Questions tagged [qgis-3]

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

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votes
3answers
77 views

Calculating attribute with formula in QGIS

I want to build a QGIS formula where I calculate one attribute from 10 others, and I only need to sum them up. My Problem is, that I don't get the actual values of the attributes. I thought about ...
0
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2answers
31 views

Refresh Oracle and Spatialite Layer with PyQgis

I'm working on a Dockwidget with PyQgis. I made an insert into an Oracle DB and a Spatialite DB and I would like to see the new insert (it's a point). The Layer where the new point is add is ...
0
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0answers
23 views

Checking Performance of QGIS plugin using PyQGIS

I wrote a Qgis Plugin and I used setAutoRefreshInterval on my layer. I would like to see the impact on time and memory. Also, sometimes I've different way to do what I want, and it would be usefull ...
2
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1answer
22 views

Adding value options in feature attribute table?

I cannot figure out why it says NULL, my goal is to be able to pick values from a classificator table made in Excel and imported into QGIS as a vector layer.
1
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0answers
22 views

Loading CSV file without geometry in graphical modeler

I'm trying to use the graphical modeler to make a join between a vector point layer and a CSV file which doesn't have geometry data. I tried to use 'Vector layer' as an input for the CSV-file but the ...
2
votes
1answer
233 views

Customizing QGIS interface?

I'm trying to customize QGIS 3.4 interface to allow data display only. None of the default QGIS geospatial data editing functionalities should be exposed to the end user. Also, the users should not be ...
2
votes
0answers
96 views

Customise splash image [duplicate]

I would like to change the splash screen of QGIS 3.4 LTR. I read the instructions from Customise the splash image of QGIS but I didn't manage to change it. Does the overwrite of the splash screen ...
2
votes
3answers
309 views

Re-docking/pining panel in layout window in QGIS?

Using QGIS v3.4.4 and accidentally closed the "Item Properties" and "Items" panels in the layout window. Cannot now get them to re-dock/pin back into place. They will only float. Have googled ...
3
votes
1answer
45 views

QGIS 3 shows and saves raw default-values from spatialite-tables

QGIS shows default values from sqlite tables as string in the edit-form when i try to create a new row. After save, the raw default values are stored in the table. How can i edit in QGIS LTR 3.4.7 a ...
1
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0answers
47 views

How to properly label colliding labels in QGIS 3.x

Is there a way to properly show the labels when "Show all labels for this layer (including colliding labels)" is selected from label properties? I was looking for adding callout lines for the labels ...
4
votes
2answers
96 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 ...
0
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2answers
32 views

How to Identify/Select features from WMS?

I'm trying to extract some features from the following WMS: http://servicios.idee.es/wms-inspire/hidrografia Namely, one layer called "Red hidrografica", which contains the traces of rivers and ...
1
vote
1answer
26 views

QGIS Raster calculation fails in Graphical Modeler

I'm trying to use the graphical modeller to automate a certain process (extracting North-South facing slopes from a DEM). The process is as follows: Calculate Slope Calculate Aspect Extract North-...
1
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0answers
34 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 ...
2
votes
0answers
36 views

Keeping a custom form permanent

I'm adding a custom form to one of my attributes fields, I want to create a drop-down menu where there is predecided values to choose from. I'm going into the layer property>Forms>Selecting the ...
2
votes
1answer
56 views

Getting current map scale in PyQGIS

I'm trying to get the current map scale in PyQGIS, running outside QGIS, with: project = QgsProject.instance() root = project.layerTreeRoot() canvas = QgsMapCanvas() bridge = ...
6
votes
3answers
305 views

Insert n points equally distributed into many polygons

I know the "Random Points inside Polygons" tool in QGIS. It generates the below output. What I want to achieve however are 8 equally distributed points for each of the polygons. I thought of dividing ...
2
votes
0answers
39 views

How can I set which layers are visible by default in a geoPDF?

