Re: [Qgis-user] Problem georeferencing images in UTM

[listsen]

I haven't been able to open the dataset but going through the discussion
I would like to offer some assistance since I believe there are some
misconceptions here:

First, the data has nothing to do with the NAD27 / NAD83 datum's since
these are North American datum's and they don't apply I believe in South
America. Moreover, the separation between NAD27 to NAD83 is about 100m.
I think Carlos mention something like being 400m off.

Another point of confusion is about the projection of Google Earth.
Google is using a Web Mercator projection based on a perfect sphere.
This has nothing to do with the UTM that has already incorporate the
Earth Flattening values into the Northing and Easting equations.

If I find some time tomorrow, I will come back and give the proper
equations showing the difference between Google's projection and UTM.

-0x906 

On 2018-05-17 19:53, Carlos Henrique Grohmann de Carvalho wrote:

> Thanks for the input Nicolas 
> 
> These are official maps so the utm grid is ok. I figured that I was using a 
> linear transformation, with the option to just create the world file, which 
> works for control points at the corners (lat/long), since the boundaries of 
> the map is defined by latitude/longitude. With UTM, this simple 
> transformation won't work, but TPS will give the correct results. 
> 
> Carlos 
> 
> On Thu, May 17, 2018 at 7:28 PM, Nicolas Cadieux 
>  wrote:
> 
> Hi, 
> The utm grid is way off or we have the wrong epsg code.  If you geofence 
> using 2 points (linear algo)  using a service like google earth, you will see 
> the distortion.  The long lat coordinate are probably ok but I did not test 
> them. 
> 
> You can either use the long lat or use more points.  With 4 points and using 
> the thin plate spline, I got good results. 
> Nicolas 
> 
> Le 17 mai 2018 à 12:42, Carlos Henrique Grohmann de Carvalho 
>  a écrit :
> 
> Thanks Nicolas, but the misalignment still persists. OTF is off, project has 
> same CRS as data (epsg 29192). There is a ~400m difference in the N-S 
> direction. 
> 
> Carlos 
> 
> On Thu, May 17, 2018 at 1:28 PM, Nicolas Cadieux 
>  wrote:
> 
> Hi, 
> Disable projection on the fly.  Make sure the project is in the same CRS as 
> your maps. 
> Nicolas 
> 
> Le 17 mai 2018 à 12:14, Carlos Henrique Grohmann de Carvalho 
>  a écrit :
> 
> Hello all 
> 
> I have two pngs of topographic maps from southeastern Brazil (a zip file with 
> images and points is available here: 
> https://www.dropbox.com/s/mexeh4be46pgsk6/images_georef.zip?dl=0 [1]) 
> 
> I'm trying to georeference them, but with partial success only. In this image 
> (https://www.dropbox.com/s/37xxqp4fkwpdyqh/utm_error.png?dl=0 [2]) you can 
> see that the X coordinate is fine, but the Y coordinate of the two maps won't 
> match. 
> 
> Both maps use South American Datum 1969. I selected points near the edges, 
> and used the UTM values.  
> 
> Interestingly, if I use Lat/Long, and place the points at the corners, using 
> decimal degrees, the maps align perfectly. 
> 
> Any help is appreciated 
> -- 
> 
> Prof. Carlos Henrique Grohmann
> Institute of Energy and Environment - Univ. of São Paulo, Brazil 
> - Digital Terrain Analysis | GIS | Remote Sensing -  
> 
> http://carlosgrohmann.com [3] 
> http://orcid.org/-0001-5073-5572 [4]
> 
> Can't stop the signal. 
> ___
> Qgis-user mailing list
> Qgis-user@lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user [5]
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user [5]

  -- 

Prof. Carlos Henrique Grohmann
Institute of Energy and Environment - Univ. of São Paulo, Brazil 
- Digital Terrain Analysis | GIS | Remote Sensing -  

http://carlosgrohmann.com [3] 
http://orcid.org/-0001-5073-5572 [4]

Can't stop the signal. 

  -- 

Prof. Carlos Henrique Grohmann
Institute of Energy and Environment - Univ. of São Paulo, Brazil 
- Digital Terrain Analysis | GIS | Remote Sensing -  

http://carlosgrohmann.com [3] 
http://orcid.org/-0001-5073-5572

Can't stop the signal. 
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user 

 

Links:
--
[1] https://www.dropbox.com/s/mexeh4be46pgsk6/images_georef.zip?dl=0
[2] https://www.dropbox.com/s/37xxqp4fkwpdyqh/utm_error.png?dl=0
[3] http://carlosgrohmann.com/
[4] http://orcid.org/-0001-5073-5572
[5] https://lists.osgeo.org/mailman/listinfo/qgis-user___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user

Re: [Qgis-user] results Measure Tool vs. length()

[Springfield Harrison]

Interesting and alarming observation.

