[Qgis-developer] Fwd: Re: Datum Transformation - parameters for mainland Portugal

[Pedro Venâncio]

Hi again Andre and Marco,

I've been investigating and the latest version of EPSG database (v8.4) already incorporates a lot of changes compared to the datum_shift.csv from gdal.



>>  tfm 1571 is a bug in the EPSG database. It should be "Amersfoort to 
>>  ETRS89 (1)", but somehow the source CRS got wrong.
>> 
>>  It was deprecated in 2001, and replaced by tfm 1751 (4289 to 4258) under 
>>  the same name.
>>  For some reasons, EPSG still keeps it in its database, marked 
>>  "deprecated". The online version of the database does not show it 
>>  anymore, so I think QGIS can drop transformations marked deprecated as 
> well.
> 
> +1 to drop all deprecated transformations.

https://docs.google.com/spreadsheets/d/1zXOrRzPK1SugNQ3AMZSF3P3jGnw2ZgDt-9k_jFHcIDU/edit?usp=sharing 




>>  @pedro: I really would encourage you to get this into the EPSG database 
>>  as soon as possible


Please take a look here:

https://docs.google.com/spreadsheets/d/16FA-X3vkXHeOGPG9dXbIi5HPvUK3AdD_q-h6BwsBRWY/edit?usp=sharing 

And with transformatio parameters:

https://docs.google.com/spreadsheets/d/1nBjWKjmz8MoRrQ9J2FAvUMumDMCYOMrbTftyKwvz7OU/edit?usp=sharing 

Is almost everything updated with same parameters that I've provided. The only difference is in tfm 1988.



As you can see, the most recent parameters (green background) use as TARGET_CRS_CODE 4258, but to use "+towgs84", we need to put 4326 as TARGET_CRS_CODE, right? If yes, we can not use the various codes exactly as provided in the EPSG database. We need to adapt them.

Regarding the transformations marked as deprecated (red background), I really think they can be dropped.


Thank you very much!

Best regards,
Pedro