Re: [Qgis-user] Merge does work (at least not as I expect)

[qgis-user]

  
  
Nyall wrote:
I suspect the lines aren't **exactly**
coincident. I'd try:
  
  
  - multiparts to single parts
  
  - snap geometries to layer, to snap the end points exactly
to each other
  
  - retry merge
  

I tried this, no joy. still getting multi-linestring with 2055
segments.
So here's what I tried next - 
multiparts to singlepart
export to csv, saving geometry as wkt.
verify that endpoints match exactly to the precision written
to the file
Import csv as layer
merge

again, no luck

I looked at the attribute table and the lines were in some random
order- adjacent segments were not consecutive rows in the attribute
table. Then I noticed that every row had the same FID. 
I closed the layer, opened the .csv in excel, verified that the rows
represented consecutive points, then assigned consecutive FIDs. 
imported csv as layer
merge

again, no luck. Still have 2055 rows in the attribute table of the
merged layer, in that same seemingly random order as before. 

A purely brute force solution was to export as csv, as above, then
edit the file by removing the endpoint of each segment, and
concatenate them into a single linestring with 2055 points. 
  

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[Qgis-user] QGIS French user days will take place on the 12 and 13th of december in Montpellier

[Régis Haubourg]

Hi here,

The french user group, t. he OSGeo local chapter and the SupAgro engineer
school of agronomics are happy to announce this year again our meeting.

We'll have on community sprint and barcamp day and then a conference day.

All the details are (in french) in our website here :

[0] http://conf.qgis.osgeo.fr/

May the QGIS force be with you !
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Re: [QGIS-it-user] File zip usati come fascicoli da aprire con Azioni

[Luca Bellani]

Ciao, credo che l'immagine non sia piú quella corretta.
Ciao



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Re: [Qgis-user] [QGIS-Developer] Geodesic Line Simplification

[C Hamilton]

Thanks Anita. This will be helpful.

Calvin

On Tue, Oct 1, 2019 at 2:45 AM Anita Graser  wrote:

> Hi Calvin,
>
> On 26 Sep 2019, at 17:13, C Hamilton>  wrote:
> > For GPS tracks I also see a need to throw out all points that are less
> than a certain distance or less than a certain time interval. I don't see
> any simplification algorithms that make use of time. Am I just missing them?
>
> I've implemented a function for this time-based generalization in
> MovingPandas:
> https://github.com/anitagraser/movingpandas/blob/c26fdf5307f2067d37a0f4cd018fe56c5d6c9839/movingpandas/trajectory.py#L372
> I hope to soon provide a plugin that makes MovingPandas accessible from
> within Processing. (However, the installation of Moving/GeoPandas
> requirements on Windows is difficult without conda.)
>
> Regards,
> Anita
>
>
>
>
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Re: [Qgis-user] [QGIS-Developer] Geodesic Line Simplification

[C Hamilton]

I am guessing this is working on Cartesian coordinates and not geodesic
which is fine if you have a local projection. I think I will go ahead and
implement some similar geodesic algorithms. Thank you for the GRASS link.
It will help.

Thanks,

Calvin

On Tue, Oct 1, 2019 at 7:45 AM Áron Gergely 
wrote:

> Hi Calvin and list,
>
> Have you looked at the GRASS GIS v.generalize tool?
> https://grass.osgeo.org/grass64/manuals/v.generalize.html
>
> The Douglas-Peucker algorithm is implemented there and I have used that
> with (topologic)success recently on many touching polygons. Should work for
> polylines too!
>
> Best regards,
> Aron
>
> On 01/10/2019 08:19, Tim Sutton wrote:
>
> Hi
>
> On 26 Sep 2019, at 17:13, C Hamilton  wrote:
>
> Are there any geodesic QGIS algorithms that simplify lines? "Simplify"
> just uses the projection units of measure. If there isn't I thought I would
> add this to the Shape Tools plugin. I could easily implement the
> Douglas-Peucker algorithm using geodesic math.
>
> For GPS tracks I also see a need to throw out all points that are less
> than a certain distance or less than a certain time interval. I don't see
> any simplification algorithms that make use of time. Am I just missing them?
>
>
> No I don’t think we have any time based simplifiers - would be a great
> addition!
>
> Regards
>
> Tim
>
>
>
>
> Thanks,
>
> Calvin
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>
>
> —
>
>
>
>
>
>
>
>
> *Tim Sutton*
>
> *Co-founder:* Kartoza
> *Ex Project chair:* QGIS.org
>
> Visit http://kartoza.com to find out about open source:
>
> Desktop GIS programming services
> Geospatial web development
> GIS Training
> Consulting Services
>
> *Skype*: timlinux
> *IRC:* timlinux on #qgis at freenode.net
>
> I'd love to connect. Here's my calendar link
>  to make finding time easy.
>
>
> ___
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Re: [Qgis-user] GeoPackage deadlocks (and new user)

[djes]

As I'm a new user of this list, hi to everyone ! 

As we had this problem, here's a working trick well known but a bit hard to
find : https://issues.qgis.org/issues/20077#note-2
Even Rouault wrote
>  il y a 12 mois
> Can you retry your tests by defining the following environment variables
> (may require restarting QGIS each time you change) ?
> 
> OGR_SQLITE_JOURNAL=DELETE
> SQLITE_USE_OGR_VFS=YES
> and possibly the combinations of both
> Note that SQLite is notoriously known not to be appropriate for databases
> stored on network shares...

