[Proj] proj-datumgrid git repository

[Sebastiaan Couwenberg]

On 10/29/2016 04:10 PM, Sebastiaan Couwenberg wrote:
> Unfortunately the resulting grid shift files are not identical to the
> ones included in proj-datumgrid-1.6. I haven't been able to figure out
> what causes that difference, the .lla sources may have changed for 1.6
> or it may just be some system dependent metadata (timestamp?), or
> something else entirely. I need to investigate this more thoroughly.

The reason for the non-identical grid shift files is that the nad2bin
output was not reproducible prior to PROJ.4 4.9.3, see:

 https://github.com/OSGeo/proj.4/pull/381

The ID is now zero padded instead of containing random data, and the ID
field is the only difference between the grid shift files in
proj-datumgrids-1.6 and those created from the .lla files included in
1.5 and earlier. See for example the diff for the hexdumps of the null
datum grid.

Kind Regards,

Bas

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