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How to find a list of polygons from one layer that intersects a polygon in another layer

Use the Union tool from the QGIS tool box, if you only want the list of intersecting polygons, then delete the rows with null values on the fields from layer B, to do that select by expression by ...
Mayo's user avatar
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How to find a list of polygons from one layer that intersects a polygon in another layer

You can create a Virtual Layer using the query: SELECT row_number() over () as id, a.polyid as "polygon-a", b.polyid as "polygon-b", a.geometry FROM ...
Bera's user avatar
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1 vote
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Arrow symbols are 180deg off rotation in QGIS

If you click on the data defined override button (to the right of the text box) you can select edit and that will take you to the Expression editor where you can write an expression to give you the ...
Ian Turton's user avatar
  • 82.1k
1 vote

How can I further clean fix geometries if the tool doesn't fix them all?

I usually try: Fix geometries If that is not enough any or all of: If you have a polygon layer Buffer with 0 or a very small distance Snap points to grid Simplify with a very small tolerance But ...
Bera's user avatar
  • 74.7k
0 votes

Combine multiple USGS topo quads into a single seamless raster?

Obtain quad corners Extracting the neatline from the map is probably ideal, but it's possible to get the quad corners from elsewhere. USGS Quad corners can be downloaded either from the Map Indices ...
Tom Brennan's user avatar
  • 5,249
2 votes
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Importing layer data to QGIS from UMAP and converting it into correct Coordinate Reference System

The longitude values are in a -360 to 0 range, rather than the usual -180 to +180 range. Add 360 to each longitude value and that should line up the data properly.
mkennedy's user avatar
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4 votes

Default QGIS style symbologies not displaying

Try clicking on the "All" tab in the style manager. I notice you are clicked on the "Favorites" tab in the image, and if you haven't saved any favorites, it might not show anything....
anzac21's user avatar
  • 61
1 vote

Finding the right Projection/CRS for a 2000's era shapefile of Bosnia Herzegovina

Best I found is modified EPSG:8678 MGI 1901 / Balkans zone 6 with different origin and added datum. It seems to work. Checked in QGIS as Custom CRS using Proj.4 notation: +proj=tmerc +lat_0=0 +lon_0=...
Ondro's user avatar
  • 111
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How to make a conditional branch in QGIS Modeler based on the raster cell size

Raster Layer Properties A conditional branch using @Raster_layer_properties_PIXEL_HEIGHT <=10 , or width. Use each branch as a dependency to the next algorithm:
Bera's user avatar
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0 votes

Clickable HTML link in QGIS print composer pdf export?

Building on other answers above, if you would like the link to be shown as text (e.g. 'click HERE'), rather than being shown as the full address (as in working examples above) then you could hide a ...
Ben Smith's user avatar
0 votes

QGIS Summing equal geometries with identical columns

Virtual layers are a good way to solve your problem. In this example a layer layer1 and a layer layer2 share attributes lanes of type integer and surface of type character. For calculating the sum of ...
Bernd Loigge's user avatar
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3 votes

QGIS (qgis2web) automatically update data set

Export your project with qgis2web, enter the "layers" folder and you will find your layer exported in .js format, your goal is to schedule a routine from the command line that acquires the ...
andreaordonselli's user avatar
0 votes
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Showing azimuth/heading of points as arrows

Okay, after trying what Erik suggested, the issue is indeed related to the Counterclockwise from East setting in the Vector Field Marker. I get the desired results if I compute azimuth = pi()/2 - ...
louisbzk's user avatar
0 votes

QGIS MacOS Installer Version 3.16

If Going to Security & Privacy > Open Anyway still didn't work for you. I had to run a command to remove QGIS from Apple's quarantine: xattr /path/to/MyApp.app sudo xattr -r -d com.apple....
sk1me's user avatar
  • 374
0 votes

Drawing rectangle of road line with width as minimum distance between two buildings in QGIS

Assuming your lines actually are the center of the road, you first run join attributes by nearest, using the lines as the first input, and the polygons as the second. Make sure you only join the one ...
Erik's user avatar
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2 votes

Creating derivative layer based on other layers in QGIS

You can do this using a Virtual Layer and an SQL UNION operation on your layers, taking care to rename columns to the same thing. For example I have two layers called "this" and "that&...
Spacedman's user avatar
  • 65k
2 votes
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Union of 2+ point datasets with overlapping and non-overlapping lat/lon points

Try this: Merge the point layers with geoprocessing tool merge vector layers Buffer the merged layer with a distance that approximates to the furthest separation you expect in a cluster. This will ...
Aquamarine's user avatar
  • 1,261
0 votes

