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Questions tagged [qgis-3]

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

1
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0answers
8 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. ...
5
votes
2answers
70 views

Measuring average, min and max of vertex height of linear shape using QGIS?

I have a linear shape, all of the vertexes of each segment has a z-value, stored in the geometry. I need for every record, segment the average, min and max height value aggregated from their vertex ...
8
votes
2answers
148 views

Setting dashed stroke style when layers have features with sharing borders in QGIS?

Layers like municipalities, countries, ... have features sharing the border of their neighbours: they share the same vertices (except for the features at the edges off course). I have a municipality ...
1
vote
0answers
25 views

Gdal raster to polygon in QGIS3 (Python3)

What shall I install to be able to run the GDAL algoritms in python3 in qgis3? In Windows if I install gdal-python version 2.4.0-3 I get the gdal_polygonize.bat file, but it required python2.7 to be ...
2
votes
2answers
45 views

QGIS3 Shape Digitizing Circles is Drawing Improperly

I'm trying to draw a circle in QGIS 3 with the shape digitizing toolbar. I've tried several of the "add circle" options and they all look normal while drawing, but once I click to finish the shape it ...
1
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0answers
23 views

How to make a database query layer editable in QGIS

I have a layer in my QGIS 3.4 project that comes from a Geopackage database. I load it using a query to select only a subset of columns / fields and to filter partial records. However, the layer ...
0
votes
0answers
38 views

How do you change the value of a Boolean column in a QGIS 3 Attribute Table?

I am editing feature in a PostgreSQL table in QGIS 3 and while I can edit the values in most columns, I cannot edit the Boolean value. I can enter the cell in edit mode, but keystrokes don't work. I'...
3
votes
1answer
87 views

How to export a layout in standalone script with QGIS 3? [closed]

I'm trying to automate map export from a QGIS project in a standalone python script, without interface. Many of the scripts founds are for QGIS 2. For example the script written by Tim Sutton here. ...
2
votes
0answers
22 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
votes
0answers
29 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 ...
1
vote
1answer
63 views

Making automatic updated date and time field in QGIS

I wish to create a field which automatically updates with the current timestamp when edits are made to a feature. I am using QGIS 3.4 and I am testing this using a shapefile. Following @Joseph's ...
6
votes
1answer
90 views

Draw streets with bridges using “feature rendering order” instead of “symbol levels” (QGIS3)

To control rendering orders of symbols, you could use the "symbol levels"-feature to give every geometry a own Z-dimension. If you want it dynamically because of complex situation like bridges over ...
1
vote
1answer
38 views

Source of QGIS (3.x) Processing Tools

Is it possible to access the Python source code of the processing tools in QGIS 3.x (for example the Package layer tool) or is there a central code repository available?
1
vote
1answer
37 views

Selecting Features in Visible Viewshed Areas using QGIS?

In QGIS 3.2 I have a viewshed raster and a shapefile with point features I'd like to select the points that intersect the visible areas of my viewshed. Is there a way to extract a vector of my ...
0
votes
0answers
42 views

libqgis_core.so.3.4.1 is missing (ubuntu 18.04)

Wile I was trying to amateurish solve the problem of that post: QGIS 3.4.1 crash without error after opening "options" (18.04. Bionic Beaver) I got a new, much more dramatic problem: /...
1
vote
1answer
122 views

PyQGIS import csv- QGIS 3.4

This is seemingly pretty simple. I have a csv file I want to add to the map. It is comma delimited and there is no lat/lon information. I will join it to a shapefile later. I used other examples from ...
3
votes
3answers
139 views

Draw line to next feature with distance as label (dynamic)

I would like to dynamically draw the shortest line to the next object (Geometry Generator?). Example: I have a network-layer (streets) and a point-layer. I know the distance from every point to the ...
3
votes
2answers
69 views

Moving a geometry using PyQGIS3

I have a layer which has one feature. I try to move the feature(multipolygon) using the script below: layer = iface.activeLayer() for feat in layer.getFeatures(): prev_pos = feat.geometry()....
2
votes
0answers
18 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 ...
1
vote
0answers
60 views

QGIS 3 Madeira Move Point Features Button

In QGIS 3 "Madeira" and "Bonn" I miss the button that allows you to move point features. Any ideas?
3
votes
1answer
70 views

How do I change the font in the QGIS Script Editor?

How do I change the font in the processing script editor? I loaded 3.4 today and it works, but the font in the editor is not set to a monospace font for English, making spaces and positions extremely ...
1
vote
1answer
34 views

Exporting separate images from one layer with categorised data

this may be a poor first question but it's been niggling me most of the afternoon! I'm trying to export a series of images from QGIS 3 based on the categorisation of the data in one layer but only ...
0
votes
0answers
91 views

Exporting maps in QGIS 3.4 with different proportion than A1 [duplicate]

As a default, in the 3.4 QGIS print composer the maps are made with an A1 proportion. The A1 relation is 841 mm Height to 594 mm Width. Is it possible exporting a map with some other relation?
0
votes
0answers
30 views

Qgis 3 Plugin, determine the kind of unload

Is there a way, a signal or another, to determine which way the unload function was called? by quitting Qgis by unloading the plugin by removing the checkbox in plugin dialog by de-install the plugin ...
1
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0answers
60 views

QGIS3 Layouts - report function

I'm trying to create a report using the new functionality in the QGIS composer layouts. I have successfully followed the North Road blog post (https://north-road.com/2018/01/23/exploring-reports-in-...
2
votes
2answers
81 views

qgis2web and keep the data in database

I just found the qgis2web plugin, what a nice plugin! Is there any possibility/option to keep the data in a database?
0
votes
0answers
17 views

