Questions tagged [qgis-3]

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

Filter by
Sorted by
Tagged with
12 votes
1 answer
8k views

Use QGIS expressions to create geometries: difference between geometry generator and geometry by expression

QGIS has a powerful expression machine that can be used (between other things) to create new geometries, based on existing layers. Basically, there are two options: Geometry generator (introduced in ...
Babel's user avatar
  • 70.5k
41 votes
3 answers
16k views

Using QGIS Processing algorithms from PyQGIS standalone scripts (outside of GUI)

I am writing a script which must work outside of QGIS GUI. I call some API functions from qgis.core but I would like to use the processing plugin. I am able to import processing with sys.path.append() ...
vidlb's user avatar
  • 699
53 votes
13 answers
19k views

Seeking QGIS user interface tutorials and web resources

I wish to familiarize myself with the capabilities of QGIS up to and beyond QGIS version 3.0. Can you recommend some good web resources and tutorials that would show me QGIS' capabilities? I am ...
6 votes
2 answers
4k views

Why does QGIS 3.2 "native:extractvertices" algorithm not work properly in standalone script?

I execute standalone python code (almost identical to the code in the accepted answer): The output file does not contain data, and I get this error message: Warning 6: Normalized/laundered field ...
Comrade Che's user avatar
  • 7,051
19 votes
7 answers
21k views

Splitting polygon into equal area polygons using QGIS

There is a Plugin in QGIS 2.18 called "Polygon Divider" which divides an irregular polygon into smaller equal-area polygons of a specified/custom-sized but in QGIS 3.x version there is no &...
Kapildev adhikari's user avatar
35 votes
2 answers
20k views

Was QgsMapLayerRegistry being removed in QGIS 3?

Is QgsMapLayerRegistry going to be availabe in PyQGIS with QGIS 3? When I typed it into the QGIS python console (2.99), python seems to recognize it because it auto-completes qgis.core....
tinlyx's user avatar
  • 11.1k
3 votes
2 answers
3k views

Layer disappears when changing from CRS in degrees to CRS in meters in QGIS

The problem I have tens of thousands of small polygons for which I want to create buffer/doughnuts for, but I don’t get the units right. I want meters and not degrees, and changing to (what I think ...
Agnes's user avatar
  • 135
55 votes
6 answers
94k views

Will the OpenLayers Plugin be updated for QGIS3?

Upon searching for the OpenLayers plugin, it shows that this plugin is incompatible with version QGIS 3.0. Will this be updated? Is there another way to add Google imagery or any other aerial imagery ...
TMAC_0819's user avatar
  • 553
15 votes
2 answers
16k views

Getting the output layer reference returned by Processing tool

After running Processing algorithm ending up with a layer by run or runAndLoadResults in QGIS 3, these methods return a result which is mostly a dictionary like {'OUTPUT': 'file_path'} etc. So, after ...
Kadir Şahbaz's user avatar
8 votes
1 answer
541 views

Projection transformation of a shapefile

I am using QGIS 3.18.1. I am working on a map around Alaska. I added a world basemap, then added DEM and finally drew a few polygon shapefiles on top. I then tried to find a projection more ...
Mario Westphal's user avatar
6 votes
1 answer
892 views

Buffer is too small (OSM Data, EPSG 3857)

I buffered some lines with 100 m in QGIS. When I measured it turns out instead of 100 m its 62. I understand the issue could relate to the CRS. I used EPSG 3857 because the OSM map in the background ...
BAE_23's user avatar
  • 601
11 votes
1 answer
6k views

Using processing.runalg in QGIS 3

I try to create a common extent for rasters in QGIS 2.99. Here is my script: import processing processing.runalg("script:unifyextentandresolution", "/qgis_data/rasters/Image2.tif; ...
Mustafa Uçar's user avatar
19 votes
1 answer
9k views

Writing a python processing script with QGIS 3.0

Following the update to QGIS 3.0, it has become very difficult to find any information concerning the writing of processing scripts in QGIS 3.0. @Underdark (see here ) has provided a basis for the ...
Kantan's user avatar
  • 1,917
14 votes
1 answer
24k views

Enable 'on the fly' CRS transformation in QGIS 3?

In QGIS 2.8 there is a clear button to 'enable on the fly CRS transformation' in the "project properties" for a new project. Seen here: But in QGIS 3.0, I cannot find it to save my life. Can ...
Erich Purpur's user avatar
  • 1,861
3 votes
1 answer
3k views

QGIS 3.16 - Print layout grid coordinates in DMS?

I am trying to create a grid with coordinates printed in degrees, minutes, and seconds in print layout of QGIS 3.16. The project is defined to EPSG:32652 WGS 84/UTM Zone 52N. When I go to Grid > ...
jjun's user avatar
  • 33
47 votes
1 answer
39k views

What is the default plugin folder location in QGIS 3?