How to modify a feature's JSON attribute on PostGIS with QGIS

Unlike jsonb, the regular json type is pretty much just a pre-validated text. You could alter table your_table alter column connectionpoints type text using (connectionpoints::text) --,add ...
Zegarek's user avatar
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0 votes

Issues loading a project with large non-local data in QGIS

Before you do any of this make sure you take a backup of your project file As your file is a .qgz, first rename the file to change the extension to .zip. You can then extract the .qgs file from within....
SirLostalot's user avatar
0 votes

Multi-thread processing in QGIS 3.8

It's not multithreading, but in recent versions of QGIS there's a possibility to accelerate some of the processing operations via OpenCL using your graphics card. I can't find documentation on what is ...
Saaru Lindestøkke's user avatar
0 votes

Finding overlapping line geometries (including subsets) in QGIS

This worked for me: Use the 'Select by location'-Tool with 'overlap', and compare the layer with itself. It will select all overlapping features in the relevant layer. I'm not completely sure how well ...
i.i.k.'s user avatar
  • 1,709
0 votes

QGIS - catch return keypress on one qplaintextedit widget form

Assuming frm is a QWidget or QMainWindow, you should add new Widgets to it using a layout and its 'addWidget'-Method I tried your CustomPlainTextEdit and it works for me in the following example: from ...
juliustoth's user avatar
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I can't fill in the gaps in the DEM map

You might find the QGIS tool "Fill nodata" useful here. This tool would allow you to fill in nodata cells by interpolating another cell within a distance you can set. For example if you have ...
anthro_01's user avatar
0 votes

QGIS Color Ramp is not being displayed properly

See https://github.com/qgis/QGIS/issues/51802 Following @nicogodet's suggestion, I solved this bug just by creating a new profile. QGIS version 3.22.9 OS version Windows 10
Wander A. Martins's user avatar
1 vote

Automatically calculating distance on specific layer in QGIS

First download the data using Quick OSM: Result should be something like this: Then use the geo-processing tool Clip with the osm layer as input and the zone of interest layer as the overlay - this ...
Aquamarine's user avatar
  • 1,261
1 vote

Finding overlapping line geometries (including subsets) in QGIS

I'm a bit surprised how tricky this appears to be. Like you say, it's straightforward enough to find duplicates, but subsets of lines not so much. Anyway, here's a way of adding a visual indication of ...
SirLostalot's user avatar
2 votes

Convert a RGB LiDAR raster image to a greyscale height map in QGIS

I'd class this as very hard to do. It's been coloured by height (there's a brown blob at the top, a different green in the valley) and then shaded by a hill-shading algorithm which considers an ...
Spacedman's user avatar
  • 65k
1 vote
Accepted

Free QGIS Retina/HiDPI map tiles still produce illegible text

You should use the following settings in QGIS: URL: https://retina-tiles.p.rapidapi.com/local/osm@2x/v1/{z}/{x}/{y}.png?rapidapi-key=MY_API_KEY Tile Resolution: Standard (256x256 / 96 DPI) ...
crnm's user avatar
  • 461
0 votes

Why input layers do not have the same grid extent in the processing, hydrological analysis?

Change your saving file format from .SDAT to .TIF or .TIFF; this has resolved my issues, which were the same as yours. Thank you for reading
Anbesaw Bilal's user avatar
1 vote

Creating polygon layer (road border) from line layer (road) and polygon layer (buildings) using QGIS

You can try using Vector > Geoprocessing > Buffer. This will give you a polygon layer of your roads. You can adjust the thickness, BUT it will not care about going over your buildings layer. To ...
MesanGeo's user avatar
0 votes

Reducing decimal places of coordinates in vector data using QGIS

If in displaying the values is the only situation where you need a lesser precision you can apply rounding as you calculate the value to display as in: round(z_min($geometry),3)
Ovidiu Jeler's user avatar
1 vote

Making population density map in QGIS

I found 'Point Displacement' and setting 'Placement method' to Grid gave a better representation of the population than 'Heatmap'.
Vic's user avatar
  • 431
0 votes

How to generate values and create a heatmap from 3 different point vector layers in QGIS

First I would merge the three layers using the 'Merge Vector layers' tool: Vector --> Data Management Tools --> Merge Vector layers Select your three point layers as the input layers and an ...
SirLostalot's user avatar
0 votes

