Questions tagged [qgis]
QGIS is a cross-platform GIS application licensed under the GNU General Public License.
35,855
questions
4
votes
3
answers
90
views
Edit polygon - QGIS - remove a line or space in middle of merged polygon
I am editing a map using QGIS. Here my steps
1. Select multiple polygons
2. Merge them into one new polygon
Question: How can I remove those line (in blue circle) and one polygon fully cover the ...
- 143
2
votes
0
answers
18
views
Any advice on how to use r.stats in QGIS
I am trying to run r.stats in QGIS to get all unique combinations of data values from 2 raster layers. The process runs, outputs an HTML file, and does not throw any errors. However the files are ...
- 21
4
votes
2
answers
111
views
Transform CRS and strip decimal places
I'm using the following expression in the QGIS attribute form default value expression box to transform the CRS EPSG:3857, EPSG:4326:
y(transform($geometry,'EPSG:3857','EPSG:4326))
This works ...
1
vote
1
answer
79
views
Google Maps not being quite top-down in QGIS
I am quite new to QGIS, but am using it for utility mapping at work.
I have added a google maps layer to my QGIS project via http://mt0.google.com/vt/lyrs=s&hl=en&x={x}&y={y}&z={z} and ...
- 33
0
votes
0
answers
18
views
Trying to write a QGIS processing script for 'native:hublines', cannot seem to get it working
I have an almost functioning script (I think) to draw hub lines in QGIS, but cannot get the last bit to function properly. Here is my script:
from qgis.PyQt.QtCore import QCoreApplication, QVariant
...
- 1
1
vote
0
answers
21
views
Create a line on polyline type m
in QGIS I have a layer "HlavniInfo" which is polyline type m. HlavniInfo is a layer which contains a list of roads - ID, name, from, to, length ...
Then I have a second table that contains ...
- 11
1
vote
0
answers
18
views
How to use raster calculator to sum multiple bands' value of a raster layer in QGIS Graphical Modeler?
I have 12 bands in a raster layer which I would like to sum up to produce a single layer. Interestingly, the raster calculator tool does the job while running it (QGIS interface)[ but fails to do so ...
- 79
1
vote
0
answers
21
views
Shortest path based on priority
I'm using the geoprocessing "Shortest path (from layer to point)" of QGIS and i'd like to get the shortest path not in the usually way, but based on priority of the routes used.
For example, ...
- 639
0
votes
1
answer
41
views
QField Cloud logo not appearing
I'm trying to work with QGis Field. I have successfully set an offline project up, but I have a problem with the cloud. The issue is that after installing the plugin, I do not see the cloud icon as it ...
- 45
0
votes
1
answer
20
views
Color scale from label
Is there a way to apply a color scale (gradient) like in image 2, based on the percentages (image 1) of the label ? (From Anti-aliased rasterization of vectors in QGIS?)
1.
2.
- 31
3
votes
1
answer
39
views
QGIS layer styling, "symbology" - automate delete and reclassify
My QGIS projects always have around 20 layers that need to be Categorized by a certain value every day. Right now, I need to manually hit the "delete" and "classify" buttons. Fine ...
- 31
8
votes
2
answers
379
views
Rotating polygons to follow the curve (line) in 90 degree in QGIS
I have created points on the line with 60m distance. Then I've made square buffers to these points. But they all stand straight. Is it possible somehow to rotate them so they follow the line curves? ...
- 123
-2
votes
1
answer
31
views
Why does the image become bright when I set transparency in the raster layer in QGIS?
Why does the image become bright when I set transparency in the raster layer in QGIS?
After setting to Nodata=0, the image becomes bright and clear. Why is that?
- 367
2
votes
1
answer
37
views
Shift points based on attribute (e.g. slope and aspect, preferably with QGIS)
I'm trying to shift point coordinates "upwards" based on a slope/aspect raster that I have computed beforehand. Working preferably with QGIS, but other means (i.e. R/ArcGIS [Standard/Pro]) ...
- 1,219
2
votes
0
answers
28
views
Multiple login challenges from PostgreSQL when using QGIS
I am using PostGIS as my main data storage. I have two different geodatabases, one with internal data and one with various background maps. Both those connections are set up with stored user ...
- 2,650
0
votes
1
answer
10
views
Why does the "OTB - BundleToPerfectSensor" use the height value?
Why does the "BundleToPerfectSensor" use the height value?
QGIS wants to use the OTB plug-in to do Pansharpening.
I wonder why the height value is needed to convert the MS image to high ...
- 367
1
vote
0
answers
29
views
QGIS 3.22 vertex editor snapping placing vertices in wrong location
I've been having a strange issue with my vertex editor over the past couple of days. I am attempting to edit a polygon such that the borders of the polygon line up with a different line segment layer ...
