Questions tagged [qgis-3]

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

788 questions with no upvoted or accepted answers
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2
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240 views

QGIS 3 Value Relation current_value() not working in custom ui form

I have a custom UI form made with Qt Designer with a couple of dropdown list, so I can easily edit a layer. I use a Value Relation on those fields to filter the displayed data. The problem is the ...
2
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0answers
33 views

Still a Python27 folder?

Can anybody tell me why there is still a python27 folder along with the python37 folder in the latest (3.x) QGIS releases?
2
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0answers
29 views

Calling a Python function for each page in an atlas

I have made a script to do some calculations for each page of a QGIS atlas (QGIS Atlas with insert map) The script is adjusting the bounding box of a map on the layout page. To make it run for each ...
2
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0answers
86 views

Disconnect between raster symbology in Layers Panel and Layer Properties (QGIS 3)

I'm working on a Python plugin for QGIS that applies a customised colorRampItemList to a single band raster. The result displays correctly on the map and in the Layers Panel but incorrectly in the ...
2
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0answers
72 views

Method in QGIS to do a select by radius but ignore “islands”

I am looking for a process in QGIS to run a selection from a given point based of a radius that ignores "islands". For example you may have a body of water which acts as a natural barrier past which I ...
2
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0answers
209 views

Adding new field and calculating in PyQGIS

I'm trying to write a script using QGIS 3.4. What I want to achieve is an Excel-style calculation where I can create a new field "field2" and calculate the difference between a current and previous ...
2
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0answers
61 views

Create filter expression by selected elements?

Is it possible to automatically create a filter expression for the Query Builder by selected elements?
2
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0answers
22 views

What is stored in Options|Advanced|PostgreSQL|connections|dbname|keys group in QGIS 3?

Since QGIS 3 in the Options|Advanced|PostgreSQL path referred to in the title there is a new group 'keys' as can be seen in this screenshot: In old QGIS 2.X: What kind of information is stored in ...
2
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0answers
35 views

QGIS 3.4.5 Attribute table expression in print composer not working

I just upgraded from QGIS 2.18 to the latest stable release (3.4.5). I am trying to filter an attribute table added to a layout by using @atlas_pagename and I can see there is a match in the ...
2
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0answers
76 views

VRT Files from QGIS2+ makes QGIS3 crash when opened

We got a bunch of VRT files that we made using QGIS 2 and which reference a varying number of ECW files (from 8 to 300). Those VRT files were perfectly runing QGIS 2.18. Problem is: Opening those ...
2
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0answers
188 views

QGIS Processing Script to Create and Add CSV Layer

I have a QGIS 3 processing script that I'm working on which has the following workflow: Get xy coordinates from a grid layer and construct a list. Make calls to the Google Distance Matrix API using ...
2
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0answers
78 views

Increase the size of overlapping lines in QGIS 3.6

In QGIS I have a layer that is a MultiLineString that has many overlapping lines, which represent driving routes around the city which are generated using OSRM. My data looks something like [ [[a,b],...
2
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0answers
54 views

Spatial join by argument closest, but based on majority of vertices

I'm often working with different polyline datasets which represent street networks. One of the most common tasks I have is to join information from one layer to another. Often there are no mutual ...
2
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0answers
169 views

Increasing zoom level in 3D View QGIS Desktop?

I would like to increase the zoom level for my mosaic raster image in the 3D View of QGIS Desktop 3.4.4. I made a mosaic out of four raster images downloaded through the STRM-plugin for DEM data. ...
2
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0answers
90 views

Updating set of attributes on vector layer from .csv table?

I have over 1,000 records in a .shp file, all with a unique ID field (LINKID), along with many other fields containing data (TXTFLD1, TXTFLD2, INTFLD1, INTFLD2, etc). These records have been copied ...
2
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0answers
24 views

Error in Graphical Modeler when converting raster to vector

I'm building a model where, among other things, I use r.watershed, from which I only keep the "stream segments" output. In addition I would like to convert that raster to vector lines. When I do that ...
2
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0answers
134 views

Calculate length of selected features in PyQGIS

I create a selection with getFeatures(QgsFeatureRequest()) and I want to calculate the length of the result which is a QgsFeatureIterator : select = QgsExpression(" myexpression ") selectedfeats = ...
2
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0answers
134 views

Call the QGIS 3D view using PyQGIS

I am working on creating a change detection script for QGIS3, that detects the differences between two DEMs and highlights the changes. Everything is working well but I have been unable to get the 3D ...
2
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0answers
39 views

Map view does not render full SVG, but layers pane and print layout does?

