Re: [Qgis-user] Legend for Heatmap option

[Neumann, Andreas]

 

Hi Ezra, 

Not so sure how useful a legend for a heatmap would be? 

What would you display or expect? A gradient - yes - I understand that -
but what numbers? Heatmaps aggregate points (potentially weighted by an
attribute) and sums up those points within a defined radius. Then it
colors the result with a gradient from min to max. How meaningful are
those aggregated numbers? 

After all - you also can't query heatmap layers with the Identify tool -
because the numbers are quite useless. 

Heatmaps are not quantitative views in my opinion, but more qualitative
views to show how distributed point data is on the same view. 

But maybe Nyall, the developer of the heatmap support in QGIS core has a
better idea of how such a legend would look like. 

Andreas 

On 2015-11-12 02:10, Ezra Boyd wrote: 

> Hello, 
> 
> I am working with QGIS 2.8.1  on Windows 7 (64-bit). 
> 
> I displaying a point layer using the 'Heatmap' option in styles.  The heatmap 
> renders great, but there is no legend in the map composer.  Does anyone know 
> if this a bug or has this feature not been created yet? 
> 
> Thanks, 
> Ezra 
> 
> -- 
> 
> Ezra Boyd, PhD 
> 
> DisasterMap.net, LLC [1] ezgi...@gmail.com 
> 
> (504)533-4447 
> 
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Links:
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[1] http://DisasterMap.net
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Re: [Qgis-user] columns in spatialite

[Paolo Cavallini]

Il 12/11/2015 00:31, Bernd Vogelgesang ha scritto:

> So, to answer to Paolo's question about what is missing in DBManager:
> Actually nothing in my case, cause I really do not want to use it at
> all. I just would like to be able to act with spatialite layers as I am
> able to do with ESRI shapefile layers.

Geopackage might be more in line with what you are looking for (still a
lengthy way to go, anyway).
All the best.

-- 
Paolo Cavallini - www.faunalia.eu
QGIS & PostGIS courses: http://www.faunalia.eu/training.html
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[Qgis-user] Legend for Heatmap option

[Ezra Boyd]

Hello,

I am working with QGIS 2.8.1  on Windows 7 (64-bit).

I displaying a point layer using the 'Heatmap' option in styles.  The
heatmap renders great, but there is no legend in the map composer.  Does
anyone know if this a bug or has this feature not been created yet?

Thanks,
Ezra


-- 
Ezra Boyd, PhD
DisasterMap.net, LLC 
ezgis 7...@gmail.com 
(504)533-4447
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Re: [Qgis-user] columns in spatialite

[Bernd Vogelgesang]

Am 11.11.2015, 21:55 Uhr, schrieb X Of :


Am 11.11.2015 um 07:59 schrieb Micha Silver:

Unfortunately I easily forget how sql
works, so doing "easy" stuff becomes very time consuming and  
frustrating.


I think this is a usual problem for us non-regular SQL-users (for any  
database-system).


To avoid figuring out complex or even simple queries (imho all  
geo-spatial queries are relatively difficult) I always keep a  
code-editor-window open, where I copy-paste to and from all successful  
queries (and also comment on how they work, even if I think it's silly.  
Next morning I'm grateful for it already).


New queries I usually draft in the code-editor first. This way I don't  
even have to remember the exact table-names or column names, I can just  
start typing and wait for the editor's autocomplete-suggestions.


I think this is quite a good way of working, because this way I can  
always and easily reproduces my work, if anything should go wrong with  
the databases/views...


Hope this helps avoiding some frustrations. To me, spatialite rocks even  
with all it's quirks here and there! Thanks to everyone contributing to  
spatialite and QGIS.

_



Of course this is a nice strategy when you are disciplined person and  
always remember to open the editor and then not forget where you stored  
your file ;)


Actually, my use-case for spatialite is much more simple. I normally do  
not need any special/spacial queries, I just want to replace ESRI shape  
file as the standard exchange format (do not have to zip 3 + x files  
before sending by email) and also as the standard work format (getting rid  
of computer-stone-age dbf limitations like column names and field lengths).


But so far, I can not really introduce it in my daily work-flows  
efficiently, cause of limitations simple as renaming or reordering  
columns. Even when you really carefully plan an attribute table set-up,  
you ALWAYS forget sth or put it in the wrong order. Having to dig out sql  
for this, I'm simply to lazy and most other users are definitely out of  
the game at this moment. (Of course it would be very rewarding to learn  
sql by heart, but for everyday quick-and-dirty tasks, this is just to much  
rocket science to be efficient)


And even when you start out correctly with all your fields and names and  
everything, you use Processing and BAMM, everything's fucked up again by  
ESRI shape files when you just want to have a temporary layer and do not  
wish to save each and every trial or iteration to a file. Of course I  
COULD do this, but then the half of the benefits of Processing are lost.  
So I stay with the be-hated ESRI format.