- 11
1
vote
1
answer
24
views
SpatiaLite visibility problem in QGIS
I have a .sqlite dataset, and I want to open it using QGIS, check the data, and plot some color maps. It's a 1 km by 1 km gridded data. When I import the data into QGIS using "add SpatiaLite ...
- 93
0
votes
0
answers
16
views
QGIS 3 connection to ArcGIS Online via ArcGIS REST service connection hanging
Have been successfully accessing the ArcGIS World Imagery via an ArcGIS REST Server connection using the URL: http://server.arcgisonline.com/arcgis/rest/services/World_Imagery/MapServer for the past ...
- 73
-1
votes
0
answers
26
views
QGIS plugin for reviewing image and label pairs for satellite image segmentation deep learning models
Does anyone know of a plugin or other offline tool, preferably but not necessarily implemented as a QGIS plugin, for reviewing and editing image/vector label pairs for satellite image segmentation?
My ...
1
vote
1
answer
26
views
Pyqgis 3 adding polygon vector layer in code and triggering iface.actionAddFeature().trigger() will give me polygons but they cannot be selected
Code to add polygon layer when a button is pressed in my plugin:
# Add polygon layer
self.poly_layer = QgsVectorLayer("Polygon", "target_polygons", "memory&...
- 75
2
votes
1
answer
33
views
Tiles XYZ plugin for newer versions of QGIS
I was wondering if anyone knows what replaced Tiles XYZ for newer versions of QGIS, as I cannot find it when I search for plugins and when I try and install it via zip file it says it only works with ...
- 109
1
vote
1
answer
100
views
QField is not Syncing back
QGIS 3.24.2-Tisler, QField 2.0.16 - Arctic Fox, QField Sync 4.0
So I have used QField for some time now and it was working great never had a problem but over the winter I did not touch it. Now nothing ...
- 11
1
vote
1
answer
26
views
Rule based symbology after clip in Qgis
I tried clipping Vector layer by Vector-Geoprocessing tools-Clip but when I clip it seems that Rule based symbology of the Vector layer is not kept.
Is there a way to clip and to keep rule based ...
- 493
0
votes
0
answers
20
views
Rendering geotiff raster on QGIS
I have various GeoTIFF raster image that I display on QGIS (3.2 or 3.4) - ortomoisaic created with agrisoft metashape
Sone raster (between 1 to 4 gb) are very slow to render/zoom on QGIS, while other (...
- 81
6
votes
1
answer
145
views
Generating x, y, coordinates within polygon/polyline with certain interval in QGIS
I need all the x- and y-coordinates with a interval of 500 meters that fit inside a polygon/polyline.
For example I want to generate a CSV file that looks like this:
x, y,
10000, 30000
10500, 30000
...
- 63
1
vote
0
answers
16
views
How to reduce number of symbols in varying size assitant
I have created a proportional symbol map in QGIS but the varying size assistant has created many different bubbles when I would just like four. I was wondering if there is any way to change this?
- 11
2
votes
0
answers
59
views
Distance along line network between set of points to set of hubs
I am trying to measure distance between towns (light grey in attached screenshot) and their district capitals (light purple) along usable roads (dashed blue). I used the GRASS v.distance plugin to ...
- 21
1
vote
0
answers
41
views
Publish a GeoTIFF file as WMS to GeoServer
I have published the GeoTIFF file which I want to use on the GeoServer without any problems, but when I want to view it on QGIS with a WMS connection, the TIFF file does not come. While uploading to ...
3
votes
1
answer
91
views
Counting polygons in polygons using QGIS
I have a layer that represents the green areas of a city and another layer that is a 36x24 mesh surface, where each square is 200x200 meters. Next, I made an intersection (orange on the 1rst image) ...
- 31
0
votes
0
answers
17
views
Java OpenMap shapefile writing problem
I am having an issue with using OpenMap in a Java application to output shapefiles. My data is in "Albers Conical Equal Area".
When I write a shapefile consisting of a line between two ...
- 1
1
vote
1
answer
31
views
Spatial join loads indefinitely in QGIS
I am trying to perform a spatial join between a very large polygon layer and a very large point layer in QGIS. I left the process running overnight but there does not appear to be any sign of progress....
- 109
0
votes
0
answers
20
views
QGIS Calculate Percentage Area of Grid Cell
I'm trying to use QGIS to calculate the area of each grid cell that has been deforested.
To do so, I have tried the following:
Create Grid to create a 30km x 30km square grid
Add Deforestation Layer (...
