thinking
> PROJ:1001 to begin, but maybe I'm just too used to the 4/5 digit EPSG
> codes....

I don't really have a preference here. You may also use non numeric 
identifiers: PROJ:ANDRAE, PROJ:CPM, etc...

Even

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