Questions tagged [qgis]
QGIS is a cross-platform GIS application licensed under the GNU General Public License.
9,872
questions with no upvoted or accepted answers
12
votes
0
answers
357
views
Processing post-execution script hook to clear scratch layers?
I've been cobbling together some Processing scripts for QGIS 2.18 (I'm not a fan of QGIS 3 scripts), and I keep running into one particular problem: my script creates a lot of scratch layers and they ...
- 565
11
votes
2
answers
2k
views
QGIS GRASS Processing Not Working on MacOS?
Recently upgraded to QGIS3 (3.0.2) for MacOS (High Sierra) and encountered GRASS (7.2.2) issues. Tried adding a custom variable and now when running GRASS algorithms (e.g. r.reclass) I get the ...
- 111
10
votes
0
answers
1k
views
Grouped "labels" for QGIS 3.0 Point Cluster styling?
I'm trying to make a cluster visualization of a vector point layer about trees with a few requirements:
The clusters need to change depending on zoom level (solved)
The clusters need to indicate how ...
- 123
9
votes
0
answers
480
views
How to use a Spilhaus/ESRI:54099 projection in QGIS
I am trying to make a map using a Spilhaus projection, similar to the one implemented by Esri here. QGIS has ESRI:54099 WGS_1984_Spilhaus_Ocean_Map_in_Square in its list of available projections, ...
- 395
9
votes
0
answers
283
views
Performance-limits of QGIS expressions
I use quite often QGIS expressions and I am wondering how performant they are compared with other possibilities. In many cases, the same problem can be resolved using different approaches like using ...
- 63.1k
9
votes
0
answers
1k
views
Nearest neighbour joins for two geodataframes using KDtree from scipy/sklearn
I have a number of large geodataframes and I want to automate the implementation of a Nearest Neighbour function using a KDtree for more efficient processing. The process I want to achieve here is to ...
- 91
9
votes
0
answers
1k
views
QGIS Automatically Converts UTC Date-Time to Local?
I imported a WFS layer from a geoserver into QGIS and also into a web service that is based on Cesium. The geoserver fetches the data from Elastic search and serves it out as WFS. The date-time ...
- 241
8
votes
0
answers
110
views
Exporting Geopackage converts milliseconds of QDateTime to zero
I use this solution to display actual QDateTime value with milliseconds in a temporary memory layer. And I use another solution to export as CSV the value including the millisecond value.
But then, I ...
- 74.7k
8
votes
0
answers
2k
views
Importing GeoParquet file in QGIS
GeoParquet is a new geospatial vector data format that is built on Parquet. It looks super efficient in terms of storage and loading/saving data files. Is there a way to read a GeoParquet in QGIS?
...
- 1,228
8
votes
0
answers
110
views
Does QGIS use data source-specific operations?
This may be a very basic question, but I couldn't find an appropriate answer.
Does QGIS use data source specific operations where available and appropriate? For example, when using the Join attributes ...
- 366
8
votes
1
answer
891
views
GRASS v.clean tool in QGIS gives empty output
I am trying to run v.clean in QGIS 3.10.7. I have a 2D LineString dataset saved in GPKG format and I want to run v.clean to clean up some messy topology.
But whenever I run it, I get the same result - ...
- 3,480
8
votes
1
answer
277
views
Filtering in QGIS attribute table similar to dropdown in Excel
I have a large amount of point data that has so far been managed in an Excel list. In the future, these should be shown in QGIS.
To convince colleagues of this, I am looking for a way to make ...
- 131
8
votes
0
answers
175
views
Clustering without aggregation with QGIS Point Displacement
I've seen the following map on twitter and am looking to create the same effect for point displacement.
I'm familiar with grid and circle point displacement as well as with clusters point to aggregate ...
- 111
8
votes
0
answers
1k
views
Add private plugin repository to QGIS 3.4
I want to add a repository to my QGIS 3.4 which is on a private server. The repository contains all files needed (plugin.xml and metadata.txt for example) and has the structure as described here:
Is ...
- 545
8
votes
0
answers
767
views
Change from LineString to MultiLineString when saving layer edits in QGIS
In QGIS, when a user creates a new single part line in an open editing session for a “Multi-Line” SpatiaLite dataset, the QGIS data type is initially a “LineString”. But, when the user commits the ...
- 957
8
votes
0
answers
1k
views
Question marks ("?") in QGIS layer panel when using SVG markers defined with "Data defined override"
When using SVG marker symbols and set the path to SVG file via Data defined override the SVGs display well in the map canvas, but not in the layers panel (applies for QGIS 2.x and 3.x).
