Questions tagged [qgis-3]

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

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20 views

SAGA Point Statistics for Polygons

I am running QGIS 3.10 on a MAC using Catalina (and I also tried on QGIS 3.4) and tried to run SAGA Point Statistics for Polygons. Every time I run it I get an error with it trying to create the layer....
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66 views

Selection on PostGIS layers is… randomly working in QGIS

Context Quick question... Since the last minor update of QGIS 3, I cannot select features anymore on some (not all) PostGIS layers (see Fig.1). Fig.1: On the left table, the selection is not ...
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41 views

Adding shapefile layer in PostGis creates two tables

When I try to upload a shapefile to my PostGIS database, it creates two tables (I can see them in QGIS). I import them by drag and dropping them on the PostGIS connection. If I delete one of them, ...
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1answer
46 views

Opening vector layer from GeoJSON file

I have a vector layer of rectangles in QGIS 3 that I export as a .GeoJSON- file. I want to change those geometries to new polygons with certain dimensions, for which I use Python. I then save those ...
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70 views

"Could not make temporary scratch layer permanent

i what to make permanent but it show me "Could not make temporary scratch layer permanent. Error: Creation of field addr:street_1 failed (OGR error: Can't create field addr_str_4 in Shape DBF file, ...
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1answer
14 views

Force reload assigned datasets for Mesh Layer

I am wondering if there is any way / python code to force QGIS 3.12 to reload the data source of mesh layer and its assigned datasets? Mesh layer is a .xmdf file that's similar to .2dm with assigned ...
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42 views

Saving changes of attribute table QGIS

I'm doing changes to a new field I created on the attribute table of a grid shapefile (.gpkg), the grid is circle clipped to the extent of a 4km radius buffer, it contains 499358 cells. The new field ...
3
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1answer
108 views

Disable “Selected features only” in Proccessing Script

I wrote a Progressing algorithm using Python. The tool clips DEM by a select polygon in the vector layer. If there is no selection, the tool gives an error. As the script runs anyway for the selected ...
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0answers
30 views

Error while running Variable distance buffer in QGIS 3.12

I have problem in QGIS 3.12 when I try to use the tool Variable distance buffer I get an Error. This is the log message I get from the error: { 'BUFFER' : 'TEMPORARY_OUTPUT', 'DARC' : 5, 'DISSOLVE '...
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19 views

Missing coordinates in the attributes list after importing osm-Files

I imported an osm-File in QGIS 3.12.1 (osm File was created with JOSM). Then I wanted to export the XY coordinates (Long.-Lat. EPSG4326 => XY UTM). But it seems that the coordinate information of the ...
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1answer
25 views

Columns order mixed up by style

I have a point layer for wich I've set the order of columns while using field calculator and Refactor fields instruments. But the order of colums is different when I'm choosing point by Identify ...
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34 views

Raster not showing on Orthographic projection when zooming out

I am trying to put together Topographic .Tif rasters (from GMTED data) on an ortographic globe on Qgis 3.4.1, for exemple these 8 layers: However when I change the projection and one of the various ...
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24 views

Error uploading to QGIS Cloud [closed]

I am getting the following error when attempting to upload data to QGISCLoud using QGIS 3.10: local variable 'hexstr' referenced before assignment Has anyone seen this before and able to point me in ...
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1answer
26 views

Georeferenced QGIS tiff is unusable

I am using Windows 10 and QGIS 3.10.5. I had this issue a few days and thought I had fixed it by cleaning the Registry. However, it has re-occurred. I load a pdf into the Georeferencer. I ...
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1answer
24 views

Missing entities when JOIN between differencce layer to origianl layer in SQL QGIS3

I have two layers : 1. layer of fake plots 2. layer that shows only the safe area inside those plots (generated with the Difference tool), and contains data about the area of each safe polygon. this ...
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1answer
44 views

OpenFeatureForm() function in QGIS not cancelling edits

I'm trying to create new features in an existing vector layer and I want to display the attribute form so the user can fill the attributes data. I successfully managed to show attribute form and users ...
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1answer
107 views

