Questions tagged [qgis-3]

for questions specific to the 3.x series of QGIS.

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6 views

/{z}/{x}/{y} Template for QgsRasterLayer in PyQgis3

I took the following code which works in QGIS2 and changed QgsMapLayerRegistry to QgsProject for QGIS3. Running the code in QGIS 3.8.3, the layer is created, but the tiles do not display. The Scale ...
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17 views

Extract borders from country polygons

I'm trying to convert a polygon GeoJSON of countries into a line layer that contains only the borders. It should not contain the edges of the polygons that border the ocean (in my polygon dataset, ...
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7 views

QGIS 3.8 MacOS - Connect to Oracle

I know that prior releases of QGIS (2.x releases) did not include drivers to connect to Oracle databases, and one would need to compile QGIS themselves with the proper Oracle drivers included if they ...
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16 views

Overlaying scanned maps with different scales point to point in QGIS? [on hold]

I have different scale scanned nautical charts of the same area, I have georeferenced these using georeference GDAL in QGIS but when I am overlaying these maps the common point features are not ...
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1answer
36 views

Create QML Widget with a picture in Attributes Form

I would like a Qmlwidget in the Attributes Form to show a picture. So far I have created the basic qml for a blue rectangle: import QtQuick 2.0 Rectangle { width: 100 height: 100 color: "...
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31 views

Distance matrix only for a specific rule [QGIS]

I am having a hard time using distance matrix vector tool in QGIS for a specific need. I know you need to have two different point layers in order to get a distance matrix, so far so good. But as I ...
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23 views

How can to find tolerance in topology?

I am working with Topology plugins in Qgis 3.8, but I don't see tolerance in topology. I hope to get help. I have attach images.
3
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0answers
31 views

Testing nodes connectivity

I'm working on a shapefile of Brussels (QGIS 3). This shapefile contains all the streets in Brussels, see below. With the attribute table, I have an "X" and "Y" position for each line (debut and end),...
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35 views

Generating slightly curved arrows in QGIS 3

In Geometry Generator in Symbology in Layer Properties, the following expression works, but the result is not satisfactory due to the middle point fixed coefficient 1,1: make_line ( start_point(...
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49 views

Running and scheduling processing jobs in QGIS 3?

Basically I want to write a script that would run on a daily basis on QGIS 3. This tutorial seems to have exactly what I want but the tutorial only works for QGIS 2. QGIS Tutorials and Tips | ...
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1answer
61 views

QGIS make line attribute

How to automatically load all my attribute values into a layer after manually adding an attribute field? Or how to achieve the effect of PointConnector plugin in a more flexible that retains ...
3
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0answers
28 views

Restricting label/line drawing to 45 deg. lines?

I've followed this tutorial to be able to move label positions and draw lines to connect them to the label dots, but I'd like to restrict the line drawing to 45˚ angles. Is there a way to do that? I ...
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23 views

QGIS 3: Browser Widget slows QGIS

I read a lot of speeding up the browser widget, but nothing seemed to help me. as long i have it closed qgis is fast but if I open it all actions slows down. My project is on a local ssd - fast dir ...
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43 views

Automatically update records in layer based on changes in another

I am using QGIS and I have two layers the first one is "Reading" layer with the attribute details The second layer is "Reading_History" layer with the attribute details I want to use the expression ...
2
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1answer
66 views

Splitting line with equal end parts

In QGIS 3.8.2 I would like to split line into equal segments. The issue is, that v.split splits the line into the required segments, except the last segment. I would like to split the line into equal ...
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21 views

QgsVectorDataProvider addFeatures doesn't take attributes

I'm trying to add features in empty QgsVectorLayer with addFeatures, I got the layers without attribute: def create_features(input_file, wid, hite, focal_lgth): features = [] filename_def = { ...
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1answer
30 views

Finding unconnected polylines and connecting them using QGIS?