My dream would be, to be able to simply use the spatialite format as  
seamless as QGIS works now with ESRI shapes.
Later on, the extended sql-abilities would be nice goody for special  
cases, but I am more for the bread-and-butter tasks at the moment.


So, to answer to Paolo's question about what is missing in DBManager:  
Actually nothing in my case, cause I really do not want to use it at all.  
I just would like to be able to act with spatialite layers as I am able to  
do with ESRI shapefile layers.


That's why I asked in the beginning about a Table-Manager-like plugin to  
at least be able to rename/reorder columns (Strange enough that Table  
Manager is not even installed and activated by default, though ESRI shape  
files are the standard work format, and novices will not so easily find  
out how to edit them, while in ArcGIS this is just possible without any  
user interaction)


Regards
Bernd

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--
Bernd Vogelgesang
Siedlerstraße 2
91083 Baiersdorf/Igelsdorf
Tel: 09133-825374
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Re: [Qgis-user] Can the point displacement center symbol be scaled based on number of corresponding points?

[Anita Graser]

On Wed, Nov 11, 2015 at 9:46 PM, Nyall Dawson 
wrote:

>
> On 12 Nov 2015 7:30 AM, "Anita Graser"  wrote:
> >
> >
> >
> > On Wed, Nov 11, 2015 at 9:09 PM, Nyall Dawson 
> wrote:
> >>
> >>
> >> On 12 Nov 2015 6:51 AM, "Anita Graser"  wrote:
> >> >
> >> > Hi,
> >> >
> >> > Is there a way, maybe a function for expression based styles, which
> makes it possible to scale the center symbol of the point displacement
> style based on the number of corresponding points?
> >> >
> >> > So if 5 points are summarized with one center symbol, make it 5 big
> and/or label it with "5".
> >>
> >> Do you also want the ring sizes to change? Or are they constant?
> >
> > ​Actually, I don't want the ring at all. I'm just looking to reproduce
> http://suite.opengeo.org/opengeo-docs/cartography/rt/pointstacker.html
>
> Ah, now I understand. Not possible at the moment, but the displacement
> renderer could be extended to allow this style (and be renamed
> "displacement/stacker"). Let me think on this - I might launch a crowdfund
> to add this feature.
>
​Great, looking forward to seeing what you come up with :)

Best wishes,
​Anita

​
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Re: [Qgis-user] columns in spatialite

[X Of]

Am 11.11.2015 um 07:59 schrieb Micha Silver:

Unfortunately I easily forget how sql

works, so doing "easy" stuff becomes very time consuming and frustrating.


I think this is a usual problem for us non-regular SQL-users (for any 
database-system).


To avoid figuring out complex or even simple queries (imho all 
geo-spatial queries are relatively difficult) I always keep a 
code-editor-window open, where I copy-paste to and from all successful 
queries (and also comment on how they work, even if I think it's silly. 
Next morning I'm grateful for it already).


New queries I usually draft in the code-editor first. This way I don't 
even have to remember the exact table-names or column names, I can just 
start typing and wait for the editor's autocomplete-suggestions.


I think this is quite a good way of working, because this way I can 
always and easily reproduces my work, if anything should go wrong with 
the databases/views...


Hope this helps avoiding some frustrations. To me, spatialite rocks even 
with all it's quirks here and there! Thanks to everyone contributing to 
spatialite and QGIS.

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Re: [Qgis-user] Can the point displacement center symbol be scaled based on number of corresponding points?

[Anita Graser]

On Wed, Nov 11, 2015 at 9:42 PM, Goyo  wrote:

> 2015-11-11 21:30 GMT+01:00 Anita Graser :
> > Actually, I don't want the ring at all. I'm just looking to reproduce
> > http://suite.opengeo.org/opengeo-docs/cartography/rt/pointstacker.html
>
> That looks more like the clustering feature available in leaflet, I
> learned about it while using the qgis2leaf plugin. CartoDB has
> something like that too.
>

​I know. But I want it in QGIS and the point displacement renderer seems to
have almost everything in place that is needed.

Best wishes,
Anita​
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Re: [Qgis-user] Can the point displacement center symbol be scaled based on number of corresponding points?

