Re: [Qgis-user] Question about Weighting Power value when running Grid-Inverse Distance to a Power

[J.O.Williams]

A power of 1 is a linear interpolation among all points in the search 
radius.



A power of 2 causes the "closest point" in the search radius to have a 
slightly higher weight.



A power of 4, 6 and especially 10 causes the closest point to behave 
like a polygonal or  theissen polygon.



A power of 0.5 causes the farther away points to have a larger influence 
than closer points



The equations used only depend on the distance the points are from each 
other.  NOT the value of any of the points.  Though David has a section 
on how the variogram can be applied to IDS.



All the power IDS theory (if there is one) came out of the mining 
industry in the early 1960's because it was simple.



Hope this helps.

J.O. Williams


On 9/17/19 4:00 AM, Daniel Zepeda Rivas wrote:


When using the Raster -> Analysis -> Grid (Inverse Distance to a Power)

At the menu just before pressing run, can somebody please explain me 
the effect of the "Weighting power" option in the interpolation process?


I'm trying to make a temperature map based on points representing each 
weather station, containing the yearly averages values of temperature, 
and when moving the number from the 2 (set it by default) to 4, 6 or 
10, the map changes significantly




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Re: [Qgis-user] Shortest path caching

[Nicolas Cadieux]

Hi,

« Is there any way to output a string from a process which you can then use as 
an input in another process? »

I am pretty sure you can do this but I don’t use the graphical modelling.  
Other users will give you better advice. You could repost this specific 
question if you don’t get anybody’s attention with this thread.

Cheers and good luck
Nicolas

> Le 17 sept. 2019 à 02:58, Paul Wittle  a 
> écrit :
> 
> Hello Both,
>  
> Thank you for your answers so far and I could indeed get on with the python 
> methods but I’m trying to build a solution which a normal user would 
> understand with minimal effort really.
>  
> I’m currently looking at using the graphical modeler to create a routing 
> which will replicate (albeit inefficiently) the Travelling Sales routing by 
> running shortest route in batch form. I think I got 90% of the way yesterday 
> before I ran into the obvious issue with the process modelling.
>  
> Is there any way to output a string from a process which you can then use as 
> an input in another process?
>  
> I ask because all the routing algorithms require at least one ‘point’ 
> (string) input. I have extracted the coordinates from my points layer as a 
> string in the form ‘x, y’ and I can see the string if I run that section 
> separately but I can’t set the string as an input for shortest route 
> algorithm in the modeler.
>  
> I’m thinking that the best method would probably be to run a distance matrix 
> and then use that to construct a series of A – B routes in order, run each of 
> those and then stick them together to create  the output. Given the comment 
> that “Both points (start A and end B) are “tied” to the graph when it is 
> built”; I’m pretty convinced that my plan of using clipped versions of the 
> network for the routing may still be the best method for QGIS.
>  
> I’m aware that this is really using a spade to dig up a road when really I 
> should be just investing in a digger but the goal here is to see what can be 
> achieved with QGIS 3.4 as it stands today. I’m not too fused if it takes 5 
> minutes to run a 30 second job so much as whether it can be achieved 
> accurately and using a method that end users might be able to understand.
>  
> Thanks,
> Paul  
>  
> From: Nicolas Cadieux  
> Sent: 16 September 2019 16:09
> To: DelazJ 
> Cc: Paul Wittle ; qgis-user@lists.osgeo.org
> Subject: Re: [Qgis-user] Shortest path caching
>  
> Hi Harrissou
>  
> I was referring to the online documentation in the developers cookbook.  The 
> user guide is effective.  I perfectly understand the problem and wish I could 
> help but despite receiving help from advance users with links to online code 
> examples (thanks), I found it easier to go with NetworkX that was well 
> documented.  Maybe I could figure it out now since I now have experience 
> working with shortest path analysis and now grasp the basic concepts of 
> networks but when I started the project, it was a big learning curve.
>  
> Cheers 
>  
> Nicolas
> 
> Le 16 sept. 2019 à 09:36, DelazJ  a écrit :
> 
> Hi,
>  
> Le lun. 16 sept. 2019 à 15:25, Nicolas Cadieux  
> a écrit :
> Hi,
>  
> You could go with NetworkX, a python library.  With that, you can build the 
> graph on the fly and maintain it as roads or edges get added and removed.
>  
> You can probably do this with QGIS but the biggest problem I found with QGIS 
> is the lack of documentation for using the network analysis tools using the 
> latest versions. Everything is, or was documented for version 2.x.  Also, 
> when using the processing tools in a batch, the graph gets rebuilt every time 
> this should not happen.  
>  
> Nicolas, about the lack of documentation, you meant the tools in the 
> processing toolbox [0] or the pyQGIS cookbook [1]. I'm not sure there's 
> anything missing in the former (and maybe Paul could find some answers) and, 
> for the latter (which is horribly outdated), it's the usual lack of skilled 
> people to provide necessary documentation. Because some parts of the docs are 
> specialized, they require advanced users to help us update. If we are giving 
> a txt (or whatever open format) file updating the section, I'm happy to push 
> it and update that page too.
>  
> [0] 
> https://docs.qgis.org/testing/en/docs/user_manual/processing_algs/qgis/networkanalysis.html
> [1] 
> https://docs.qgis.org/testing/en/docs/pyqgis_developer_cookbook/network_analysis.html
>  
> Regards,
> Harrissou
> For those reasons, I went with NetworkX python library.  Out of curiosity, 
> how many edges are you dealing with? How many queries?
>  
> Nicolas
>  
>  
>  
>  
> 
> Le 16 sept. 2019 à 08:03, Paul Wittle  a 
> écrit :
> 
> Hi,
>  
> I’m aware that you can use things like the pgRouting plugin for shortest path 
> calculations but when looking at the default functions is there a sensible 
> way to speed up the calculations?
>  
> I’ve just run a couple of tests using an Oracle database based routing layer 
> and it runs but seems 

