Questions tagged [qgis-3]

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

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12 views

QGIS: Return if a value/string if a Geometrie had to be simplified by the Simplify Geometry proces

To kind of automate some length and value caluculations I have created a model to just let a Line Layer from an DXF go through it (the layers get selected out). I had to introduce an extra step to &...
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7 views

PyQGIS: cropToContents does not work properly

I have a template qpt which I read via pyqgis script to export multiple maps as png. I have a map and a legend in qpt file and I chose "Only show items inside linked map" so the legend shows ...
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1answer
78 views

Open .laz point clouds not available in QGIS 3.18

The recent release of QGIS 3.18 supports point cloud data. As can be seen on the screenshot in the linked Visual Changelog (above), .laz files should be supported. However, in my installation on ...
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23 views

How exactly does QGIS compute the 3D Tiles for rendering a 3D Map View

In QGIS, we can click "View > New 3D Map View". This allows us to see our map in 3D, as long as we have a DEM layer available. But QGIS takes some time to actually compute the 3D tiles ...
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1answer
42 views

Missing parameter INPUT_A in qgis:rastercalculator

I simply want to sum up two rasters with PyQGIS. To this end, I'm trying to use the qgis:rastercalculator but I encounter an error. Here's the code: import processing output_layer = '/tmp/result.tif' ...
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1answer
40 views

Can QGIS open the file type .pitemx or .pkinfo?

The following file types are associated with ArcMap(.pitemx) and ArcGIS Pro(.pkinfo). Can QGIS open the file types .pitemx or .pkinfo? Please see the example image & weblink below for where to ...
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1answer
35 views

Missing results from ReshapeGeometry method on PyQGIS

I am trying to use the method reshapeGeometry from QgsGeometry class in a script to reshape a feature geometry (polygon) according to a line. The result of the process is 0, so positive, but I can't ...
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20 views

QGIS: $area calculation returns NULL while I can see the derived Area (Ellipsoidal) in feature info [closed]

In QGIS 3.10.14, I am adding a column to the Attribute Table of a Natural Earth shapefile (polygon) (US states; https://www.naturalearthdata.com/http//www.naturalearthdata.com/download/110m/cultural/...
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1answer
28 views

Remove annotations

Is there a way to remove annotations from a QGIS project? Can I navigate to a folder and delete them instead of going into the map canvas and deleting them there?
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2answers
46 views

QGIS: copying a value from one row to another one in the attribute table?

I'm trying to replace the values of the column A and B by the value of the row 1 and row 2 of column C. (15B70C should be replaced by 63F200 and 94JH5 by 35V145) How can I automate that in the ...
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1answer
19 views

How to make multipart feature call outs start at the same point from the annotation text in QGIS3

I have a map showing multipart features and map text. The text is too large for the features so I want to use call outs but the call out lines extend from the text in what appears to be the shortest ...
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31 views

Is there a plugin for calculating the walking time in QGIS 3

In the previous QGIS version there's this plugin: Walking time but it's not compatible with QGIS 3. Is there another plugin doing the same thing?
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1answer
23 views

Raster product in PyQGIS does not produce correct results

I'm trying to mask (set with no data values) pixels in a raster not fulfilling a condition based on another raster. It runs well but it produces huge numbers that are not the values in the raster that ...
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10 views

Distance between two vector lines in each east-west raster row (in QGIS)

I have 2m-resolution raster LiDAR data of a marsh edge from two moments in time and I am trying to calculate how much the marsh has "retreated" between the datasets. I used the LiDAR data to ...
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2answers
38 views

How to enable Python scripts in processing toolbox in QGIS 3.16

I'm not able to enable Python scripts in the processing toolbox. It should turn up in the toolbox (see the third screenshot). The Python logo is also missing from the toolbox. Is there something wrong ...
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1answer
33 views

World Topographic Map in QGIS is blocky pixelated

The ArcGIS World Topographic Map in QGIS is pixilated, specifically the text and lines. View the images below in full screen to see the blocky pixelation. How can the World Topographic Map be added to ...
2
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1answer
77 views

PyQGIS: deleting selected features

I have been facing issues trying to achieve a very simple task which consists in deleting selected features with pyqgis. Here is a sample of my code : I select manually the features of the shapefile ...
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20 views

