Re: [Qgis-user] line in dem from max to min

[Micha Silver]

v.botz wrote
> Hi,
> 
> i have some geometrys (multipolygon) and a dem (digital elevation model)
> -> I need a line from the max value to the lowest value of the dem, for
> every multipolygon
> 
> is qgis a tool i could use - or do i need PostGIS ?
> 
> how could i realize this problem ??
> 
> any ideas?  THANKS

I can see a possible solution using GRASS. It's a bit complicated, but
*should* work.

Starting with the vector module v.rast.stats you can add to your polygons
the minimum and maximum elevation values for each polygon as new attribute
columns.
Now you need to loop thru all the polygons (using your favorite scripting
language). The v.db.select module will give a list of cat values and the
min/max from above. Loop thru that list and for each cat value create a
raster mask based on that polygon: something like 
r.mask raster=MASK vector= cats=. 
Then, with that mask in place, use an r.mapcalc expression to create a new
raster with only the min/max values. Such as: 
r.mapcalc --o "min_max = if(dem>=max OR dem<=min, dem, null() )"

All other raster cells will be NULL. Now convert this new raster to a point
vector. It will have only two points, the min and max elevation within the
current polygon. And using those two points, create your line.
Finally remove the mask and loop to the next...
 
HTH,
Micha



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Re: [Qgis-user] R algortihms do not work in Geoprocessing

[Lene Fischer]

Hi Luis,
You can only use ASCII characters a-z A-Z 0-9.
If you have a folder with other characters (as in your name) or space, the 
program get an error.

Regards


Lene Fischer
Associate Professor

Department of Geosciences and Natural Resource Management
University of Copenhagen

MOB +45 40115084
l...@ign.ku.dk


[cid:image001.gif@01D03029.2F3EC6A0]



Fra: qgis-user-boun...@lists.osgeo.org 
[mailto:qgis-user-boun...@lists.osgeo.org] På vegne af Luís Miguel Royo Pérez
Sendt: 7. juli 2015 11:36
Til: qgis-user@lists.osgeo.org
Emne: [Qgis-user] R algortihms do not work in Geoprocessing

Hello everyone,

I have problems to work with the R algortihms in QGIS. I'm using Windows 8.1, 
Rx64 3.2.1 and QGIS 2.10.0. I have set the path correctly in R options in the 
providers window, but when I try to run any R algorithm this is what I get.

'ascii' codec can't encode character u'\xed' in position 11: ordinal not in 
range(128) See log for more details

The log do not show useful info. Can anyone adress me in order to make these 
algorithms work properly?

Thank you!!
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Re: [Qgis-user] Google Satellite and Measure line tool wrong results

[Marco]

Hi.

Tnx to Nicolas for the input concerning how to work-around the problem
with the Google images.

And I will try to use Landsat images first, some years ago I did, now it
I have just to remember how it works :-)

Have a nice day

Marco

Il 07. 07. 15 09:14, Andreas Neumann ha scritto:
> Hi Marco,
>
> On 06.07.2015 20:19, Marco wrote:
>> Hello.
>>
>> Yes tnx. I don't have any problem with shp files and the measuring
>> tool, only with the Google layers.
>>
>> I will have to load the sat images from another source
>
> that is a good idea. It is legally questionable if you are allowed to
> use Google satellite images. Better use another source of "real"
> geodata and you won't have problems with offsets, scales, projections.
>
> Andreas
>
>
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Re: [Qgis-user] Supervised and Unsupervised classification

[Paolo Cavallini]

Il 07/07/2015 19:49, Mariana Buzzi ha scritto:
> Hello People.
> I am writing to tell you that want to perform supervised and
> unsupervised classification of images SPOT 5. The aim is to to see the
> different land uses having the study area. How I can make these
> classifications with QGIS?
> Once you make the classification (with QGIS), I want to apply metrics
> landscape with FRAGSTAT program.
> From already thank you very much !!!