Re: [Qgis-user] Problems with the tool: join by attributes

[Hans Erik Jacobsen]

Try 'Join attributes by location (summary)'

[cid:image001.png@01D56D56.22BA2FE0]

Venlig hilsen

Hans Erik Jacobsen
GIS Analytiker
Regional Udvikling, Sekretariat og Analyse
E-mail:

h...@rsyd.dk

Direkte:

76631314

Mobil:

23347747


[logo]
Region Syddanmark
Damhaven 12, 7100 Vejle
Hovednummer:

7663 1000

www.rsyd.dk

Fra: Qgis-user  På vegne af Jennifer Schubert
Sendt: 17. september 2019 10:13
Til: qgis-user@lists.osgeo.org
Emne: [Qgis-user] Problems with the tool: join by attributes

Hi,
I want to spatially join points with individual values to a polygon grid.
The resulting shapefile should have a column where the values oft the points 
are summed up - according to the grid cell they are found in.
This simple operation works fine in QGIS 2.18 where you can click "sum" as the 
method of statistics.
However, the newer versions of QGIS don't have the possibility to indicate the 
method of statistics or I cannot find them, so I cannot get the task done with 
it.
Does anybody now how to perform this tool successfully in QGIS 3.8.2?

Thanks in advance
Jennifer Schubert

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Re: [Qgis-user] Question about Weighting Power value when running Grid-Inverse Distance to a Power

[Falk Huettmann]

Dear Colleagues,

as we work on such topics ourselves,
let me point out please that those 'sophisticated methods' of interpolation
etc
have 100% nothing to do with climate, or temperature, and such units,
and likely are very misleading for outcome.

One may call it 'data smearing' but not more.

(Scientifically,
if we see it, we usually reject it in full;
student failed and publication rejected.
No kidding. Lots of literature on what I state here;
krigging being among the worse).

So I propose not to fall into that trap.

"It can be done" (Ronald Reagan)
Reply: " Yeah, technically, but if it's crap, no need to".
Coder's delight.

Very best
Falk Huettmann PhD, Professor
  Uni of Alaska Fairbanks

PS I am sorry to raise those issues sometimes,
but it matters for context and best performance
and tools + relevant progress.
Follow up as needed please.