I have a pipeline network, during manual digitization have a lot pipes unconnect. Is there any way to find pipes unconnect and edit it in QGIS?
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35 views

local variable 'elevation' referenced before assignment"

I had got this error when I try run Qwater model. "2019-09-15T19:47:05 WARNING Traceback (most recent call last): File "C:/Users/OS10/AppData/Roaming/QGIS/QGIS3\profiles\default/python/...
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12 views

QGIS Server - fragile regarding file formats? [closed]

This might seem an overly general question, but... Is qgis_mapserv.fcgi known to be fickle about its data sources? If so, which ones are known to be without problems? I've been experimenting for ...
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28 views

How to join PyQGIS scripts parts?

On my way to find a solution to This Question, I´m trying to merge some automatic generated script with This example. My thought is that after the last step, I could insert the script that does ...
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1answer
47 views

Comparing between layers name and merging layers having same name using PyQGIS?

I'm trying to write python script in QGIS to merge layers having the same name. To do that I specify the name of layer in the script, so all layers having this name, will be merged. However, since ...
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1answer
20 views

Can't see multiple layers when adding a WMS

I am using QGIS 3.8.2. I have a WMS (https://openwms.statkart.no/skwms1/wms.topo4.graatone?) that I want to add, and in Arcgis it lists several layers (33 total) in the table of contents. When I add ...
4
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1answer
32 views

ModuleNotFoundError when installing plugin from zip

I have a plugin that I have developed for work and we have less than 10 users that will want to use it, so rather than publishing on the QGIS online plugin repository (https://plugins.qgis.org/plugins/...
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12 views

QGIS WMS mapserver not showing all layers

I'm publishing a map via qgis_mapserv.fcgi and the WMS behaves strangely, without giving me any errors or other clues as to what might be wrong. I am wondering: is the problem with using GeoJSON as ...
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20 views

Cut polygon by line QGIS [closed]

I am looking to split a polygon by a line layer that bisects the polygon in QGIS. Ideally this will be used to split a tiger/line county shapefile so that it ends at the coast instead of in the ocean. ...
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20 views

QGIS Export REST API

I am looking for any API that can export/expose QGIS Map data as an REST API to be consumed by front-end Web GIS application Can you suggest a suitable solution for same.
2
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1answer
29 views

Measure Line while editing in Edit Mode (Workaround?)

It's unfortunate that QGIS does not allow the use of the Measure Line tool while activiely editing something with Add feature or Vertex tool. As soon as one of the latter tools are switched on the ...
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19 views

QGIS 3.4 crashes on exit

Every time I exit QGIS 3.4 recently insalled I get this message. Crash ID: 41bd556bfb4cb3857ad8b303df49560eb10217ac Stack Trace proj_lpz_dist : proj_lpz_dist : QgsCoordinateTransform::...
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1answer
36 views

Polygon from QgsPoints - QGIS 3.8 python

I'm trying to create a polygon layer from 4 points that I have already defined. There issue here is that I'm always getting the following error: AttributeError: type object 'QgsGeometry' has no ...
2
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1answer
34 views

How to use maximum and minimum operator in raster calculator QGIS

I would like to normalize a raster, using the raster calculator in QGIS 3.x but I don't know how to use the maximum and minimum operator. I have tried the following sequence but it does not recognize ...
2
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3answers
50 views

How to load external files in PyQGIS?

I have lots of models in QGIS 3.8. I´m translating them to Python scripts to still use in the Tollbox but qith reduced processing time. Using the QGIS automatic "export model as Python script", I´m ...
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18 views

Script PyQGIS without Interface in Ubuntu

please can you help me? I tried many times to do a script of pyqgis but without interface qgis. I use QGIS 3.6.3 and Ubuntu 18.04, does Somebody know do this?
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24 views

'python-qgis' is not recognized as an internal or external command, operable program or batch file

As per - https://root676.github.io/installation.html - I am trying to install QNEAT3 via the OSGeo4W shell using python-qgis -m pip install matplotlib, however I am getting the following error message:...
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0answers
27 views

Layer converted into attribute

I am using QGIS 3.8. I am creating a geological map, and because I wanted to merge two different polygons, it created a separate layer. I want to convert this dissolved layer into the attribute to my ...
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1answer
48 views

Setting CRS on QGIS?