In map view where I want to do all design and small changes the SVGs for "MELLANTID" does not render the added outline, only original size. The SVG for "SJUKVARD" only renders the left half of the SVG,...
2
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0answers
74 views

Configuring QGIS new OAuth2 support for WMS or WFS

Has anyone successfully configured QGIS new OAuth2 support for a WMS or WFS service? I have an ArcGIS 10.6.1 service published as a WFS service but cannot get past the OAuth2 authentication.
2
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0answers
95 views

QGIS 3.44 heatmap to contour file

I am trying to convert a point file, currently displayed into a contour file. The methods that I have tried, all expect a raster file as an input, but my source file is a vector file points, i.e. I ...
2
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0answers
28 views

QGIS turn right click — “Toggle Editing” off

In QGIS3, Interface customization I have turned off the mEditMenu but when a user right clicks on a dateset they still see "Toggle Editing". Is it possible to remove this? and also any keyboard ...
2
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0answers
111 views

QGIS Server 3.4 - No labels in WMS

I have successfully installed the current version of the QGIS Server on a Ubuntu 16.04. WFS, WCS run fine, but in WMS no text is rendered in the map. In the legend you can see text. Does anyone have ...
2
votes
1answer
446 views

Wrong or missing parameter QgsProcessingParameterFile QGIS 3.4 Python plugin

I'm making a script that can be called by the processing.execAlgorithmDialog function. For one of the parameters, I want to use the QgsProcessingParameterFile class for selecting a .csv file. I tried ...
2
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0answers
63 views

QGIS crashes when toggle editing for child layer in QgsDualView

The crash occurs for: Ubuntu 18.04 bionic QGIS 3.4.2 For reproduce the crash, I use the data from Natural Earth Data: https://www.naturalearthdata.com/http//www.naturalearthdata.com/download/110m/...
2
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0answers
173 views

What is a general purpose of “Update SQL layer” in QGIS 3?

Can someone explain to me, what is a general purpose of "Update SQL layer"? When I "update" it becomes not editable... (see gif ▼)
2
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0answers
284 views

Does the Clipper plugin for QGIS work with Shapefile layers?

I created 2 overlapped polygons in one Shapefile layer, run the intersection tool with another layer and then run the Clipper plugin. This causes the error: TypeError: MultiPolygon geometry cannot be ...
2
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0answers
60 views

Setting raster visibility on/off in QGIS Python API 3

I'm having a bit of a trouble migrating an algorithm from pyqgis 2 to pyqgis 3. The thing is I want to make visible and invisible a series of layers as I iterate through a list and render some images. ...
2
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0answers
66 views

Unexpected behavior of collect() in geometry generator

I'm having unexpected results using geometry generator with the following expression: buffer(collect($geometry),0) …which was an answer given in this topic. I have used this previously with the ...
2
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0answers
30 views

Showing split polygons in different layers in QGIS

I used the split feature to split a polygon into two parts. Is it possible to show the split parts in sub-layers in the layers panel, so that I can hide them individually? I am using QGIS 3.
2
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0answers
207 views

Unresponsive MessageBar in QGIS 3

I created a little plugin to geocode addresses using the HERE API and QGIS 3. Especially in batch mode, I can see that the plugin is iterating over my features in a table and my messageBar progress ...
2
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0answers
176 views

Rendering Google Terrain in QGIS Layout Manager

I am using the Google Terrain map (via XYZ Tiles). This seems to make the system very slow, and when making a .jpeg through the Layout Manager, the Google Terrain will not display (render) when ...
2
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0answers
54 views

In QGIS 3 Graphical Modeler can you add a check box to allow for different model path

In the Graphical Modeler in QGIS 3 is it possible to add a check box to the model GUI that if selected takes you down a different path of the tree so to speak. Example: Within a model I want to have ...
2
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0answers
81 views