Integrate Python script with QGIS plugin

I am new to QGIS and trying different things. A Python script (link), which is running perfectly in QGIS Python console but I want it to run as a QGIS plugin. I am trying to do but getting confused ...
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0answers
51 views

PyQGIS 3.4 Processing Memory Issue

I am using GDAL to clip my DEM by the selected polygon in the active layer with QGIS 3.4. I am facing a problem with the memory layer. I read the questions asked before related to this topic PyQGIS ...
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1answer
156 views

Curved arrows in QGIS using geometry generator

I use QgGIS 3.10 and this tutorial https://anitagraser.com/2019/05/04/flow-maps-in-qgis-no-plugins-needed/. I am able to create lines of varying thickness and color depending on the weight of the ...
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1answer
39 views

Adding new nodes or moving segments with Vertex Tool in QGIS 3.10

I'm used to work with simple polygons and the vertex tool. But now the Vertex Tool doesn't show me the capability of adding new nodes in centerline neither move polygon's segments. The function just ...
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0answers
35 views

QGIS DXF contours with elevation

I have followed all instructions from this YouTube tutorial. Create contours and show elevation values Open GRASS plugin on QGIS - create new mapset and choose the "import loaded vector" command from ...
2
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1answer
62 views

Repeat polygon marker line by interval: neighboring polygons

As you can see in the screenshot below, I use a polygon marker line with interval. If there are 2 neighboring polygons, the markers will be doubled - of course. But I need to suppress this effect. ...
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1answer
26 views

Iso-Area jumping over parts without streets (QGIS QNEAT3 Plugin)

I am using the QGIS Plugin 'QNEAT3' (version 1.0.4) to calculate Iso-Areas. They are only relevant for me in one country, so I only have this country's street network. But the Iso-Areas are jumping ...
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1answer
17 views

Rasterizing each line features separately in a layer

I have a vector layer which is consists of channels in a watershed. I want to rasterize each individual line in the layer separately in PyQGIS. I could not manage to loop through in the layer and ...
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0answers
66 views

QField - Display attributes table frame in pdf with editing offline mode

I'm using QField and QFieldSync to synchronize my data. In a project I build a composer with an attribute table frame, wich show attributes of my layer. When I run the project in QField and create a ...
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3answers
48 views

Splitting map, island tied in same polygon as mainland using QGIS

I have a map originally as a shapefile. The map includes a country (mainland) and an island far away from the mainland. I want to cut the map so that only the mainland is shown and save it again as a ...
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1answer
42 views

Calculating overlap of several lines in QGIS

I've traced several lines that represent people's paths. Some of these lines overlap several times. I would like to get a view showing for each segment of my lines the number of line overlaps. The ...
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0answers
9 views

Programmatically remove default shortcut of Locator

Using Python, how may I go about changing or removing the default shortcut of the Locator? I have a list of desired_shortcuts that I leverage as a comparison point against QGIS defaults to remove ...
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1answer
42 views

QGIS cluster character symbol visibility based on cluster size

I want to display the cluster size with a condition : I don't want to display this information for small clusters. The expression is working fine but I don't know I can add else... case when @...
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1answer
78 views

Group points by expression to create pie charts in QGIS

Is the any way to group multiple points by attribute to make pie charts that shows types by locations? I have a layer with groups of points with two fields (group and type). Every group of points is ...
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0answers
22 views

Changing default settings for Arrow Item in print layout of QGIS 3.10

I am using the print layout of QGIS 3.10 to make maps and some reports. I frequently use the Arrow Layout Item. I need to change the default values for the Arrow Stroke Color, Arrow Stroke Width, ...
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1answer
122 views

QGIS - QField - Retrieve target field value when source feature intersects target feature in target layer

I have a simple project in QGIS 3.10.5: a polygon layer and a point layer. When the user add a point feature which intersects a polygon feature, a calculate field make this intersection and get the id ...
2
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1answer
53 views

GeoTools ShapefileReader “Random Access not enabled” when trying to read files edited by QGIS 3.12?

