Questions tagged [qgis-3]

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

1,088 questions with no upvoted or accepted answers
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14
votes
0answers
203 views

Unit testing for QGIS 3 plugins

There is a nice resource on unit testing for QGIS. There is also a post on this, Writing automated tests for QGIS plugins, which requires the use of docker and relies on QGIS 2 plugin - QGIS Tester. ...
12
votes
1answer
466 views

Point cluster symbology for different categories without overlapping symbols

I'm trying to visualize crimes based on if the crime happened during day or night time. I've tried using the point displacement tool but I'm not satisfied with the results because the readability for ...
11
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0answers
355 views

High PostgreSQL/PostGIS memory and disk usage when saving QGIS project

Why would simply pressing the "save" button in QGIS cause my local PostgreSQL instance to cause memory and disk usage to spike to "Not Responding" levels? Seems to me like the ...
9
votes
1answer
2k views

Editing Layout-Items after loading a QPT-Template in QGIS 3 with Python

I am facing a problem with the new Layout API while implementing a plugin for QGIS 3. Starting point is a layout template in qpt-Format, which contains different elements like (attribute) tables, map, ...
6
votes
0answers
381 views

QGIS crashes when running script from Processing Script Editor

Encountering this weird bug. I'm using QGIS 3.4.7. I am trying to write a script but it crashes when I run it from the editor. But it does not crash when run from the Processing Toolbox. Right now the ...
6
votes
0answers
2k views

QGIS 3.4 and loading raster from multiple variable NetCDF file

Using QGIS version 3.4.4 when loading a NetCDF file out.nc which contains multiple variables on a fresh Ubuntu 18.04 install I encounter the following error: CRITICAL Invalid Layer : Raster layer ...
6
votes
0answers
994 views

Join attributes by location very slow on QGIS 3.0

"Join attributes by location" is very slow on QGIS 3.0. I have tried it with a CSV file and also with a shapefile (point layer) and a grid (made of polygons). On QGIS3.0 it takes about 3 hours to ...
6
votes
1answer
1k views

QGIS GRASS Processing Not Working on MacOS?

Recently upgraded to QGIS3 (3.0.2) for MacOS (High Sierra) and encountered GRASS (7.2.2) issues. Tried adding a custom variable and now when running GRASS algorithms (e.g. r.reclass) I get the ...
5
votes
0answers
154 views

PyQgis Exporting Print Layout: “ERROR 6: The PNG driver does not support update access to existing datasets.”

I am trying to export a .tif loaded into a pre-configured print layout template and further exported as .png def openLayer(project, fp, basename, vector=True): layer = QgsVectorLayer(fp, basename) ...
5
votes
1answer
254 views

Symbol in layers panel not visible

I have a layer with symbology that includes geometry generators. It would appear that because of these the symbol is not visible in the layers panel. Is there a way to show the up most symbol (green ...
4
votes
0answers
120 views

Accessing the spatial index of a layer (shapefile) with PyQGIS

I built a manual index on a shapefile, through the process "Create spatial index", which can be found in the process toolbox > general vector tools. This process creates a persistent ...
4
votes
0answers
33 views

Adding nodes automatically without clicking the mouse

Is there a way in QGIS (or maybe in another GIS (ArcMap, for example))) to automatically create nodes at a given interval when digitizing a raster? For example, I decided to create a Polyline object. ...
4
votes
0answers
44 views

Why is QGIS holding references to layers that are not in layer list

I have a QGIS project, which has about 30 layers in the layer list. I removed one of the layers from the list, saved the project, closed QGIS. (The layer itself was from a Geopackage database, which ...
4
votes
0answers
51 views

Optimizing identification of tree stand boundaries

I am working on a workflow to identify tree stand boundaries. My desired result is the blue lines - I know it will never be like that, but I need it to be as good as possible. My best result is the ...
4
votes
0answers
91 views

+0-180 degrees of mesh layer are displaying as horizontal lines [QGIS]

I have been trying to display weather data from ECMWF in QGIS on top of a base map, but half of the heatmap rendered from the mesh layer (imported via grib) displays as straight horizontal lines. I ...
4
votes
0answers
71 views

How to use all QGIS 3 custom widgets in Qt Designer?

