Questions tagged [qgis]

QGIS is a cross-platform GIS application licensed under the GNU General Public License.

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2answers
36 views

Offset raster boundary by elevation

I've been given a raster with flood elevation limits along a river, it's not a constant flood level so elevations range by ~35m. I need to do an analysis of the impacts if these elevations were 2m ...
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4answers
93 views

Merge several polygons/features into one continuous area not working

I am using QGIS version 3.10. I have a farm boundaries layer (https://drive.google.com/drive/folders/1xYZmSboM75GACCWQyx-06wZ3EdHBcMrM?usp=sharing), and want to merge certain adjacent polygons into ...
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0answers
31 views

``Qt: QUndoStack::endMacro(): no matching beginMacro()`` error on PyQGIS script

I am working on a QGIS plugin that allows redrawing a selected feature without losing its original attributes. The plugin works properly and the process ends well but I am receiving a QT error that I ...
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0answers
29 views

Can't calculate raster using QGIS

So I'm new to QGIS (2 days) but have spent HOURS on it everyday trying to learn it to process raw SRTM data make 3D relief maps on another software, so I can work my way around it but can't really do ...
3
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0answers
44 views

QGIS transformation local coordinate system to UTM35

I am creating a geo database for an archaeological excavation. We want to put data from a local system and from UTM35 in the same QGIS-project. I have Ground Control Points and I calculated ...
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1answer
36 views

How to filter dropdown options in QGIS attribute table?

I have the following layer table Prim | Secondary |Tertiary Apple | Apple Pen | Apple Pen White Apple | Apple Pen | Apple Pen Red Apple | Apple Phone | Apple Phone Black Apple | ...
2
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1answer
68 views

Using PyQt in PyQGIS inside QGIS 3.16

This code Using PyQt5 extracted from http://www.tutorialspoint.com does not work when I add it in a script in the console of QGIS 3.16. Can you enlighten me on this subject? import sys from PyQt5 ...
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1answer
48 views

Extract raster properties and use them in QGIS graphical model

I would like to generate a tool that reclassifies rasters in 10 classes with equal intervals. Since QGIS reclassifies tools does not allow to automatically create classes with such methods, I was ...
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0answers
23 views

The proportion of population covered by created isochrones in QGIS

I created isochrones using Iso-Area as polygons algorithm is QGIS. I would like to calculate the proportion of the population covered by the created isochrones. Is there any tool in QGIS to do this?
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1answer
27 views

Line still appearing but not existing in the metadata of a shapefile

For a project, I had to merge the cells of a grid to upscale it. It was possible to merge all I wanted but there is kind of a displaying problem: there is this line which appears visualy but that is ...
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2answers
27 views

Deleting data by location using another shapefile

I have two shapefiles: one is main file and another is a part divided (manually by selecting) from the main file. Now i want to delete the divided part from the main file with the help of divided part....
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0answers
22 views

Finding and deleting overlapping polygons using QGIS

I have generated these (green) polygons in ArcMap 10.5.1 by: import XY data > buffer 5 m > minimum bounding geometry (plus a couple of other steps). self-intersect of polygons The screenshot is ...
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0answers
31 views

Unusual QGI3S “Exception: Unkowns”

I'm trying to process some OSM data extracted via Osmium. I've managed to process some of my smaller datasets, but as I've begun working on the bigger ones, I'm receiving some odd errors. Specifically,...
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0answers
18 views

Display DrillHole locations in QGIS from SQL Server database source

I'm using QGIS 3.10.9, and I want to be able to display some drill hole data from my source database, which is on a SQL server. (I've been able to export the data into CSV format and display the data ...
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0answers
20 views

Connection database failed in Qfield

I'd like to take a test about the connection to the database in QField in my smartphone Android but it failed; so I cannot view the layer Postgis on the map. The database Postgresql is installed and ...
2
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1answer
33 views

Exporting a group of raster layer bounds from QGIS to a GeoJSON

I have a QGIS project with a lot of raster layers; and I want to build a Mapbox map based on this project; that would display those images on a website's map. I need a way to export a group of raster ...
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0answers
22 views

