Re: [Qgis-user] Question about results of Union in QGIS

[SEGGIE Graeme]

Thanks Luigi,


That doesn't seem to help unfortunately.


I tried with the same two shapefiles in 2.14 and in both cases get 463 zones 
unioned to 463 resulting in over 4000 features with nulls in attributes and 
lots of features which seem to not highlight any polygon when selected.


Simplifying things, I created a new polygon shapefile with just three polygons  
- one overlapping each of the other two. Result of unioning this with itself is 
17 features. Doing same on two copies of same shapefile also results in 17 
features. However, two different shapefiles, same 3 features in one and a 
single feature in another, which overlaps two of the 3, results in 6 features 
when unioning which makes some sense.


Graeme


From: Luigi Pirelli 
Sent: 25 October 2016 20:46:42
To: SEGGIE Graeme
Cc: Qgis-user@lists.osgeo.org
Subject: Re: [Qgis-user] Question about results of Union in QGIS

may you test using 2.14? if I well remember that version suffered a
severe regression on ftools geoprocessing modules due the introduction
of the new 3d geometry. During the hackmeeting in Gran Canaria we
seriously though to announce the deprecation of that version, but a
fix was found => and a new qgis version + processing tests where
introduced.

regards
Luigi Pirelli

**
* Boundless QGIS Support/Development: lpirelli AT boundlessgeo DOT com
* LinkedIn: https://www.linkedin.com/in/luigipirelli
* Stackexchange: http://gis.stackexchange.com/users/19667/luigi-pirelli
* GitHub: https://github.com/luipir
* Mastering QGIS 2nd Edition:
* 
https://www.packtpub.com/big-data-and-business-intelligence/mastering-qgis-second-edition
**


On 25 October 2016 at 10:44, SEGGIE Graeme  wrote:
> Hello,
>
> I was doing some analysis on UNION against the same feature (on itself) to 
> get an understanding of what happens with slivers and overlaps. I started in 
> ArcGIS and was able to understand what happened with the combinations 
> available there as follows:
>
> Zone system used as input features composed of 463 zones including some 
> accidental overlap.
>
> File with accidental overlaps:
> Case 1 - self union, 1 ref to source, no gaps  - Generates 525 - due to 
> lakes (3) and slivers (16) and overlaps (43)
> -- overlaps times number of contributors i.e. two zones overlap, two overlap 
> features with same area but different source zone
> -- slivers -1 as source (since there is none) and single feature.
> Case 2 - self union, 1 gaps  - 506
> - due to overlaps
> Case 3 - self union, 2 refs to source, no gaps  - 577
> Case 4 - self union, 2 gaps  - 558
>
> Having done all this in Arc, I now wanted to check that QGIS produced the 
> same thing. I could not check for gaps / no gaps as there is no setting to 
> select regarding this. Also, the two tools I used via  (1) menu Vector --> 
> Geoprocessing --> Union and (2) Toolbox Geoalgorithms --> Vector --> Polygons 
> --> Union do not allow for a single reference to the source feature set.
>
> What puzzles me though is that instead of feature counts of the order listed 
> above, I get much more features and many, but not enough with nulls and 0 for 
> source ID fields etc. I cannot see an obvious way to get the resultant 4,139 
> features (with tool 2) down to approx 500 or so.  Tool 1, returns 3,950 
> features on the same input feature set.
>
> I also when selecting features in the area with overlaps return normal counts 
> of features i.e. 2, not multiple orders higher as I'd expect given the count 
> of features in the attribute table. Do some (lots) of them have no geometry? 
> - Actually having just added a field of area, I see this is not the case 
> either as too many have geometry on that basis.
>
> Am I missing a key difference employed in the processing of QGIS union and a 
> way to get to the relevant features which approximate to the 500+ I expect?
>
> Am using 2.12 on Windows if that has a bearing on this.
>
> Graeme.
> ___
> Qgis-user mailing list
> Qgis-user@lists.osgeo.org
> List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
 This message has been 
scanned for malware. This message and any attachments (the "message") are 
confidential, intended solely for the addressees, and may contain legally 
privileged information. Any unauthorised use or dissemination is prohibited. 
E-mails are susceptible to alteration. Neither our company or any of its 
subsidiaries or affiliates shall be liable for the message if altered, changed 
or falsified. 

Re: [Qgis-user] inconsistenty when calculating area depending on file type or projection?

[Carlos Cerdán]

And light was done!

