Questions tagged [qgis]
QGIS is a cross-platform GIS application licensed under the GNU General Public License.
31,097
questions
3
votes
2answers
47 views
Converting/expanding line into 2D polygon using QGIS
I am brand new to GIS and am attempting to use QGIS to take an existing line from a shapefile and create a 2D polygon based on it i.e. I want to take a line and fatten it out a bit so it has an area.
...
2
votes
0answers
23 views
Calculate intersection of two 3D vector polygons
I have not found a solution yet to intersect two 3d vector layers. The solution is to calculate the intersection of the two polygonal 3d surfaces.
Does anyone know a solution to intersect two vector ...
2
votes
3answers
52 views
Filling polygon with 2 different colours representing 2 different sets of data using QGIS
I have a map of England where counties are polygons. I would like to fill them with 2 colours; each half corresponding to a specific set of data. Is there a way to do that?
I have included an example ...
0
votes
2answers
24 views
Why won't QGIS import my DDF Raster files? [closed]
Why won't QGIS import my DDF Raster files? It says there is an invalid GDAL error
0
votes
0answers
24 views
The following layers were not correctly generated. Pit Removed Elevation Grid [closed]
I am using TauDEM in QGIS 2.18.17 and doesn't working properly. anyone have ideas to fix this issue?
2
votes
2answers
36 views
Updating a field while editing another
When creating a feature, I want that, if I change the value of field A that field B is also updated with the same value, like an onChange event.
For Example: Imagine you have a basket of apples and ...
0
votes
1answer
28 views
ogr2ogr SHP to MSSQL import leaves geometry column empty
I am trying to import a Shapefile with polygon features into MSSQL database with this command:
ogr2ogr -f "MSSQLSpatial" "MSSQL:server=***;uid=***;pwd=***;database=***" "D:\...
2
votes
1answer
74 views
QGIS default projection used to render a WGS84 map
This question seems naive at first glance, but it's subtle. I was recently pondering... How does QGIS actually represent maps and features when we select the 'WGS84' CRS at the project level?
I ...
5
votes
2answers
249 views
How to format latitude and Longitude labels to show only degrees with suffix without any decimal or minutes?
I am setting my latitude and longitude labels in the QGIS map > map grid properties > draw coordinates > format but this only has decimal, decimal with suffix, degree minutes (w and w/o ...
3
votes
2answers
73 views
Why do I get gaps in the isochrones polygons with ORS tool in QGIS?
I am trying to represent isochrones from a points layer using ORS Tools in QGIS 3.8.3-Zanzibar.
Does anyone know why there are some gaps in the resulting polygons, even though the road, according to ...
-1
votes
0answers
29 views
GeoPackage error in QGIS
I have a problem concerning the saving of a layer in QGIS as geopackage... while creating it, it shows me this window:
What does this error message mean? How can I save the layer?
1
vote
0answers
39 views
Error when creating raster using QGIS
Version 3.16.0 Hannover
I am trying to create a simple raster from x,y,z data
Using Raster-->>Analysis-->>Grid (IDW)
Please see the error log below:
Can anyone help?
QGIS version: 3.16.0-...
2
votes
1answer
36 views
How can I get values from a array (which is evaluated by spatial query) as default-values in other fields
In QGIS 3.16.0 I have a postgis-polygon-layer with a field "array_polygon" which contains an array.
When digitizing a postgis-point-layer-point I would like to use the different array-values ...
2
votes
1answer
37 views
Computing the line of equal distance among several polygons in R
I have a simple GIS problem I was not able to find the solution on the internet.
My aim is quite simple: I have a polygons layer that contains several entities, and I would like to compute a new layer ...
2
votes
1answer
22 views
QGIS 3.4 Vertex tool highlight colour change
I can change the colour for selected items fine. I have even figured out how to change the colour of the preview when moving a vertex. How can I change the colour of the highlight when hovering over a ...
0
votes
1answer
24 views
How do I calculate average depth of a 250m square using points at 125m spacing using QGIS
I have a set of points spaced at 125m intervals across an area, an average depth value is assigned to each point.
I need to calculate from these points a single average depth value for a 250m square, ...
4
votes
2answers
52 views
Save x,y,z values to a GeoJSON file from QGIS
I would like to save x,y,z values for polygon vertices as a geoJSON file using Python in QGIS. I've made several attempts, but all have issues. I've found that the QgsPoint object must be used as ...