I'm using the latest QGIS version 3.10 that has the option to export to geoPDF. Currently the output has all layers visible. I'd like to set which layers are visible by default, so that the user is ...
3
votes
3answers
78 views

Testing different values in one CASE WHEN ELSE

I am making an inventory of certain buildings in a city. In the object attributes, I'm - amongst other infos - linking to pictures of that building, so that in the layout, for each building, you have ...
1
vote
3answers
41 views

QGIS labeling: expression that shows values from one attribute except when the objects has a value x at another attribute

I want to label each object of my layer with the values of a certain attriubte. However, if an object has the value "1" at another attribute, this label should be invisible or not rendered. Any ...
2
votes
1answer
31 views

Persisting layer tree between QGIS instances using PyQGIS

I have been working on a PyQGIS project for a bit, and I have been using QgsProject.instance().addMapLayer to add layers to the map. However, now I need to add layers to my canvas and legend in ...
0
votes
1answer
37 views

QGIS 3.10 - Python problem with double for loop

I am new to Python and I am trying to write a custom function which iterates through a table of points and adds a field with all of the lines that touch it. At the moment I am getting a partially ...
1
vote
1answer
35 views

How to make a polygon from contour lines extracted from a raster QGIS 3.6?

I'm trying polygonize the elevation level 200 m of Europe map from raster GeoTIFF (The raster is projected in EPSG:3120). At first I tried with Raster > Extraction > Contour, but the lines are ...
5
votes
1answer
190 views

Adjusting query in field calculator in QGIS 3.2?

I have a geopackage file which contains point data with a column of 'depth of cover' and score. In the score column I am using the field calculation to create an expression so that any number less ...
1
vote
0answers
27 views

Identifying line intersection in QGIS [closed]

I have 1 shp line, I want to determine the intersection positions of the roads at 4 the intersection. I used "intersection point at the road" but it gave an unexpected result (picture 1) I want to ...
1
vote
1answer
544 views

How to set the “LAYERS” parameter of the QGIS 3 algorithm “native:mergevectorlayers”

I do not understand how to set the LAYERS parameter for the QGIS 3 native: mergevectorlayers algorithm (for standalone python code). Merge vector layers (native:mergevectorlayers) ... ----------------...
0
votes
0answers
17 views

Adding float attribute to layer using PyQGIS

QGIS 3.10 -- Mac OS I am creating a layer from a GPX file and other data using a script. One of the fields I want to add is a floating point number (a distance). I am accessing the dataprovider ...
2
votes
3answers
2k views

How do I change the snapping sessions for a layer in QGIS 3

In QGIS 2 I would go the the settings menu and select the snapping options but this option is not there in version 3. I have found the snapping options in digitising options but these don't seem to ...
4
votes
1answer
154 views

Using R-scripts in QGIS 3.4

I installed the Plugin, and activated R in the provider options. When I go to the processing toolbox R is available, but I don't have the use online R-scripts, which are mentioned in the documentation....
1
vote
3answers
33 views

Drawing rectangle with geo coordinates (north/south, east/west) using QGIS

I need a layer with a rectangle that maps it's top left and bottom right corners to north/south and east/west coordinates. This is an Area of Interest which I need to overlay another image layer to ...
5
votes
3answers
97 views

Making curved stroke shape of polygon

I have a lot of polygons representing Forest land use type. Is it possible to style these polygons in such a way like on this picture? Example polygon I have now: So the polygon doesn't have edges, ...
1
vote
2answers
64 views

QGIS: Export 3D map in pdf not working

I am trying to export and save a 3D map as a pdf in QGIS 3.10 (using the composer). I am using the native 3D viewer and I am trying to understand how I can export and save it as a pdf. I set my 3D ...
1
vote
2answers
34 views

With QGIS adjacent polygons, is it possible to “copy” one polygon edge to a new one? Like a “snap to” or “smooth to” the adjacent polygon?