You can use several tools, check OTB, GRASS and SAGA, also from
Processing in QGIS. Also see
http://plugins.qgis.org/plugins/SemiAutomaticClassificationPlugin/
Good luck.
-- 
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QGIS & PostGIS courses: http://www.faunalia.eu/training.html
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[Qgis-user] Supervised and Unsupervised classification

[Mariana Buzzi]

Hello People.
I am writing to tell you that want to perform supervised and unsupervised
classification of images SPOT 5. The aim is to to see the different land
uses having the study area. How I can make these classifications with QGIS?
Once you make the classification (with QGIS), I want to apply metrics
landscape with FRAGSTAT program.
>From already thank you very much !!!
Regards,

Mariana
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Re: [Qgis-user] Export .shp file to .osm file format

[Clifford Snow]

The ogr2osm python script works great for converting shapefiles to .osm
files. I use the one found at https://github.com/pnorman/ogr2osm.

ogr2osm allows you to create a translation script to convert shapefile
features to osm tags. The github repository includes examples of the
translation tables.

As a note - please don't upload data to OSM without following the import
guidelines.

Clifford

On Tue, Jul 7, 2015 at 9:03 AM, Jorge Guevara 
wrote:

> Hello,
>
> I'm new in QGIS and need to convert .shp files to .osm files.
>
> I read the user guide without succeed.
>
> Can you help me?
>
> Regards
> Jorge Guevara
>
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Re: [Qgis-user] Export .shp file to .osm file format

[Andre Joost]

Am 07.07.2015 um 16:03 schrieb Jorge Guevara:

Hello,

I'm new in QGIS and need to convert .shp files to .osm files.

I read the user guide without succeed.

Can you help me?



No, it is not possible, because the OSM driver is read-only.

See my answer here:
http://gis.stackexchange.com/questions/152298/creating-protocolbuffer-binary-format-pbf-file-using-qgis/152323#152323

for a workaround.

HTH,
André Joost


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Re: [Qgis-user] aggregate map of maximum value

[Nicolas Cadieux]

Hi, 
I am not sure you can use max value in QGIS raster calculator. (Please correct 
me if I am wrong). 
I think you can do it with gdal calc.py.  and most likely in Grass or Saga 
using the processing plugin. 
http://gis.stackexchange.com/questions/107257/combine-overlapping-rasters-in-gdal-calc-py-taking-the-maximum-value-from-each
 
If you want more flexibility but don't mind the lost of speed, you could 
convert the raster in a vector format and use the field calculator to do it. 
This work's OK up to a few million points or pixels. After that, it's very 
slow.  You can speed things up by using R for the statistics. 
I think there is a raster to point module in the QGIS processing plugin or just 
look at this:  
http://fr.slideshare.net/shencoop/qgis-raster-to-point 
Then you could do the reverse operation on the results. 
Nicolas Cadieux M.Sc. 
Les Entreprises Archéotec inc.  
8548, rue Saint-Denis Montréal H2P 2H2 
Téléphone: 514.381.5112  Fax: 514.381.4995 
www.archeotec.ca 
On Jul 7, 2015 8:06 AM, "Giacomo Fontanelli-2 [via OSGeo.org]  " 
 wrote: 

dear community I have a stack (bsq) of 5 images. I would like to make 
an aggregate map of the maximum of each pixel of the bands. I Googled and I 
found contrasting opinions on how to do it. Can you help me? Thank you 
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Re: [Qgis-user] line in dem from max to min

[Nicolas Cadieux]

Hi, 
I would have a column ID each polygon or multipolygone with a unique name.  I 
would then densify  the geometry to create new vertex along the line then 
extract these vertex to a point layer.  I would then use the point value plugin 
to extract the value of the DEM for each point and then use a group statistic 
(grouping with the polygon name field) to get the min and max value for each 
object. 
Nicolas Cadieux M.Sc. 
Les Entreprises Archéotec inc.  
8548, rue Saint-Denis Montréal H2P 2H2 
Téléphone: 514.381.5112  Fax: 514.381.4995 
www.archeotec.ca 
On Jul 7, 2015 7:50 AM, "v.botz [via OSGeo.org]" 
 wrote: 

Hi,
i have some geometrys (multipolygon) and a dem (digital elevation model)
-> I need a line from the max value to the lowest value of the dem, for 
every multipolygon
is qgis a tool i could use - or do i need PostGIS ?
how could i realize this problem ??
any ideas?  THANKS








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[Qgis-user] Export .shp file to .osm file format

[Jorge Guevara]

Hello,

I'm new in QGIS and need to convert .shp files to .osm files.

