Re: [Qgis-user] Minimum bounding circle from cluster of points

[Micha Silver]

  
  
This can be achieved using the
PostGIS function ST_MinimumBoundingCircle(). If you can import
your subplots point layer into a PostGIS database, then
(assuming the points have an attribute "subplot_id", and
geometry column "the_geom") you could do something like:

  SELECT s.subplot_id,
ST_MinimumBoundingCircle(ST_Collect(s.the_geom))
as the_geom
      FROM subplots AS s
      GROUP BY s.subplot_id;

(Based on the example from
http://postgis.net/docs/ST_MinimumBoundingCircle.html)


I would also point out that there's a concept "Standard
Deviational Ellipse" for encircling points by an ellipse at a
certain stdev distance from the "center of gravity" of the
points. If this is of interest, you can implement it in
GRASS-GIS with the v.ellipse addon. 

  
On 08/07/2016 16:49, Tina Cormier
  wrote:


  Hi all,


Looking for help aggregating some field data subplots to
  the plot level. In the attached screenshot, you can see
  clusters of 4 points (4 subplots = 1 plot). I'd like to create
  a circle around each cluster that is the smallest circle that
  would encompass all 4 points. Sort of like a convex hull, but
  a circle (convex hull, in this case, would give me a
  triangle). Is there a tool or a series of steps to accomplish
  this without doing it manually? In the attribute table, I have
  a unique ID for each plot/cluster. So for each plot ID (in
  this case, consisting of 4 subplots), I'd like to build a
  circle around all of the subplots.


I should also mention that it's not always 4 points
  (subplots), and they aren't always covering the same size area
  on the ground.


I have QGIS 2.14.2 as well as one of the nightly builds
  from a few weeks ago (can download the newest one if
  necessary).


Thanks in advance for any ideas/insights! Google has not
  helped me so much yet with this one!
Tina






  
  
  
  
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-- 
Micha Silver
Arava Drainage Authority
+972-523-665918
  

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Re: [Qgis-user] QGIS won't open Martian .img files

[Adam Neather]

Thanks to Even Rouault and Nicolas Cadieux for the replies. I think we
can say that I need the GDAL driver to open the Mars data .img files
with QGIS.

Next question - how do I install the driver? Thanks to Even and Nicolas
I've found the download page and have the software, but I'm not sure how
to use it with QGIS. Do I have to load it as a custom plug in? If so,
how? If I follow Even correctly, then I can load it at the same time as
the .img; is that simply a matter of opening both files (the .img and
the GDAL driver) at the same time, when loading a raster?

Thanks again for all the help so far, it's very much appreciated.

-- 
-

Adam Neather


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Re: [Qgis-user] QGIS won't open Martian .img files

[Even Rouault]

Le dimanche 10 juillet 2016 20:33:12, Adam Neather a écrit :
> Thanks to Even Rouault and Nicolas Cadieux for the replies. I think we
> can say that I need the GDAL driver to open the Mars data .img files
> with QGIS.
> 
> Next question - how do I install the driver? Thanks to Even and Nicolas
> I've found the download page and have the software, but I'm not sure how
> to use it with QGIS. Do I have to load it as a custom plug in? If so,
> how? If I follow Even correctly, then I can load it at the same time as
> the .img; is that simply a matter of opening both files (the .img and
> the GDAL driver) at the same time, when loading a raster?

You don't have to download anything. The driver is built in base GDAL. Just 
open the .lbl file in QGIS with "Add raster layer" or drag the .lbl and 
that should work.


-- 
Spatialys - Geospatial professional services
http://www.spatialys.com
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Re: [QGIS-it-user] export maschera per editare gli attributi

[Marco Spaziani]

Leggendo questa discussione stavo pensando che, avere a che fare con un
software altamente performante come Qgis, possa, nel tempo, farti sembrare
normali e banali opzioni che invece, a volerle fare con altri software, pur
se blasonati (ma non FOSS), risultano contorte e faticose. Provate a
personalizzare le maschere per l'input dati in Excel oppure, sempre in
Excel, provate a far comparire un calendarietto per l'immissione di una
data in una cella. Certo, si può fare, ma devi prima diventare “esperto” in
VBA. Con Qgis invece, ….due clic su Preferenze e mi personalizzo le
maschere di input (addirittura suddividendo i campi in Schede tematiche),
...due clic su widget e il calendarietto per l'input delle date è li,
pronto all'uso. Lunga vita a Qgis!

Il giorno 6 luglio 2016 13:09, AV  ha scritto:

> /
> possi...@libero.it wrote
> > mi sono creato una maschera per editare gli attributi di una tabella in
> un
> > progetto
>
> /
> Mi è gradito comunicarti che la maschera di modifica attributi è
> nativamente
> integrata in Qgis, pertanto è disponibile indipendentemente dal progetto.
>
> Si attiva con *CTRL-SHIFT-I*, previo attivazione della modalità editazione
> nella tabella attributi...
>
>
>
>
> --
> View this message in context:
> http://osgeo-org.1560.x6.nabble.com/export-maschera-per-editare-gli-attributi-tp5274888p5274915.html
> Sent from the QGIS Italian User mailing list archive at Nabble.com.
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Re: [QGIS-it-user] export maschera per editare gli attributi

[Totò]

possi...@libero.it wrote
> Ciao a tutti,
> è possibile esportare una maschera (editor degli attributi)?
> Mi spiego: mi sono creato una maschera per editare gli attributi di una 
> tabella in un progetto.
> Se ora volessi utilizzare la stessa maschera su un altro progetto qgis,
> devo 
> ricrearmela da capo o c'è un qualche modo per salvarla ed importarla nel
> nuovo 
> progetto?

La maschera di inserimento dati personalizzata creata per un layer tramite
le sue proprietà campi -> crea maschera di inserimento, fa parte dello stile
del layer quindi appena salvi lo stile .qml salvi pure la maschera.
Quindi se vuoi riutilizzarla basta usare lo stesso file .qml

ciao



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