Questions tagged [qgis]

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

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PyGeodesy package not opening PGM file in QGIS

I am trying to evaluate geoid heights using Earth Gravitational Models. I use the following script: (Reference) # geoid.py from pygeodesy import GeoidKarney from pygeodesy.ellipsoidalKarney import ...
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8 views

Create a route animation with a large amount of lines

I am working since a few days to find a solution to my problem: I am trying to build a user interface which allows, after clicking "play", to see a route appearing on the map canvas, every x ...
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QGIS 3.24 Tisler Semi-automatic Classification Plugin create new training input error

I'm currently working on a group project that involves classifications of land covers. I have been using SCP for the preprocessing of Landsat 8 images and it works fine. However when I'm trying to ...
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1 vote
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How to delete an island in NetCDF file using QGIS

I have a NetCDFf file (https://drive.google.com/drive/folders/10XvLZPC9vX9odkfU6aV6qBIxRe9IQvyZ?usp=sharing) The variable in the plot below is inside yelmo2d.nc --> z_srf The file contains height ...
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Changing depth colorscale showing the intervals instead of only the minimum and maximum in print layout

I have made a legend with the bathymetry color scale in it example: It only shows 0 and -30 while I have made the color scale using 10 meter intervals, so 0, -10, -20, -30. Does anyone know how to ...
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1 answer
20 views

Dynamic stats in the decoration title lable, by time stamp, in QGIS

I am trying to create a visualisation method of simple stats using the title label in QGIS canvas. I need to observe temporal changes in the stats, so I have tried to specify a dynamic chunk of text ...
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1 vote
1 answer
25 views

QGIS converting text field with special characters to numeric (real) field

I have a dataset with a text field (INL_EL) containing mix formatted values likes: {92.066} and 94.461 I want to make a new numeric field (INL_EL_N) containing the above values. Tried to write the ...
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What is unit of Heatmap (Kernel Density Estimation)? [duplicate]

I want to calculate a housing density using a points layer in the “WGS84 / UTM zone 56S” projection, setting the parameters as follows: RADIUS = 1000 PIXEL_SIZE = 100 KERNEL = “Quartic” OUTPUT_VALUE =...
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-1 votes
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Add coordinate points to QGIS [closed]

I have a shapefile and a .csv table with coordinates. I imported it to QGIS as a Delimited Text Layer but found many of my points are outside my area of interest. I also need to color code the points ...
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Measuring geographic isolation of mountaintop "islands" [closed]

I need to quantify geographic isolation of alpine areas similar to what is done in this paper: “Geographic isolation was calculated as the area (km2) of non-alpine tundra habitat within a 10-km ...
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21 views

Forcing multiple rasters to same orientation despite their geolocation using QGIS

I have a bunch of rasters and I need them all lined up left-to-right superimposed over each other (overlapping in a new coordinate system). The goal is to feed these rasters individually into a neural ...
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Joining line data to points using QGIS

Assets: Green point layer Blue point layer (with alphabetical FID attribute) Red line layer (with numerical FID Attribute) Blue line layer Goal: Join red line FID attribute to Blue point in order away ...
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How to define a hidden string as an imput in QGIS scripts

I have an R Script in QGIS as a processing tool and it logs into a location with a username and password using the ##username=string ##password=string it works fine but the password shows mypassword21!...
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1 vote
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Issues splitting a polygon layer by line

So we have a problem, and we can't a find solution. if feat_L.geometry().intersects(feat_P.geometry()): success, splits, topo = feat_P.geometry().splitGeometry(feat_L.geometry().asPolyline(), True)...
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QGIS adjust the numbers in my layout

I'm pretty new with QGIS and I have an issue. I created a "tree cadastre" and in my layout I wanted to sort the numbers of my trees from low to high. But the counting is not hundred percent ...
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'QGIS Processing Executor'_Issue: "sqlite3_open ... unable to open database file"

Trying to run a self built-in QGIS-model (*.model3) using the followoing 'QGIS Processing Executor' (qgis_process) command in the command line does not work. C:\Program Files\QGIS 3.24.1\apps\Qt5\bin&...
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1 vote
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21 views

QGIS 3.x Python - Some VectorLayer signals not working?

