Questions tagged [qgis]
QGIS is a cross-platform GIS application licensed under the GNU General Public License.
35,865
questions
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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
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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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8
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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 ...
1
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0
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19
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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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0
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15
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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
vote
1
answer
20
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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 ...
1
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1
answer
25
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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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0
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0
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14
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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
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0
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25
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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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-1
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0
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23
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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 ...
0
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0
answers
21
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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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0
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0
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22
views
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 ...
- 175
0
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0
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11
views
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!...
- 1,159
1
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0
answers
24
views
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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0
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0
answers
14
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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 ...
0
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0
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9
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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
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0
answers
21
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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
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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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0
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0
answers
25
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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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0
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0
answers
13
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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. ...
- 33
0
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0
answers
29
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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
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0
answers
17
views
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 ...
- 3,594
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
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0
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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 ...
1
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0
answers
27
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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....
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 ...
- 6,973
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0
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17
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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. ...
- 8,082
0
votes
1
answer
30
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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 ...
- 311
0
votes
1
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20
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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
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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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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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1
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29
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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
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
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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
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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 ...
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 ...
1
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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 ...
-1
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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 ...
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 ...
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
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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
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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 ...
- 414
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0
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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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0
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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
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0
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14
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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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0
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17
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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 ...
- 493
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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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