Questions tagged [qgis-3]

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

989 questions with no upvoted or accepted answers
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8
votes
1answer
388 views

Point cluster symbology for different categories without overlapping symbols

I'm trying to visualize crimes based on if the crime happened during day or night time. I've tried using the point displacement tool but I'm not satisfied with the results because the readability for ...
6
votes
0answers
71 views

QGIS 3 Display negative values bar diagrams

Suppose I have a dataset with an id (for each geographic entities) and 2 numeric fields NUM1 and NUM2. These numeric fields have positive and negative values. When I use bar diagrams, only theses ...
6
votes
0answers
1k views

QGIS 3.4 and loading raster from multiple variable NetCDF file

Using QGIS version 3.4.4 when loading a NetCDF file out.nc which contains multiple variables on a fresh Ubuntu 18.04 install I encounter the following error: CRITICAL Invalid Layer : Raster layer ...
6
votes
1answer
262 views

Setting grid in QGIS that automatically adjust its intervals?

I am setting a template for multiple maps in QGIS 3 Layout and i was wondering if there is a way of automatically adjusting the grid's interval as a function of the scale of the map? I did a bit of ...
6
votes
0answers
892 views

Join attributes by location very slow on QGIS 3.0

"Join attributes by location" is very slow on QGIS 3.0. I have tried it with a CSV file and also with a shapefile (point layer) and a grid (made of polygons). On QGIS3.0 it takes about 3 hours to ...
5
votes
1answer
1k views

QGIS GRASS Processing Not Working on MacOS?

Recently upgraded to QGIS3 (3.0.2) for MacOS (High Sierra) and encountered GRASS (7.2.2) issues. Tried adding a custom variable and now when running GRASS algorithms (e.g. r.reclass) I get the ...
4
votes
0answers
73 views

+0-180 degrees of mesh layer are displaying as horizontal lines [QGIS]

I have been trying to display weather data from ECMWF in QGIS on top of a base map, but half of the heatmap rendered from the mesh layer (imported via grib) displays as straight horizontal lines. I ...
4
votes
0answers
34 views

How to use all QGIS 3 custom widgets in Qt Designer?

For example, QGIS 3.4 has various custom widgets such as QgsFieldValuesLineEdit and QgsColorWheel (and later versions have even more widgets) but they are not listed in the QGIS custom widgets list of ...
4
votes
0answers
56 views

Creating child entries in QGIS form with Spatialite many-to-many relationship

I am trying to reproduce the example from Introducing many-to-many (N-M) relations using Spatialite. Creating the tables and the relations works fine, but when I try to create a child element in a ...
4
votes
0answers
45 views

QGIS processing tools - saving/exporting graph

I just tried QGIS processing tools for the first time. When using shortest path search for the first time, the algorithm is building a path graph (of course). However, the graph is never re-used. ...
4
votes
0answers
80 views

Select extent on canvas - QGIS Plugin

I'm designing a QGIS plugin where I'd like to offer the user the functionality to select the extent of a bounding box from the canvas like in some tools like Create grid. I've explored QT Designer ...
4
votes
0answers
79 views

Showing labels as they will be printed/exported in my print layout?

I set up a print layout for a map I want to print in QGIS. Some of my layers have labels on them. When I zoom in and out in the screen, without changing anything else on the print layout, some labels ...
4
votes
0answers
55 views

Measure loading times of QGIS projects

For QGIS there is already a method to measure loading times of plugins ( qgis.utils.plugin_times): How to tell which QGIS plugins are slow to load? Is there something similar to measure loading ...
4
votes
0answers
82 views

Using Python code from QGIS 3.x Graphical Modeler in console?

I want to use "Join Attribute by Location (summary)" processing algorithm in Python console of QGIS 3.10. After design my algorithm process (join sum of field name "abc" form layer 2 (point layer) to ...
4
votes
1answer
92 views

Distance between points along line

How do I determine the distance between points to the neighbor point that connected via the line(road)? In QGIS 3.8.3 I have tried v.distance and v.net.distance but they do not help. The line(roads) ...
4
votes
0answers
66 views

QGIS 3 3D Marker

In the 3D view I add 3d.obj files as Marker.works very well. Is it possible to add different 3D markers on different layers or categories. When I use 2 different layers with different obj files 3D ...
4
votes
0answers
76 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, ...
4
votes
1answer
181 views

Symbol in layers panel not visible

I have a layer with symbology that includes geometry generators. It would appear that because of these the symbol is not visible in the layers panel. Is there a way to show the up most symbol (green ...
4
votes
1answer
106 views

Joining attributes by location error when finding polygons within district boundaries?