And how do those results compare with output from the $length variable?

Cheers . . . . .   Springfield
Samsung Tab 4
On May 17, 2018 5:26 AM, "Michel Stuyts"  wrote:

> In the length() function QGIS uses the CRS unit of the layer to calculate
> the result. When I use for example a layer in a local CRS like EPSG:31370
> or EPSG:5439 and a layer in EPSG:3857 (that all use meters as unit) the
> results are very different (+40% difference). Changing the project CRS
> makes no difference. When I check the length using the Measure Tool the
> results are very similar to the local CRS.
>
>
>
> How can I measure the length of a line and use it as a label independent
> from the layer CRS and get results similar to the results of the Measure
> Tool?
>
>
>
> Michel
>
> ___
> Qgis-user mailing list
> Qgis-user@lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user

Re: [Qgis-user] Problem georeferencing images in UTM

[Carlos Henrique Grohmann de Carvalho]

Thanks for the input Nicolas

These are official maps so the utm grid is ok. I figured that I was using a
linear transformation, with the option to just create the world file, which
works for control points at the corners (lat/long), since the boundaries of
the map is defined by latitude/longitude. With UTM, this simple
transformation won't work, but TPS will give the correct results.

Carlos


On Thu, May 17, 2018 at 7:28 PM, Nicolas Cadieux <
nicolas.cadi...@archeotec.ca> wrote:

> Hi,
> The utm grid is way off or we have the wrong epsg code.  If you geofence
> using 2 points (linear algo)  using a service like google earth, you will
> see the distortion.  The long lat coordinate are probably ok but I did not
> test them.
>
> You can either use the long lat or use more points.  With 4 points and
> using the thin plate spline, I got good results.
> Nicolas
>
> Le 17 mai 2018 à 12:42, Carlos Henrique Grohmann de Carvalho <
> carlos.grohm...@gmail.com> a écrit :
>
> Thanks Nicolas, but the misalignment still persists. OTF is off, project
> has same CRS as data (epsg 29192). There is a ~400m difference in the N-S
> direction.
>
> Carlos
>
> On Thu, May 17, 2018 at 1:28 PM, Nicolas Cadieux <
> nicolas.cadi...@archeotec.ca> wrote:
>
>> Hi,
>> Disable projection on the fly.  Make sure the project is in the same CRS
>> as your maps.
>> Nicolas
>>
>> Le 17 mai 2018 à 12:14, Carlos Henrique Grohmann de Carvalho <
>> carlos.grohm...@gmail.com> a écrit :
>>
>> Hello all
>>
>> I have two pngs of topographic maps from southeastern Brazil (a zip file
>> with images and points is available here: https://www.dropbox.com/
>> s/mexeh4be46pgsk6/images_georef.zip?dl=0)
>>
>> I'm trying to georeference them, but with partial success only. In this
>> image (https://www.dropbox.com/s/37xxqp4fkwpdyqh/utm_error.png?dl=0) you
>> can see that the X coordinate is fine, but the Y coordinate of the two maps
>> won't match.
>>
>> Both maps use South American Datum 1969. I selected points near the
>> edges, and used the UTM values.
>>
>> Interestingly, if I use Lat/Long, and place the points at the corners,
>> using decimal degrees, the maps align perfectly.
>>
>>
>> Any help is appreciated
>>
>>
>> --
>> Prof. Carlos Henrique Grohmann
>> Institute of Energy and Environment - Univ. of São Paulo, Brazil
>> - Digital Terrain Analysis | GIS | Remote Sensing -
>>
>> http://carlosgrohmann.com
>> http://orcid.org/-0001-5073-5572
>> 
>> Can’t stop the signal.
>>
>> ___
>> Qgis-user mailing list
>> Qgis-user@lists.osgeo.org
>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>
>>
>
>
> --
> Prof. Carlos Henrique Grohmann
> Institute of Energy and Environment - Univ. of São Paulo, Brazil
> - Digital Terrain Analysis | GIS | Remote Sensing -
>
> http://carlosgrohmann.com
> http://orcid.org/-0001-5073-5572
> 
> Can’t stop the signal.
>
>


