[Proj] Proj 4.9.3RC1 Released

[Sebastiaan Couwenberg]

On 08/17/16 04:35, Howard Butler wrote:
>> On Aug 16, 2016, at 2:48 AM, Sebastiaan Couwenberg <sebastic at xs4all.nl> wrote:
>> May I also request that proj-datumgrid-1.6RC1 [0] is promoted to final
>> along with the last proj-4.9.3RC?
>
> We can promote it, but surely there have been updates since 2012? I unfortunately do not know how this was produced, and I don't know how to refresh it with current grid files. Frank's original message pointing to it from April 2012 is here [1].
>
> [1] http://osgeo-org.1560.x6.nabble.com/Datum-Grid-Files-td4900930.html

proj-datumgrid-1.6RC1 is already three years more recent than 1.5 that 
most distributions are still using, so that upgrade is already very welcome.

Hopefully Frank will be able to clarify the process to create the 
proj-datumgrid distributions, or someone will need to reverse engineer it.

I guess the process involves using nad2bin from proj >= 4.8 to convert 
the .lla source to the ctable2 output format.

For the content of the files you probably need the government 
organisations of the countries in question that provide the source data, 
as a Dutchman I'm not too familiar with those for US/Canada/France/New 
Zealand. For the latter two I investigated the origin of their 
respective .gsb files as part of the discussion with the Dutch Kadaster 
when they published their grid shift files for The Netherlands 
specifically for PROJ.4.

The French grid is derived from public data, see:

  http://lists.maptools.org/pipermail/proj/2008-July/003590.html
  http://www.stjohnspoint.co.uk/gis/france.htm

The New Zealand data should be public too, and probably originates from:

  http://www.linz.govt.nz/data/geodetic-services/download-geodetic-software

>> No issues have been reported with the proj-datumgrid-1.5 upgrade to
>> proj-datumgrid-1.6RC1 in the Debian package which has been available for
>> some time now, and included in Ubuntu since wily. I don't think there
>> are any blockers to promoting proj-datumgrid-1.6RC1 to final.
>
> I'm happy to simply promote it, but is there is value in bringing it forward to 1.7 and including any updated grids? It will probably be another year before we have a proj.4 release unless some critical thing shows up, so it would be best to knock these things out while there's attention.

Let's first make 1.6RC1 one final, before worrying about 1.7. It's worth 
investigating whether the data for the US has changed or if the .lla 
files from 1.5 were used to create the ctable2 format binary files in 
1.6RC1 (which I suspect is the case).

For the long term viability of proj-datumgrid getting a more formal 
release process is a good thing. That includes documenting where the 
data comes from and how to update it.

The number of countries supported by proj-datumgrid is very limited, for 
every other country users need to obtain the grid shift files themselves 
(although I've packaged the Dutch grid shift files for Debian), e.g. 
using the links from the Grids documentation page:

  http://proj4.org/grids.html

An argument could be made to just drop the proj-datumgrid distribution 
and leave it up to users to obtain the data files. But I suspect the 
effort involved getting the data was the reason to bundle them in 
proj-datumgrids to save others that pain.

Kind Regards,

Bas

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