I am using QGIS 3.5. I have a large shapefile (760 MB) with 1800 polygons representing different bird species ranges (download link) I have a second shapefile with polygons of district boundaries (...
4
votes
0answers
848 views

CadTools plugin functionality in QGIS 3 beyond Advanced Digitising Panel?

I've recently migrated to QGIS 3.6.0, and I've realised that the wonderful CadTools plugin is not compatible with QGIS 3. I tried to use the Advanced Digitising Panel, but it's cumbersome and not ...
4
votes
0answers
88 views

QGIS Server Adding a virtual layer

All my layers in the qgs-project-file are working fine as WMS-layers, but I only can't provide the virtual layer. The virtual layer is an ODBC-Connection of an Access-Database which contains one ...
4
votes
0answers
89 views

How to render features that are just outside the map canvas extent in QGIS 3.4?

I am trying to generate a cloudy mask, following the recipe in "Qgis Map Design 2nd ed. Edition". For the most part, I have it working. But when panning around, the mask changes. And I think that ...
4
votes
0answers
1k 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 ...
4
votes
1answer
573 views

Backup QGIS (3.2.1) layer to independent PostGIS table?

I'd like to make multiple, progressive backup copies of QGIS (3.2.1) layers that are stored in PostGIS tables. I've tried multiple routes to export them as files on disk, but they all seem to destroy ...
4
votes
0answers
110 views

QGIS rule based symbology for rasters in Atlas?

I'm making species distribution maps and have got the Atlas working perfectly using a polygon layer to show the quarter degree grid cells for species observation records. I have ~ 250 species. Problem ...
4
votes
0answers
232 views

Unable to connect to postgres server in Database Manager

I try to connect to my postgres server, hence I got this failure And following error: 2018-04-26T18:02:05 WARNING Traceback (most recent call last): File "C:/OSGEO4~1/apps/qgis/./python/...
4
votes
0answers
237 views

Connectors do not appear automatically in easy custom labelling

I'm using the easy custom labelling plugin in QGIS 3. When I move a label away from its associated polygon a connector does not automatically appear as in QGIS 2.18. How do I get connectors to appear ...
4
votes
2answers
481 views

QGIS 3.6 picture in ui form (Qt5 Designer)

I'm facing trouble with display a picture in a ui form based on a field (path). With the autogenerate form it works but when I try with a personalized form I cannot see the picture. I tried with a ...
3
votes
0answers
33 views

Using the conditional branch algorithm in QGIS modeler gives unexpected results

I'm trying to implement the new conditional branch algorithm in a model with the following statements: if( @Udtræk_til_grøfter_OUTPUT > 0, true, false) if( @Udtræk_til_grøfter_OUTPUT <= 0, ...
3
votes
0answers
36 views

Selecting features by current map extent in QGIS 3

I'd like to select all features in the current map extent that also satisfy some other condition via "Select by Expression". For instance I'd like to do something like this: intersects($...
3
votes
0answers
50 views

QGIS 3.12 - Setting Project default CRS causes “Ballpark Transform”

I'm coming across an issue that I am unsure of whether it is a bug or the result of my error. My work data is all projected in NAD83 (CSRS) / MTM Zone 10. EPSG Code: 2952. I set QGIS to default to ...
3
votes
0answers
32 views

Creating an HTML-style label item in the layout that links to an anchor in the page

Initial research tells me this might not be possible, but let's try it anyway. In a Layout, I'd like to have an HTML-rendered label near the top of page 1 like: <a href="#table">Jump to table&...
3
votes
0answers
106 views

QGIS QMessageBox in a personalize form

I want to personalize a form in QGIS 3.4. Just a basic case: when a user open attributes table, a message box fire up. For an incomprehensible reason this message box open a first time, I click "OK" ...
3
votes
0answers
40 views

Automatically installing plugins on QGIS, deploying QGIS plugins on an IT infrastructure