Attributes comparison in QGIS

If you want to compare based on the attribute values only, I made this script for the plugin toolbox. It selects your option of features that are in one or both layers, and takes user input for the ...
Swordnut's user avatar
0 votes

Comparing two different layers with duplicates in QGIS

If you want to compare based on the attribute values only, I made this script for the plugin toolbox. It selects your option of features that are in one or both layers, and takes user input for the ...
Swordnut's user avatar
6 votes
Accepted

Assigning unique ID to new points in QGIS

First add a numerical field named id or whatever you wish to your layer. Then open the layer properties and navigate to "Attributes form". Select your id field and scroll down to default. ...
MrXsquared's user avatar
  • 34.9k
0 votes

Graduated symbology

You can't graduate using a string field, you need to convert it to real first, using the field calculator to create a new field with the follwing expression to_real("correlation")
Erik's user avatar
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0 votes
Accepted

Close small gaps between line geometries with QGIS automatically

UPDATE: I strongly advise to use the v.clean tool. With the tool 'Snap geometry to layer' I had the problem that it creates invalid geometries. Easier than the v.clean tool (as described below) is ...
i.i.k.'s user avatar
  • 1,709
0 votes

Capture canvas mouse click in QGIS QDialogue plugin

You could use the 'mapToolSet' signal of QgsMapCanvas. from qgis.utils import iface def handle_change_maptool(new_maptool, old_maptool): print(new_maptool, old_maptool) # do stuff canvas = ...
juliustoth's user avatar
1 vote

Close small gaps between line geometries with QGIS automatically

Ok so you're talking about snapping, and there are a couple of solutions. But if you want to avoid having to correct them in the first place (prevention is better then a cure after all), at the start ...
lhowarth's user avatar
  • 613
1 vote

Grouped "labels" for QGIS 3.0 Point Cluster styling?

Right-click the clustered layer Select ‘Properties…’ Select the fourth icon ‘Label’ on the left At the top of the window, you can see that the default setting is ‘Single Labels’. In the ‘Value’ field, ...
Cayley Lee's user avatar
0 votes

Reducing decimal places of coordinates in vector data using QGIS

Use the tool Refactor Fields. With this tool you can edit the precision of each field. It works for me.
Daryl Ernesto Ayala Saavedra's user avatar
0 votes

Labeling a multiline layer in QGIS

thanks a lot for your help! It was really clever to use the tool 'Multipart to singleparts'. I could solve the problem with the segmentation and didnt have to code anything. It looks pretty cool for ...
Juan Sebastian Barajas Narvaez's user avatar
1 vote

Reducing decimal places of coordinates in vector data using QGIS

QGIS has a specific tool for this in the "Processing toolbox": "Snap points to grid". Note that simply rounding the coordinates (as this tool currently does) can lead to invalid ...
Pieter's user avatar
  • 3,124
0 votes

QGIS How to calculate closest point referenced to centroid?

The expression inside the overlay_nearest function is "an optional expression to evaluate on the features from the target layer". So the centroid function inside the other answers is ...
Tom Brennan's user avatar
  • 5,249
8 votes
Accepted

Can I set QGIS to summarize icons above a certain scale and display only the number of icons in an area?

Yes, the symbolization style you are looking for is 'Point cluster' In the layer styling pane, choose the 'Point cluster' style. See the example below. The first image is a random assortment of points ...
Nigel Van Nieuwenhuizen's user avatar
3 votes

Reducing decimal places of coordinates in vector data using QGIS

You can use a process tool called Geometry by Expression and use an expression which will round every vertex to 3 decimals: make_polygon( close_line( make_line( array_foreach( ...
Bernd Loigge's user avatar
  • 2,905
0 votes

How to add OpenStreetMap layer as bottom layer via QGIS processing script

You can try not adding your layer as bottom, but to move it after adding. from qgis.utils import iface #your_layer = iface.activeLayer() ltv = iface.layerTreeView() ltv.setCurrentLayer(your_layer) ...
Dezmonder's user avatar
0 votes
Accepted

Storing password in your Keychain failed: OS X Keychain error (OSStatus -25293)

As described here on QGIS github the trick is to go into Keychain Access, search for QGIS, open up that entry, select Access Control and change the setting to "Allow all applications to access ...
seancarmody's user avatar
0 votes

I'm not able to load plugins in QGIS due to an error when calling its classFactory()

In qdrawsettings.py replace self.move((screen.width() - size.width()) / 2, (screen.height() - size.height()) / 2) with self.move(int((screen.width() - size.width()) / 2), int((screen.height() - size....
BlueIris's user avatar
  • 101

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