I am searching for default location for QGIS 3 Plugin folder I checked here but could not find: C:\Program Files\QGIS 3.0\apps\qgis\python\plugins C:\Users\Abhijit\.qgis2 (cannot locate .qgis3, ...
Abhijit Gujar's user avatar
9 votes
6 answers
10k views

Installing QGIS3 on Ubuntu 16.04 Xenial: dependency problem

I am trying to install QGIS3 on my Ubuntu 16.04 Xenial. Following the instructions on the QGIS Website I added the following lines to my sources.list: deb https://qgis.org/ubuntugis xenial main deb-...
user116945's user avatar
5 votes
3 answers
8k views

Calculating percentage of overlap of two layers in QGIS 3

I am trying to compare two different vector layers on QGIS 3. They are species distribution maps. I would like to calculate the percentage of overlap of two vector layers. My goal is to determine how ...
JS5687's user avatar
  • 99
14 votes
7 answers
7k views

Map display not filling window in QGIS on Mac?

In this screenshot of QGIS, you can see that the map is not filling the window. I have tried resizing the window in various ways. Am I missing something obvious, or is this a bug? Versions: ...
amiga_os's user avatar
  • 143
14 votes
1 answer
3k views

What is the new alglist and alghelp in QGIS 3.0 Processing?

Accessing the new QGIS 3.0 processing scripts through the Python console is proving to be a challenge for me, especially since the old processing.alglist() and processing.alghelp() commands appear to ...
Nick_W's user avatar
  • 565
10 votes
1 answer
830 views

Re-locating points randomly at certain distance in QGIS

I have GPS coordinates which identify aid projects in Africa. Now, I want to re-locate these projects, such that each project is re-located by 100 km in a random direction from its original location. (...
Franziska's user avatar
  • 119
8 votes
1 answer
2k views

Importing QGIS3 processing tools in standalone script

Inspired by this question, but for QGIS 3 (and therefore Python 3), I would like to use the QGIS processing algorithms in a standalone Python script without a GUI, with a standard installation of ...
alphabetasoup's user avatar
7 votes
1 answer
5k views

Photo Map tip in QGIS 3 on windows

How do you display a photo map tip in QGIS 3 on Windows? As a new user I'm not sure if this is my lack of experience or a bug, so I've tried to simplify it as far as I can: This is the contents of ...
sandyscott's user avatar
6 votes
1 answer
1k views

Is there a QGIS 3 setting to completely turn off plugins?

I would like to turn off all plugins without uninstalling them. I usually do this while testing to rule out an issue being caused by a plugin. I am looking for the QGIS equivalent to the ArcMap ...
Jay Cummins's user avatar
  • 14.6k
5 votes
2 answers
2k views

Copying and pasting features using PyQGIS

I have created a table join between two shapefiles which I've named 'OSMM' and 'Mastermap'. I want to copy and paste all features (polygons) without a match from the target layer ('Mastermap') into ...
James B's user avatar
  • 2,139
3 votes
2 answers
6k views

Creating custom CRS in QGIS

I am trying to define a custom CRS in QGIS 3.4 to work on some data in Central Asia. I want to use the Albers Equal Area Conic but change the parameters so that the transformation works best for my ...
Florian Mlehliv's user avatar
3 votes
2 answers
863 views

Geocoding addresses from Excel in QGIS 3 [duplicate]

I have a set of addresses in Belgium in Excel and I would want to geocode/transform them in coordinates in order to be able ta visualize them in QGIS 3.4. Does someone know how I could do?
mvh's user avatar
  • 31
2 votes
3 answers
198 views

Spatial query to return multiple values

I have a woodland scheme advice layer that has a polygon for each area of advice (brown layer in the picture). I also have a polygon layer of UK local authorities (red boundary layer in the picture). ...
Catocala nupta's user avatar
27 votes
2 answers
31k views

Using QGIS vertex editor? [closed]

I'm having two main problems: When hovering over a map with multiple layers, even though I only have one layer editable and visible, I am seeing all the nodes of all layers show up as red dots when ...
John N's user avatar
  • 387
19 votes
2 answers
17k views

Unable to snap vertices and segment in QGIS 3.0

I'm unable to snap 2 polygons in QGIS 3.0. I tried snapping 2 polygons from the same layer and also 2 polygons from different layers. I ensured that snapping is enabled in the Settings>>Options>>...
adele.k's user avatar
  • 245
13 votes
2 answers
18k views

Why "Export as Python script" button is unaccessible in QGIS 3.0/3.1 Modeler by default?

In QGIS 3.0, "Processing Modeler" window has no "Export as Python script" button unlike QGIS 2.x. If you look at the codes (in DlgModeler.ui and ModelerDialog.py files), you see the code lines ...
Kadir Şahbaz's user avatar
12 votes
1 answer
1k views

Changing parameter values according to other parameter choice in Processing script using QGIS 3?

I couldn't find anything about this problem. Suppose to have the first parameters in a Processing script defined as an Enum: self.addParameter( QgsProcessingParameterEnum( ...
matteo's user avatar
  • 3,304
10 votes
2 answers
8k views

How to compile QtDesigner user interface (.ui) and resource (.qrc) files with QGIS 3 on Windows?

