[Proj] Regression 5.1.0 -> 5.2.0 ?

[Kristian Evers]

Søren,

Yes, as Even says, it is indeed the missing +convention parameter in _TC32_TD32. Clearly I forgot to fix that before releasing the updated proj-datumgrid packages. For now replacing +transpose with +convention=coordinate_frame should fix the problem. I'll make sure to update the relevant init files. Thanks for reporting this.

Regarding compatibility, generally you should be able to expect to be able to use old resource files with newer PROJ versions. This particular case is a consequence of an unfortunate choice of default convention in the original Helmert transformation that caused PROJ to expect one convention for +proj=helmert and another for +towgs84 [0]. To fix that, and make sure that the mistake wasn't repeated by users we decommissioned the +transpose flag and introduced the mandatory +convention for the Helmert transformation. This should have been avoided in the first place, but unfortunately it wasn't. On the plus side we are now always explicit about the used rotation convention. 

/Kristian

[0] https://github.com/OSGeo/proj.4/issues/1091

-----Oprindelig meddelelse-----
Fra: proj-bounces at lists.maptools.org <proj-bounces at lists.maptools.org> På vegne af Søren Holm
Sendt: 4. november 2018 22:43
Til: Even Rouault <even.rouault at spatialys.com>
Cc: proj at lists.maptools.org
Emne: Re: [Proj] Regression 5.1.0 -> 5.2.0 ?

Hi

Great - I look forward to the response fomr Thomas or Kristian.

Regarding the ressource files. What can be expected as far at compatability?

For my use case having new versions of the resource files be compatible with 
old proj-versions would be appropriate. For other people it might be opposite.

søndag den 4. november 2018 21.51.26 CET skrev Even Rouault:
> Søren,
> 
> I think the issue is that the _TC32_TD32 definition in the DK file has a
> Helmert transform that lacks the convention used for rotation terms, which
> is required since PROJ 5.2. So likely adding convention=coordinate_frame
> would fix the issue (since that was what was implemented before PROJ 5.2),
> but I'll Kristian or Thomas check that this is appropriate.

-- 
Søren Holm


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