QGIS - Network join issue with cost allocation using OSM dataset

I've been trying to create a cost allocation map, using the v.net.alloc tool on QGIS with Grass. Some of the results don't connect to the network fully, even though they should in real life. This has ...
1
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1answer
33 views

QGIS Processing Modeler not showing algorithms anymore

I use QGIS 3.4 on Linux Mint 18.1 and have happily created models once I came to know about this awesome feature. But some days ago the algorithms disappeared. If I right click in processing modeler I ...
1
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1answer
37 views

Batch processing error in QGIS

I get a Python error when I run any plugins as batch processing in QGIS 3.6.3. The problem does not solve if I change layers. Any idea how to solve it? The error I get is: WARNING Traceback (most ...
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1answer
38 views

QWC2 - Projects not available as themes

We have a folder accessible by QGIS server containing some projects to be served as WMS: Projects are available in the qwc admin qui when creating a new theme: There is a theme for each project: I ...
1
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1answer
58 views

Changing number of decimal places of a String variable within a Vector Layer using PyQGIS

I have earthquake data and within the data, there are magnitude, longitude and latitude values. However, these values have around 6/7 decimal places but I would like to only have 2 decimal places for ...
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1answer
26 views

QGIS custom Python expressions not loading on startup

My custom Python expressions are not loading at startup and I dont know why. Its a real pain because I have virtual layers depending on those expressions, so after I load them I have to manually ...
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0answers
17 views

QGIS: Exporting/saving extents of WMS raster layer in a batch process

In QGIS is it possible to run: Export -> Save As as a batch command? I have WMS-raster layers from which I'd like to extract certain extents (based on quite a number of features from a vector layer)...
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1answer
34 views

How to calculate mean of GPS data assigned to 30 m segment in QGIS?

I have collected some temperature data from a Google Car dataset with each data having Lat/Lon and temperature values. The data is stored in CSV file. I already fixed the GPS lat/lon by using "...
2
votes
1answer
63 views

Building exaggerated elevation profiles from VRT DEM in QGIS

I have this little challenge, where I need to build an elevation profile from a VRT DEM mosaic of +5000 TIF files. All Z-values should be exaggerated by factor 10 as it's common in road construction. ...
2
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5answers
222 views

Changing style of points while moving them in QGIS

I have 1000 points in QGIS. I want to move them one by one and I want to know which of those I have already moved. I want to change style of point that I moved before. How can I do that?
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1answer
34 views

How to set image as background for a shapefile polygon using QGIS

I would like to change the background of a polygon to an image using QGIS. Under Symbology, there is an option for Raster Fill but the .jpg image is so zoomed in you cannot see it. Is there a way to ...
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0answers
21 views

QGIS georeference a Mesh layer with wind vectors?

I have an .nc file with u and v components to create a map of wind speed and direction. When I add the layer as a mesh in QGIS, I am able to get the arrow vectors correctly (image below), however, the ...
1
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1answer
43 views

Display QGIS Temporal Controller widget within custom plugin widget

I am building a QGIS-Plugin retrieving time-series raster data from several sources, which is then supposed to be visualized (so far separately and manually) via the Temporal Controller widget, added ...
1
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1answer
43 views

How to convert points to polygons

I have a csv file with the positions (x and y) outlining multiple complex polygons. Each point is numbered in a separate field and each polygon is numbered in a separate field. I can load those points ...
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0answers
39 views

Sharing and editing data remotely in QGIS

I have a colleague who has some data in his server (Geopackage and some layers). Is there any way I can access from my QGIS project remote from my home to this data in his PC for editing and running ...
1
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1answer
29 views

Using themes in print layout in QGIS

I can't work out how to create a print layout directly from a map theme - even though the QGIS 3.10 manual says "All configured themes are also accessible in the print layout, allowing you to ...
0
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0answers
18 views

Copy/Paste features as a Tool in QGIS

I am an generating a proccess with the process simulator from QGIS. My final task is to 'append' the features from one temporary layer created within the proccess to another layer in my proyect. I ...
0
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1answer
19 views