For example, QGIS 3.4 has various custom widgets such as QgsFieldValuesLineEdit and QgsColorWheel (and later versions have even more widgets) but they are not listed in the QGIS custom widgets list of ...
4
votes
0answers
111 views

Creating child entries in QGIS form with Spatialite many-to-many relationship

I am trying to reproduce the example from Introducing many-to-many (N-M) relations using Spatialite. Creating the tables and the relations works fine, but when I try to create a child element in a ...
4
votes
0answers
52 views

QGIS processing tools - saving/exporting graph

I just tried QGIS processing tools for the first time. When using shortest path search for the first time, the algorithm is building a path graph (of course). However, the graph is never re-used. ...
4
votes
0answers
76 views

Close gaps between some polygons, which are adjacent in reality

I have tens of thousands of polygons (farmer plots) which have been measured while on the fields. This has caused plenty of gaps between some polygons, which is not the reality. I would need to close ...
4
votes
0answers
142 views

Showing labels as they will be printed/exported in my print layout?

I set up a print layout for a map I want to print in QGIS. Some of my layers have labels on them. When I zoom in and out in the screen, without changing anything else on the print layout, some labels ...
4
votes
0answers
473 views

Data Plotly QGIS 3.10

I'm new with QGIS and Data Plotly and I have a problem with pie charts feature for Plotly. I load a shape in QGIS and I use it with Atlas to display a pie chart depending of the selected area on the ...
4
votes
1answer
125 views

Calling the correct element of an output via PyQGIS Script

I am trying to apply a style to the output file of a script that I´m running from the toolbox in QGIS 3.4.7. The last step is as described below. def processAlgorithm(self, parameters, ...
4
votes
0answers
100 views

Using Python code from QGIS 3.x Graphical Modeler in console?

I want to use "Join Attribute by Location (summary)" processing algorithm in Python console of QGIS 3.10. After design my algorithm process (join sum of field name "abc" form layer 2 (point layer) to ...
4
votes
0answers
79 views

QGIS 3 3D Marker

In the 3D view I add 3d.obj files as Marker.works very well. Is it possible to add different 3D markers on different layers or categories. When I use 2 different layers with different obj files 3D ...
4
votes
1answer
305 views

Where did checkbox option in Points to Path tool go?

I made considerable use of the "Points to Paths" tool. I forgot which QGIS version I was using, but it was most likely 2.x, probably 2.14. According to my memory and notes the tool had a ...
4
votes
2answers
543 views

Running standalone QGIS model script in Python

I am trying run an exported QGIS model as Python script from Anaconda. I followed Executing a standalone QGIS python script on Windows 10, and I get no error of modules, when running this I get no ...
4
votes
0answers
93 views

Using shared database authentication settings for organization environment?

My company is willing to share common QGIS3 configuration parameters between its users (ie. proxy configuration, WFS/WMS connections definitions, database connection definitions). For doing this, ...
4
votes
0answers
143 views

Added raster layers with PyQGIS do not show up

I have a list ("datList") with names of raster layers which I want to add. When I add raster layers in the Python Console everything works fine: for da in datListe: layerDir = "C:/[...
4
votes
0answers
100 views

Functionalities of expression builder in Autofield plugin available in QGIS 3.4?

Basically, what I try to do is automated calculation while editing (not with field calculator). In QGIS 2.18 you could do automated calculations while editing with the Autofield Plugin. Since QGIS 3....
4
votes
0answers
761 views

QGIS 3.4.6 “Network access is disabled” on WiFi only

I get this error message when connecting to OWS from GeoServer in QGIS 3.4.6 LTR on Windows 10 on WiFi only. Failed to download capabilities: Download of capabilities failed: Network access is ...
4
votes
1answer
138 views

Joining attributes by location error when finding polygons within district boundaries?

I am using QGIS 3.5. I have a large shapefile (760 MB) with 1800 polygons representing different bird species ranges (download link) I have a second shapefile with polygons of district boundaries (...
4
votes
0answers
1k views

CadTools plugin functionality in QGIS 3 beyond Advanced Digitising Panel?

I've recently migrated to QGIS 3.6.0, and I've realised that the wonderful CadTools plugin is not compatible with QGIS 3. I tried to use the Advanced Digitising Panel, but it's cumbersome and not ...
4
votes
0answers
95 views

QGIS Server Adding a virtual layer

All my layers in the qgs-project-file are working fine as WMS-layers, but I only can't provide the virtual layer. The virtual layer is an ODBC-Connection of an Access-Database which contains one ...
4
votes
0answers
95 views

How to render features that are just outside the map canvas extent in QGIS 3.4?

