Questions tagged [qgis-3]

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

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7 views

Looping zonal statistics in QGIS?

Has anybody successfully used Zonal statistics in a loop in qgis 3.8? I have to go through several rasters using a vector file. Batch processing seems to fail in qgis 3.8 too - see Zonal statistics ...
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6 views

QGIS SAGA Overland flow distance to channel network not working

I am trying to run the QGIS SAGA tool "Overland flow distance to channel network" with a DEM and the channel network raster developed from this same DEM using the SAGA tool "Channel network." However, ...
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16 views

In QGIS Layout Manager, padding inside html table not working?

For a HTML field in the QGIS Layout Manager I have in the "Source" field a table like: <table> <tr> <td>1</td> <td>2</td> </tr> <tr> &...
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0answers
26 views

QGIS3 run model with python script

I want to run a model with a python script, including the parameters, because I can't "translate" the model easily into a script. I have tried to run a copy of the processing log after running the ...
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23 views

Importing WKT in QGIS? [on hold]

When I import to QGIS 3.4 or to QGIS 2.18 a file with 50000 geometries some of the geometries are bigger than they actually are (in purple in the picture). Since this is not correct I select one of ...
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1answer
21 views

Unremovable objects/lines QGIS 3.x

How can I remove "red lines" that become permanent to my map canvas while trying to digitize different shapes. The program just leaves the outline of what I'm trying to draw. It still remains even if ...
1
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1answer
22 views

QGIS 3 : Qt Signal emmitted when selecting a layer?

I am currently writing a QGIS 3 plugin. I would like to catch the signal emmited each time the user selects a new layer in the layer panel. I have already searched in the QGIS API (QgsProject, ...
5
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1answer
120 views

CRS interpretation in QGIS?

I know there are related questions like this one, this question, and this one all over this site. I have tried the many possible solutions I have seen at the point. The problem: I am trying to make a ...
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44 views

Unable to import shp to QGIS 3.0

I'm using QGIS Desktop 3.8, and unable to import a shapefile. I get the following error: "The layer already exists. Are you sure you want to overwrite the existing file?" I'm super frustrated, ...
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2answers
31 views

How to select a specific print layout (by name) in QGIS 3?

I'm a real beginner in Python. I'm using a Python script to produce maps automatically. This script is working but it is failing in the last part: saving the current map with a specific print layout. ...
2
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0answers
31 views

Delayed function calling inside QgsTask

I try to add a function to the qt event loop via QTimer.singleShot(...) from within a QgsTask. However the function is never executed. I wrote a short script that isolates this issue: import time ...
1
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1answer
20 views

PyQGIS error when running zonal statistics?

I want to extract the sum of my raster cell values with a specific area through zonal statistics and have prepared the following code (see below). When I run the code I get the following error message ...
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1answer
20 views

Is there a way to save a default layer name to a spatialite/geopackage table?

I'm a huge fan of being able to save default symbology to spatialite/geopackage tables, however I don't like that when I import a table as a layer it takes on the name "database name table_name". Is ...
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15 views

Assign layer style from qml file

I am adding a number of spatial csv files as layers and want to assign a qml layer style. import processing # User Dialog to pick Import_QGIS folder Folder_Path = QFileDialog.getExistingDirectory(...
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1answer
28 views

How to use the ExactIntersect flag for QgsFeatureRequest() object

I have two layers, a polygon_lyr and a line_lyr. I want to use a QgsFeatureRequest() for the line_lyr.getFeatures() but instead of returning the lines which intersect the bounding box of a polygon, I ...
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20 views

QGIS Bad Allocation when trying to view table from virtual layer SQL

I created a virtual layer using Layer--Add Edit Virtual When I try to zoom to selection I get the "Bad Allocation" error I am currently in 3.9.0-Master but have also tried in the current LTR. Is ...
1
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1answer
23 views

QGIS performance wtih many unique value widgets in the attributes form

I'm creating a QGIS 3.8 workflow and made about 15 attributes as unique values generated from the data already in the form but now the info view and attribute table that's used to open almost ...
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9 views