I am just learning how to use QGIS (3.4.1) and am having some issues overlaying some data (CSV file) with a QuickMapServices base map. I feel like this is an issue with the CRS, but am not 100% sure. ...
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42 views

Points from WKT File are in Wrong Location [closed]

When I load my WKT file (truncated sample below) into QGIS 3.8, the points load into the wrong location. label,geometry 96962283,POINT(-15.43 28.30) 96963030,POINT(-15.39 28.41) 96963031,POINT(-15....
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0answers
30 views

Use of QGIS/GRASS/SAGA procedures on Geometry Generator

Im new at QGIS, started 2 weeks ago. I'm trying to automatize the display of a map and get rid of some "duplicated" layers and all the extra work. I need to know if SAGA's dissolve can be used in the ...
3
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0answers
44 views

Running Standalone PyQGIS Script with Multiprocessing?

Is it possible to run a standalone PyQGIS script using multiprocessing for better performance? I'm creating 1,800 rendered map images and would like to run it across 4 processes to speed it up. If I ...
3
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1answer
38 views

Geometry Generator - Straight lines not curved

I have QGIS 3.8.2 installed and started to look at the Geometry Generator. I have a layer of airline tracks and trying to create a curved line linking start and end points. I did a lot of searching ...
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31 views

Serving a QGIS Project to Leaflet / MediaWiki Maps Extension

I'm currently serving a custom map with qgis-mapserver and that works well. However, my next step is Mediawiki integration, and for reasons of GeoJSON overlays, I must use the Leaflet option there. ...
2
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0answers
20 views

Getting layers path in Layer properties window in QGIS 3.4 by PyQGIS?

I'm going to know how I can get layers full path in table of contents in QGIS3.4 when my QGIS is closed and it's running such as daemon? Rememebr: my shapefiles are in some different folders. This ...
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1answer
41 views

Finding matching field values between two layers in QGIS?

I have two attribute tables, 1 from a shapefile layer (left) and 1 from a csv layer (right). I would like to find values in the first column ("KEY" column in shapefile layer) that appears in the ...
2
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0answers
29 views

Standalone PyQGIS file lock

I have a simple script for processing thousands of rasters/shapefiles. i am not able to delete temporary files, which are created by processing. I can pass them to: 'memory:output_file' but not for ...
1
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1answer
57 views

Is Labeling toolbar no longer available in QGIS 3.8.2 running on Mint 19.2 Tina?

It seems the Labeling toolbar is no longer available with this version on Mint 19.2 Tina, though I have seen it on the Windows version of QGIS 3.8. Moving labels is a vital part of a large research ...
2
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1answer
32 views

Controlling line width at different points in QGIS [closed]

I have vector data for rivers including their width at various points. From what I have seen so far, QGIS 3.8 can set the line width only per linestring, no per segment. Is it possible (maybe with a ...
1
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1answer
46 views

Line at map scale that do not vanish when zoomed out? (QGIS 3.8)

I'm drawing rivers and roads as linestrings with width set in map units from an attribute. When zooming out, of course they vanish quickly, because 10, 20 or 100m is less than a pixel at 1:100,000 ...
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1answer
38 views

Adding label to map layer by clicking feature or similar action in QGIS?

I have searched the web (including stack exchange) quite extensively and haven't found anything. I've tweaked the 'repeat' setting on the label position tab on a line layer to where it labels enough ...
1
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1answer
47 views

Importing DEM to QGIS?

I downloaded a DEM file (package, rather?) of the entire US from usgs.gov. It's 30GB and contains quite a few files. Is it possible to import this to QGIS to overlay the data on my map?
4
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1answer
37 views

QGIS-3 does not recognize “-3.40282e+38” float raster values as NoData

I have DEMs with "-3.40282e+38" values that are supposed to be the NoData values. However, if the rasters are loaded into QGIS (3.4.11), the value can not get assigned with "add additional no data ...
2
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1answer
70 views

Change Output name in Script - QGIS 3

I exported a model as script using the properly option in QGIS 3.8. The Script works perfectly, but the output name is changed. Heres a print of the model: I want that the script´s output name, from ...