SVG marker ...
- 14.6k
8
votes
0
answers
13k
views
Creating in-line variable in field calculator of QGIS
I create new field based on other fields. For example; if "Field_A" is smaller than "Field_B", value of new field is 'A', otherwise it is 'B'. So I want to create new variable for ...
- 74.7k
8
votes
0
answers
188
views
Issues with atlas generator and labelling across maps/images
I have a lot of layers in my project and I am trying to use the atlas generator in the print composer to create a tiled map. Some of the layers have labels which have different configurations with ...
- 4,450
8
votes
0
answers
615
views
QGIS/Spatialite cluster analysis with density
I am trying to analyse a large set of points (2 millions) over a set of polygons (3000), and particularly find clusters of points. Doing it in QGIS was taking too long/crashing the computer so I ...
- 651
8
votes
0
answers
2k
views
Can I use GeoJSON GeometryCollection in QGIS?
I want to create a GeoJSON that contains multiple geometries to be used in QGis later on.
Now I red through the specs here: http://geojson.org/geojson-spec.html#geometrycollection
When I simply copy ...
- 393
8
votes
0
answers
643
views
Setting up PyCharm CE 4 to work with PyQGIS library in Mac OS
I am trying to set up PyCharm to work with PyQGIS library. I am using PyCharm CE v4 and QGIS version 2.8 I have tried to implement the instructions of several posts like:
http://osgeo-org.1560.x6....
- 221
7
votes
1
answer
213
views
QGIS Model Designer: 'Algorithm is not available' and 'NoneType' object has no attribute 'displayName'
I am building a model to automate a process of generating points at street intersections. When I run the model, there is no output. Checking the error logs, I see this:
2022-04-26T10:55:36 WARNING ...
- 81
7
votes
0
answers
242
views
Increase tolerance of QGIS processing tools
I have 2 line layers in QGIS 3.22.0 and I
create a 10cm-buffer around line layer A (red)
perform a difference of line layer B (blue) with the buffer of layer A (light red)
As a result I get 1 ...
- 2,217
7
votes
0
answers
278
views
Time-Space aquarium with paths
I am trying to reproduce this kind of spatial representation with QGIS. It's a space-time aquarium where each line represents a path compared to time:
It is a representation from the Time geography, ...
- 81
7
votes
0
answers
376
views
QGIS contextual menu overriding
I would like to override the default contextual menu in QGIS 3 in the ToC.
I've created a class that inherit from QgsLayerTreeViewMenuProvider.
from qgis.gui import QgsLayerTreeViewMenuProvider
from ...
- 513
7
votes
0
answers
1k
views
How to change QGIS 3 default encoding
When I import shapefile layers their encoding is System while the data is in UTF-8. How to change the default encoding to UTF-8?
This question answer here "
Is it possible to change default ...
- 71
7
votes
0
answers
110
views
Why is QGIS holding references to layers that are not in layer list
I have a QGIS project, which has about 30 layers in the layer list. I removed one of the layers from the list, saved the project, closed QGIS.
(The layer itself was from a Geopackage database, which ...
- 3,365
7
votes
1
answer
177
views
Counting upstream dams along river network in QGIS
I am working on QGIS. I have a river network where each segment is a line with ID from the upstream one (if any) and the downstream one (if any).
I also have information on:
location of dams
location ...
7
votes
0
answers
402
views
Getting layer id of processing step in QGIS graphical modeler for usage within aggregate() function
How can I get the layer name or layer id of the result of an processing algorithm within QGIS graphical modeler, so I can use aggregate() function in a later processing step? Is this somehow possible ...
- 32.6k
7
votes
1
answer
576
views
Showing labels as they will be printed/exported in my print layout?
I set up a print layout for a map I want to print in QGIS. Some of my layers have labels on them. When I zoom in and out in the screen, without changing anything else on the print layout, some labels ...
- 311
7
votes
0
answers
1k
views
QGIS 3: Set custom project variables with input dialog
I am using QGIS 3.10.0 and Windows 10. I have a project where I want the user to define custom project variables. I want to make this user friendly, I don't want the user to need to open the project ...
- 143
7
votes
0
answers
931
views
Creating LineString geometry in QGIS
The default geometry type for a newly created line seems to be MultiLineString. It can be changed to LineString using the "Multipart to Singleparts" tool while saving in memory. However, ...
- 191
7
votes
0
answers
317
views
QGIS plugin external libraries in plugin’s directory
I’m developing my first QGIS plugin and I have to use two external libraries not included in the default OSGeoW64 installation: Couchdb and Pandas.