On Tue, Sep 17, 2019 at 2:39 AM DelazJ  wrote:

> Hi,
> Tracking information from the Help button in the algorithm dialog led me
> to
> https://gdal.org/tutorials/gdal_grid_tut.html#inverse-distance-to-a-power
>
> Hope that helps,
> Harrissou
>
> Le mar. 17 sept. 2019 à 12:00, Daniel Zepeda Rivas 
> a écrit :
>
>> When using the Raster -> Analysis -> Grid (Inverse Distance to a Power)
>>
>> At the menu just before pressing run, can somebody please explain me the
>> effect of the "Weighting power" option in the interpolation process?
>>
>> I'm trying to make a temperature map based on points representing each
>> weather station, containing the yearly averages values of temperature, and
>> when moving the number from the 2 (set it by default) to 4, 6 or 10, the
>> map changes significantly
>>
>> ___
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Re: [Qgis-user] Question about Weighting Power value when running Grid-Inverse Distance to a Power

[DelazJ]

Hi,
Tracking information from the Help button in the algorithm dialog led me to
https://gdal.org/tutorials/gdal_grid_tut.html#inverse-distance-to-a-power

Hope that helps,
Harrissou

Le mar. 17 sept. 2019 à 12:00, Daniel Zepeda Rivas  a
écrit :

> When using the Raster -> Analysis -> Grid (Inverse Distance to a Power)
>
> At the menu just before pressing run, can somebody please explain me the
> effect of the "Weighting power" option in the interpolation process?
>
> I'm trying to make a temperature map based on points representing each
> weather station, containing the yearly averages values of temperature, and
> when moving the number from the 2 (set it by default) to 4, 6 or 10, the
> map changes significantly
>
> ___
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[Qgis-user] Question about Weighting Power value when running Grid-Inverse Distance to a Power

[Daniel Zepeda Rivas]

When using the Raster -> Analysis -> Grid (Inverse Distance to a Power)

At the menu just before pressing run, can somebody please explain me the effect 
of the "Weighting power" option in the interpolation process?

I'm trying to make a temperature map based on points representing each weather 
station, containing the yearly averages values of temperature, and when moving 
the number from the 2 (set it by default) to 4, 6 or 10, the map changes 
significantly

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[Qgis-user] Problem Running v.sample in QGIS 3

[Terry Morse]

I am trying to run the GRASS tool v.sample in 64 bit QGIS 3.8.2 and 3.4.11 with GRASS 7.6.1, and 3.2.3 with GRASS 7.4.1 on a 64-bit Windows 10 laptop, following directions in Learn QGIS, Fourth Edition: Your step-by-step guide to the fundamental of QGIS 3.4, by Andrew Cutts and Anita Glaser (Packt Publishing, 2018).The data layers are from the QGIS Alaska sample data set: airports.shp and landcover.img, both EPSG 2964.. I've attached a screen capture of the dialog box showing the main settings. All advanced settings are the defaults.When I run v.sample, I get the following errors:1) WARNING: Concurrent mapset locking is not supported on Windows. [I've read on the internet that this error isn't significant]2) WARNING: Unable to initialise PROJ with the following parameter list: +proj=aea +lat_1=55 +lat_2=65 +lat_0=50 +lon_0=-154 +x_0=0 +y_0=0 +no_defs +a=6378206.4 +rf=294.9786982 +nadgrids=C:\PROGRA~1\QGIS3~1.4\share\proj\@conus,@alaska,@ntv2_0.gsb,@ntv1_can.dat3) WARNING: Unable parse GRASS PROJ_INFO file4) ERROR: Unable to create OGR spatial reference5) The following layers were not correctly generated.C:/Users/Terry/Documents/My Books/Learn QGIS 4th ed/Data/samples_2.shpYou can check the 'Log Messages Panel' in QGIS main window to find more information about the execution of the algorithm.Perplexingly, the algorithm ran successfully back in January, but not this week. I ran it from the processing history from January to ensure the settings were all the same. The only difference I can think of between then and now is that I was running QGIS under 64-bit Windows 7 at the time. I installed Windows 10 a couple weeks ago. I'm not sure which version of QGIS 3 I had installed at the time, which is why I tried running it with 3.2, 3.4, and 3.6 this week. It didn't work in any of them.Can anyone help me figure this out? I've copied the full log file below.Thank you,Terry MorseFull log file:

QGIS version: 3.8.2-Zanzibar
QGIS code revision: 4470baa1a3
Qt version: 5.11.2
GDAL version: 2.4.1
GEOS version: 3.7.2-CAPI-1.11.0 b55d2125
PROJ version: Rel. 5.2.0, September 15th, 2018
Processing algorithm…
Algorithm 'v.sample' starting…
Input parameters:
{ 'GRASS_MIN_AREA_PARAMETER' : 0.0001, 'GRASS_OUTPUT_TYPE_PARAMETER' : 0, 'GRASS_REGION_CELLSIZE_PARAMETER' : 0, 'GRASS_REGION_PARAMETER' : None, 'GRASS_SNAP_TOLERANCE_PARAMETER' : -1, 'GRASS_VECTOR_DSCO' : '', 'GRASS_VECTOR_EXPORT_NOCAT' : False, 'GRASS_VECTOR_LCO' : '', 'column' : 'ID', 'input' : 'C:/Users/Terry/Documents/GIS/QGIS Sample Data/qgis_sample_data/shapefiles/airports.shp', 'method' : 0, 'output' : 'C:/Users/Terry/Documents/My Books/Learn QGIS 4th ed/Data/sampled_points.shp', 'raster' : 'C:/Users/Terry/Documents/GIS/QGIS Sample Data/qgis_sample_data/raster/landcover.img', 'zscale' : 1 }

g.proj -c proj4="+proj=aea +lat_1=55 +lat_2=65 +lat_0=50 +lon_0=-154 +x_0=0 +y_0=0 +datum=NAD27 +units=us-ft +no_defs"
v.in.ogr min_area=0.0001 snap=-1.0 input="C:\Users\Terry\Documents\GIS\QGIS Sample Data\qgis_sample_data\shapefiles\airports.shp" output="vector_5d809faeb5d0d2" --overwrite -o
r.external input="C:\Users\Terry\Documents\GIS\QGIS Sample Data\qgis_sample_data\raster\landcover.img" band=1 output="rast_5d809faebafab3" --overwrite -o
g.region n=7809680.0 s=1367760.0 e=4897040.0 w=-7117600.0 res=3280.0
v.sample input=vector_5d809faeb5d0d2 column=ID raster=rast_5d809faebafab3 zscale=1 method="nearest" output=output3138c3949b014923adb9b8d44c37e6ba --overwrite
v.out.ogr type="point" input="output3138c3949b014923adb9b8d44c37e6ba" output="C:\Users\Terry\Documents\My Books\Learn QGIS 4th ed\Data\sampled_points.shp" format="ESRI_Shapefile" --overwrite
Starting GRASS GIS...
WARNING: Concurrent mapset locking is not supported on Windows
Executing  ...
C:\Users\Terry\Documents>chcp 1252 1>NUL
C:\Users\Terry\Documents>g.proj -c proj4="+proj=aea +lat_1=55 +lat_2=65 +lat_0=50 +lon_0=-154 +x_0=0 +y_0=0 +datum=NAD27 +units=us-ft +no_defs"
Default region was updated to the new projection, but if you have multiple mapsets `g.region -d` should be run in each to update the region from the default
Projection information updated
C:\Users\Terry\Documents>v.in.ogr min_area=0.0001 snap=-1.0 input="C:\Users\Terry\Documents\GIS\QGIS Sample Data\qgis_sample_data\shapefiles\airports.shp" output="vector_5d809faeb5d0d2" --overwrite -o
Over-riding projection check
Check if OGR layer  contains polygons...
0..2..5..7..9..11..13..15..17..19..21..23..25..27..30..32..34..36..38..40..42..44..46..48..50..52..55..57..59..61..63..65..67..69..71..73..75..77..80..82..84..86..88..90..92..94..96..98..100
Creating attribute table for layer ...
Importing 76 features (OGR layer )...
0..2..5..7..9..11..13..15..17..19..21..23..25..27..30..32..34..36..38..40..42..44..46..48..50..52..55..57..59..61..63..65..67..69..71..73..75..77..80..82..84..86..88..90..92..94..96..98..100
-
Building topology for vector map ...
Registering primitives...

Re: [QGIS-it-user] R: Re: Nuovo Plugin CDU Creator

[Roberta Fagandini]

Grazie mille Salvatore!
Abbiamo già inserito nel manuale sia il video che il dataset.
Per quanto riguarda il video per noi sarebbe un piacere se comparisse sul
tuo canale ;-)

Grazie ancora per il contributo!!