Couldn't load plugin 'openlayers_plugin' due to missing 'QtWebKitWidgets'

I am using Qgis 3.8 and I am trying to use the plugin OpenLayers. However, when I try to install the plugin I receive the following error: Couldn't load plugin 'openlayers_plugin' due to an error ...
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24 views

Error message when using iface.AddRasterLayer command [on hold]

I am fairly new to PyQGIS and am trying to add a raster layer in my QGIS project using the following code in PyQGIS: uri = "C:/Users/Anna Nilsson/Desktop/hrslkenpop" rlayer = iface.addRasterLayer(...
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0answers
13 views

QGIS georeferencer distorts colours

I try to use the georeferencer to geofreference certain building plans, but the referencer really distorts colours As you can see in the picture. it hollows out what used to be solid red, black and ...
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0answers
16 views

QGIS3x Layer-Import via URI [on hold]

I want to import a spatial csv-file with uri = "file:///C:/users/username/name with spaces.csv?type=csv&delimiter=,&detectTypes=yes&xField=X_Wert_Pos&yField=Y_Wert_Pos&crs=epsg:...
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15 views

Splitting a layer containing multiple polygons into multiple layers each containing one polygon [duplicate]

So firstly, I used the buffer tool in Qgis3 to create (twenty) polygons with a certain width from (twenty) points. This lead to the situation below, where o1 and o2 are two original points and 1 and 2 ...
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1answer
19 views

Python3 Replace “/” With “\” [on hold]

I want to import several spatial csv files (points) into QGIS. The path to the folder, where the csv files are located is stored in the variable "Folder_Path". The file names are stored in a list. It ...
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2answers
55 views

Update a value by nearest polygon

I'm looking to be able to update a value by its nearest polygon. The below image shows polygons in green where the column roadclass = 'A' and shows polygons where column roadclass IS NULL in brown. ...
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23 views

Rasterize a shapefile - Qgis 3.4

I got a problem with the rasterization of a shapefile. Basically my aim is to rasterize a shapefile 'Building' by defining boundaries (Output extent from another simple polygon layer) and output ...
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0answers
18 views

Add spatial csv-layer in QGIS3 using Python3 code

I need to add a spatial csv-file with a specific path (folder and file name) in QGIS3x using a python script. I have tried: PyQGIS import csv- QGIS 3.4 uri = "file:///C:/users/heubacha/Test.csv?type=...
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0answers
28 views

All 0s result from raster calculator in python

Raster calculator is not working correctly for a single calculation using a standalone Python script. I am trying to add 1 to a pre-existing raster. It processes, but the resulting tiff file is all 0s....
4
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0answers
50 views

Importing text as legend or to legend in QGIS?

I have a layer consisting of appr. 30-45 classes. The majority of the classes has an item description containing multiple lines of text. In ArcMap I can achieve a layout like this Is a similar layout ...
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0answers
16 views

QGIS: zoom further than threshold in WMTS

Is there a way to zoom further than the threshold allowed by a wmts feed? Of course the idea is not to load any more images as that would be impossible. I just want to scale up the images of the ...
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0answers
25 views

QGIS 3.8 could not start ''Qgis_app.dll is missing'' check runtime environment check C:\OSGEO4W64\bin\qgis-dev-bin-g.exe

I had Qgis 3.4 running well on my PC Windows 10, 64 bit. I tried to upgrade to Qgis 3.8 Zanzibar and I had the error message: ''Qgis_app.dll is missing check runtime environment check C:\OSGEO4W64\bin\...
2
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1answer
30 views

Adding new attribute field to processing output algorithm in PyQGIS?

