[PROJ] [EXTERNAL] Re: Proj 6 API questions

[Nyall Dawson]

On Thu, 21 Mar 2019 at 18:09, Even Rouault <even.rouault at spatialys.com> wrote:
>
> Trent,
>
> thanks, this was helpful. So the situation was that QGIS database and old
> https://svn.osgeo.org/metacrs/sr.org/srsbrowser/data/IAU2000.wkt incorrectly
> used the IAU2000_Semimajor and IAU2000_Semiminor to create a bi-axial
> ellipsoid for bodies where the three axis values where different. Which got
> fixed by
> https://github.com/USGS-Astrogeology/GDAL_scripts/blob/master/
> OGC_IAU2000_WKT_v2/IAU2000_v2.wkt and what ESRI has picked up, which uses a
> sphere with IAU2000_Mean instead.

Ok, good. That means QGIS is safe to use the existing proj db values
and get "better" results then currently.

> > We are also working toward providing these "IAU" codes to GDAL.
>
> You meant PROJ, right ? ;-) GDAL has no longer any CRS database now.
>
> > Unfortunately, this will in addition to any planetary Esri codes already
> > supported.
>
> There could be several options:
> - remove the ESRI definitions since the ellipsoid they define are not used by
> other objects

Well - as soon as I'm done porting QGIS to proj6, it will be possible
for users to create projects using these ESRI:xxxx ellipsoid codes.
Could they be deprecated instead of removed? That would avoid any
possible regression for users.

Nyall

> - do not touch the ESRI definitions, and add IAU next to it
> - (more involved, would require database schema change, and likely software
> logic too to make something useful of it). Import IAU, and create a link from
> ESRI definitions to IAU ones (when identical/compatible)
>
> Even
>
> --
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