-- 
Prof. Carlos Henrique Grohmann
Institute of Energy and Environment - Univ. of São Paulo, Brazil
- Digital Terrain Analysis | GIS | Remote Sensing -

http://carlosgrohmann.com
http://orcid.org/-0001-5073-5572

Can’t stop the signal.
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user

Re: [Qgis-user] Problem georeferencing images in UTM

[Nicolas Cadieux]

Hi,
The utm grid is way off or we have the wrong epsg code.  If you geofence using 
2 points (linear algo)  using a service like google earth, you will see the 
distortion.  The long lat coordinate are probably ok but I did not test them.

You can either use the long lat or use more points.  With 4 points and using 
the thin plate spline, I got good results.
Nicolas

> Le 17 mai 2018 à 12:42, Carlos Henrique Grohmann de Carvalho 
>  a écrit :
> 
> Thanks Nicolas, but the misalignment still persists. OTF is off, project has 
> same CRS as data (epsg 29192). There is a ~400m difference in the N-S 
> direction.
> 
> Carlos
> 
>> On Thu, May 17, 2018 at 1:28 PM, Nicolas Cadieux 
>>  wrote:
>> Hi,
>> Disable projection on the fly.  Make sure the project is in the same CRS as 
>> your maps.
>> Nicolas
>> 
>>> Le 17 mai 2018 à 12:14, Carlos Henrique Grohmann de Carvalho 
>>>  a écrit :
>>> 
>>> Hello all
>>> 
>>> I have two pngs of topographic maps from southeastern Brazil (a zip file 
>>> with images and points is available here: 
>>> https://www.dropbox.com/s/mexeh4be46pgsk6/images_georef.zip?dl=0)
>>> 
>>> I'm trying to georeference them, but with partial success only. In this 
>>> image (https://www.dropbox.com/s/37xxqp4fkwpdyqh/utm_error.png?dl=0) you 
>>> can see that the X coordinate is fine, but the Y coordinate of the two maps 
>>> won't match.
>>> 
>>> Both maps use South American Datum 1969. I selected points near the edges, 
>>> and used the UTM values. 
>>> 
>>> Interestingly, if I use Lat/Long, and place the points at the corners, 
>>> using decimal degrees, the maps align perfectly.
>>> 
>>> 
>>> Any help is appreciated
>>> 
>>> 
>>> -- 
>>> Prof. Carlos Henrique Grohmann
>>> Institute of Energy and Environment - Univ. of São Paulo, Brazil
>>> - Digital Terrain Analysis | GIS | Remote Sensing - 
>>> 
>>> http://carlosgrohmann.com
>>> http://orcid.org/-0001-5073-5572
>>> 
>>> Can’t stop the signal.
>>> ___
>>> Qgis-user mailing list
>>> Qgis-user@lists.osgeo.org
>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> 
> 
> 
> -- 
> Prof. Carlos Henrique Grohmann
> Institute of Energy and Environment - Univ. of São Paulo, Brazil
> - Digital Terrain Analysis | GIS | Remote Sensing - 
> 
> http://carlosgrohmann.com
> http://orcid.org/-0001-5073-5572
> 
> Can’t stop the signal.
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user

Re: [Qgis-user] Problem georeferencing images in UTM

[Nicolas Cadieux]

Hi,

I am looking at your maps now. If I understand, it works with lat long but not 
the UTM Coordinates.  It could be a mistake in the utm grid.  Perhaps one utm 
grid is in NAD27 and the other in NAD83.  That could explain the shift.  
I will look at it.