I am trying to generate a cloudy mask, following the recipe in "Qgis Map Design 2nd ed. Edition". For the most part, I have it working. But when panning around, the mask changes. And I think that ...
4
votes
2answers
312 views

QGIS plugin development environment variables?

I want to develop a plugin gor QGIS3. I downloaded Osgeo4w network installer 64Bit. I created a bat file as following for set my environment variables; @echo off call "%~dp0\o4w_env.bat" call ...
4
votes
0answers
2k views

Invalid geometry error when running Vector Intersection tool in QGIS 3

I am reworking an exercise that runs fine in QGIS 2.14 and 2.18 but have encountered an error in QGIS 3.2. I am using Windows 8. I am using the Alaska training data and adding the majrivers and trees ...
4
votes
0answers
299 views

pyinstaller package of pyqgis 3 standalone program failed import qgis.core

I have a working standalone pyqgis program with mapping ability, it was in python 2.7 and qgis 2.x library. I used pyinstaller to package it up. Now I have migrated this application to python 3.6 and ...
4
votes
1answer
671 views

Backup QGIS (3.2.1) layer to independent PostGIS table?

I'd like to make multiple, progressive backup copies of QGIS (3.2.1) layers that are stored in PostGIS tables. I've tried multiple routes to export them as files on disk, but they all seem to destroy ...
4
votes
0answers
139 views

QGIS rule based symbology for rasters in Atlas?

I'm making species distribution maps and have got the Atlas working perfectly using a polygon layer to show the quarter degree grid cells for species observation records. I have ~ 250 species. Problem ...
4
votes
0answers
239 views

Unable to connect to postgres server in Database Manager

I try to connect to my postgres server, hence I got this failure And following error: 2018-04-26T18:02:05 WARNING Traceback (most recent call last): File "C:/OSGEO4~1/apps/qgis/./python/...
4
votes
0answers
246 views

Connectors do not appear automatically in easy custom labelling

I'm using the easy custom labelling plugin in QGIS 3. When I move a label away from its associated polygon a connector does not automatically appear as in QGIS 2.18. How do I get connectors to appear ...
4
votes
2answers
574 views

QGIS 3.6 picture in ui form (Qt5 Designer)

I'm facing trouble with display a picture in a ui form based on a field (path). With the autogenerate form it works but when I try with a personalized form I cannot see the picture. I tried with a ...
3
votes
0answers
25 views

Prioritize label rendering

It seems that by default, vector layer labels only render after everything else is loaded. Some wms/wmts feeds being very slow, this means you have to wait for a while before you can see your labels, ...
3
votes
0answers
30 views

Generating Styled Vector Tiles with QGIS 3

I have generated raster tiles before with QGIS 3.14 (which worked fine) and now wanted to generate vector tiles. Once I tried that and viewed the mbtiles file in QGIS, I saw that all the styling that ...
3
votes
0answers
69 views

Load layers from SQLite database in Model Designer

Regularly, I have to load layers from SQLite databases through Spatialite in Qgis 3.16 and perform some algorithms. Extension of these SQLite databases is not *.sqlite but another format (proprietary)....
3
votes
0answers
32 views

Is it safe to access layer object(e.g. QgsVectorLayer) in background task(QgsTask) in QGIS3

I was confused if it's safe for developers to access QgsVectorLayer in a background task(QgsTask), like reading data from layers? Because descriptions in PyQGIS cookbook are different with different ...
3
votes
0answers
33 views

Unavailable algorithm in QGIS

When I try to launch my model (graphical modeler) in QGIS I get this message (in french) : Cet algorithme ne peut pas être lancé :-( Le modèle que vous essayez de lancer contient un algorithme qui n'...
3
votes
0answers
40 views

Displaying an alert before closing QGIS

I would like to display a message before QGIS close. But I can't intercept the closeEvent of the main window from my plugin. I've tested this code which doesn't work. # Main method QgsApplication....
3
votes
0answers
19 views

How to prevent not visible objects (scale rules) from being identified?

In Symbology tab I am using rule-based symbols and I have defined visibility rules dependent on the minimum scale. Above some scale threshold some features are not visible as I expected. But when I am ...
3
votes
1answer
60 views

Editing attribute cell data/text in “edit” mode using QGIS

I am using QGIS3.4. I turn my layer on "edit" mode. I want to type text into a blank cell or paste text. I don't know why it will not allow me to enter anything while the layer is in "...

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