Questions tagged [qgis-3]

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

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2
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0answers
7 views

Change datasource of multiple layers from one db to other db in QGIS project?

I have a QGIS project with around 100 layers referring to a postgres database. Since we're migrating to a new server, the database will be transfered too, but will be given a new IP. The connection ...
2
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0answers
78 views

Query a QGIS server WMTS using a RESTful URL as defined by the OGC

Context I'd like to use the WMTS from a QGIS server to serve a raster image as a base map in OpenStreetMap. Description of the issue I have set up a QGIS server to serve my raster image. Both WMS and ...
0
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1answer
24 views

Performing land cover classification over whole country

I am doing land cover classification over the whole country of Djibouti. I am downloading Sentinel 2 images for this purpose. I have realised doing land cover classification over a large area needs ...
0
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1answer
65 views

QGIS function like ArcGIS Planarize

I have a city road network. I have to divide sections that are separated by intersections into one level. With ArcGIS this is done with Planarize. I tried split commands, but it applies to all ...
4
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2answers
147 views
+100

Display lines which share segments by offsetting them only where they overlap?

Background: As part of a route selection process I have multiple route options which often share segments. I need to keep the underlying data correct while displaying all routes in a way that they ...
1
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1answer
147 views

Setting selection border color in red and save the map of the resulting selection

I'm attempting to create a plugin in QGIS 3 in order to zoom on a selected feature and get the map picture exported in .jpg format. I've been able to perform the zoom and selection of my selection, ...
0
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1answer
50 views

Do SAGA tools work on QGIS 3.10.7?

Is anyone successfully using SAGA tools in QGIS 3.10.7? I have downloaded QGIS 3.10.7 on multiple PCs and a Mac. All of them have resulted in the same problem when I try to run SAGA tools. A message ...
0
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1answer
25 views

Where is the source code of QGIS Processing algorithms?

I am beginning to learn QGIS 3 up from QGIS 2. I see many changes. In QGIS 2 one could find the scripts for the algorithms located in the Processing Toolbox. But here in QGIS 3 I cannot find the ...
2
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1answer
29 views

How to easily toggle outlines and fills for polygon layers (in QGIS 3.x)?

So I want to be able to easily toggle outlines and fills for polygon layers in the Layers List. I managed to make two rules (both with the rule 'true') and then they will show up in the Layers List: ...
2
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1answer
75 views

Adding feature to PostGIS layer that has joins is really slow

I have a large project that I've been setting up to work with QGIS 3.12 and I have now hit a problem with using "joins" to join several attribute tables with a geometric one. I have reduced the ...
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0answers
31 views

How do I get the number of rows in an attribute table?

In processing modeler in Qgis 3.14, how do I get the number of rows in an attribute table?
3
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3answers
249 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 ...
2
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1answer
144 views

Merging DEMs in QGIS?

Not the first problem I've had with DEMs in QGIS 3.4. Trying to merge 6 DEM tiles together into one. Process for this is simple: go to Raster --> Miscellaneous --> Merge. Once in the menu, select ...
0
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1answer
64 views

Unable to run freshly updated QGIS 3.14 on Ubuntu 18.04 using libprotobuf-lite version greater than 10

Context (see bottom EDIT for the fix, thanks to ThomasG77) After having run my daily updates using; apt update && apt upgrade, on Ubuntu 18.04 I've seen that QGIS 3.14 was newly shipped and ...
0
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1answer
143 views

.tif to PCraster format conversion in QGIS 3.2

I am using QGIS 3.2 and trying to convert a resampled .tif file into PCRaster format which is used for a downstream model. Unfortunately when i try to export the resampled.tif file into PCRaster ...
1
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1answer
23 views

QGIS 3: How to count the mean of shapefile attributes that lie in a specific area

so I have a shapefile with buildings and the shapefile has the height of the buildings in the attribute table. I have a second shapefile with the districts the buildings are located in. Now I would ...
0
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0answers
19 views

Printing Output in PyQGIS Plugin

In developing a PyQGIS plugin, I would like to be able to print out variable values to ensure that my program has the desired functionality. I am aware that I can print messages with something like ...
0
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0answers
14 views