Objective: to get planimetric-UTM-my-zone areas, in square Km, from a
LatLong layer, just at one step: in Fields calculator

area( transform( $geometry,'EPSG:4326', 'EPSG:32717' ))/100

Sorry, I was wrong for years, reprojecting layers; deactivating OTF SRC;
and using $area function: It happens when you don't read help in front of
you and don't try "new" functions.

Carlos


2016-10-19 15:11 GMT-05:00 Carlos Cerdán :

>
> > Under project properties, general tab - change "ellipsoid" to "None
> /Planimetric".
>
> Done, but calculated area is still... geodetic area?. I've tried ArcGIS
> and, for my GEO layer, It gives me desired area (same as an UTM layer,
> calculated with OTF off); so, it's me or QGIS, but I can't do this task in
> one step on QGIS: first I've to reproject mi GEO layer into an UTM one;
> disable OTF and finally calculate area (planar, as UTM is) in the new UTM
> layer.
>
>
> Carlos樂
>
>
>
>
> 2016-10-18 19:58 GMT-05:00 Nyall Dawson :
>
>> On 19 October 2016 at 02:22, Carlos Cerdán  wrote:
>> > It was my fault. I was used to consider plane areas as "correct",
>> forgetting
>> > ellipsoidal areas. So, QGIS give us freedom to calculate planar or
>> > ellipsoidal (geodetical) areas, but we must be careful about settings;
>> Is
>> > not it?. Sometimes, too much freedom is annoying!
>> >
>> > But, How can I calculate UTM (planar) area from a GEO layer in one step?
>>
>> Under project properties, general tab - change "ellipsoid" to "None /
>> Planimetric".
>>
>> I keep meaning to split up the concept of ellipsoidal measurement from
>> OTF reprojection. In my view these are two different concepts - one is
>> just about display of data, the other relates to measurement. Ie, you
>> should be able to perform ellipsoidal calculations even if OTF
>> rendering is disabled.
>>
>> I just keep forgetting to do it early in a release cycle for extensive
>> testing...
>>
>> Nyall
>>
>>
>>
>
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user

Re: [Qgis-user] Question about results of Union in QGIS

[Luigi Pirelli]

may you test using 2.14? if I well remember that version suffered a
severe regression on ftools geoprocessing modules due the introduction
of the new 3d geometry. During the hackmeeting in Gran Canaria we
seriously though to announce the deprecation of that version, but a
fix was found => and a new qgis version + processing tests where
introduced.

regards
Luigi Pirelli

**
* Boundless QGIS Support/Development: lpirelli AT boundlessgeo DOT com
* LinkedIn: https://www.linkedin.com/in/luigipirelli
* Stackexchange: http://gis.stackexchange.com/users/19667/luigi-pirelli
* GitHub: https://github.com/luipir
* Mastering QGIS 2nd Edition:
* 
https://www.packtpub.com/big-data-and-business-intelligence/mastering-qgis-second-edition
**


On 25 October 2016 at 10:44, SEGGIE Graeme  wrote:
> Hello,
>
> I was doing some analysis on UNION against the same feature (on itself) to 
> get an understanding of what happens with slivers and overlaps. I started in 
> ArcGIS and was able to understand what happened with the combinations 
> available there as follows:
>
> Zone system used as input features composed of 463 zones including some 
> accidental overlap.
>
> File with accidental overlaps:
> Case 1 - self union, 1 ref to source, no gaps  - Generates 525 - due to 
> lakes (3) and slivers (16) and overlaps (43)
> -- overlaps times number of contributors i.e. two zones overlap, two overlap 
> features with same area but different source zone
> -- slivers -1 as source (since there is none) and single feature.
> Case 2 - self union, 1 gaps  - 506
> - due to overlaps
> Case 3 - self union, 2 refs to source, no gaps  - 577
> Case 4 - self union, 2 gaps  - 558
>
> Having done all this in Arc, I now wanted to check that QGIS produced the 
> same thing. I could not check for gaps / no gaps as there is no setting to 
> select regarding this. Also, the two tools I used via  (1) menu Vector --> 
> Geoprocessing --> Union and (2) Toolbox Geoalgorithms --> Vector --> Polygons 
> --> Union do not allow for a single reference to the source feature set.
>
> What puzzles me though is that instead of feature counts of the order listed 
> above, I get much more features and many, but not enough with nulls and 0 for 
> source ID fields etc. I cannot see an obvious way to get the resultant 4,139 
> features (with tool 2) down to approx 500 or so.  Tool 1, returns 3,950 
> features on the same input feature set.
>
> I also when selecting features in the area with overlaps return normal counts 
> of features i.e. 2, not multiple orders higher as I'd expect given the count 
> of features in the attribute table. Do some (lots) of them have no geometry? 
> - Actually having just added a field of area, I see this is not the case 
> either as too many have geometry on that basis.
>
> Am I missing a key difference employed in the processing of QGIS union and a 
> way to get to the relevant features which approximate to the 500+ I expect?
>
> Am using 2.12 on Windows if that has a bearing on this.
>
> Graeme.
> ___
> Qgis-user mailing list
> Qgis-user@lists.osgeo.org
> List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user

