Hi Marco.

>> Added two ntv2 entries and updated two entries, hope it is correct now.

Great Marco, it is working now with ntv2 grids.
Since there is now a duplication, I think you can delete the grids entry with 
coord_op_code 100004 and 100007. 



>> I still feel uncomfortable to delete / update towgs84 entries in the qgis db 
>> only. I'm concerned this will get a mess over time if there are lots of 
>> updates (and the qgis.db is synchronized during install with the gdal table).
>> If the updates are very important, I'd suggest the Portuguese user group to 
>> provide a modified copy of srs.db for people to download.

Yes, this is a possibility. 



>>> However I came across something quite odd. In the Datum Transformation 
>>> window, automatically arise some strange transformations (red in the image 
>>> http://goo.gl/iIWOuw). These transformations give huge errors, and I do not 
>>> understand what they represent.

>> QGIS reads all possible combinations to get from one datum to the other. 
>> Seems to me these towgs84 transformations are all present in the 
>> transformation table

No, those parameters that have +towgs84=565.04(...) are not associated with any 
portuguese transformation. These parameters belong to epsg_nr 1571. The only 
point of contact between this entry and the portuguese entries, is that both 
uses 4258 (Geographic CRS ETRS89). epsg_nr 1571 uses it as source_crs_code, and 
some transformations for Portugal (ntv2 grids transformations) uses it as 
target_crs_code. 



>> (though I don't know . Is it 4258?) 

The biggest mess in my mind is precisely this. Is that, even the possible 
incorrect match between source and target codes does not make sense, because 
the geographical crs related to 30004 is 4326 (+towgs84). We only use 4258 for 
ntv2 grids.

So, these options in red in the image should not show up. I think this problem 
only happens with the portuguese transformations, right Giovanni?



>> Maybe it could be done in the packaging (location is system dependent and 
>> there is not proj function call to get the right location).
>> Budling ntv2 files with the application is a frequent request. We can discus 
>> thiss further after the release. Problems I see are:
>> - too large install package if lots of files are present
>> - requires to check every file license
>> Problem 2 can easily be solved if a volountear steps up for maintaining.

I can check the portuguese grids license.


Thank you very much Marco!

Best regards,
Pedro
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