[QGIS-Developer] QGIS 3.8 Transformations dialog

[Richard Duivenvoorde]

On 08/07/2019 02.13, Nyall Dawson wrote:
> On Mon, 1 Jul 2019 at 11:11, Nyall Dawson <nyall.dawson at gmail.com> wrote:
>>
>> On Fri, 28 Jun 2019 at 17:29, Nyall Dawson <nyall.dawson at gmail.com> wrote:
>>>
>>> On Fri, 28 Jun 2019 at 17:11, Richard Duivenvoorde <rdmailings at duif.net> wrote:
>>>>
>>>> On 28/06/2019 01.28, Nyall Dawson wrote:
>>>>>> That one shows 'just' 2 options (added to the qgis.nl post)
>>>>>> IF the green line is just the first one, but we are not sure if it is
>>>>>> the right one... should we make it green anyway?
>>>>
>>>>> Ah, on proj 6 builds, we ARE sure that the first/green one is the most
>>>>> recommended one :) That's because proj gives us an ordered list of
>>>>> possible operations in order of preference (calculated using all
>>>>> proj's internal smarts and knowledge about the accuracy of different
>>>>> transform operations).
>>>>
>>>> Mmm, then my last question, after this I'll move to proj ;-)
>>>>
>>>> See:
>>>>
>>>> http://www.qgis.nl/media/2019/06/Screenshot-20190627104509-716x467.png
>>>>
>>>> This is QGIS with proj6: As you see there are 2 options. The first one
>>>> being green 'numbered' (3). But the bottom one having a higher number
>>>> between brackets having a (4) between brackets?
>>>>
>>>> Now /me wondering what these numbers are: because given your answer
>>>> above, the green one being 'THE one' :-) I wonder what this other
>>>> numbers are (I was wondering ordered by date/relevance or so)??
>>>
>>> These are how proj identifies the coordinate operation -- I'm not
>>> entirely sure what they represent, but I assume they are just indexes.
>>
>> Just for followers of this thread - conversation moved to the proj
>> mailing list, and looks like it will result in improved descriptive
>> strings coming as a result...
> 
> Following all this discussion, here's a quick comparison of before vs current:
> Before: http://www.qgis.nl/media/2019/06/Screenshot-20190627104509-716x467.png
> Now: https://user-images.githubusercontent.com/1829991/60775333-f4f4db80-a164-11e9-8076-225ba2322aba.png
> 
> Iterative design at its finest ;)

Thanks Nyall, nice work!

I will update the blogpost and hope that we can add a short intro int
crs & transformations to the docs there:

https://docs.qgis.org/testing/en/docs/user_manual/working_with_projections/working_with_projections.html

Regards,

Richard