Roberta

Il giorno mar 17 set 2019 alle ore 09:46 Totò Fiandaca <
pigrecoinfin...@gmail.com> ha scritto:

> Ciao,
> per me nessun problema,
> vi passo i due file:
> video:
> https://mega.nz/#!UdoGSKDK!BThGeIVuMZrno8svhzEPFVFLGdbjS-LObvPnS-E2xi4
> dataset:
> https://mega.nz/#!FF52iQZR!HhQaMayT-yd3ZrRnKRGb-GZyM_QFG7vew3wmLC8W8Wg
>
> potete usarli senza restrizioni.
>
> saluti
>
> Il giorno mar 17 set 2019 alle ore 09:13 Roberta Fagandini <
> robifagand...@gmail.com> ha scritto:
>
>> Ciao Salvatore,
>> grazie mille sia per il dataset che per il video molto chiaro ed
>> esplicativo.
>> Per quanto ci riguarda, non è assolutamente un problema renderlo
>> pubblico..anzi ci chiedevamo se potevamo inserire nel manuale del Plugin
>> sia il link al video che il dataset. Credo sarebbe molto utile per chi
>> vuole fare qualche test!
>>
>> Grazie ancora!
>> Roberta
>>
>> Il giorno lun 16 set 2019 alle ore 21:39 Totò 
>> ha scritto:
>>
>>> robertomarzocchi wrote
>>> > Con Salvatore Fiandaca, come al solito entusiasta delle novità, si
>>> > ragionava sulla creazione di un dataset su cui testare il plugin.
>>> >
>>> >
>>> > Le mie perplessità riguardano la proprietà dei dati catastali, ma mi
>>> > faceva notare che il plugin cxf_in ha incluso un dataset.
>>> > L'ideale usare lo stesso e aggiungerci un layer dell'urbanistica.
>>> >
>>> >
>>> > L'alternativa è crearci un layer delle particelle fittizio.
>>> >
>>> >
>>> > Cosa ne pensate?
>>>
>>> Buonasera,
>>> ho usato una parte del dataset presente nel plugin CXF_in di Fabio
>>> Saccon e
>>> ho modificato radicalmente la tabella attributi.
>>>
>>> allego video tutorial [0] e dataset con progetto QGIS 3.4 [1]
>>>
>>> [0] https://youtu.be/m21L1KO6hJg
>>> [1]
>>> https://mega.nz/#!UcgWWapA!HhQaMayT-yd3ZrRnKRGb-GZyM_QFG7vew3wmLC8W8Wg
>>>
>>> PS1. il video è non in elenco, possono vederlo solo chi ha il link.
>>>
>>> PS2: posso disattivare i link in qualsiasi momento :-)
>>>
>>> buon lavoro
>>>
>>>
>>>
>>>
>>> -
>>> https://pigrecoinfinito.wordpress.com/
>>> --
>>> Sent from:
>>> http://osgeo-org.1560.x6.nabble.com/QGIS-Italian-User-f5250612.html
>>> ___
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>>> QGIS-it-user@lists.osgeo.org
>>> https://lists.osgeo.org/mailman/listinfo/qgis-it-user
>>>
>>
>
> --
> *Ing. Salvatore Fiandaca*
> *mobile*.:+39 327.493.8955
> *m*: *pigrecoinfin...@gmail.com *
> *C.F*.: FNDSVT71E29Z103G
> *P.IVA*: 06597870820
> *membro QGIS Italia - http://qgis.it/ *
> *socio GFOSS.it - *http://gfoss.it/
> *blog:*
> * https://pigrecoinfinito.wordpress.com/
>  FB: Co-admin
> - https://www.facebook.com/qgis.it/ **
>  *
> *TW:  **https://twitter.com/totofiandaca
> *
>
> 43°51'0.54"N  10°34'27.62"E - EPSG:4326
>
> “Se la conoscenza deve essere aperta a tutti,
> perchè mai limitarne l’accesso?”
> R. Stallman
>
> Questo documento, allegati inclusi, contiene informazioni di proprietà di
> FIANDACA SALVATORE e deve essere utilizzato esclusivamente dal destinatario
> in relazione alle finalità per le quali è stato ricevuto. E' vietata
> qualsiasi forma di riproduzione o divulgazione senza l'esplicito consenso
> di FIANDACA SALVATORE. Qualora fosse stato ricevuto per errore si prega
> di informare tempestivamente il mittente e distruggere la copia in proprio
> possesso.
>
>
>

