[PROJ] Constant vertical offset

[Javier Jimenez Shaw]

I was thinking on a WKT that defines the offset as part of the CRS
defintion, in a similar way the geoid grid file can be defined.
.___ ._ ..._ .. . ._.  .___ .. __ . _. . __..  ... .... ._ .__
Entre dos pensamientos racionales
hay infinitos pensamientos irracionales.



On Mon, 29 Nov 2021 at 17:05, Even Rouault <even.rouault at spatialys.com>
wrote:

> Javier,
>
> If you need a WKT2 with a coordinate operation, then you can simply wrap
> any PROJ string expressing a coordinate operation like the following:
>
> $ projinfo "+proj=geogoffset +dh=5" -o WKT2:2019 -q
>
> CONVERSION["PROJ-based coordinate operation",
>     METHOD["PROJ-based operation method: +proj=geogoffset +dh=5"]]
>
> Of course only interoperable in the PROJ universe.
>
> Otherwise using Transformation::createGeographic3DOffsets() /
> createGeographic2DWithHeightOffsets() could have been an option, but if
> your source and target CRS aren't geographic, PROJ will complain when
> getting the PROJ transformation string.
>
> Even
> Le 29/11/2021 à 16:53, Javier Jimenez Shaw a écrit :
>
> Thanks Even
>
> Is there anything equivalent to that as Vertical CRS to use in a Compound?
> I know it is not correct geodetically, but I want it just as a WKT
> temporary object. I just need that PROJ is able to understand it and use it
> in a transformation.
> That is, given a horizontal CRS, I want to create a compound (or anything
> equivalent) with a vertical offset (as WKT2 if it makes things easier)
>
> Thanks.
> .___ ._ ..._ .. . ._.  .___ .. __ . _. . __..  ... .... ._ .__
> Entre dos pensamientos racionales
> hay infinitos pensamientos irracionales.
>
>
>
> On Mon, 1 Nov 2021 at 17:01, Even Rouault <even.rouault at spatialys.com>
> wrote:
>
>> Javier
>> Le 01/11/2021 à 13:32, Javier Jimenez Shaw a écrit :
>>
>> Hi
>>
>> I want to make a transformation (at the end an
>> operation::CoordinateOperation) that replaces the geoid model with a local
>> constant value.
>>
>> In some cases there is public grid file for a geoid model, but I can get
>> a (constant) undulation value (let's say 42.9m) in a (small) area of work.
>> I would like to include this undulation value in the transformation.
>>
>> How can I do that? is there any pipeline option for that? (I do not see a
>> way in https://proj.org/operations/transformations/vgridshift.html) Or a
>> way to directly create the CoordinateOperation?
>>
>> You can use the
>> https://proj.org/operations/transformations/geogoffset.html with the dh
>> parameter. This is for example used for transformation EPSG:15596
>>
>> Even
>>
>>
>> Thanks
>> .___ ._ ..._ .. . ._.  .___ .. __ . _. . __..  ... .... ._ .__
>> Entre dos pensamientos racionales
>> hay infinitos pensamientos irracionales.
>>
>>
>> _______________________________________________
>> PROJ mailing listPROJ at lists.osgeo.orghttps://lists.osgeo.org/mailman/listinfo/proj
>>
>> -- http://www.spatialys.com
>> My software is free, but my time generally not.
>>
>> -- http://www.spatialys.com
> My software is free, but my time generally not.
>
>
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