I tried to transpose the QGIS 2 process with no success. I first had to edit C:\Program Files\QGIS 2.99\etc\ini\python-core.bat which contains references to Python27 instead of Python36. I run C:\...
sigeal's user avatar
  • 879
10 votes
2 answers
2k views

Will core functions in QGIS exploit multi-threading?

After reading Enabling multithreaded processing in QGIS?, I was wondering if QGIS 2.6 will include this when running various processes. I checked online and I could only find that multi-threaded ...
Joseph's user avatar
  • 75.6k
10 votes
1 answer
4k views

Reading and setting label settings in PyQGIS

In QGIS 2.18 I read and set label style settings like this: props = { "labeling": "pal", "labeling/enabled": "true", "labeling/fontFamily":...
Kezah's user avatar
  • 856
9 votes
1 answer
6k views

Value relation widget in QGIS

I would like to create a cascading select in QGIS using the value relations widget. I'm using QGIS 3.14 (pi) and all layers are stored in a geopackage. The geopackage shown in this example can be ...
Oliver Burdekin's user avatar
8 votes
1 answer
2k views

How to edit geometry of multiple layers simultaneously in QGIS 3?

I have several line layers (route, pipes, cables) that share the same geometry and would like to edit them simultaneously. Is there a way to easily snap the geometry of the pipes and cables layers ...
Fabian Kratz's user avatar
7 votes
1 answer
2k views

Printing only selected features in report QGIS 3?

My layer has more than 2900 elements, and I would like to release a map with 1 or 10 or 50 selected elements but never 2900 in the time. I can't select them other than visually (no column to identify)...
user138010's user avatar
2 votes
1 answer
843 views

Vector grid id generation [duplicate]

I generated a grid with 300m spacing but the ids generated from top to bottom in sequential oder. How could I get in horizontal from left to right sequence.
allamalla mohan's user avatar
45 votes
2 answers
44k views

Setting print layout to portrait using QGIS 3?

I can't get the print layout to appear in portrait. It opens in landscape and Layout/Page Setup... allows for portrait, but the layout canvas remains in landscape. In 2.18 the "Composition" Panel ...
David's user avatar
  • 453
31 votes
6 answers
22k views

Installing QGIS3 on Mac?

Kyngchaos installer is not finding python3. I installed python3 using HomeBrew and is not located at /usr/local/Cellar/python/3.6.4_4/Frameworks/Python.framework/Versions/3.6/bin/python3.6 How do I ...
Greg's user avatar
  • 899
21 votes
7 answers
13k views

QGIS 3.0 can't load plugin processing, no module named 'osgeo', on Manjaro Linux

I have installed QGIS3 from the AUR package, as well as all optional dependencies: https://aur.archlinux.org/packages/qgis/ However, when launching, I receive the following error: Couldn't load ...
thi_sanna's user avatar
  • 429
18 votes
2 answers
9k views

Save and load user profiles in QGIS

Is there a way use a configuration file, maybe .ini to load in the relevant settings for QGIS when it is setup, maybe to share with various people? Plugins installed and plugin repositories filled in ...
maskin's user avatar
  • 611
15 votes
3 answers
3k views

Controlling rule-based labelling using PyQGIS?

Following on from this question: How to turn on/off all labels of all layers in QGIS, OP mentioned in his comment that he uses rule-based labels. I tried searching online as to how these types of ...
Joseph's user avatar
  • 75.6k
13 votes
1 answer
5k views

Change vector layer symbology PyQGIS 3?

I'd like to change the symbology of my vector layer and can't figure it out how to read the documentation. I would like to have an polygone with an orange outline, a dashed fill style and an orange ...
SaskiaG's user avatar
  • 429
12 votes
1 answer
4k views

Exporting Processing Modeler as Python script in QGIS 3?

How do I export my model from Processing Modeler as .py so that I can edit its code? This does not seem as intuitive as in previous QGIS versions.
Mary Johnson's user avatar
10 votes
1 answer
9k views

Difference between Layer Definition File (qlr) and QGIS Layer Style File (qml)?

What is the difference between Layer Definition File (qlr) and QGIS Layer Style File (qml)? Which one is recommended? I have only used qlr so far. It seems store all the data displayed in the "...
Ken T's user avatar
  • 438
9 votes
2 answers
2k views

No custom widgets in Qt Designer for QGIS 3

There are no custom widgets in my "Qt Designer with QGIS 3.0.3 custom widgets". Is it a bug or I should somehow manually enable them?
Basile's user avatar
  • 3,543
8 votes
4 answers
1k views

Arranging GUI elements in QGIS 3 processing model user interface

Using QGIS 3 graphical modeler I created a model with a variety of input parameters (> 10). When starting the model, a nice user interface is generated. But the arrangement of the GUI elements is ...
Jochen Schwarze's user avatar
7 votes
2 answers
2k views

Is there a maximum number of features that QGIS can save into a shapefile?

I have a very large .gdb that I want to reduce to my study area. Unfortunately, the study area is still quite big. I could select features that intersected my study area but when I tried Export > ...
user3386170's user avatar
  • 1,937

1
2 3 4 5
13