-- 
​*Arch. Roberta Fagandini, PhD*
*GIS and Remote Sensing Technician*
*Gter srl (Unige spin-off)*
*Piazza De Marini 3/61 - 16123 Genova*
*P.IVA/CF 01998770992*
*ph: 010-8694830 *
*E-mail: **roberta.fagand...@gter.it* 
*skype: roberta.fagandini*
*www.gter.it* 
*--*
*Gter social*
*www.twitter.com/Gteronline* * - *
*www.facebook.com/Gteronline* * -*
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[Qgis-user] Problems with the tool: join by attributes

[Jennifer Schubert]

Hi,
I want to spatially join points with individual values to a polygon grid. 
The resulting shapefile should have a column where the values oft the points 
are summed up - according to the grid cell they are found in. 
This simple operation works fine in QGIS 2.18 where you can click "sum" as the 
method of statistics. 
However, the newer versions of QGIS don't have the possibility to indicate the 
method of statistics or I cannot find them, so I cannot get the task done with 
it. 
Does anybody now how to perform this tool successfully in QGIS 3.8.2?
 
Thanks in advance
Jennifer Schubert___
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Re: [QGIS-it-user] R: Re: Nuovo Plugin CDU Creator

[Totò Fiandaca]

Ciao,
per me nessun problema,
vi passo i due file:
video:
https://mega.nz/#!UdoGSKDK!BThGeIVuMZrno8svhzEPFVFLGdbjS-LObvPnS-E2xi4
dataset:
https://mega.nz/#!FF52iQZR!HhQaMayT-yd3ZrRnKRGb-GZyM_QFG7vew3wmLC8W8Wg

potete usarli senza restrizioni.

saluti

Il giorno mar 17 set 2019 alle ore 09:13 Roberta Fagandini <
robifagand...@gmail.com> ha scritto:

> Ciao Salvatore,
> grazie mille sia per il dataset che per il video molto chiaro ed
> esplicativo.
> Per quanto ci riguarda, non è assolutamente un problema renderlo
> pubblico..anzi ci chiedevamo se potevamo inserire nel manuale del Plugin
> sia il link al video che il dataset. Credo sarebbe molto utile per chi
> vuole fare qualche test!
>
> Grazie ancora!
> Roberta
>
> Il giorno lun 16 set 2019 alle ore 21:39 Totò 
> ha scritto:
>
>> robertomarzocchi wrote
>> > Con Salvatore Fiandaca, come al solito entusiasta delle novità, si
>> > ragionava sulla creazione di un dataset su cui testare il plugin.
>> >
>> >
>> > Le mie perplessità riguardano la proprietà dei dati catastali, ma mi
>> > faceva notare che il plugin cxf_in ha incluso un dataset.
>> > L'ideale usare lo stesso e aggiungerci un layer dell'urbanistica.
>> >
>> >
>> > L'alternativa è crearci un layer delle particelle fittizio.
>> >
>> >
>> > Cosa ne pensate?
>>
>> Buonasera,
>> ho usato una parte del dataset presente nel plugin CXF_in di Fabio Saccon
>> e
>> ho modificato radicalmente la tabella attributi.
>>
>> allego video tutorial [0] e dataset con progetto QGIS 3.4 [1]
>>
>> [0] https://youtu.be/m21L1KO6hJg
>> [1]
>> https://mega.nz/#!UcgWWapA!HhQaMayT-yd3ZrRnKRGb-GZyM_QFG7vew3wmLC8W8Wg
>>
>> PS1. il video è non in elenco, possono vederlo solo chi ha il link.
>>
>> PS2: posso disattivare i link in qualsiasi momento :-)
>>
>> buon lavoro
>>
>>
>>
>>
>> -
>> https://pigrecoinfinito.wordpress.com/
>> --
>> Sent from:
>> http://osgeo-org.1560.x6.nabble.com/QGIS-Italian-User-f5250612.html
>> ___
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>> https://lists.osgeo.org/mailman/listinfo/qgis-it-user
>>
>

-- 
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 *
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*