Supervised Classification Sentinel 2 using QGIS Semi Automatic Classification Plugins: virtual raster/virtual band set

I am using QGIS semi-automatic classification plugin, supervised classification (LC Classification) of Sentinel 2. My Question is: According to the online tutorials (please check the tutorial: https://...
0
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1answer
34 views

set z-value from table

In qgis 3, postgis, no DEM and zero python knowledge. I've got linestring 3d but Z coordinates is empty, Z-values are stored in table. Z1 for the first node, Z2 for the last node. I found a lot of ...
1
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1answer
42 views

Progress bar does not show progress during processing

I am trying to show the progress in the progress bar, but it is not running, I have seen several solutions but none has solved me. This is part of the code that I am using : def progress_changed(...
1
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1answer
106 views

How to resize label in PyQGIS?

How can i make it so the legend on the left bottom don't cover the map?
3
votes
1answer
35 views

Varying page size of maps within an Atlas in QGIS?

I would like to create an atlas of a series of maps covering a number of woodlands and to have them all at the same map scale. This would work best visually if some of the maps were in landscape, and ...
2
votes
1answer
31 views

Intersect overlapping entities and their attributes

I have a shapefile containing 6 classes of polygons on QGis 3.14. Some of these polygons overlap each others, but they're not geometry errors or duplicates, just polygons with different attributes. ...
0
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1answer
91 views

Loading layers from PostGIS db (populated with osm2pgsql) in QGIS?

I have downloaded some OSM data from geofabrik and used this to create a PostgreSQL/PostGIS database using the osm2pgsql tool: osm2pgsql -G -d <db> -U postgres myfile.osm Examining the ...
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0answers
22 views

How can you send by Python console an expression to a layer property and activate its corresponding check box

Try this code but it has only worked for me with fixed and short values for example 'hello' or '777' layer = iface.activeLayer() idx = layer.fields().indexFromName('cp') layer....
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0answers
21 views

How to use a IF statement to change colors for layers using PyQgis?

How to change the colors according the values in 'C_index' field? I tried a FOR loop, in order to read all values in this field, and an IF STATEMENT to set all 'red' and 'blue' values to the same ...
-1
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1answer
50 views

QGIS 3x problem with CRS for comma delimited layer

Good afternoon, I would like to overlay my .csv comma delimited layers in QGIS 3x properly. I have got the Ordnance Survey Maps as the raster players, which CRS is EPSG 27700 1936 British National ...
1
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1answer
159 views

Feature Count for Categorized Layers with the Atlas function of Print Layout in QGIS 3

In QGIS, is it possible to count the features of each class in a categorized layer where the features being counted are limited to those that are inside the current atlas feature? I have tried ...
0
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1answer
29 views

QGIS 3x can't run the custom crs for Ordnance Survey maps

Recently I solved the problem regarding the mismatch between British National Grid CRS and WGS 84 in the query below: QGS 3x Ordnance Survey map doesn't overlay the Google Maps properly I ...
1
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1answer
250 views

QGIS 3 PyQGIS Script - Merge Layers and Export to csv with KML geom field

I previously had a script in 2.18 that exported csv files with kml geometry's file by file. I'm now wanting to move to QGIS 3 and do the same process except Merge the point layers then add the ...
1
vote
1answer
187 views

Using Click locations to determine azimuth in QGIS 3

I am using QGIS 3 64bit. While adding points to a shapefile (layer), what expression captures the insertion point coordinates of a point feature to use as a start point for an azimuth determination ...
0
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0answers
18 views

Pyqgis QgsTemporalProperty visible features

I have a project with Temporal Controller, I have a QgsVectorLayer which 'Start and End Date/Time',I would like to know what features are visible in every moment I use Qgis 3.14, thanks
0
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1answer
38 views

Time Manager runs with different speed in QGIS 3.10

I created a map to show my data with time manager. The feature type is polygon. Changes in "Show frame for x milliseconds" affect the time the frames are shown. But the first frame is shown for x ...
0
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1answer
34 views

Aligning Cartosat-2 Image?