[Nyall Dawson]

On 12 Nov 2015 7:30 AM, "Anita Graser"  wrote:
>
>
>
> On Wed, Nov 11, 2015 at 9:09 PM, Nyall Dawson 
wrote:
>>
>>
>> On 12 Nov 2015 6:51 AM, "Anita Graser"  wrote:
>> >
>> > Hi,
>> >
>> > Is there a way, maybe a function for expression based styles, which
makes it possible to scale the center symbol of the point displacement
style based on the number of corresponding points?
>> >
>> > So if 5 points are summarized with one center symbol, make it 5 big
and/or label it with "5".
>>
>> Do you also want the ring sizes to change? Or are they constant?
>
> ​Actually, I don't want the ring at all. I'm just looking to reproduce
http://suite.opengeo.org/opengeo-docs/cartography/rt/pointstacker.html

Ah, now I understand. Not possible at the moment, but the displacement
renderer could be extended to allow this style (and be renamed
"displacement/stacker"). Let me think on this - I might launch a crowdfund
to add this feature.

Nyall

>
> Best wishes,
> Anita
>
>
>
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Re: [Qgis-user] Can the point displacement center symbol be scaled based on number of corresponding points?

[Goyo]

2015-11-11 21:30 GMT+01:00 Anita Graser :
> Actually, I don't want the ring at all. I'm just looking to reproduce
> http://suite.opengeo.org/opengeo-docs/cartography/rt/pointstacker.html

That looks more like the clustering feature available in leaflet, I
learned about it while using the qgis2leaf plugin. CartoDB has
something like that too.

Goyo
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Re: [Qgis-user] Can the point displacement center symbol be scaled based on number of corresponding points?

[Anita Graser]

On Wed, Nov 11, 2015 at 9:09 PM, Nyall Dawson 
wrote:

>
> On 12 Nov 2015 6:51 AM, "Anita Graser"  wrote:
> >
> > Hi,
> >
> > Is there a way, maybe a function for expression based styles, which
> makes it possible to scale the center symbol of the point displacement
> style based on the number of corresponding points?
> >
> > So if 5 points are summarized with one center symbol, make it 5 big
> and/or label it with "5".
>
> Do you also want the ring sizes to change? Or are they constant?
>
​Actually, I don't want the ring at all. I'm just looking to reproduce
http://suite.opengeo.org/opengeo-docs/cartography/rt/pointstacker.html

Best wishes,
Anita
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Re: [Qgis-user] ECW on Ubuntu

[Micha Silver]

  
  
Hi Carlos:
I'd like to add that I tried Andre's procedure from the
StackExchange post (on a couple of Mint 17 machines) and it worked
fine.
Compiling the ERDAS SDK was OK. I set the link to the required lib
version as he explained.
Then I downloaded the older libgdal-ecw-src deb,
  opened it up and compiled as he wrote. Now I've got read access to
  ECW's.
  

On 11/11/15 17:30, Carlos Cerdán wrote:


  

  Andre:

  
  Thank you very much for your advice, but I had not success
  installing ECW support for my QGIS 2.12 on Ubuntu 14.04. I was
  trying many advices, and I've probably left a mess in my
  installation then, I've surrendered and when I need to
  work with ECW images I turn on my virtual PC with Windows.
  
  I hope that developers will can do easy to read ECW images on
  Linux in a close future.
  

Carlos Cerdán


  

  
2015-11-04 14:21 GMT-05:00
  Andre Joost :
  Am
  04.11.2015 um 16:43 schrieb Carlos Cerdán:
  
Thank you very much Richard.

After reading (and trying) your link, I've been
looking for more recent
help. I found this:

[1] How to install QGis with ECW Support on
Linux

As there isn't libgdal-ecw-src on last ubuntugis
repository, when [1] says
"sudo apt-get install libgdal-ecw-src",  I've
tried install it following:

[2]  libecw building for gdal

  
  

If you are on Ubuntu 14.04, you can still try my
advice here:

http://gis.stackexchange.com/questions/94870/unable-to-install-ecw-support-on-lubuntu-14-04

And yes, it is a kind of self-compiling.

HTH,
André Joost

  


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Re: [Qgis-user] Can the point displacement center symbol be scaled based on number of corresponding points?

[Nyall Dawson]

On 12 Nov 2015 6:51 AM, "Anita Graser"  wrote:
>
> Hi,
>
> Is there a way, maybe a function for expression based styles, which makes
it possible to scale the center symbol of the point displacement style
based on the number of corresponding points?
>
> So if 5 points are summarized with one center symbol, make it 5 big
and/or label it with "5".