Getting a list for Gdal “Merge” in QGIS Graphical Modeller

I am looking for a way to create an array from the attributes of a multipolygon layer for the algorithm "Gdal Merge". In my layer I have stored file paths to .xyz-data that I want to read so ...
1
vote
1answer
29 views

Apply transformation to layer on the fly when using tools like Buffer

I know that you can have an on-the-fly transformation on a layer when rendering on the canvas, but is there a way to run a tool like Buffer where the layer should be re-projected on-the-fly just ...
0
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1answer
32 views

Embed title to qgis2web map

Is it possible to show a title "ProjectName" within the map generated by qgis2web? I can put a title in above the map described here and tried to follow the answer here to put it above the ...
0
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0answers
22 views

QGIS/PostGIS finding shortest route going through all the polylines at least once

I have a QGIS 3.10 map with two main PostGIS 3.0 layers: Zones (Polygons): the town is divided in 26 zones. Each municipal street sweeper only works inside his zone. Street lines (Linestrings): These ...
0
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1answer
25 views

QGIS Lost my layer settings

I am new user of QGIS and I am facing this problem I created a map in my main project and so some layers. it was working pretty good. But I don't know what I'd changed in parameters. and it gave me a ...
3
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1answer
36 views

Selecting a feature in an attribute table using keyboard cursor with QGIS 3

How to select feature (row) in QGIS 3 attribute table using keyboard cursor? I can't find a hotkey for this. Is this even possible?
0
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1answer
24 views

QGIS - Changing the length of Shortest_Line for CAD-like slope pattern?

I haven't found a tool/plugin that could do this, but I am almost there. Here is what I want to do: I want to create a slope like the ones from CAD programms, but I don't have and don't need a DEM. ...
2
votes
3answers
68 views

How to connect points to lines in order using QGIS?

I have a set of points and I want to create lines from them. Points belonging to one line have unique UniqueID to be grouped by. I try to use QGIS' Points to path algorithm. What I don't have is an ...
0
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1answer
16 views

Intersecting geometry sum - sharing the boundary count as intersection

This question stems from Calculating proportion of area covered by another layer - not just the intersection I have narrowed down the problem. I am attempting to find the percent of district layer(...
1
vote
2answers
52 views

Add unique id to merged attributes tables QGIS

I need to find a way to stack up numeric id fields from two tables without duplications. To put it simply here is what I want to do schematically : Table 1 Id 1 2 Table 2 Id 1 2 3 Expected ...
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1answer
55 views

Use PyQGIS to export PDF ATLAS

I have written a plugin in QGIS 3.16.0, and the result of the process is a project with atlas configured. The project is opened in the end with success, but the last step is to export the configured ...
2
votes
0answers
35 views

Creating several new fields at once with QGIS field calculator in batch mode in the same layer/file

How is it possible to create several new fields at once in the same layer, using QGIS field calculator in batch mode? There is a similar question, but using Python - I'm interested in a solution ...
0
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1answer
49 views

QGIS SRTM downloader does not download [closed]

I have installed the SRTM downloader, it calculates the number of tiles and then start the download in a flash, but without actually download. It does not ask to log in... and proceeds!
1
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1answer
20 views

Opening PDF w/ action based on variable crashes QGIS

I found this script which I modified a bit to open a pdf based on a page number given in the attribute list. Upon trying to execute the action it works just find but QGIS (3.4.15) is crashing! Any ...
1
vote
0answers
28 views

Show ValueMap values based on value of another field in QGIS widgets

I'm applying a Value Map widget to two text fields in my layer. The two fields are as follows: I have a hierarchy consisting of Landcover, and under that Landuse, where the color is code for the ...
1
vote
1answer
41 views

How to get the name of the geometry column in QGIS?

Depending on the table I'm working on, the geometry column does not always have the same name, for example in my data it is called sometimes "the_geom", "geometry", or even "...
2
votes
2answers
479 views

What's the difference between Integer 16bit, 32bit and 64bit in QGIS?

When creating a new attribute field in QGIS, these three options are offered for integer numbers but what is the difference between Integer 16bit, 32bit and 64bit in QGIS?

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