Recently our company purchased Cartosat-2 Image from NRSC. Our Mining Lease area Boundary is not aligning with Image.It is around 100 meter offset.We are using QGIS 3.4.Spatial reference of Cartosat-...
0
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1answer
35 views

QGIS find and replace several unicode symbols in a single field

I work with languages that use Unicode symbols in their placenames. I often receive layers with labels that are messed up, but they are messed up in the same way all the time eg: the place name shows ...
0
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0answers
20 views

QGIS 3x image georeferencing - problem with transformation type and resampling method

Good morning, I would like to georeference my image in QGIS. I know the process, but I don't know which transformation type & resembling method should I use. I found some answer here: ...
2
votes
1answer
83 views

QGIS Time Manager with joined layers

I am using QGIS version 3.6 and Time Manager version 3.2.3 to create a temporal map of the US's energy usage over time. I have a polygonal shapefile of the US with each row of the .dbf file containing ...
6
votes
4answers
420 views

Mask Labels in QGIS 3.12

New feature in QGIS 3.12 does not seem to work. And it looks different from shown in changelog https://qgis.org/en/site/forusers/visualchangelog312/#feature-selective-masking This is how it actually ...
1
vote
1answer
237 views

QGIS 3.2 - Poor conversion from high-resolution vector to raster

I have a shapefile with polygons with several sizes, and I want to convert it to a raster with 30mx30m pixel resolution. Although I was able to obtain the raster with the pretended resolution (using ...
1
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0answers
14 views

Shortest Path No route found QGIS 3

I am using shortest path point to point and I have found the following problem. I am using a road network which includes some roads that have one way and others are bidirectional. My origin and ...
2
votes
0answers
28 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($...
0
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0answers
33 views

QGIS 3 export PostGIS layers to DWG

I'm having three PostGIS layers (points, lines, polygons) that I'd like to export to a single DWG file. So far, I could export the layers as an AutoCAD DXF file with a right-click on the layer and ...
1
vote
1answer
35 views

Loop inside polygon shapefile to clip another shapefile using PyQGIS

I'm a beginner in PyQGIS and need help to figure out how to automate a process in QGIS. I want to write a script that enables me to loop inside a polygon shapefile (shown in brown) and use extent of ...
4
votes
3answers
1k views

Moving node in QGIS?

I am trying to move a vertex in QGIS 3.2. I can select nodes in QGIS 3.2 (which show up blue), but every time I try to move it with the node tool it just deselects the vertex. How do I move a node ...
1
vote
0answers
24 views

Making a 3D map by interpolation by stacking data for different depths

So, I have the data of shipping Noise levels at various coordinates (300x300 km grid, with 900 coordinates). I have the Noise levels for 5 depths (10m, 30m, 50m, 70m, 90m) and I while I am able to ...
0
votes
1answer
41 views

QGIS 3 Python support disabled Linux

Couldn't find a similar question for Linux, just Windows. I'm running Linux Mint 19.3. Traceback (most recent call last): File "", line 1, in File "/usr/lib/python3/dist-packages/qgis/__init__....
0
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1answer
54 views

QGIS 3.10 not recognising projection information from raster created using GDAL

Problem QGIS 3.10 only partly reads projection information from raster file however QGIS 3.4 correctly reads information from same raster file. I thought I had an issue creating the raster – I may ...
1
vote
1answer
37 views

Calculate the distance between points and the start of each lines

I am trying to calculate the distance between the green points and the red point on their left and add that distance to the green points attributes. The lines are roads and I made the red dots using ...
1
vote
1answer
74 views

Connecting lines with point in QGIS

I have two shapefiles Blue network yellow locations as shown in the below figure. I want to connect all yellow dots with the blue lines blue as shown in red color in the figure. Is there a way to ...
4
votes
3answers
971 views

Call QGIS geoprocessing tools from command line (terminal, bash-script)

Is there any possibility to call tools found in the QGIS processing toolbox from the command line, other than using python? It is my understanding that if you use any GDAL tools, the QGIS gui is just ...

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