I read the user guide without succeed.

Can you help me?

Regards
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Re: [Qgis-user] aggregate map of maximum value

[Olav Peeters]

Hi,
I would use the Raster calculator (Processing > GDAL/OGR) for this.
This uses gdal_calc.py. Google for more info about usage.
The maximum of two layer would be done like this:

maximum(A,B)

this should also work for multi-bands but I have never tried this..
Compared rasters need to have the same dimensions.

Cheers,
Olav

On 07/07/15 14:10, Giacomo Fontanelli wrote:

dear community

I have a stack (bsq) of 5 images.

I would like to make an aggregate map of the maximum of each pixel of 
the bands.


I Googled and I found contrasting opinions on how to do it.

Can you help me?

Thank you


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Re: [Qgis-user] qgis atlas : problem with scale bar

[Nyall Dawson]

On 7 Jul 2015 9:00 pm, "image93"  wrote:
>
> Hello,
>
> Someone has any ideas?
>
> It seems that the bug has been already notified : hub.qgis.org/issues/8995
>
> The ticket seems to be closed 2 months ago. But, on my side (qgis 2.8.1),
> the bug is not fixed...

That change won't be backported to 2.8 - it's a new feature in 2.10. Only
bug fixes are candidates for backporting.

Nyall
>
>
>
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[Qgis-user] aggregate map of maximum value

[Giacomo Fontanelli]

dear community

I have a stack (bsq) of 5 images.

I would like to make an aggregate map of the maximum of each pixel of the
bands.

I Googled and I found contrasting opinions on how to do it.

Can you help me?

Thank you
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Re: [Qgis-user] qgis atlas : problem with scale bar

[image93]

Hello,

Someone has any ideas? 

It seems that the bug has been already notified : hub.qgis.org/issues/8995

The ticket seems to be closed 2 months ago. But, on my side (qgis 2.8.1),
the bug is not fixed...



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Re: [Qgis-user] R algortihms do not work in Geoprocessing

[Bernd Vogelgesang]

Hi,
Best bet is, that you have some special characters in your path or file  
name, which are not strictly ascii. So nothing with R itself.
But to be honest, I never got R running successfuly on my machine as well  
for other reasons ;)


Bernd


Am 07.07.2015, 11:36 Uhr, schrieb Luís Miguel Royo Pérez  
:



Hello everyone,

I have problems to work with the R algortihms in QGIS. I'm using Windows  
8.1, Rx64 3.2.1 and QGIS 2.10.0. I have set the path >correctly in R  
options in the providers window, but when I try to run any R algorithm  
this is what I get.


'ascii' codec can't encode character u'\xed' in position 11: ordinal not  
in range(128) See log for more details


The log do not show useful info. Can anyone adress me in order to make  
these algorithms work properly?


Thank you!!




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[Qgis-user] R algortihms do not work in Geoprocessing

[Luís Miguel Royo Pérez]

Hello everyone,

I have problems to work with the R algortihms in QGIS. I'm using Windows 
8.1, Rx64 3.2.1 and QGIS 2.10.0. I have set the path correctly in R 
options in the providers window, but when I try to run any R algorithm 
this is what I get.


'ascii' codec can't encode character u'\xed' in position 11: ordinal not 
in range(128) See log for more details


The log do not show useful info. Can anyone adress me in order to make 
these algorithms work properly?


Thank you!!
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Re: [Qgis-user] Google Satellite and Measure line tool wrong results

[Andreas Neumann]

Hi Marco,

On 06.07.2015 20:19, Marco wrote:

Hello.

Yes tnx. I don't have any problem with shp files and the measuring 
tool, only with the Google layers.


I will have to load the sat images from another source


that is a good idea. It is legally questionable if you are allowed to 
use Google satellite images. Better use another source of "real" geodata 
and you won't have problems with offsets, scales, projections.


Andreas
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