I have a processing script that will carry out a selection by expression of the input layer, then do a join attributes by location with a join layer. The next stage will be to add a new field and ...
3
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0answers
31 views

Disable map zooming with QGIS 3.5 +

I am trying to disable zooming with the mouse wheel for QGIS 3.8. Past versions have had an option to under Settings/Preferences -> Map tools, but this appears to have moved with the newer versions. I ...
2
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1answer
31 views

Removing selection area from canvas when no layer is available or selected

I am new to QGIS 3 and I can not figure out the way to remove the selection from empty canvas or with Google Maps layers selected this area can not be removed. I tried to remove it by selecting a ...
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0answers
15 views

Import OSMAND tracks in QGIS

I would like to import GPS tracks created in osmand to QGIS. First, I exported the tracks in gpx format from OSMand. then I tried using the vector-->GPS tools --> load GPX file dialog. The file is ...
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0answers
19 views

Undo all layers at once in QGIS

I am used to undo feature of ArcMap that undo everything in sequence irrespective of the layer which is selected. In QGIS it only undo the edits made in the layer selected. Is there a way to change ...
3
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0answers
24 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, ...
2
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1answer
96 views

QGIS Welcome page: What is 'pin to list' for?

In QGIS 3 Welcome page when I right click a project a tiny context menu with 'pin to list' rsp. 'unpin from list' as first entry appears. 'pin to list' produces a little pin near the project name and ...
3
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0answers
31 views

Pyqgis: Added raster layers 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:/[path]/" + da ...
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1answer
38 views

How to access/edit QGIS3 Plugin folder in Flatpak version from external software in Linux Mint 19.1?

I am glad to share my first question in this forum with you. I hope I can formulate the problem correctly. I have been working in a QGIS3 Python plugin in a Windows system with QGIS 3.8. From today ...
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0answers
5 views

Configure my local raster tiles for the local network to open in Qgis 3.4

I had open the raster tile locally as explained in "Using Open Google Earth cache file in QGIS?". I have small local network with 30 systems and want to open these raster tiles in all system from ...
2
votes
1answer
41 views

How can I make use of the QGIS authentication manager in PyQGIS processing scripts?

I have developped a set of QGIS processing scripts that rely on some background data stored in a postgreSQL database. During my development phase I had the database on my localost server and connected ...
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0answers
14 views

Map frame in the map composer doesn't show the project layers when the size of the map is too large. Small size maps work fine [closed]

I drew a map in QGIS print composer, but it does not render my layer from the QGIS project. When I reduce the size of my map it works. Here are two pictures to illustrate my issue. Why is that and ...
2
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2answers
43 views

QGIS 3 shapefile attribute table sort order

If I open a shapefile in two empty QGIS projects and view the attribute table the rows are in completely different orders. How does QGIS decide which order to display the rows in an attribute table ...
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0answers
12 views

r.watershed not completing task?

When executing ​the r.watershed ​command, you do ​not finish the ​procedure, ​staying in ​Section 2: A * ​Search, the ​module has not ​been finalized ​or killed. ​Someone can ​help give me a ​solution ...
2
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2answers
47 views

Creating lines from points preserving gaps in QGIS [closed]

I have CSV sets of navigation points, with the following scheme: Easting, Northing, Line_name, Fiducial. I can connect the lines with Points to Path, using the Line_name as the Group field and ...
1
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1answer
29 views

QGIS XYZ Tiles extents / bounds?

I have added a online tile source in the 'XYZ Tiles' option, and added it as a layer, which works fine. But im trying to understand where the extents shown in the layer properties is coming from? When ...
3
votes
1answer
64 views

Handling projections with QGIS?

I know this may sound like a silly question, and it is, but I've read lots of questions and tutorials, watched a few videos and still can't properly understand what I should do... I am trying to work ...
2
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0answers
63 views

Accessing downloaded shapefiles/attribute data?

Using 3.8, I am attempting to create a simple map of the UK showing the county boundaries, with a couple of specific locations shown for reference. My approach for attempting this has been to attempt ...
3
votes
2answers
202 views

QGIS Zanzibar how to crop?

I have georeferenced an old OS map and I have now imported the OS data shapefile for boundaries for England. How can I get rid of the extra data that extends beyond my map and just leave my scanned ...
0
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1answer
17 views

Offline Map-Matching freezes

I am using Offline Map-Matching and the process always freezes at the same time (8% of calculating transition probabilities, as shown on the image): I get no messages and have no idea what could be ...