Nicolas

> Le 17 mai 2018 à 12:42, Carlos Henrique Grohmann de Carvalho 
>  a écrit :
> 
> Thanks Nicolas, but the misalignment still persists. OTF is off, project has 
> same CRS as data (epsg 29192). There is a ~400m difference in the N-S 
> direction.
> 
> Carlos
> 
>> On Thu, May 17, 2018 at 1:28 PM, Nicolas Cadieux 
>>  wrote:
>> Hi,
>> Disable projection on the fly.  Make sure the project is in the same CRS as 
>> your maps.
>> Nicolas
>> 
>>> Le 17 mai 2018 à 12:14, Carlos Henrique Grohmann de Carvalho 
>>>  a écrit :
>>> 
>>> Hello all
>>> 
>>> I have two pngs of topographic maps from southeastern Brazil (a zip file 
>>> with images and points is available here: 
>>> https://www.dropbox.com/s/mexeh4be46pgsk6/images_georef.zip?dl=0)
>>> 
>>> I'm trying to georeference them, but with partial success only. In this 
>>> image (https://www.dropbox.com/s/37xxqp4fkwpdyqh/utm_error.png?dl=0) you 
>>> can see that the X coordinate is fine, but the Y coordinate of the two maps 
>>> won't match.
>>> 
>>> Both maps use South American Datum 1969. I selected points near the edges, 
>>> and used the UTM values. 
>>> 
>>> Interestingly, if I use Lat/Long, and place the points at the corners, 
>>> using decimal degrees, the maps align perfectly.
>>> 
>>> 
>>> Any help is appreciated
>>> 
>>> 
>>> -- 
>>> Prof. Carlos Henrique Grohmann
>>> Institute of Energy and Environment - Univ. of São Paulo, Brazil
>>> - Digital Terrain Analysis | GIS | Remote Sensing - 
>>> 
>>> http://carlosgrohmann.com
>>> http://orcid.org/-0001-5073-5572
>>> 
>>> Can’t stop the signal.
>>> ___
>>> Qgis-user mailing list
>>> Qgis-user@lists.osgeo.org
>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> 
> 
> 
> -- 
> Prof. Carlos Henrique Grohmann
> Institute of Energy and Environment - Univ. of São Paulo, Brazil
> - Digital Terrain Analysis | GIS | Remote Sensing - 
> 
> http://carlosgrohmann.com
> http://orcid.org/-0001-5073-5572
> 
> Can’t stop the signal.
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user

Re: [Qgis-user] Problem georeferencing images in UTM

[stevejking]

When using the georeferencer some of the methods require at least 3 points,
even though you might think it not necessary. Otherwise you can get unusual
results.
Steve



--
Sent from: http://osgeo-org.1560.x6.nabble.com/QGIS-User-f4125267.html
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user

Re: [QGIS-it-user] Qgis 2.18 - DWG\DXF Import

[Leonardo Donnini]

non ritengo che togliere una utilissima e ben fatta importazione dei DWG 
sia una soluzione ,
mi sembra come andare dal dottore perché mi fa male la gamba e quello 
dice tagliamola !


se abbiamo un DWG da portare in QGIS si fa prima ad importarlo 
direttamente che trasformarlo usando un terzo sw. nel formato di 
intescambio per  poterlo importare.

Saluti
Leonardo

Il 17/05/2018 13:20, nino formica ha scritto:

Riassumendo un pò tutti gli interventi riportati in questo thread,
secondo me la conclusione è questa:
l'apertura diretta come layer vett. o la importazione in GeoPackage
-) dei file DXF funziona sempre
-) dei file DWG no, e non è molto chiaro da cosa dipenda la riuscita o
meno (dalla versione AutoCad o cos'altro ?)

Per questo secondo me, sarebbe meglio togliere del tutto da QGIS il
riferimento ai DWG e lasciare solo DXF.
Meglio "togliere opzioni" evitando così di mettere in confusione gli
utenti, ... no?

D'altra parte si tenga anche conto che, come già altri hanno fatto
osservare, il DWG è un formato proprietario.

Cari saluti
Nino

Il 16 maggio 2018 16:44, Martina Savarese 
ha scritto:

Il 14 maggio 2018 17:04, Marco Guiducci
 ha scritto:

Mi aggancio per chiedere se qualcuno ha avuto problemi del tipo che avevo
segnalato qualche mese fa [1] e se ci sono novità in questo nuovo modo di
aprire i file di AutoCad. Quindi la domanda è: QGis, importando un dwg o dxf
senza gdal (cioè l'apertura diretta), legge e tiene di conto del $INSUNITS ?
Ciao e grazie

[1] https://lists.osgeo.org/pipermail/qgis-it-user/2017-November/003161.html


Ho provato con importazione diretta di un DXF con $INSUNITS 0 (cioè
impostato in metri) e lo ha importato correttamente.