I would like to include those libraries in my ...
7
votes
0
answers
319
views
Identification of roof peaks on a Raster in Qgis
I am trying to map all the flat roofs of a city. After processing my data I have a huge raster with the zones that are flat (=1) and not flat (=0).
I can overlap the roof polygons over this raster and ...
- 241
7
votes
0
answers
365
views
Change default label font for styling
Where can I change the default labeling font "MS Shell Dlg 2" to a different one?
I don't want to change the default layout font (Options --> Generel Settings)
Maybe there is a solution to use the ...
- 816
7
votes
0
answers
3k
views
When does a QGIS .qix spatial index of a shapefile need to be re-created?
I understand the basics of spatial indexes but would like to understand when exactly a spatial index would need to be re-created or updated?
The reason I ask is because when a folder was moved to a ...
- 3,180
7
votes
0
answers
164
views
Speed up identify in QGIS
I have just transferred my Postgis database onto an RDS server, and there is a bit of a performance hit when using the Identify tool in QGIS (3) compared to localhost. I presume this is mostly network ...
- 6,634
7
votes
1
answer
254
views
Loading vector layers from database/ schema using login username and password in QGIS?
I have a QGIS setup with a PostgreSQL / PostGIS database on a server and multiple clients.
I have created schemas in the database for each user. With a username password combination, each user is ...
- 145
7
votes
0
answers
1k
views
QGIS plugins not installing
I'm trying to install plugins on a fresh install of QGIS 2.18.12. I can connect to the plugins repository but trying to install any plugin fails with the error message:
Failed to unzip plugin package....
- 1,432
7
votes
0
answers
1k
views
Import Pandas or any Python module into QGIS internal Python
(Also asked in stack overflow -
https://stackoverflow.com/questions/43244062/import-pandas-or-any-python-module-into-qgis-internal-python )
I am developing a plugin for the current LTR version of ...
- 788
7
votes
0
answers
216
views
How to change the color ramp of a rule based styling in QGIS?
I use rule-based styling in QGIS, in order to do spatial quantile, computed in R.
If I want to change the color ramp, I need to either:
change every class color,
or set graduated then change the color ...
- 171
7
votes
0
answers
535
views
Is it possible to link symbol fill colors between different geometry types in QGIS
I would like to link symbol colors between two layers of different geometry types (point and polygon). I have tried to save/load style and to copy/paste but I don't think its designed to work that way ...
- 71
7
votes
0
answers
848
views
PDF looks different from print composer
When I create a map in print composer the map looks exactly how I want it, but when I save it as a PDF some of the sympbols have changed. Note the roads are still visible in the PDF but some have ...
- 71
7
votes
0
answers
427
views
QGIS doesn't handle PostGis connection resets?
I'm highly frustrated by the fact that if I leave the database alone for a more than a few minutes, I can no longer insert new lines. If I restart QGIS, everything goes back to normal. I believe this ...
- 171
7
votes
0
answers
665
views
QGIS Align Rasters how to retain pixel values?
I am attempting to align and then merge a number of rasters of the same resolution and extent, but where the pixels are slightly misaligned (creating small gaps when merged). This works fine using the ...
- 71
7
votes
1
answer
437
views
Topological editing of two different layers in QGIS
Is there a way to apply topological editing to move vertices between two coincident features that are not in the same layer?
For example, if I have a crop land polygon coincident with a soil polygon (...
- 143
7
votes
0
answers
772
views
Using QGIS' "network protocol" to import data from OPeNDAP?
After looking at the OPeNDAP documentation
I assumed I could import data into QGIS by downloading the .ascii file OPeNDAP generates. However the downloaded OPeNDAP .ascii doesn't seem to be compatible ...
7
votes
0
answers
1k
views
QGIS cannot open output layers
I have problem with QGIS 2.0.1. Everytime I run tool from SAGA or GRASS, I get exactly the same error, for example:
Oooops! The following output layers could not be open
Channel Network: /tmp/...
- 71
7
votes
1
answer
374
views
Spatialite KNN view in QGIS
My task is to calculate the average ground survey level for each tree in my dataset, using the 3 closest survey points (optionally within a 3m radius of the tree). I want to write this in a Spatial ...
- 10.1k
6
votes
0
answers
62
views
Get rotation and scale of picture after georeferencing using QGIS
How can I access the rotation and scaling information, that is visible during the georeferencing process in QGIS (see yellow marked text in the picture), after the georeferencing is completed and the ...
- 61