My company is preparing a default QGIS configuration file (qgis_global_settings.ini) for deploying on a great number of MS Windows workstations. We have selected a few QGIS plugins we want to be ...
3
votes
0answers
41 views

Delete “children” feature, if “father” feature is deleted, inheritance

I am developing a dimensioning tool, and I would like that the "son" feature been deleted, when the father is deleteted, (on the fly). How can I do this? It can be done via application or PyQGIS. ...
3
votes
0answers
35 views

Evenly spaced labels for polyline layers

I'm using QGIS 3.8 and am attempting to label roadway segments (OSM) of varying length. By checking the "Merge connected lines" box and hiding features below a certain size, I can generally limit the ...
3
votes
0answers
83 views

QGIS C++ 3D Map Scene

I want to use QGIS with c++ api like ArcGis runtime sdk. I tried to use Qgs3DMapScene class like QgsAbstract3DEngine *m_window3DEngine; Qgs3DMapSettings *m_mapSettings = new Qgs3DMapSettings; ...
3
votes
0answers
95 views

Creating convex hull by expression by aggregating points

I would like to recieve the centroid of a convex hull of a group of points in a layer, grouped by its name. This needs to be done by expressions, available in QGIS 3.4. E.g. I have this list of points:...
3
votes
0answers
77 views

Processing script returns no layer

I am trying to run a processing script without a user defined layer output. The example below should create a vector layer with one point. The script runs without any error but the layertree is empty. ...
3
votes
0answers
167 views

QGIS 3.10.x WMS Problem

Using Ubuntu 18.04. I have problems loading UK Environment Agency WMS layers. This first arose when I installed QGIS 3.10 and persists in QGIS 3.10.1. It appears that when QGIS makes a WMS request ...
3
votes
0answers
37 views

Delineating zones based on number of polygons that are in overlay

I am working in urbanism and I have a number of polygons that represent perimeters where certain "programs of revaluation" have been carried out. However, as can be seen on the map below, over time, ...
3
votes
0answers
25 views

Deleting input vector or raster being used in QGIS 3 modeler

As it is explained in the title I am writing a script to process this task. The script is already written but I need it to be triggered when the inputs are not needed anymore. In other words : I need ...
3
votes
1answer
131 views

Invalid geometry in point layer when running 'Count points in polygon'

I have a persistent problem I can't seem to fix. I'm trying to run Count points in polygon. I keep getting this error: Feature (747) has invalid geometry. Please fix the geometry or change the ...
3
votes
0answers
49 views

How to reimport a QGIS 3.10 Vector-GeoPDF, generated from layout manager, so that all items not belonging to layers are hidden?

I'm very impressed with the new GeoPDF export capabilities of QGIS 3.10 (Windows 10). Now we can create Vector-GeoPDFs with layers included! With the help of GDALs "Geospatial PDF" file format ...
3
votes
0answers
53 views

Different distance when using “Measure Line” tool and manually with scale in QGIS 3

Using QGIS's "Measure Line" tool I get a distance of 1.22km between two points. But if I use the scale indicated at the bottom of the screen, 1:50000, and measure with a ruler, the distance is 2.5km (...
3
votes
0answers
34 views

Find distance between multiple discrete sets of points QGIS3.8

No similar question seems to relate to my issue but I desperately need help with calculating distances. I have a CSV with the residential postcode of 200 000 patients. For each patient, I also have ...
3
votes
0answers
49 views

PyQGIS Layout - Change Image Source QGIS 3

Looking for a solution to loop through existing layouts in a QGIS 3.6 document and change a source of an image. The image is the same in each of the layouts. What I have is: from qgis.core import ...
3
votes
0answers
49 views

“Bring All to Front” is missing in QGIS 3

I am using QGIS 3.4 and 3.10 and a plugin's window ends up hiding behind the canvas. In QGIS 2.10 I had the option "Bring All to Front" to bring all windows to front. Is there an alternative for it ...
3
votes
0answers
45 views

Joining attributes from points to polygon

I am working with two shapefile, polygons and points. These shapefiles do not overlap and have different attribute values. The point layer contains data that I want to join to the beginning and end ...
3
votes
0answers
110 views

Error while running batch processing in QGIS 3

I have built a straightforward model in the Graphical Modeller in QGIS 3.4 to select features by expression and then save the selected features to a new shapefile. It works when running singly but ...

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