A questo punto però mi è sorto un altro problema: il corrispondente
dwg, fornito insieme al dxf , non mi si è aperto, nonostante si tratti
di una versione vecchia (AC1014). Aprendolo con Autodesk Trueview gli
risulta salvato con software
Autocad. Trasformato con Trueview alla 2000 (AC2015) sono riuscita a
fare l'importazione diretta ma i layer non si vedono se non a grande
scala, cioè zoomando più nel dettaglio scompaiono le linee (e NON è
attivo lo zoom dipendente dalla scala). Ricordo che qualcuno aveva
avuto lo stesso problema un po' di tempo fa in altra conversazione ma
non riesco a ritrovarla

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

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



---
Questa e-mail è stata controllata per individuare virus con Avast antivirus.
https://www.avast.com/antivirus

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

Re: [Qgis-user] Problem georeferencing images in UTM

[Carlos Henrique Grohmann de Carvalho]

Thanks Nicolas, but the misalignment still persists. OTF is off, project
has same CRS as data (epsg 29192). There is a ~400m difference in the N-S
direction.

Carlos

On Thu, May 17, 2018 at 1:28 PM, Nicolas Cadieux <
nicolas.cadi...@archeotec.ca> wrote:

> Hi,
> Disable projection on the fly.  Make sure the project is in the same CRS
> as your maps.
> Nicolas
>
> Le 17 mai 2018 à 12:14, Carlos Henrique Grohmann de Carvalho <
> carlos.grohm...@gmail.com> a écrit :
>
> Hello all
>
> I have two pngs of topographic maps from southeastern Brazil (a zip file
> with images and points is available here: https://www.dropbox.com/
> s/mexeh4be46pgsk6/images_georef.zip?dl=0)
>
> I'm trying to georeference them, but with partial success only. In this
> image (https://www.dropbox.com/s/37xxqp4fkwpdyqh/utm_error.png?dl=0) you
> can see that the X coordinate is fine, but the Y coordinate of the two maps
> won't match.
>
> Both maps use South American Datum 1969. I selected points near the edges,
> and used the UTM values.
>
> Interestingly, if I use Lat/Long, and place the points at the corners,
> using decimal degrees, the maps align perfectly.
>
>
> Any help is appreciated
>
>
> --
> Prof. Carlos Henrique Grohmann
> Institute of Energy and Environment - Univ. of São Paulo, Brazil
> - Digital Terrain Analysis | GIS | Remote Sensing -
>
> http://carlosgrohmann.com
> http://orcid.org/-0001-5073-5572
> 
> Can’t stop the signal.
>
> ___
> Qgis-user mailing list
> Qgis-user@lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>
>


-- 
Prof. Carlos Henrique Grohmann
Institute of Energy and Environment - Univ. of São Paulo, Brazil
- Digital Terrain Analysis | GIS | Remote Sensing -

http://carlosgrohmann.com
http://orcid.org/-0001-5073-5572

Can’t stop the signal.
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user

Re: [Qgis-user] Problem georeferencing images in UTM

[Nicolas Cadieux]

Hi,
Disable projection on the fly.  Make sure the project is in the same CRS as 
your maps.
Nicolas

> Le 17 mai 2018 à 12:14, Carlos Henrique Grohmann de Carvalho 
>  a écrit :
> 
> Hello all
> 
> I have two pngs of topographic maps from southeastern Brazil (a zip file with 
> images and points is available here: 
> https://www.dropbox.com/s/mexeh4be46pgsk6/images_georef.zip?dl=0)
> 
> I'm trying to georeference them, but with partial success only. In this image 
> (https://www.dropbox.com/s/37xxqp4fkwpdyqh/utm_error.png?dl=0) you can see 
> that the X coordinate is fine, but the Y coordinate of the two maps won't 
> match.
> 
> Both maps use South American Datum 1969. I selected points near the edges, 
> and used the UTM values. 
> 
> Interestingly, if I use Lat/Long, and place the points at the corners, using 
> decimal degrees, the maps align perfectly.
> 
> 
> Any help is appreciated
> 
> 
> -- 
> Prof. Carlos Henrique Grohmann
> Institute of Energy and Environment - Univ. of São Paulo, Brazil
> - Digital Terrain Analysis | GIS | Remote Sensing - 
> 
> http://carlosgrohmann.com
> http://orcid.org/-0001-5073-5572
> 
> Can’t stop the signal.
> ___
> Qgis-user mailing list
> Qgis-user@lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user

[Qgis-user] Problem georeferencing images in UTM

[Carlos Henrique Grohmann de Carvalho]

Hello all

I have two pngs of topographic maps from southeastern Brazil (a zip file
with images and points is available here: https://www.dropbox.com/
s/mexeh4be46pgsk6/images_georef.zip?dl=0)

I'm trying to georeference them, but with partial success only. In this
image (https://www.dropbox.com/s/37xxqp4fkwpdyqh/utm_error.png?dl=0) you
can see that the X coordinate is fine, but the Y coordinate of the two maps
won't match.