[Qgis-user] Question about results of Union in QGIS

[SEGGIE Graeme]

Hello,

I was doing some analysis on UNION against the same feature (on itself) to get 
an understanding of what happens with slivers and overlaps. I started in ArcGIS 
and was able to understand what happened with the combinations available there 
as follows:

Zone system used as input features composed of 463 zones including some 
accidental overlap.

File with accidental overlaps:
Case 1 - self union, 1 ref to source, no gaps  - Generates 525 - due to 
lakes (3) and slivers (16) and overlaps (43)
-- overlaps times number of contributors i.e. two zones overlap, two overlap 
features with same area but different source zone
-- slivers -1 as source (since there is none) and single feature.
Case 2 - self union, 1 gaps  - 506- 
due to overlaps
Case 3 - self union, 2 refs to source, no gaps  - 577
Case 4 - self union, 2 gaps  - 558

Having done all this in Arc, I now wanted to check that QGIS produced the same 
thing. I could not check for gaps / no gaps as there is no setting to select 
regarding this. Also, the two tools I used via  (1) menu Vector --> 
Geoprocessing --> Union and (2) Toolbox Geoalgorithms --> Vector --> Polygons 
--> Union do not allow for a single reference to the source feature set.

What puzzles me though is that instead of feature counts of the order listed 
above, I get much more features and many, but not enough with nulls and 0 for 
source ID fields etc. I cannot see an obvious way to get the resultant 4,139 
features (with tool 2) down to approx 500 or so.  Tool 1, returns 3,950 
features on the same input feature set.

I also when selecting features in the area with overlaps return normal counts 
of features i.e. 2, not multiple orders higher as I'd expect given the count of 
features in the attribute table. Do some (lots) of them have no geometry? - 
Actually having just added a field of area, I see this is not the case either 
as too many have geometry on that basis.

Am I missing a key difference employed in the processing of QGIS union and a 
way to get to the relevant features which approximate to the 500+ I expect? 

Am using 2.12 on Windows if that has a bearing on this.

Graeme.
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user

Re: [QGIS-it-user] QGIS 2.18 Las Palmas de G.C.

[matteo]

>  in questo percorso (.qgis2/python/plugins) NON trovo nessuna cartella
> processing;

forse perchè l'hai cancellata prima.. altriment il plugin Processing
funzionante personalizzato (o vecchio che sia) che sovrascrive quello di
dafault in apps è qui dentro

> vero, ho perduto tutti gli script che avevo fatto (ma ho fatto una copia
> prima di rimuovere la cartella processing).
> Poi, reinstallando QGIS, la cartella processing in /.qgis2 è stata ricreata. 

yes.. .qgis2 se c'è viene letta, se non c'è viene ricreata o aggiustata
se qualcosa dentro è stato eliminato (nel tuo caso la cartella con gli
script e i modelli)..

___
QGIS-it-user mailing list
QGIS-it-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-it-user

Re: [QGIS-it-user] QGIS 2.18 Las Palmas de G.C.

[matteo]

> Grazie Matteo, sempre preciso e puntuale
> 
> in realtà si trova direttamente qui: /.qgis2

NIET! :)

la cartella .qgis2/processing non la toccare! è la cartella dove vengono
salvati i modelli, gli script e dove ci sono gli script per far girare GRASS

il plugin vero e proprio è in .qgis2/python/plugins

Matteo
___
QGIS-it-user mailing list
QGIS-it-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-it-user

Re: [QGIS-it-user] QGIS 2.18 Las Palmas de G.C.