4
votes
1answer
45 views
QGIS Processing algorithm output
I am developing a plugin in QGIS using Python language. This plugin uses algorithms from Processing Toolbox and I save some results in the temporary folder assigning "QgsProcessing....
5
votes
2answers
95 views
Count number of features in a geopackage and write to a file
I'm tasked to create a simple catalogue of 2000+ geopackages, and hope there is a way to do that with QGIS.
The idea is to batch run over all these geopackages and write the following to a CSV file;
...
2
votes
2answers
28 views
WFS in QGIS : different boundingbox CRS than Feature CRS
I want to add a WFS 2.0 layer to my QGIS 3.16 and I have a bounding box issue: QGIS sends a bounding box in the same CRS than the layer CRS. But the server expects the bounding box to be in WGS84, ...
4
votes
2answers
93 views
Using the field calculator to calculate intersections
I'm comparing several maps of one area (made by different people) to each other, and used intersection to find how much of specific selected features (polygons) overlapped. I soon realised that the ...
4
votes
0answers
28 views
Error message while running Strahler order for river delineation
I wanted to make river network using Strahler order in SAGA with filled DEM as the input, but there is an error message keep appearing:
QGIS version: 3.14.0-Pi
QGIS code revision: 9f7028fd23
Qt ...
3
votes
1answer
34 views
Error when installing the “Minkowski fractal dimension calculator” Plugin in QGIS 3
I have tried to install the Minkowski fractal dimension calculator via the QGIS Plugin Repository, but got this error shown in the screenshot.
4
votes
0answers
55 views
Error while doing Watershed analysis using Python
I am trying to do watershed analysis using Python in jupyter notebook. Whenever I am passing commands regarding watershed delineation in Python I am getting output as raster matrix and when I am ...
4
votes
0answers
29 views
How to eradicate excess lines in a singly recorded polygonal line (road) network? QGIS 2.8
I'm a beginner in GIS software.
I'm trying to create a road network shapefile within the reserve I work at. To do this, I've driven each and every road inside the property with my GPS app set to ...
0
votes
0answers
28 views
How to give a value of 0 in a raster only in a certain area? [duplicate]
I want to give the value of 0 in this raster but only in the area within the polygon. So the final outcome is the same raster file but with 0 values in that area
How can I do that?
1
vote
0answers
51 views
Polygons and colors do not appear in qgis2web export
I have been trying to export a map from QGIS using the qgis2web plugin. But my polygons and classification colors are not displayed in the exported HTML file, I only can see the Google Street Map ...
3
votes
1answer
41 views
Relation aggregate function error in QGIS using Geometry by expression
I have a point layer, consisting of 12 points with fid 1 to 12. I want to render points with fid > median (fid) - thus in this case, point 7 to 12.
That works perfectly if using geometry generator ...
5
votes
3answers
183 views
Adding scripts to Processing toolbox via PyQGIS
Is there a way for adding new Processing scripts into Processing toolbox using PyQGIS?
In the GUI, I can click on "Add script to toolbox", but I want to add scripts using PyQGIS.
QGIS ...
1
vote
0answers
43 views
Datum transformation not working properly [closed]
I want to create a map with 20 coordinates (UTM), that I have loaded as a CSV-file into QGIS 3.12. The area is located in UTM zone 32 U (northwest of Munich).
As a background I want to use an 80 cm ...
0
votes
0answers
44 views
GDAL2Tiles has low resolution quality
I have a project with a bunch of large, high-resolution Tiff images that I will tilling with gdal2tiles and use on Openlayers.
Those Tiff images have been taken on a drone. Example:
While I tilling ...
2
votes
0answers
51 views
Different layer.name() in batchmode in QGIS processing script
Different layer.name() in single layer processing and batchmode in QGIS scripts.
QGIS version 3.10.7.
My example script:
# -*- coding: utf-8 -*-
"""
***********************************...
3
votes
3answers
116 views
Joining/merging rows by attribute
I have a beautiful grid/polygon, each square having its own "ID", and several observations for each square. But, I have three categories of observation, each with its own row, matching the ...
2
votes
0answers
21 views
Show Image in Callout Label
I have a layer of point data that includes fields for an ID number and an image file path. I would like to display the ID number for each point by default and be able to display the image in a callout ...