Both maps use South American Datum 1969. I selected points near the edges,
and used the UTM values.

Interestingly, if I use Lat/Long, and place the points at the corners,
using decimal degrees, the maps align perfectly.


Any help is appreciated


-- 
Prof. Carlos Henrique Grohmann
Institute of Energy and Environment - Univ. of São Paulo, Brazil
- Digital Terrain Analysis | GIS | Remote Sensing -

http://carlosgrohmann.com
http://orcid.org/-0001-5073-5572

Can’t stop the signal.
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user

Re: [QGIS-it-user] Qgis 2.18 - DWG\DXF Import

[Totò]

nformica wrote
> Riassumendo un pò tutti gli interventi riportati in questo thread,
> secondo me la conclusione è questa:
> l'apertura diretta come layer vett. o la importazione in GeoPackage
> -) dei file DXF funziona sempre
> -) dei file DWG no, e non è molto chiaro da cosa dipenda la riuscita o
> meno (dalla versione AutoCad o cos'altro ?)
> 
> Per questo secondo me, sarebbe meglio togliere del tutto da QGIS il
> riferimento ai DWG e lasciare solo DXF.
> Meglio "togliere opzioni" evitando così di mettere in confusione gli
> utenti, ... no?
> 
> D'altra parte si tenga anche conto che, come già altri hanno fatto
> osservare, il DWG è un formato proprietario.

Secondo me il modo migliore, anche perchè funziona sempre, è il passaggio
dal geopackage.

Sarebbe utile la lettura diretta dei DWG solo per una veloce consultazione
del dato altrimenti non servirebbe a nulla.

m2c



-
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

Re: [Qgis-user] model built in QGIS2 to be imported in QGIS3

[Alexander Bruy]

Hi,

Processing in QGIS 3 was refactored a lot and many algorithms
were changed. So it is not possible to covert old models into new
format. You need to recreate it.

2018-05-17 16:47 GMT+03:00 frippe12573 :
> Hi all,
>
> I'm using Qgis3, and I would like to use the models I prepared in the past
> with Qgis2.
> I saw that the created files (i.e., .model and .model3) look like different.
> I presume it is not possible to import the old model file,
> so that I wonder if there is a way to convert the old file in the news.
>
> Thanks for any hint,
>
> Eugenio
>
>
>
> --
> Sent from: http://osgeo-org.1560.x6.nabble.com/QGIS-User-f4125267.html
> ___
> Qgis-user mailing list
> Qgis-user@lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user



-- 
Alexander Bruy
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user

[Qgis-user] model built in QGIS2 to be imported in QGIS3

[frippe12573]

Hi all,

I'm using Qgis3, and I would like to use the models I prepared in the past
with Qgis2.
I saw that the created files (i.e., .model and .model3) look like different.
I presume it is not possible to import the old model file,
so that I wonder if there is a way to convert the old file in the news.

Thanks for any hint,

Eugenio



--
Sent from: http://osgeo-org.1560.x6.nabble.com/QGIS-User-f4125267.html
___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user

[Qgis-user] results Measure Tool vs. length()

[Michel Stuyts]

In the length() function QGIS uses the CRS unit of the layer to calculate the 
result. When I use for example a layer in a local CRS like EPSG:31370 or 
EPSG:5439 and a layer in EPSG:3857 (that all use meters as unit) the results 
are very different (+40% difference). Changing the project CRS makes no 
difference. When I check the length using the Measure Tool the results are very 
similar to the local CRS.

How can I measure the length of a line and use it as a label independent from 
the layer CRS and get results similar to the results of the Measure Tool?

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

Re: [QGIS-it-user] Qgis 2.18 - DWG\DXF Import

[nino formica]

Riassumendo un pò tutti gli interventi riportati in questo thread,
secondo me la conclusione è questa:
l'apertura diretta come layer vett. o la importazione in GeoPackage
-) dei file DXF funziona sempre
-) dei file DWG no, e non è molto chiaro da cosa dipenda la riuscita o
meno (dalla versione AutoCad o cos'altro ?)

Per questo secondo me, sarebbe meglio togliere del tutto da QGIS il
riferimento ai DWG e lasciare solo DXF.
Meglio "togliere opzioni" evitando così di mettere in confusione gli
utenti, ... no?