QGIS 3 imports DATE type colum in Oracle Database as QDate, losing hh:mm:ss

I am at the moment working on a lift for an QGIS 2 plugin to work with QGIS 3. The plugin specifies a QgsDataSourceUri and uses it in an QgsVectorLayer. In the specific table, laying in an Oracle ...
2
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0answers
77 views

Prevent labels being cut off at edge when using Layout-Atlas

Im creating an atlas but the labels on the edges sometimes get cut off: When it should look like this: The text is coming from a Point layer, and the Point is located at the "E" letter above. I know ...
2
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0answers
52 views

Vector reprojected to the same projection in different GIS are not aligned

I have a vector file from the land use area around a river in South America. It was mapped originally in Datum SIRGAS2000 and Projection UTM, zone 23S - EPSG:31983. As the area of study is much ...
2
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0answers
268 views

How to make a QGIS 3 Layer refresh after a joined data source is updated

I have a layer of ZCTA features that is sourced from a SpatiaLite table that is joined to an Excel spreadsheet and rendered with categorized symbology. That all works fine. The join configuration is: ...
2
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0answers
96 views

PyQgis How could I open the “identify results” dock using “onSelectionChange()”

Using iface.mapCanvas().selectionChanged.connect(function) I'd like to open the Identify result dock for the selected feature as shown below: it could be manually done by selecting the feature with ...
2
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0answers
541 views

Creating a flow graph in QGIS 3.4

I attempting to make flow graph in QGIS 3.4, some thing like I have found several 'ways to do it' in QGIS 2.xx eg QGIS2.0 method I known its possible to get a line with arrows by just change the ...
2
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0answers
63 views

Using QgsExpression in a custom validation?

We use our own validation in QGIS, which can be called from different areas of the plugin. In addition, reports can be generated from the results. Now we have switched to our own attribute forms in ...
2
votes
1answer
679 views

Nearest Neighbor Analysis Results

I'm fairly new and entirely self-taught in using QGIS 3.4. I'm looking at turtle nest sites and trying to run a nearest neighbor analysis to analyze their distribution and establish whether or not ...
2
votes
2answers
207 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 ...
2
votes
0answers
139 views

QGIS not coming to foreground

I recently upgraded from QGIS 3.2 to 3.4 using the standalone installer (Windows 64 bit), and uninstalling 3.2 beforehand. When I open 3.4 it goes the background behind all my other open programs and ...
2
votes
0answers
27 views

Improving speed while adding QgsVectorLayer

In my QGIS plugin I'm adding some different layers to the QGIS canvas with a uri connection to my Postgres database, adding one layer takes no time, hence adding 20 layers takes some time. So I tried ...
2
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0answers
127 views

QGIS Export Webmap with QGIS2Web only using Python Console?

I want to automatically export my QGIS map to Webmap using only pyQGIS commands. By now I just know how to run the plugin with commands on python console: import qgis.utils qgis2web = qgis.utils....
2
votes
1answer
446 views

Draw rectangles with Shape Digitizing Toolbar and using a snapping function in QGIS 3

I draw rectangles with the Shape Digitizing Toolbar. In QGIS 3 there is a Snapping Toolbar which provides a snapping function. But unfortunately it is not possible to use both together. So whenever I ...
2
votes
0answers
67 views

Redrawing raster layer after file changed in QGIS?

I'm trying to find a way to redraw a raster layer after the original source file has been changed in QGIS 3.2+. However, it redraws only sometimes (~10%), which means there is some deep caching that I ...
2
votes
0answers
41 views

How to impose constraints on drop lists of two fields of the same layer?

Is it possible to impose with pyqgis3.0 some constraints on a drop list of a field attribute in order to govern the drop list attributes of another linked field? To better clarify this issue, I attach ...
2
votes
1answer
289 views

QGIS3 Creating spatial index in a standalone script as a part of output vector layer

I am making a buffer analisys in a standalone script. Is it possible to automatically during the analisys add index to the output vector layer (".qix" file)? I tried to add after the analisys like in ...
2
votes
0answers
61 views

Achieving the opposite of the shortest_line() function in QGIS?

I currently use the Geometry Generator styling on a point layer to draw the intersection between protection buffers around tree points and another polygon (say a building footprint) using the ...