QGIS spline plugin tool cannot be imported

I'm using QGIS 3.10.14 and installed the spline plugin for digitizing curves. However, I get the error message below when I try and load the spline plugin. Traceback (most recent call last): File &...
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1answer
39 views

Clipping/Splitting line layer based on another layer line running in parallel/alongside it using QGIS

I know how to Clip layers files based on another layers thanks to the Geoprocessing toolbox but how do I clip/split a line layer based on another line that is following parrelel/allong side it? Look ...
4
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1answer
67 views

Bivariate legend plugin throws NameError exception

While using QGIS 3.10 and 3.16 on Mac OS X Big Sur, the Bivariate legend plugin throws a NameError exception. How do I fix this or work around it? The following stack trace is from QGIS 3.10. The 3.16 ...
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1answer
15 views

Georeferencer Plugin: Installed but does not appear in raster menu (QGIS 10.3, Windows 10)

I see that others have had problems finding a rouge georeferencer window, or using the plugin. But when my student tries to use the confirmed installed georeferencer plugin in QGIS 3.10 on Windows 10 ...
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0answers
21 views

Allowing identification tool to click on symbol instead of feature in QGIS

Working on a rather crowded map, I would like to ease the identification of colocated point features, each one linked to a photo. I usually have 2 or 3 photos on the same point and would like to keep ...
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1answer
40 views

Measure distance between 2 points on curve line

I am using QGIS 3.10 version. Since, i am new to QGIS. Could someone please help me solving my confusion ? Image those 2 blue lines are points. How to measure the white line between those points.
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1answer
45 views

Save and load the classes definition table in the QGIS reclassify by table tool

I'm reclassifying an aspect raster which cells values ranges from 0 to 359.999 using the Reclassify by table tool: Setting the reclassification table manually is painful, especially when you have ...
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32 views

QGIS keeps crashing when exporting print layout map - how to stop this?

When exporting my map which contains vector data and two maps (one as a global locator insert map) as an SVG file QGIS keeps crashing. I need the map to be exported as an SVG file as I want to edit it ...
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1answer
114 views

Why QGIS crashes when constructing QgsGraduatedSymbolRenderer object by QgsGraduatedSymbolRenderer.createRenderer() method?

Today I want to render a vector layer in QGIS by using PyQGIS QgsGraduatedSymbolRenderer renderer. When I directly construct it by using the constructor, it works. But when I want to use the ...
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0answers
50 views

Obtaining file path in QGIS Training Manual

6.2.5 Try Yourself: Convert Layers’ CRS ... 8. Repeat this process for each layer, creating a new layer in the vector_analysis.gpkg GeoPackage file with _34S appended to the original name and removing ...
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27 views

When I add a layer by uploading .shp file in QGIS in layer order Its greyed out, unable to edit. using QGIS 3.16 [closed]

here on left hand side layer order the sweden counties are greyed out.
3
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1answer
24 views

Export theme and its associated layers in xml file in PyQGIS

I was trying to export all themes and its corresponding layers information through PyQGIS so that xml can be read later .There is method in Class: QgsMapThemeCollection, writeXml(self, doc: ...
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1answer
28 views

KML layer not saving, invisible styling

I have two issues, one related to saving edits on a vector layer, the other related to the visibility of layers, and I'm assuming they have the same root cause, so I'm posting it as a single question. ...
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2answers
38 views

Displaying raster layer in QGIS without any formatting

I have nine adjoining DEM layers (3x3) styled as 'hillshade' but there are some obvious artefacts, particularly where tiles meet. I've exported the hillshade layers to TIFFs in QGIS using the '...
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28 views

Calculating polygon areas in QGIS generates NULL results

I'm having a problem using QGIS and can't find a solution ... I searched this site and found a similar question (QGIS $area field calculator always produces NULL -produces-null), but I couldn't solve ...
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17 views

Why do I get a classFactory error when I run the PlanHeat QGIS plugin?