D'altra parte si tenga anche conto che, come già altri hanno fatto
osservare, il DWG è un formato proprietario.

Cari saluti
Nino

Il 16 maggio 2018 16:44, Martina Savarese 
ha scritto:
> Il 14 maggio 2018 17:04, Marco Guiducci
>  ha scritto:
>>
>> Mi aggancio per chiedere se qualcuno ha avuto problemi del tipo che avevo
>> segnalato qualche mese fa [1] e se ci sono novità in questo nuovo modo di
>> aprire i file di AutoCad. Quindi la domanda è: QGis, importando un dwg o dxf
>> senza gdal (cioè l'apertura diretta), legge e tiene di conto del $INSUNITS ?
>> Ciao e grazie
>>
>> [1] https://lists.osgeo.org/pipermail/qgis-it-user/2017-November/003161.html
>>
>
> Ho provato con importazione diretta di un DXF con $INSUNITS 0 (cioè
> impostato in metri) e lo ha importato correttamente.
>
> A questo punto però mi è sorto un altro problema: il corrispondente
> dwg, fornito insieme al dxf , non mi si è aperto, nonostante si tratti
> di una versione vecchia (AC1014). Aprendolo con Autodesk Trueview gli
> risulta salvato con software
> Autocad. Trasformato con Trueview alla 2000 (AC2015) sono riuscita a
> fare l'importazione diretta ma i layer non si vedono se non a grande
> scala, cioè zoomando più nel dettaglio scompaiono le linee (e NON è
> attivo lo zoom dipendente dalla scala). Ricordo che qualcuno aveva
> avuto lo stesso problema un po' di tempo fa in altra conversazione ma
> non riesco a ritrovarla
>
> Martina
> ___
> QGIS-it-user mailing list
> QGIS-it-user@lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/qgis-it-user
___
QGIS-it-user mailing list
QGIS-it-user@lists.osgeo.org
https://lists.osgeo.org/mailman/listinfo/qgis-it-user

Re: [QGIS-it-user] Plugin line to polygon

[Marco Spaziani]

...scusa se mi intrometto nelle tue scelte ma perchè non passi alla
2.18 LTR ?  ...è aggiornatissima e stabilissima ...o, addirittura,
perchè non provi il brivido della 3.x ?

Il giorno 17 maggio 2018 12:07, Matteo Collimedaglia <
matteo.collimedaglia...@gmail.com> ha scritto:

> Ho risolto, pare che sia per via della versione installata. Ora so come
> cercare le varie funzioni passando dal processing. Devo vedere se la mia
> versione 2.18.4 c'è, nella 2.18.7 c'è
>
> Il gio 17 mag 2018, 09:15 Matteo Collimedaglia  gmail.com> ha scritto:
>
>> Non mi sono spiegato bene.
>> In strumenti di geometria ho solo due funzioni snap geometry e check
>> geometry e niente altro.
>>
>> Il gio 17 mag 2018, 09:04 Marco Spaziani  ha
>> scritto:
>>
>>> Probabilmente non ho capito bene o mi sfugge qualcosa della tua
>>> richiesta.
>>> In Vettore --> Strumenti di geometria c'è la storica funzione per
>>> trasformare le polilinee in poligoni e comunque, in Processing, puoi
>>> trovare una vagonata di funzioni simili.
>>> Forse ti riferisci ad uno specifico Plugin (che non conosco) che faceva
>>> qualcosa di particolare rispetto agli strumenti di cui sopra?
>>>
>>> Il giorno 17 maggio 2018 00:56, Matteo Collimedaglia <
>>> matteo.collimedaglia...@gmail.com> ha scritto:
>>>
 Buona sera a tutti,
 Stavo cercando su Qgis 2.18.4 il plugin multi-line to polygons per
 convertire le linee in poligoni. Possibile che nella mia versione non ci
 sia? Ho cercato tra i plugin ho trovato solo point to polygon.
 Grazie mille e buona notte

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


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

[QGIS-it-user] R: Problema all'avvio QGIS

[Selene Viola]

Buongiorno,

e scusate il ritardo della risposta. Innanzitutto, vi ringrazio per i 
suggerimenti che mi avete dato finora.