How to place a feature form in a composer on QGIS 3.x

Is there a way of displaying the form of a feature inside a print composer instead of a table atribute? ideally what I need is to show on the side of a atlas map the forms of the features inside the ...
1
vote
1answer
67 views

QGIS3 in custom application via PyQGIS (Linux)

I am trying to establish a QGIS3 custom application under Linux (Arch Antergos), according to the documentation (section 1.4.2) the following should work (but it doesn't). I executed the subsequent ...
1
vote
1answer
29 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
32 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 ...
1
vote
0answers
68 views

QGIS3 Python Export PNG after layout resize

I have maps being created that have nice colour banding on them for the contours. I want to be able to export the legend for that colour banding as an image so it can be imported into another ...
1
vote
1answer
24 views

QGIS Bonn - Trying to use query builder to exclude multiple test strings

I am entering "textString" != 'Hilltop' OR "textString" != 'Amberley' in to the Provider specific filter expression in order to EXCLUDE these two names in OS Cartographic text. The query correctly ...
0
votes
0answers
37 views

QGIS 3.2.3 attribute table conditional formatting does not auto update

I've enabled some simple conditional formatting in the attribute table for QGIS 3.2.3 and whenever I've saved layer edits that should change the formatting, the formatting doesn't auto-update - it ...
0
votes
1answer
50 views

QGIS crashes when setting new Symbol to layer with python

I followed the QGIS 3 cookbook and created a new custom symbol layer class. But when I try to create a new the symbol, QGIS crashes. I create it like this. symbol = QgsMarkerSymbol({FooMarker(20)}) ...
0
votes
0answers
73 views

pyinstaller package of pyqgis 3 standalone program failed import PyQt5.QtGui

PyInstaller versions 3.4.1 and 3.5.dev0+268f57a06 were used to package up a standalone pyqgis 3 (Bonn) application. It fails when loading module hook "hook-PyQt5.QtGui.py" with the following errors: ...
0
votes
1answer
52 views

Set size of a simple marker Symbol in QGIS

I am having trouble setting the size of a simple marker. My marker is a circle and I want it to have a radius of 500m. How could I possibly do this? The only options that I see are Millimeters, Points,...
1
vote
0answers
71 views

QGIS 3 on Mac, Can't run semi-automatic classification system plug-in

I am trying to use QGIS 3 as it has a feature the previous version does not have, and have run into an issue when trying to run the semi-automatic classification system plug-in. Instead of opening up ...
1
vote
0answers
58 views

How to render a vector layer using a QgsMapCanvas in QGIS 3? [closed]

I updated this ShapeViewer Demo for QGIS 3 and the layer does not render. All that shows is a white rectangle. The updated code is here. What am I missing?
0
votes
0answers
12 views

Buffer tool returns huge buffer in QGIS3 [duplicate]

I am trying to apply a buffer in QGIS3 using the buffer tool. The layer I apply the buffer is a CSV layer with EPSG4326-WGS84 reference system. In the first image are my points. When I apply the ...
1
vote
1answer
92 views

Access string output of QGIS 3 processing script in graphical modeler

In the good ould days of QGIS 2 I created a processing script, that takes as input a table and a table field (table has only one record) and returns the string attribute value of the table field: ##...
1
vote
0answers
42 views

How to create pattern fill via geomtry generator in QGIS3?

I would like to style polygon layer using geometry generator to create point patterns but using just generated points geometry. Is it possible? How can I achieve that? I know that I can use just use ...
1
vote
0answers
28 views

Set mandatory output format and folder in graphic modeler

I'm working with the graphic modeler in QGIS3.2 Bonn. I have created some models and they work quite well. In order to make them more easy to use for others: Is it possible to set the output format ...
1
vote
1answer
138 views

Vector Fields as Input Variable in Field Calculator

I’m working with QGIS 3.2 Bonn and I try to build a workflow in the graphic modeler. The model aims to build variable buffers depending on values from two attribute fields of an input vector layer. ...
3
votes
1answer
57 views

Stop QGIS from printing true in python console when updating records

How can I stop QGIS from printing True twice in python console for each updated record? This is slowing down the calculations. Example: layer = iface.activeLayer() with edit(layer): for feature ...
2
votes
1answer
91 views

How to change labels language on XYZ tiles

I added quite a few XYZ tile basemaps to my project, they all come out with Hebrew letters (I am in Israel). I overridden the ISR locale with no success. I gues there is a URL parameter that will do ...
1
vote
1answer
411 views

Heatmap Processing Exception in QGIS 3.2

I am working through training exercises with the Alaska training data using QGIS 3.2 on Windows 8. To create a Heatmap, I load the airports shapefile. I cannot find the Heatmap plugin using the ...
1
vote
0answers
368 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 ...
0
votes
1answer
152 views

Unable to clip by mask a raster in QGIS 3.2

OS: Windows 8 with QGIS 3.2 when attempting the following clip-by-mask exercise, the result works on 2.18 but not 3.2. The data I am using is the QGIS training data with the Alaska Shapefile and ...
1
vote
0answers
43 views

Generate additional files with map meta information using QGIS3 Atlas

I am using QGIS3 Atlas/Layouts to generate thousands of PDFs from a coverage layer. In addition to the PDFs, I want to save meta information (place names, dates, coordinates, custom IDs, etc) ...
2
votes
0answers
88 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 ...