It does the trick, even if sometimes it could be impossible to save changes
when concurrent users are accessing the same layers. But the speed boost and
most of the problems are going away.



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Re: [Qgis-user] [QGIS-Developer] Geodesic Line Simplification

[Áron Gergely]

Hi Calvin and list,

Have you looked at the GRASS GIS v.generalize tool? 
https://grass.osgeo.org/grass64/manuals/v.generalize.html


The Douglas-Peucker algorithm is implemented there and I have used that 
with (topologic)success recently on many touching polygons. Should work 
for polylines too!


Best regards,
Aron

On 01/10/2019 08:19, Tim Sutton wrote:

Hi

On 26 Sep 2019, at 17:13, C Hamilton > wrote:


Are there any geodesic QGIS algorithms that simplify lines? 
"Simplify" just uses the projection units of measure. If there isn't 
I thought I would add this to the Shape Tools plugin. I could easily 
implement the Douglas-Peucker algorithm using geodesic math.


For GPS tracks I also see a need to throw out all points that are 
less than a certain distance or less than a certain time interval. I 
don't see any simplification algorithms that make use of time. Am I 
just missing them?


No I don’t think we have any time based simplifiers - would be a great 
addition!


Regards

Tim





Thanks,

Calvin
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—








*Tim Sutton*

*Co-founder:*Kartoza
*Ex Project chair:*QGIS.org 

Visit http://kartoza.com  to find out about open 
source:


Desktop GIS programming services
Geospatial web development
GIS Training
Consulting Services

*Skype*: timlinux
*IRC:*timlinux on #qgis at freenode.net 

I'd love to connect. Here's my calendar link 
 to make finding time easy.



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Re: [Qgis-user] Check Geometries: nice tool, but bad integration

[Alexandre Neto]

Hi,

Actually, users-oriented-crowdfundings have proven quite successful in the
past. And it works something like this:

- A small number of non-developers members of the community (aka users)
discuss and gather ideas of how to improve or implement a certain feature;
- They contact one or more core developers with a requirements document to
understand if it's feasible and how much would it cost;
- They choose the best deal;
- Then, they launch a crowdfunding and do some marketing around it to
gather the necessary funds.
- Having gathered the money, the developer implements the new feature or
improvement, which becomes available in a next release.

Obviously, like every change in the code, the feature or improvement must
be somehow consensual, but I believe that check geometries tool is a good
candidate for this.

Alexandre Neto

On Tue, Oct 1, 2019 at 5:38 AM Paolo Cavallini 
wrote:

> Hi Tobias,
>
> On 30/09/19 21:32, Tobias Wendorff wrote:
>
> > Maybe we should think about a concept, LibreOffice uses: Either a user
> > delivers a patch or pays for the bug fix or feature.
>
> this is what we are suggesting, and what we do normally.
>
> > Croundfunding is
> > unfortunately still too expensive
>
> could you please elaborate on this?
> Thanks.
>
> --
> Paolo Cavallini - www.faunalia.eu
> QGIS.ORG Chair:
> http://planet.qgis.org/planet/user/28/tag/qgis%20board/
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Re: [Qgis-user] [QGIS-Developer] Geodesic Line Simplification

[Anita Graser]

Hi Calvin,

On 26 Sep 2019, at 17:13, C Hamilton>  wrote:
> For GPS tracks I also see a need to throw out all points that are less
than a certain distance or less than a certain time interval. I don't see
any simplification algorithms that make use of time. Am I just missing them?

I've implemented a function for this time-based generalization in
MovingPandas:
https://github.com/anitagraser/movingpandas/blob/c26fdf5307f2067d37a0f4cd018fe56c5d6c9839/movingpandas/trajectory.py#L372
I hope to soon provide a plugin that makes MovingPandas accessible from
within Processing. (However, the installation of Moving/GeoPandas
requirements on Windows is difficult without conda.)

Regards,
Anita
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Re: [Qgis-user] [QGIS-Developer] Geodesic Line Simplification

[Tim Sutton]

Hi

> On 26 Sep 2019, at 17:13, C Hamilton  wrote:
> 
> Are there any geodesic QGIS algorithms that simplify lines? "Simplify" just 
> uses the projection units of measure. If there isn't I thought I would add 
> this to the Shape Tools plugin. I could easily implement the Douglas-Peucker 
> algorithm using geodesic math. 
> 
> For GPS tracks I also see a need to throw out all points that are less than a 
> certain distance or less than a certain time interval. I don't see any 
> simplification algorithms that make use of time. Am I just missing them?

No I don’t think we have any time based simplifiers - would be a great addition!

Regards

Tim



> 
> Thanks,
> 
> Calvin
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—









Tim Sutton

Co-founder: Kartoza
Ex Project chair: QGIS.org

Visit http://kartoza.com  to find out about open source:

Desktop GIS programming services
Geospatial web development
GIS Training
Consulting Services

Skype: timlinux 
IRC: timlinux on #qgis at freenode.net

I'd love to connect. Here's my calendar link  to 
make finding time easy.

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