I'm drawing adjacent polygons in QGIS. Whenever I create a new adjacent polygon, or if I've moved a polygon that has an adjacent polygon, I need to adjust the borders of the adjacent polygon to be ...
3
votes
0answers
35 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
45 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 (...
2
votes
1answer
36 views

QGIS polygonize issue: GDAL DLL load failed

I am using QGIS Desktop 3.10.0 and I have some issues with the polygonize tool. When I run the polygonize tool, a warning shows up saying that there is an “Import Error: DLL load failed” (see Figure 2)...
2
votes
1answer
467 views

Saving styles for all layers using PyQGIS - SLD, QML, databases

I wrote a script (for QGIS 3) that saves styles for all visible vector layers in QML and SLD files: import processing self=qgis.utils layers = self.iface.mapCanvas().layers() for layer in layers: ...
2
votes
1answer
35 views

Writing txt file from Virtual Layer

I have a Virtual Table which is a result set for a particular process. select "RECORD_IDENTIFIER", CAST ("UPRN" AS textstring) AS UPRN, "KEY", "WARNING_CODE", "EXCEPTION" from Exceptions ...
1
vote
1answer
207 views

Import of CSV vs. Join by attributes Batch

-Using QGIS 3.2- I am trying to join 110 different CSV's with the corresponding shapefiles. I started to use the 'Join Attributes by Field Value' batch process to quickly do this. First, is there any ...
1
vote
0answers
26 views

Distance matrix returns points in wrong order QGIS 3.4

I'm using QGIS 3.4 on Windows 10 and scripting in pyqgis. I have a layer representing building centroids that is in a projected CRS. I want to find the azimuth between each building and its nearest ...
5
votes
1answer
158 views

QGIS Field Calculator Expression - GeoHash32

I am attempting to write a QGIS 3.10 Field Calculator Expression that will use the mz2geohash library to encode the centroid of the current feature as LAT/LON, and then pass this tuple to the ...
2
votes
1answer
580 views

QGIS 3.4 Couldn't load SIP module. Python support will be disabled on Windows 10

I upgraded from QGIS 3.2 to 3.4 and bad things happened. On start-up I get the error. Couldn't load SIP module. Python support will be disabled. Traceback (most recent call last): File "", line 1,...
1
vote
1answer
48 views

QGIS and ArcGIS Pro give different results on spatial join

I have two point layers that one has 2885 and the other has same 2885 plus 1748 more features. The second one is a result of "v.net.centrality" analysis and now I want to join the result spatially ...
1
vote
0answers
83 views

Getting Maxar Premium Imagery in QGIS

When you edit OpenStreetMap you have access to the Maxar Premium Satelite Imagery. That is more recent than other imagery in certain areas. How can I get Maxar Premium Satelite Imagery as a layer ...
0
votes
3answers
274 views

QField sync.FileNotFoundError: [Errno 2]

I am using QGIS 3.4.5 (Madeira) alongside with QField 1.0.3 (Matterhorn) with the QField Sync 3.1.3. Everthing worked fine. I made my Project, made it to a QField-Project (with QFiledSync), then to ...
2
votes
1answer
38 views

How to delete features selected by expression using graphical modeler in QGIS3

I can't find an algorithm for deleting features (points), so I can't delete features in the graphical modeler. I found related information (Select by expression and remove points). However, I want to ...
1
vote
1answer
30 views

How to add points using coordinates to QGIS without having to create a CSV? [duplicate]

Is there a way that I can add single points to QGIS (v3.4) by inputting coordinates directly into QGIS, rather than creating a CSV and adding them that way? I know there used to be a plugin that ...
1
vote
1answer
31 views

Filtering features only in layout

Is it possible to only show one certain point of a layer in the print composer, but have them all shown in the QGis main window? For an inventory of buildings, I want to have an overview of all ...
1
vote
0answers
33 views

Object has no attribute “dlg”

I am creating a QGIS plugin and want to list the layers loaded in a Combobox when writing self.dlg the error message object has no attribute appears. I am new in this domain. The code below is for the ...
1
vote
2answers
61 views

Adding layer from cliprasterbymask using PyQGIS

In my plugin I would like to use the gdal tool "cliprasterbymask" and add the new clipped raster to my project. According to the Documentation the output has the type "raster". So it returns a ...