- 19
0
votes
0
answers
23
views
merge XYZ Files: ERROR 1: Attempt to create 6961x-8398 dataset is illegal,sizes must be larger than zero
So I am trying to merge 200+ XYZ files to one Raster-layer. And i get the following Exception:
2022-05-01T14:18:23 INFO gdal_merge.bat -n -398.0 -ot Float32 -of GTiff -o C:/Users/magni/AppData/...
- 13
2
votes
2
answers
68
views
Apply the same filter expression at the provider level to several layers of the TOC in QGIS in one single operation
I have a QGIS project with plenty of geometric layers coming from a PostGIS database.
Each and every layer has the same filter expression to limit the display to a same object: the filter simply being ...
- 6,698
1
vote
0
answers
57
views
Using LIKE in QGIS Graphical Modeler
I am using the Graphical Modeler in QGIS for the first time, and would like to filter a very large point layer of postcodes in the UK by the first letter of the postcode (for now 'B') before doing a '...
- 11
0
votes
0
answers
12
views
"CityJSON" Plugin, "Railway" Demo Download Problem
I am using the "CityJSON" plugin.
Is there a method to alter the color of the labels on the .json file once it's been loaded into QGIS? see picture below
0
votes
0
answers
22
views
Attempting to "Merge" Tiles
I just searched the GIS Stack Exchange using "how to merge DEM tiles" and found out about 'GDAL' -> 'Raster miscellaneous' -> 'Merge'. I tried to utilize this tool to merge 9 rasters ...
2
votes
0
answers
25
views
Retrieve and use query params inside a QGIS server project file
I have a QGIS project hosted using the camptocamp/qgis-server docker image.
Everything goes fine. But I would like to retrieve (and use inside the QGIS project itself) some of the query parameters ...
- 6,698
1
vote
0
answers
28
views
PostGIS role limitations overcome via QGIS
I'm using PostgreSQL 14 with PostGIS extension. I've created the following role and grants
create role prueba login nocreatedb password 'prueba';
grant select, references, trigger
on all tables in ...
- 2,271
1
vote
0
answers
39
views
Orthorectification in QGIS [closed]
I'm a beginner in QGIS. I georeferenced 2 satellite photos and merged them, and now I want to orthorectify it but I don't know the steps in doing so.
- 11
2
votes
0
answers
19
views
Why opens QGIS context menu always on different screen?
I have Macbook and an external screen connected to my Macbook. I have the problem that EVERY single context window I open in QGIS by right-clicking opens on my other screen. Not matter if I want to ...
- 1,903
1
vote
1
answer
34
views
QGIS rasterize does not cover full polygon
When I rasterize my polygon, it does not cover the upper part, as well as a small part in the bottom right. What is the reasoning for this, and how do I change it?
I rasterized the following way:
- 9
1
vote
0
answers
33
views
QGIS Print composer bitmaps everything
I have been exporting maps as PDFs for some time now, and now, all of a sudden, the Printcomposer "converts" everything (except the North arrow and the scale bar) to a single bitmap, ...
- 111
-1
votes
0
answers
23
views
Translating ArcGIS expression to QGIS expression [duplicate]
Can you help me translate the following ArcGIS raster calculator expression to a QGIS 3.22.5 expression?
Con("raster.tif" < 0.004, 0.004, "raster.tif")
2
votes
1
answer
75
views
gdalinfo authenticate for remote file
I am trying to access the metadata for the following COG (Cloud Optimized GeoTIFF) using
gdalinfo /vsicurl/https://landsatlook.usgs.gov/data/collection02/level-2/standard/oli-tirs/2022/082/070/...
- 585
0
votes
0
answers
17
views
Applying HDR (high dynamic range) rendering in QGIS
I want to automatically (without manual adjustments) apply HDR (high dynamic range) rendering to Sentinel-2 satellite images so that the image can distinguish between very bright objects (e.g. clouds, ...
- 5,622
1
vote
0
answers
29
views
QGis can't read ECW format after update
I have updated from 2.18.16 "Las Palmas" to 3.24 "Tisler". After that QGis can't read ECW format. This is the error:
Fuente de datos no admitida: path_to_file/...
- 811
1
vote
1
answer
33
views
Osm2pgsql error: authentication method 10 not supported
I'm getting the following error when trying to import osm data using osm2pgsql. I just installed pgAdmin4 today so it should all be up to date.
osm2pgsql version 0.92.0 (64 bit id space)
pgAdmin4 ...
- 710
1
vote
1
answer
26
views
QgsAttributeForm disappears using it in a QGIS plugin
I'im trying to make appear a QgsAttributeForm of one feature in my QGIS plugin, but the form disappears just after it appears.
Here is my code (used with QGIS 3.22):
class TestAttForm:
# ...
- 329