I'm writing a plugin and was really hoping to get the featureAdded signal when the user is interacting with a VectorLayer object in the plugin, but I never see that signal. To try and figure out what'...
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19 views

QGIS - Photo Widget

Is it possible to append info to the file name of a photo? We use QGIS in office Merginmaps in the field to collect data. When we setup the layers to collect utility pole data, we have added a photo ...
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Discrepancy in output volume calculation for same rasters in QGIS and Rasterio

I have been comparing my volume calculation results on the same rasters with QGIS Raster Surface Volume tool and the following python script: import rasterio import numpy as np filename = 'D:/raster....
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13 views

QGIS Atlas with fixed scale not printing all polygon

I have a QGIS Atlas generated map and I have a question. I have polygons (coverage layer) that are printed in just one "piece". So, I have these 2 polygons When I am in Atlas he is printing ...
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3 votes
1 answer
69 views

Making new field with formatted values in QGIS

I have a column called "Kiinteistötunnus". The values ​​are in the form 73479400010025. Values in the whole column ​​should be changed to form 734-794-0001-0025. The data type is Integer64. ...
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0 votes
0 answers
29 views

How to Orthorectify satellite images through DEM? (in any GIS software) because I am not getting any specific method to do this [closed]

How to Orthorectify satellite images through DEM? (in any GIS software) because I am not getting any specific method for doing this. I have done in envi software but its require RPC file but i am ...
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1 vote
0 answers
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QGIS autoadjust the line to another existing line nearby

I have the line created by the "Point to path" function. The algorithm produces just a straight line, whereas I would like to have this line auto-adjusted to the other line (or buffer) which ...
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3 votes
1 answer
103 views

QGIS doesn't like the number 6?

Something seems to be wrong with the layout manager/export function, leading to some weird error that it misses exactly one line string (in this case: the number "6") in the finished PDF/...
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-1 votes
0 answers
26 views

Creating polygons from centroid and bounds

I am looking to create multiple overlapping administrative boundary polygons, but only have centroid and "bounds" columns to draw from at the moment (the latter being four, comma-separated ...
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1 vote
0 answers
27 views

SpatiaLite ST_Transform does not return geometry in QGIS virtual layer

I am using the following query to SpatiaLite in a QGIS virtual layer but it is returning null geometries (looking to transform from ESPG:4326/WGS 84 to ESPG:27700/OSGB 1936): SELECT st_transform(p....
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0 votes
1 answer
58 views

Attribute form constraint, using NULL

At 3.24.2, I have a Geopackage table containing two fields: "interior_observed" is a Boolean, with a Checkbox widget type, true or false. "egg_number" is an integer, with a Range ...
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1 vote
0 answers
17 views

Modifying features in-place with a model

QGIS has some processing algorithms that allow modifying the layer's features in-place. How can I create a tool in the graphical modeler that allows for the same in-place editing functionality, e. g. ...
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  • 8,082
0 votes
1 answer
30 views

Polygonize/Vectorize large raster

A raster(.tif) of 6.70GB needs to be converted into polygons. The raster is binary (0 & 1), currently I am using Polygonize (raster to vector) and its taking a considerable amount of time and the ...
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  • 311
0 votes
1 answer
20 views

Separate canopy from ground - based on DEM generated from thermal imaging

I've never worked with QGIS but I need to use it for a project. I have thermal images of a vineyard that were added together in Agisoft Metashape to form a DEM (tif-file). When I load this into QGIS I ...
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0 answers
38 views

QGIS Buffer tool: Why do buffers of points not show up?

I've got a point layer and I want to have a very simple buffer around each point. I have been playing around with different options and all worked somehow except for a flat end cap style. But why is ...
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1 vote
1 answer
33 views

QGIS - copy/paste symbology labels

I often have layer metadata like labels for each unique value in a categorical map in a separate file, like in Excel. Is there a way to copy/paste entire columns from Excel into QGIS (and the other ...
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0 votes
1 answer
29 views

Export PNG in QGIS, same extent but outputs are not exactly the same

I export the PNG with same extent, same resolution and scale but the output width are not exactly the same. It's quite annoying to me, and I have no idea why could this happen Are there any ...
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1 vote
1 answer
22 views

When moving layer labels the labels connect

in my qgis project i have a layer with multiple points. I labelled all of these points different and suddenly when i move the layers they "connect" all on the same spot and i cant split them ...
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-1 votes
1 answer
31 views

How to draw a scale or a graduated marker on QGIS? [closed]

I need to place points at regular intervals on a map. How can I proceed? In order to have regular spacing and have my rectangles all aligned, I need a tool to place my points with regular spacing. So ...
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1 vote
0 answers
18 views

Can I use the dropdown list in attributes table for several selected features in one time?

