[Qgis-user] Atlas generation - help please

[Sergio Vignali]

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
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