[Totò]

ghtmtt wrote
> Ciao Totò,
> 
> in realtà potevi ridurre il tempo e il lavoro semplicemente eliminando a
> mano la cartella processing da .qgis2/python/plugin e riavviare QGIS
> senza passare dal Gestore Plugin

Grazie Matteo, sempre preciso e puntuale

in realtà si trova direttamente qui: /.qgis2



--
View this message in context: 
http://osgeo-org.1560.x6.nabble.com/QGIS-2-18-Las-Palmas-de-G-C-tp5292411p5292516.html
Sent from the QGIS Italian User mailing list archive at Nabble.com.
___
QGIS-it-user mailing list
QGIS-it-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-it-user

Re: [QGIS-it-user] QGIS 2.18 Las Palmas de G.C.

[matteo]

Ciao Totò,

in realtà potevi ridurre il tempo e il lavoro semplicemente eliminando a
mano la cartella processing da .qgis2/python/plugin e riavviare QGIS
senza passare dal Gestore Plugin

Matteo
___
QGIS-it-user mailing list
QGIS-it-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-it-user

Re: [QGIS-it-user] QGIS 2.18 Las Palmas de G.C.

[Paolo Cavallini]

Il 25/10/2016 10:45, Luca Mandolesi ha scritto:
> In Gestisci e installa plugins io leggo che Processing sta in:
> 
> Versione installata: 2.12.99 (in
> C:\OSGeo4W\apps\qgis\.\python\plugins\processing)
> 
> Però c'è anche dentro a .qgis2, che non ho piazzato io...
> 
> Domanda: vanno tenute entrambe? Lavorano insieme?

mi hai letto? ;)

-- 
Paolo Cavallini - www.faunalia.eu
QGIS & PostGIS courses: http://www.faunalia.eu/training.html
https://www.google.com/trends/explore?date=all=IT=qgis,arcgis
___
QGIS-it-user mailing list
QGIS-it-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-it-user

Re: [QGIS-it-user] QGIS 2.18 Las Palmas de G.C.

[Luca Mandolesi]

In Gestisci e installa plugins io leggo che Processing sta in:

Versione installata: 2.12.99 (in
C:\OSGeo4W\apps\qgis\.\python\plugins\processing)

Però c'è anche dentro a .qgis2, che non ho piazzato io...

Domanda: vanno tenute entrambe? Lavorano insieme?

Ciao
Luca


Il giorno 25 ottobre 2016 10:44, Totò  ha
scritto:

> Paolo Cavallini wrote
> > rimuovi il plugin dall'installer dei plugins e la versione standard
> > apparirà.
> > (sì, lo so: è una noja, e confonde gli utenti).
>
>
> Ecco cosa ho fatto:
>
> 1. da gestione plugin ho rimosso 'processing'; (con non poche noie: si è
> bloccato tutto, ho dovuto forzare chiusura);
> 2. dalla cartella  .qgis2 ho rimosso la cartella processing;
> 3. ho reinstallato QGIS 2.18 (da OSGeo4W);
> 4. ora funziona tutto benissimo!!!
>
> grazie!!
>
>
>
>
>
>
> --
> View this message in context: http://osgeo-org.1560.x6.
> nabble.com/QGIS-2-18-Las-Palmas-de-G-C-tp5292411p5292497.html
> Sent from the QGIS Italian User mailing list archive at Nabble.com.
> ___
> QGIS-it-user mailing list
> QGIS-it-user@lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/qgis-it-user
>
___
QGIS-it-user mailing list
QGIS-it-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-it-user

Re: [QGIS-it-user] QGIS 2.18 Las Palmas de G.C.

[Totò]

Paolo Cavallini wrote
> rimuovi il plugin dall'installer dei plugins e la versione standard
> apparirà.
> (sì, lo so: è una noja, e confonde gli utenti).

 
Ecco cosa ho fatto:

1. da gestione plugin ho rimosso 'processing'; (con non poche noie: si è
bloccato tutto, ho dovuto forzare chiusura);
2. dalla cartella  .qgis2 ho rimosso la cartella processing;
3. ho reinstallato QGIS 2.18 (da OSGeo4W);
4. ora funziona tutto benissimo!!!

grazie!!






--
View this message in context: 
http://osgeo-org.1560.x6.nabble.com/QGIS-2-18-Las-Palmas-de-G-C-tp5292411p5292497.html
Sent from the QGIS Italian User mailing list archive at Nabble.com.
___
QGIS-it-user mailing list
QGIS-it-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-it-user

Re: [Qgis-user] How do you all upload your webmaps?