Do you also want the ring sizes to change? Or are they constant?

Nyall

>
> Best wishes,
> Anita
>
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[Qgis-user] Can the point displacement center symbol be scaled based on number of corresponding points?

[Anita Graser]

Hi,

Is there a way, maybe a function for expression based styles, which makes
it possible to scale the center symbol of the point displacement style
based on the number of corresponding points?

So if 5 points are summarized with one center symbol, make it 5 big and/or
label it with "5".

Best wishes,
Anita
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[Qgis-user] New behavior of Node Tool

[Piotr Kania]

Hi all!

There is new Node tool in qgis dev. I have opened the bug - 
http://hub.qgis.org/issues/13793


I think new working mode of Node Tool (semitransparent red background 
appears when user clicks with Node Tool at polygon feature) isn't 
convenient when someone needs to digitize lots of polygon features using 
rasters, wms etc. Additionally during editing session after moving one 
or few vertexes we can still see old position of moved vertexes.


In my job (forestry) I use qgis to digitize stand's borders, dirt roads 
and streams etc., etc. - I do that using aerial photo (which is rather 
too old - my employer isn't generous). All polygon layers in my projects 
have transparent background (symbol layer type - "Outline: simple 
line"), because I need to see what is on underlaying rasters.


I have created the bug ticket because I couldn't find in qgis settings 
how to change the new background color into sth more transparent (or 
even to sth completely transparent :) ). My "problem" is similar to the 
question that was asked here:

http://gis.stackexchange.com/questions/79783/add-feature-tool-qgis-2-0-polygon-fill-blocks-view-of-what-i-want-to-digitiz

As you can guess, I'd set all to transparency more than 50 %.:).

I would like to ask everyone - would you like to have somewhere in qgis 
settings for that new Node tool? - because right now it's possible to 
set selection tool's colors (and transparency), Identify Features Tool's 
colors, measure tool's colors, Rubberband's colors. Why not Node Tool's 
colors? It could be event sth deeply hidden in new "Advanced Settings 
Editor". I think all qgis users would have some benefits having options 
for setting color and transparency for line and background of new Node Tool.


What do you think? if you agree -make some comments on 
hub.qgis.org/issues/13793


Sorry for long mail, but as someone wrote once -" (...)it's not a 
twitter but mailing list, so write man as much as you can..." :)

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Re: [Qgis-user] Simultaneous extraction of coordinates & elevation

[Goyo]

2015-11-10 23:46 GMT+01:00 Allan López :
> Hi,
>
> How to perform a simultaneous extraction of coordinates and elevation in a
> DEM or at least in a few steps ?. I need the points in their real locations
> NOT in the center of polygons within a given grid. Thank you in advance.

Export your DEM as .xyz (Raster > Conversion > Translate)

Goyo
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[Qgis-user] Location of qgis.core and qgis.gui modules for python import?

[Richard Males]

I am trying to develop an external python script using qgis capabilities.
My understanding is that I need to import qgis.core and qgis.gui.   I would
like to do this with the fully qualified path name of the location of these
modules, but cannot seem to find them on my computer, where I have QGIS
Pisa installed.

Thanks in advance

Dick Males
Cincinnati, Ohio, USA
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Re: [Qgis-user] ECW on Ubuntu

[Carlos Cerdán]

Andre:

Thank you very much for your advice, but I had not success installing ECW
support for my QGIS 2.12 on Ubuntu 14.04. I was trying many advices, and
I've probably left a mess in my installation then, I've surrendered and
when I need to work with ECW images I turn on my virtual PC with Windows.

I hope that developers will can do easy to read ECW images on Linux in a
close future.

Carlos Cerdán

2015-11-04 14:21 GMT-05:00 Andre Joost :

> Am 04.11.2015 um 16:43 schrieb Carlos Cerdán:
>
>> Thank you very much Richard.
>>
>> After reading (and trying) your link, I've been looking for more recent
>> help. I found this:
>>
>> [1] How to install QGis with ECW Support on Linux
>>
>> As there isn't libgdal-ecw-src on last ubuntugis repository, when [1] says
>> "sudo apt-get install libgdal-ecw-src",  I've tried install it following:
>>
>> [2]  libecw building for gdal
>>
>>
> If you are on Ubuntu 14.04, you can still try my advice here:
>
>
> http://gis.stackexchange.com/questions/94870/unable-to-install-ecw-support-on-lubuntu-14-04
>
> And yes, it is a kind of self-compiling.
>
> HTH,
> André Joost
>
>
>
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