43°51'0.54"N  10°34'27.62"E - EPSG:4326

“Se la conoscenza deve essere aperta a tutti,
perchè mai limitarne l’accesso?”
R. Stallman

Questo documento, allegati inclusi, contiene informazioni di proprietà di
FIANDACA SALVATORE e deve essere utilizzato esclusivamente dal destinatario
in relazione alle finalità per le quali è stato ricevuto. E' vietata
qualsiasi forma di riproduzione o divulgazione senza l'esplicito consenso
di FIANDACA SALVATORE. Qualora fosse stato ricevuto per errore si prega di
informare tempestivamente il mittente e distruggere la copia in proprio
possesso.
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[Qgis-user] QGIS metadata options ? (Thanks; re-post)

[Falk Huettmann]

Hi there, QGIS community,

very sorry,
but I am still struggling with xml ISO compliant FGDC metadata in
QGIS.

I only see the great webpage on MetaEdit;
well, except, I cannot find it in the PlugIns and the
 website seems to be not supported anymore; no reply upon request.
 http://gis-lab.info/qa/metatools-eng.html

I would welcome any suggestions here on what to do; big thanks.

QGIS, like any GIS and software and data, cannot live without metadata and
such an editor.
Even more so, that's where Open Source can entirely outcompete
and winI am thinking here for instance of (biological species taxonomy)
survey data with GIS data sources all read-in automatically  for modeling
and predictions; with automated workflows...and then readily documented
with XML metadata and parsed and presented in html, for instance.

See here a monopoly piece in gitub; how can that be linked with QGIS
effectively ?.
https://github.com/usgs/fort-pymdwizard/

For projects - commercial and science-, compliant ISO metadata can be the
deal breaker

And I think we should probably not work with 'homebrew' code and rely on it.

Thanks so much again for any pointers; very best
  Falk Huettmann
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Re: [QGIS-it-user] R: Re: Nuovo Plugin CDU Creator

[Roberta Fagandini]

Ciao Salvatore,
grazie mille sia per il dataset che per il video molto chiaro ed
esplicativo.
Per quanto ci riguarda, non è assolutamente un problema renderlo
pubblico..anzi ci chiedevamo se potevamo inserire nel manuale del Plugin
sia il link al video che il dataset. Credo sarebbe molto utile per chi
vuole fare qualche test!

Grazie ancora!
Roberta

Il giorno lun 16 set 2019 alle ore 21:39 Totò 
ha scritto:

> robertomarzocchi wrote
> > Con Salvatore Fiandaca, come al solito entusiasta delle novità, si
> > ragionava sulla creazione di un dataset su cui testare il plugin.
> >
> >
> > Le mie perplessità riguardano la proprietà dei dati catastali, ma mi
> > faceva notare che il plugin cxf_in ha incluso un dataset.
> > L'ideale usare lo stesso e aggiungerci un layer dell'urbanistica.
> >
> >
> > L'alternativa è crearci un layer delle particelle fittizio.
> >
> >
> > Cosa ne pensate?
>
> Buonasera,
> ho usato una parte del dataset presente nel plugin CXF_in di Fabio Saccon e
> ho modificato radicalmente la tabella attributi.
>
> allego video tutorial [0] e dataset con progetto QGIS 3.4 [1]
>
> [0] https://youtu.be/m21L1KO6hJg
> [1] https://mega.nz/#!UcgWWapA!HhQaMayT-yd3ZrRnKRGb-GZyM_QFG7vew3wmLC8W8Wg
>
> PS1. il video è non in elenco, possono vederlo solo chi ha il link.
>
> PS2: posso disattivare i link in qualsiasi momento :-)
>
> buon lavoro
>
>
>
>
> -
> https://pigrecoinfinito.wordpress.com/
> --
> Sent from:
> http://osgeo-org.1560.x6.nabble.com/QGIS-Italian-User-f5250612.html
> ___
> QGIS-it-user mailing list
> QGIS-it-user@lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/qgis-it-user
>
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Re: [Qgis-user] Shortest path caching

[Paul Wittle]

Hello Both,

Thank you for your answers so far and I could indeed get on with the python 
methods but I’m trying to build a solution which a normal user would understand 
with minimal effort really.

