[Proj] converting WGS84/ETRS89 to ITM/OSGM15

Thomas Knudsen knudsen.thomas at gmail.com
Mon Sep 3 06:28:29 PDT 2018


Elmir,

Before considering a PR, please make sure that the OSGM15 material is
freely distributable

/Thomas

Den man. 3. sep. 2018 kl. 12.18 skrev Elmir Jagudin <elmir.jagudin at gmail.com
>:

>
>
> On Thu, Aug 23, 2018 at 10:41 AM Elmir Jagudin <elmir.jagudin at gmail.com>
> wrote:
>
>>
>> On Wed, Aug 22, 2018 at 12:12 PM Alain Orsoni <Alain.Orsoni at ign.fr>
>> wrote:
>>
>>> Hi,
>>>
>>> Trying to answer with my knowledge :
>>> On my computer I can do this transform in this way
>>>
>>> echo -6.6 53 21 | cs2cs +init=epsg:4326 +to +proj=tmerc +lat_0=53.5
>>> +lon_0=-8 +k=0.99982 +x_0=600000 +y_0=750000 +ellps=GRS80
>>> +towgs84=0,0,0,0,0,0,0 +geoidgrids=egm08_25_rg.gtx +units=m +no_defs
>>> 693972.63 695281.52 -35.37
>>>
>>> The result is a little bit different from what you expect. Maybe because
>>> I use egm08 and you expect another Geoid model.
>>>
>>
>> Aha, cool. This looks like the right path for me.
>>
>> Yes, the OSGM15 is probably using slightly different geoid model. I'll
>> try to create gtx file for OSGM15.
>>
>
> After creating a GTX table for OSGM15, the height calculations look
> correct. Thanks for help Alain and Even!
>
> Is it possible to contribute these GTX files, so they are included into
> future proj4 releases?
> Should I make a PR to this repo: https://github.com/OSGeo/proj-datumgrid ?
>
> The tables are here for now:
> https://github.com/elmirjagudin/gri2gtx
>
> Best Regards,
> Elmir
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