I am getting the error below when I try to load the PlanHeat plugin for QGIS. "Couldn't load plugin 'planheat' due to an error when calling its classFactory() method " "ImportError: ...
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13 views

QGIS' 3.x - Atlas feature not printing second pdf page

So, I have created a layout managed by Atlas; every layout has 2 A4 pages, one with the atlas view and another with a table based on visible objects. It works perfect when printing to paper (duplex), ...
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0answers
19 views

QGIS Legend for multi-band Raster

Is there a simple way to generate labels for a multiband Raster in QGIS like it is implemented as Default in ArcGIS? I want to write a Variable Name of each Band in the legend ArcGIS example:
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32 views

How to colour vector tiles based on filter in QGIS 3.16

I have a vector tiles layer that displays fine in QGIS 3.16: A fill without a filter works as well: However, the fill based on a filter on the feature properties does not work (result can be seen in ...
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1answer
20 views

Qgis 3.16.3 - tk package, ModuleNotFoundError: No module named '_tkinter'

I am developing a plugin that uses tk package. When I tried to import tk I got an error: ModuleNotFoundError: No module named '_tkinter'. I tried to reinstall tk but it didn't work. I would say that ...
1
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1answer
26 views

Substitute new CRS for one specified in the Training Manual, Module 6, Lesson 6.2.5?

This question came up on the page at the link https://docs.qgis.org/3.16/en/docs/training_manual/vector_analysis/basic_analysis.html. 6.2.5 Try Yourself: Convert Layers’ CRS Item 6. Change the [CRS] ...
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25 views

Projection issues with QGIS 3.16 Swellendam Training data

I am following this QGIS 3.16 training, following it exactly as shown (https://docs.qgis.org/3.16/en/docs/training_manual/vector_analysis/basic_analysis.html), using their provided training data. And ...
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0answers
16 views

Splitting multigeometries in a Virtual Layer (SQL query)

I have a virtual layer already set up and working, the only thing that could make it better is getting rid of multipart geometries. The query is: SELECT ejido, circ, radio, mzna, cc, ten, registrado, ...
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1answer
24 views

Exporting layer symbology using PyQGIS

I need to save the symbology of several layers and I would like to do it with a PyQGIS-3 script. I think I have to use the QgsMapLayerStyle class but I don't understand what is a QDocument and how to ...
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0answers
21 views

QGIS: vector union produces a single feature only, same as the input layer

I have two layers in QGIS 3.16, a MultiPolygon layer with a single feature, the area of Papua New Guinea a MultiLineString layer of OpenStreetMap roads, clipped to the extent of the first layer ...
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0answers
9 views

(QGIS 3.16) Trouble with an SQL output generated from an OD-Matrix [duplicate]

I recently ran an SQL output in order to compress my Origin-Destination Matrix based off fastest travel time. The resulting SQL should have reported 2478 routes, but it only computed 2458 routes. I am ...
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0answers
30 views

Specify absolute center for bi-directional color ramp in QGIS?

How do I center the color ramp on '0' for a series of raster with positive and negative values? The values are non-normally distributed. There doesn't seem to be a an 'absolute' option, only relative (...
1
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1answer
40 views

PyQGIS. Field calculator based on the rank of another field

I am trying to make a script to calculate a field "rank" [RANK] based on the feature rank in another field "population" [POP]. My current script can found below. In this script, I ...
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1answer
35 views

QGIS Query Builder button greyed out [closed]

I want to query features under [Layer Properties] -> [Source] -> [Query Builder] but the query builder button is greyed out. The layer I'm using is from a shapefile with multiple demographic ...
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1answer
31 views

Can't open world.qgs as in Training Manual 6.1.1

I’m working through the training manual located at https://docs.qgis.org/3.16/en/docs/training_manual/index.html. I have QGIS 3.16 running on OS 10.15.7 (Catalina). The following describes my problem: ...
3
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2answers
62 views

Buffer algorithm doesn't work in a new script from template

I use QGIS 3.10.14 and I begin with PyQGIS. When I tried to make a simple script which use the native buffer algorithm, the output layer came out exactly like the input layer, with the same polygons ...
2
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2answers
106 views

Conditional statements PyQGIS

I am looking for a simple example to create a conditional statement in the pyQGIS console. Today I wrote a simple script to add a field [CAT] to a vector layer. This script can be found below. I want ...
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0answers
16 views

Confusing QNEAT3 Exception: Unknown

When I try to run QNEAT3's "OD Matrix as Lines/CSV" function, I am getting a very strange error. Traceback (most recent call last): File "C:/Users/dicki/AppData/Roaming/QGIS/QGIS3\...

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