[Paolo Cavallini]

Il 25/06/2016 17:38, Paolo Cavallini ha scritto:
> Il 20/06/2016 13:07, Paolo Cavallini ha scritto:
>> Il 19/06/2016 15:36, Tom Chadwin ha scritto:
>>> Your opinion had been mine, but more than one QGIS user looked very
>>> discouraged when I answered their question "How do I get my qgis2web map
>>> online?"
>>>
>>> We are up against the end-to-end ArcGIS Online ease of use, in my opinion.
>>> As you say, if we can help a significant proportion of users, it should be
>>> considered.
>>
>> Agreed, having a readymade solution would be a major plus.
>> Perhaps we can use GitHub for this?
>> I understand they have some support for maps, but never explored it fully.
>> All the best, and thanks a lot for the suggestion, quite important in my
>> experience.
>>
> 
> any news on that? I think it might be relatively easy, and a great
> improvement for many users and the project as a whole.

Hi all,
I resurrect this old thread, which I think is still worth of attention.
I opened a ticket not to forget about it:
https://hub.qgis.org/issues/15751
Perhaps the plugin authors whose output could use this function could
join and do something together.
I'm also interested and available for help.
All the best.
-- 
Paolo Cavallini - www.faunalia.eu
QGIS & PostGIS courses: http://www.faunalia.eu/training.html
https://www.google.com/trends/explore?date=all=IT=qgis,arcgis
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user

Re: [QGIS-it-user] QGIS 2.18 Las Palmas de G.C.

[Paolo Cavallini]

Il 25/10/2016 10:07, matteo ha scritto:

> credo che l'inghippo sia questo (qualche esperto in caso corregga):
> 
> Processing **non** c'è di default nella cartella .qgis2/python/plugins
> ma è in Utente/qgis/apps (o simile, perdonatemi ma non ho un Windows
> sotto mano ora).. e all'avvio viene letta questa cartella..
> 
> l'utente può però piazzare una copia di Processing dentro
> qgis2/python/plugins e a quel punto all'avvio viene letto questo
> Processing..

esatto
saluti

-- 
Paolo Cavallini - www.faunalia.eu
QGIS & PostGIS courses: http://www.faunalia.eu/training.html
https://www.google.com/trends/explore?date=all=IT=qgis,arcgis
___
QGIS-it-user mailing list
QGIS-it-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-it-user

Re: [QGIS-it-user] QGIS 2.18 Las Palmas de G.C.

[matteo]

mi intrometto anche se non sono sicuro di come funzionino le cose in
Windows..

la cartella .qgis2 non viene toccata durante l'aggiornamento di QGIS
(altrimenti se cosi fosse verrebbero persi i vari plugin, le
impostazioni, ecc...)..

credo che l'inghippo sia questo (qualche esperto in caso corregga):

Processing **non** c'è di default nella cartella .qgis2/python/plugins
ma è in Utente/qgis/apps (o simile, perdonatemi ma non ho un Windows
sotto mano ora).. e all'avvio viene letta questa cartella..

l'utente può però piazzare una copia di Processing dentro
qgis2/python/plugins e a quel punto all'avvio viene letto questo
Processing..

ed ecco la frittata.. versione aggiornata in apps vs. versione vecchia
in plugins


potrei davvero sbagliarmi in questo ragionamento, però in linux lavoro
proprio cosi per poter leggere versioni aggiornate di Processing o per
testarlo con feature aggiunte..

Matteo
___
QGIS-it-user mailing list
QGIS-it-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-it-user

Re: [QGIS-it-user] QGIS 2.18 Las Palmas de G.C.

[Totò]

Paolo Cavallini wrote
> Il 24/10/2016 21:10, Totò ha scritto:
>> ho appena installato la nuova versione e noto subito che in processing
>> NON
>> trovo:
>> 
>> 1. Dissolve con la nuova caratteristica di selezione di più campi;
>> 2. Merge line.
>> 
>> OSGeo4W 64 bit win 10!!!
>> 
>> qualcuno puo' verificare, grazie!!!
> 
> confermo, i comandi sono presenti.
> possibile che tu abbia una versione vecchia di Processing in .qgis2?
> saluti.

Sarà certamente utile anche ad altri,
come capire la versione del processing e come aggiornarla!!!

grazie!



--
View this message in context: 
http://osgeo-org.1560.x6.nabble.com/QGIS-2-18-Las-Palmas-de-G-C-tp5292411p5292474.html
Sent from the QGIS Italian User mailing list archive at Nabble.com.
___
QGIS-it-user mailing list
QGIS-it-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-it-user