0
votes
1answer
16 views
Error [37] : Unable to calculate. Metadata error - SCP plugin in QGIS - Preprocessing landsat 8
I am trying to preprocess Landsat 8 data using the SCP plugin - all the bands are processed except for bands 1 and 9. The metadata is read correctly in the table but on clicking "Run" I hit ...
3
votes
2answers
61 views
Attaching vertex or polygon to line in QGIS
I want to connect the green polygon and the blue line. The buffer tool is not suitable because it makes the whole shape bigger. I'd like to make longer the length of the green one to attach to the ...
5
votes
2answers
102 views
Deciding whether to Select Transformation in QGIS
I've installed QGIS and downloaded the sample files (I'm on a Mac). Following the documentation for getting started I double-click on the landcover.img file which is supposed to load in the background....
-1
votes
0answers
27 views
Calculating the effect of sea level rise on land use in QGIS [closed]
In QGIS I need to calculate how many km of "Agriculture/buildings/bare soil" will be affected by "1m,2m,3m, & 3.5m" of sea level and I am using Landsat8 image and Landsat7 ...
1
vote
0answers
29 views
PostGIS difference between polygons - Ring Self-intersection?
I want to take ST_Difference or ST_Intersection to take the difference between two polygons.
SELECT a.id, a.geom, st_difference(a.geom, b.geom)
FROM liechtenstein.flaechen_norden a, liechtenstein....
2
votes
1answer
32 views
Counting population from grid based on travel time
I have a dataset that consists of the 125x125m grid with population count and time travel vector layers (for example, 5, 10, 15 mins by car). I'd like to mark every grid that's within the buffer range ...
8
votes
2answers
127 views
Exporting features when column value between specific percentiles
I want to do a statistical analysis. I need to export some features. Their column value between 10%-90% (or 20%-80%) percentile in order to avoid outliers' effect. I can't find a function in the ...
0
votes
2answers
54 views
I obtained some elevation data from the USGS website and tried importing it into BlenderGIS and SVDesigner (SoilVision). However, I get a weird render [closed]
The first image is rendered on SVDesigner, the second image is rendered on Blender GIS and the third image is the raster file I obtained from the USGS website.
0
votes
0answers
32 views
WFS Layer not displaying in ArcGIS and QGIS, but appears in the browser
I am using django-gisserver to open GIS models to WFS layers. I have configured the view and URLs in my Django project without any issues, and when I check the WFS URL running our Django project ...
0
votes
0answers
27 views
How do you reproject a raster file or any file in QGIS to fit the original project projection? [closed]
How do you reproject a raster file or any file in QGIS to fit the original project projection?
1
vote
0answers
29 views
Simultaneously habitat fragmentation metrics calculation within more buffers
Within several raster buffers I need to calculate habitat fragmentation metrics (i.e., number of patches, mean patch area, Euclidean distance among patches, landscape proportion) using the landscape ...
0
votes
0answers
22 views
How to do Query Builder and Labeling of Attribute Features of a Layer in QGIS [closed]
Does anyone know how I would complete these directions---basically I'm asking how you use a query builder in the Mac version of the latest QGIS? And how you layer features from a particular field of a ...
1
vote
1answer
33 views
Warning: skipping unsupported geometry type 'Compound Curve' when using v.transform
I am trying to transform data in QGIS from a DXF file.
I keep getting the error:
Warning: skipping unsupported geometry type. Compound Curve
when I do a v.transform.
Eventually, I want to store the ...
1
vote
0answers
33 views
QGIS 3.16.3 uses Python 3.7.7 while I want it to use Python 3.9.1 already on my MacOS Big Sur
MacOS: Big Sur 11.1
QGIS: 3.16.3
KyngChaos said that QGIS 3.16 is using Python 3.9.X (strictly) and I installed this in my system, however the Python bundled with QGIS is 3.7.7. It is strange that ...
5
votes
1answer
55 views
Choosing extent and scale while exporting a map
I'm exporting a map to a PNG file in QGIS 3.10.4 via Project > Import/Export > Export Map to Image. In the dialog that shows up, I can select the extent (exported area), scale, resolution (DPI), ...
7
votes
1answer
89 views
Cannot select input layers for the “Polygonize” tool in QGIS
I am trying to convert a raster layer to a polygon layer using QGIS 3.16. 2. When I open the polygonize tool, the program does not allow me to select any existing raster layers from the 'Input layer' ...