Sono riuscita solo ora a mettere in pratica tutto quanto mi avete detto, e ho 
provato anche ad installare quelle librerie che  mancavano.  Il messaggio di 
errore (che compare con entrambe le versioni di QGIS) che mi compare ora è:

“oops, looks like an error loading QGIS

Detail: Could not load qgis_app.dll
Windows Error: impossibile trovare il modulo specificato.
Help: Check C:\Program Files\QGIS 3.0\bin\qgis-bin.env for correct environment 
paths”



Se non altro qualcosa è cambiato, ma mi sembra di essere punto a capo…



Selene Viola





Selene Viola




Da: QGIS-it-user  per conto di girarsi AT 
posteo DOT eu 
Inviato: Friday, May 11, 2018 6:08:37 PM
A: qgis-it-user@lists.osgeo.org
Oggetto: Re: [QGIS-it-user] Problema all'avvio QGIS

On 11/05/18 17:22, Luigi Pirelli wrote:
> prova a installare qgis no la versione standalone e vedere che ti succede
>
> cioe'
> http://download.osgeo.org/osgeo4w/osgeo4w-setup-x86_64.exe
>
> e non questo
> http://qgis.org/downloads/QGIS-OSGeo4W-3.0.2-1-Setup-x86_64.exe
>
>
> ti posso dire che al limite e¡ un problema della tua versione di Windows
> (+service pack) visto che sono qui con un sacco di persone che lo hanno
> appena istallato su win7 e win10
>
> pero si, magari l¡installer dovrebbe essere piu' robusto
>
> ti posso dire
>
> Luigi Pirelli

Io invece, oltre a quanto suggerito da Luigi, al di la del sistema
operativo in uso, visto che dici di aver installato due versioni, andrei
per gradi per affrontare il problema e cercare di risolverlo, forse, te
e valido, forse per altri.

Primo, se hai configurazioni particolari a cui tieni, salvati la copia
dell cartella di QGIS da un'altra parte (magari nei tuoi documenti),
lascio a te trovarla, perchè non ho windows, e rinominala in modo da
evitare confusione, o di essere ricaricata.

Poi disinstalla tutte e due le versioni, cancella le cartelle di sistema
"qgis2" o "qgis" ora non ricordo, questo per effettuare un'installazione
pulita, sarebbe il caso in windows di cancellare anche le chiavi nel
registro, però io ricordo che quando avevo windows usavo Ccleaner, oggi
non so se è ancora valido e che programmi validi alternativi ci sono, di
solito cancella le chiavi associate a programmi non esistenti.

Poi procederei ad installare prima una versione, provarla, e vedere se
c'è il problema, poi se il problema c'è, disinstallarlo, effettuare la
solta pulizia, e provare la versione più recente, se il problema
persiste, probabile sia un bug.


--
Simone Girardelli
_|_|_|_|_|_|_|_|_|_
|_|_|_|_|_|_|_|_|_|_|


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

Re: [QGIS-it-user] Join tabellare con due campi di unione

[sarag]

Grazie mille, ma alla fine ho risolto con la concatenazione delle coordinate
del baricentro in un'unica colonna (sia su csv che sugli attributi dello
shp), facendo attenzione però alla precisione delle cifre decimali (questo
mi ha impiegato un po' di tempo). 
Ho usato quindi come campo di unione univoco la colonna così creata.
Resta comunque la curiosità di capire se sia possibile realizzare un join
con due campi di unione invece che uno solo.

Grazie ugualmente per il suggerimento,
Sara



--
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

Re: [QGIS-it-user] Plugin line to polygon

[Marco Spaziani]

Probabilmente non ho capito bene o mi sfugge qualcosa della tua richiesta.
In Vettore --> Strumenti di geometria c'è la storica funzione per
trasformare le polilinee in poligoni e comunque, in Processing, puoi
trovare una vagonata di funzioni simili.
Forse ti riferisci ad uno specifico Plugin (che non conosco) che faceva
qualcosa di particolare rispetto agli strumenti di cui sopra?

Il giorno 17 maggio 2018 00:56, Matteo Collimedaglia <
matteo.collimedaglia...@gmail.com> ha scritto:

> Buona sera a tutti,
> Stavo cercando su Qgis 2.18.4 il plugin multi-line to polygons per
> convertire le linee in poligoni. Possibile che nella mia versione non ci
> sia? Ho cercato tra i plugin ho trovato solo point to polygon.
> Grazie mille e buona notte
>
> ___
> QGIS-it-user mailing list
> QGIS-it-user@lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/qgis-it-user
>
>
___
QGIS-it-user mailing list
QGIS-it-user@lists.osgeo.org
https://lists.osgeo.org/mailman/listinfo/qgis-it-user