I use some dropdown lists for several attributes. Now I want to select several features (objects) and edit a field using the dropdown list. Is there a way to do it in one time, because it looks like ...
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0 votes
1 answer
10 views

Exporting raster of a map to QGIS from GGplot in R

I used R to make density surface models of whales in GGPLOT. However, l can not work out how to get the model into a raster so i can use it in QGIS. I have been trying as below but the squares of the ...
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1 vote
0 answers
27 views

In QGIS Modeler, how to merge the outputs of conditional branches of which some are performed and some are not?

I need to do a processing model that has several optional vector inputs, but that produces only one output. I have separate conditional processing branches for all inputs, but in the end I would need ...
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-1 votes
1 answer
53 views

Clip Line Layer to Polygon but retain the Lines outside the polygons

I want to clip a line layer to a polygon layer, but retain the lines outside the polygons. Can anybody assist me in doing this please? On the image included, the lines are in red and the polygon in ...
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-1 votes
0 answers
17 views

Nighttime Lights Data to CSV [closed]

I'm very new to ArcGIS and I'm using it for this project I'm doing that involves nighttime light images from https://www.ngdc.noaa.gov/eog/dmsp/downloadV4composites.html. As of right now I just want ...
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2 votes
0 answers
26 views

Relations in QGIS

I have the following relationship implemented in Postgres I have designed the following form for QGIS in QT Designer for save project What I can't find is how to save the many-to-many relationship ...
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1 vote
1 answer
36 views

Merge a .gpx with a DEM

I have two files, a DEM and a .GPX. How can I mix the two files so that the .gpx is part of the DEM (in black and white), but rendering the color at an elevation 10m higher than the DEM? The color of ...
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0 votes
0 answers
21 views

Geometry error with QGIS

I create rectangles from the tool "Rectangles, ovals, diamonds" on a layer (shapefile) of type point that I created before. Because I need to create rectangle with specifics dimensions then ...
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1 vote
1 answer
20 views

How can I activate GeoTIFF compression in QGIS 3.x gdal_translate?

I am a beginner at Python so please excuse this stupid question. I am working on a simple QGIS plug-in for saving GeoTIFFs and I want to give the user the option to switch on compression when saving ...
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6 votes
1 answer
154 views

QGIS - Connection Lines using geometry generator between 2 layers in a relation N-1

I would like to know if there is any way to generate a connecting line between 2 points layers (blocks-points representing a watershed, concpoints-points representing the concentration location of the ...
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0 votes
0 answers
16 views

What do CORE_EXPORT and GUI_EXPORT keywords mean?

In some QGIS classes there is a statement CORE_EXPORT or GUI_EXPORT between class operator and class name. What does this statement mean? Example in this part of surce code: https://api.qgis.org/api/...
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-2 votes
0 answers
24 views

Creation of rectangle on QGIS

I create rectangles from the tool "Rectangles, ovals, diamonds" on a layer (shapefile) of type point that I created before. When I want to leave my project I am informed of an error on some ...
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0 votes
0 answers
14 views

print layout for map bug

I want to create a map with legend and so on but when I actually press New print layout and then I add a map I have a blank (see img attached). Is anyone does know why? enter image description here
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  • 399
1 vote
0 answers
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How to remove all resources loaded from QGIS plugin?

I used the QGIS Plugin Builder to create a plugin where the main.py file imports dockwidgets and class from its own file and from other files. A button on the toolbar executes the run(self) function ...
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  • 493
1 vote
0 answers
11 views

What does "Fill Increment" mean with SAGA - Fill Sinks (QM of ESP) tool?

I am using the SAGA tool Fill Sinks (QM of ESP). The only adjustable parameter is called "Fill Increment". And the documentation is not very explicit about what it means. Is it the depth ...
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