I’m currently looking at using the graphical modeler to create a routing which 
will replicate (albeit inefficiently) the Travelling Sales routing by running 
shortest route in batch form. I think I got 90% of the way yesterday before I 
ran into the obvious issue with the process modelling.

Is there any way to output a string from a process which you can then use as an 
input in another process?

I ask because all the routing algorithms require at least one ‘point’ (string) 
input. I have extracted the coordinates from my points layer as a string in the 
form ‘x, y’ and I can see the string if I run that section separately but I 
can’t set the string as an input for shortest route algorithm in the modeler.

I’m thinking that the best method would probably be to run a distance matrix 
and then use that to construct a series of A – B routes in order, run each of 
those and then stick them together to create the output. Given the comment that 
“Both points (start A and end B) are “tied” to the graph when it is built”; I’m 
pretty convinced that my plan of using clipped versions of the network for the 
routing may still be the best method for QGIS.

I’m aware that this is really using a spade to dig up a road when really I 
should be just investing in a digger but the goal here is to see what can be 
achieved with QGIS 3.4 as it stands today. I’m not too fused if it takes 5 
minutes to run a 30 second job so much as whether it can be achieved accurately 
and using a method that end users might be able to understand.

Thanks,
Paul

From: Nicolas Cadieux 
Sent: 16 September 2019 16:09
To: DelazJ 
Cc: Paul Wittle ; qgis-user@lists.osgeo.org
Subject: Re: [Qgis-user] Shortest path caching

Hi Harrissou

I was referring to the online documentation in the developers cookbook.  The 
user guide is effective.  I perfectly understand the problem and wish I could 
help but despite receiving help from advance users with links to online code 
examples (thanks), I found it easier to go with NetworkX that was well 
documented.  Maybe I could figure it out now since I now have experience 
working with shortest path analysis and now grasp the basic concepts of 
networks but when I started the project, it was a big learning curve.

Cheers

Nicolas

Le 16 sept. 2019 à 09:36, DelazJ mailto:del...@gmail.com>> a 
écrit :
Hi,

Le lun. 16 sept. 2019 à 15:25, Nicolas Cadieux 
mailto:nicolas.cadi...@archeotec.ca>> a écrit :
Hi,

You could go with NetworkX, a python library.  With that, you can build the 
graph on the fly and maintain it as roads or edges get added and removed.

You can probably do this with QGIS but the biggest problem I found with QGIS is 
the lack of documentation for using the network analysis tools using the latest 
versions. Everything is, or was documented for version 2.x.  Also, when using 
the processing tools in a batch, the graph gets rebuilt every time this should 
not happen.

Nicolas, about the lack of documentation, you meant the tools in the processing 
toolbox [0] or the pyQGIS cookbook [1]. I'm not sure there's anything missing 
in the former (and maybe Paul could find some answers) and, for the latter 
(which is horribly outdated), it's the usual lack of skilled people to provide 
necessary documentation. Because some parts of the docs are specialized, they 
require advanced users to help us update. If we are giving a txt (or whatever 
open format) file updating the section, I'm happy to push it and update that 
page too.

[0] 
https://docs.qgis.org/testing/en/docs/user_manual/processing_algs/qgis/networkanalysis.html
[1] 
https://docs.qgis.org/testing/en/docs/pyqgis_developer_cookbook/network_analysis.html

Regards,
Harrissou
For those reasons, I went with NetworkX python library.  Out of curiosity, how 
many edges are you dealing with? How many queries?

Nicolas





Le 16 sept. 2019 à 08:03, Paul Wittle 
mailto:paul.wit...@dorsetcouncil.gov.uk>> a 
écrit :
Hi,

I’m aware that you can use things like the pgRouting plugin for shortest path 
calculations but when looking at the default functions is there a sensible way 
to speed up the calculations?

I’ve just run a couple of tests using an Oracle database based routing layer 
and it runs but seems to take a long time to build the graph. I wondered if 
there is a plugin which stores some sort of optimised network to speed up the 
process or perhaps a type of index I could put on the network?

At present the network is big so I guess perhaps some form of clip then run 
process might be helpful?

I just thought I’d email to see what others do as I’ve not looked at routing in 
QGIS for some years now and I’d prefer to avoid more complex options such as 
pgRouting if possible.

Thanks,
Paul
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