Questions tagged [qgis-3]
for questions specific to the 3.x series of QGIS.
1,639
questions
0
votes
0answers
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 ...
0
votes
0answers
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, ...
0
votes
0answers
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>
&...
2
votes
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 ...
0
votes
0answers
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 ...
1
vote
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
vote
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
votes
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 ...
0
votes
0answers
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, ...
1
vote
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
votes
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
vote
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 ...
0
votes
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 ...
0
votes
0answers
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(...
1
vote
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 ...
0
votes
0answers
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
vote
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 ...
0
votes
0answers
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 ...
0
votes
0answers
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(...
0
votes
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 ...
0
votes
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:...
0
votes
0answers
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 ...
0
votes
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 ...
0
votes
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.
...
0
votes
0answers
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 ...
1
vote
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=...
1
vote
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
votes
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 ...
0
votes
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 ...
0
votes
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
votes
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
votes
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
votes
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 ...
0
votes
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 ...
1
vote
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
votes
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
votes
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
votes
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
...
0
votes
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 ...
0
votes
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 ...
1
vote
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
votes
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 ...
0
votes
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
votes
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
vote
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
votes
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
votes
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 ...
