[Qgis-user] Atlas generation - help please

[Sergio Vignali]

This is great! Many thanks, now is really cool.

Greating

2014-09-13 13:01 GMT+02:00 Alexandre Neto <senhor.neto at gmail.com>:

> Hello Sergio,
>
> You can use a view,  all you need is to recreate an id with unique values
> to use as key in qgis.
>
> This will do:
>
> With query as
> (SELECT * FROM specie_a UNION ALL SELECT * FROM specie_B UNION ALL
> SELECT....)
> SELECT rownumber() over() as id, query.*
> FROM query
>
> Best regards,
>
> Alexandre Neto
> Em 12/09/2014 21:11, "Sergio Vignali" <vignalisergio30 at gmail.com>
> escreveu:
>
> Thanks Alexandre,
>>
>> now I understood and it work fine! I created an union table as followed
>> your explanation.
>> I try to better explain:
>> I have a table for each species in postgis, I created a table like that:
>>
>> CREATE TABLE atlas AS SELECT * FROM specie_a UNION ALL SELECT * FROM
>> specie_B UNION ALL SELECT....
>>
>> I created a polygon layer with several polygons but all equal to itself
>> and with a field with the name of the specie
>>
>> then the join and the ruled based style as you described and all is fine
>>
>> the only pity is I can't use a VIEW created in the same way instead of a
>> TABLE (at least I can't create a primary key) because with a view you don't
>> need to change nothing if you add some entry in the specie tables, what do
>> you think?
>> You can find two images below:
>>
>> https://www.dropbox.com/s/rq5ysd6lcfic5zp/atlas1.png?dl=0
>> https://www.dropbox.com/s/fyd0w2ztiuddvyj/atlas2.png?dl=0
>>
>> All the best
>>
>> 2014-09-12 17:36 GMT+02:00 Alexandre Neto <senhor.neto at gmail.com>:
>>
>>> Hello Sergio,
>>>
>>> If I understood you well, You have several layer\tables? One per specie?
>>> Because that wasn't  the case study presented by John, where all species
>>> were in one unique table\layer. If you have several layers, atlas won't be
>>> able to iterate over them or turning them on and off for you without the
>>> same amount of work that would involve making the species maps one by one.
>>>
>>> Anyway, regarding the basemap, I'm not sure about what you are asking.
>>> but you can create the grid yourself.
>>>
>>> Alexandre Neto
>>>
>>>
>>>
>>> On Fri, Sep 12, 2014 at 1:51 PM, Sergio Vignali <
>>> vignalisergio30 at gmail.com> wrote:
>>>
>>>> Hi Alexandre,
>>>> many thanks for your explanation! This is the first time I use the
>>>> atlas generation and I begin to understand how it work. But I have another
>>>> question, you suppose to have several point layers of species distribution,
>>>> but all in the same area, so in this case you need to have a basemap good
>>>> for all the species but you want to change only the points above the
>>>> basemap. Something like the Atlas of species distribution in which you have
>>>> a basemap with an utm grid and above a dot only in the square where the
>>>> specie occurs.
>>>> This is what I'd like to do, I have all the data in a postgis database
>>>> where I have also several tables with the centroid of the square in which
>>>> the specie occurs.
>>>> What solution you suggest?
>>>>
>>>> All the best
>>>>
>>>> Sergio
>>>>
>>>> 2014-09-03 15:51 GMT+02:00 Alexandre Neto <senhor.neto at gmail.com>:
>>>>
>>>>> Hello all,
>>>>>
>>>>> On Mon, Sep 1, 2014 at 9:52 PM, Nyall Dawson <nyall.dawson at gmail.com>
>>>>>  wrote:
>>>>>
>>>>>> I'm 99% certain that what you are after is possible in QGIS 2.5 (the
>>>>>> unreleased development version of 2.6). But do you mind posting this
>>>>>> question over at gis.stackexchange.com with some screenshots of your
>>>>>> data format so I can be certain? I'll send through a step by step answer
>>>>>> over at stack exchange with screenshots for you.
>>>>>>
>>>>>> Cheers,
>>>>>> Nyall
>>>>>>
>>>>>
>>>>> Nyall, I think I will post the question myself, as I'm curious about
>>>>> how is the correct way to do this in QGIS 2.5 :-P
>>>>>
>>>>> On Tue, Sep 2, 2014 at 12:30 PM, Sergio Vignali <
>>>>> vignalisergio30 at gmail.com> wrote:
>>>>>
>>>>>> Hi Alexandre,
>>>>>> you say that you know a way to do that with postgis,
>>>>>> please could you explain that?
>>>>>>
>>>>>
>>>>> Sergio, not really, it would still need qgis help. Postgis would only
>>>>> facilite things (see below).
>>>>>
>>>>> On Wed, Sep 3, 2014 at 1:18 PM, Thomas Colley <
>>>>> t.colley at neath-porttalbot.gov.uk> wrote:
>>>>>
>>>>>> How about creating a polygon layer with a bounding polygon for all
>>>>>> points per species? The polygon features would have the species name as an
>>>>>> attribute.
>>>>>>
>>>>>>
>>>>>>
>>>>>> You can then use this polygon layer for your atlas and use rule based
>>>>>> styling to filter the points based on the species name attribute of the
>>>>>> atlas feature.
>>>>>>
>>>>>
>>>>> Like I said before I think this is not possible since you cannot
>>>>> access the atlas feature atributes from the expression builder, but the
>>>>> idea was that one. Using postgis would just make the task of creating the
>>>>> polygon layer for each specie easier.
>>>>>
>>>>> Meanwhile, talking with Giovanni Manghi, he came up whit a workaround
>>>>> idea that can actually work quite nice.
>>>>>
>>>>> One thing you can get from the atlas feature is the feature id (that
>>>>> represents his position on the table). So instead of using the specie name
>>>>> attribute, one could use this ID.
>>>>>
>>>>> Having a layer with a bounding polygon for each specie, with a column
>>>>> with the specie name, I would do the following:
>>>>>
>>>>> - Using field calculator, add a new column (boundary_id) in the
>>>>> boundary polygons layer (the one that will be used in atlas) with it's ID
>>>>> using $id;
>>>>> - In the data layer (the one with all species presences) join the
>>>>> boundary polygons layer using the specie name;
>>>>> - Now use the rulebased symbology on the data layer to filter only the
>>>>> points where "boundary_id" = $atlasfeatureid
>>>>>
>>>>> Runing atlas generation with the boundary polygons layer, should do
>>>>> what is asked.
>>>>>
>>>>> The caveat of this procedure is that any change on the dataset (for
>>>>> example adding a new specie, or removing all presences from another) would
>>>>> require changes in the  boundary feature. This can originate id changes,
>>>>> and to make sure all spicies maps are printed , one should repeat all the
>>>>> steps described before. But, that's much better than doing the map on by
>>>>> one!
>>>>>
>>>>> BTW, I don't think any other GIS software allow this kind of
>>>>> interation and filtering. Can anyone comment on that?
>>>>>
>>>>> Best regards,
>>>>>
>>>>> Alexandre Neto
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Sergio Vignali
>>>>
>>>>
>>>
>>
>>
>> --
>> Sergio Vignali
>>
>>


-- 
Sergio Vignali
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