I have some code where the relevant part looks like this: private static List<GisShape> shapes(String shapefile) { DataStore dataStore; try { dataStore = getDataStore(...
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0answers
37 views

How to create a wavy line on QGIS [duplicate]

I'm looking for a way to quickly transform simple lines into wavy, zigzag lines and so on in QGIS. I already tried to use the method reported by @christoph in a question posted in this forum (Drawing ...
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0answers
31 views

PyQgis Exporting Print Layout: “ERROR 6: The PNG driver does not support update access to existing datasets.”

I am trying to export a .tif loaded into a pre-configured print layout template and further exported as .png def openLayer(project, fp, basename, vector=True): layer = QgsVectorLayer(fp, basename) ...
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1answer
65 views

Ubuntu 16.04 and 18.04 won't install Version 3

sudo apt install qgis installs 2.8 (on 16.04) or 2.18 (on 18.04), but I would like to install version 3 (especially the 3.10 ltr) so I've tried: sudo add-apt-repository https://qgis.org/...
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1answer
24 views

Faster way to get layer information in PyQGIS?

I know that you can quickly access the active layer with layer = iface.activeLayer() Currently I'm working with multiple files in a Python script and my current method of accessing layer extents is ...
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0answers
53 views

QGIS : OGR error when editing Geopackage layers : database is locked

I started to draw new polygons in a layer within an existing Geopackage that I previously created. However, after editing several layers, I sometimes (apart that it don't happen when editing one ...
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
37 views

Add GDAL tools to QGIS 3.12.1

I have QGIS 3.12.1 which doesn't have any GDAL options in the Raster Menu. Also in the Plug-In menu I cannot find GDAL. Does any know how I can add this?
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1answer
47 views

Compute closest distance between points to polygons with PyQGIS

I have the following situation: Some points are outside the polygons and some are in. I want a new field in my point layer with the closest distance to its closest polygon. The points inside a ...
2
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2answers
45 views

Changing database connection parameters in QGIS projects stored in PostgreSQL

We have stored our QGIS projects in a PostgreSQL database. Now we have to move the server that hosts the database that many projects access. Is there a way to change the connection parameters within ...
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0answers
30 views

Adding two rasters results in negative infinity and positive infinity

I'm trying to create a hydro-flattened DEM according to USGS specifications. I have two rasters, a DEM of my study area and a raster that only contains the water bodies that I have flattened so the ...
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0answers
44 views

How to change the Python Version in QGIS?

I have installed ImageMagick via Homebrew and apparently it's within Python 3.8. But my QGIS is using Python 3.7.3, therefore, it's telling me that I don't have ImageMagick installed (and therefore ...
4
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2answers
268 views

Basemaps provided by Esri

I have a general question for those who use Esri software: Is there a big difference between the basemaps available for QGIS and those provided free by Esri to its customers? I tried to use the Esri ...
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1answer
30 views

Correcting TIFF image in QGIS

I'm very new to QGIS. I try to open satellite images about night lights. When I open the images in TIFFf format with QGIS 3.12, only a black image opens. Thumbnail as it looks. I adjust the symbology ...
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1answer
48 views

Feature sink as output

I am writing a processing algorithm and I would like to return a feature sink as an output, but without treating it as a parameter. The point is I want to just add it to the table of content as a ...
2
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0answers
42 views

Printing layer name using label element in Print Composer in QGIS 3.12?

I'm trying to print the layer name using a label in print composer in QGIS 3.12. It's not responding to layer_property(@layer_id, 'name'), or [%layer_property( @layer_id, 'name')%] or [%@layer_name%]....
2
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2answers
116 views

Adding coordinates to attribute table

If I use the 'Add coordinates to point' it adds the coordinates to in the file, however splits the data into the amount of objects in the original file. If I try to add separate columns in the ...
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1answer
29 views

QGIS Zonal Statistics (Variety) returns zero or keymap error depending on QGIS version

I need to calculate Variety of pixels for every polygon in a shapefile but the analysis returns zero. Polygons are much bigger than a raster cell which is 10 m. Polygons are completely covered with ...

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