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Questions tagged [qgis-processing]

Spatial data processing framework that brings advanced analysis capabilities to QGIS.

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1 answer
42 views

Load results of split vector tool into group using PYQGIS

I try to write a script to automatically merge some input layers (all of the same structure) of a geopackage into one, afterwards split it by a specific attribute and save the output as geopackages to ...
0 votes
0 answers
17 views

Performing Empirical Bayesian Kriging in Qgis [closed]

Does anyone know if a plugin to perform Empirical Bayesian Kriging (EBK) is being developed for QGIS? I'm interested in this method because, according to Perera-Burgos et al., 2024: "EBK is an ...
2 votes
1 answer
75 views

Drawing rectangle of road line with width as minimum distance between two buildings in QGIS

I have two layers: line vector layer representing the road polygon vector layer representing the buildings How can I derive a rectangle shape (refer to green rectangle) for each road line whereby ...
0 votes
0 answers
25 views

MapTool in Processing Provider Plugin

I created a simple plugin using the Plugin Builder and placing the "Tool button with a dialog" option, however, as I added more things to the plugin, I saw the need to place it as a ...
0 votes
0 answers
26 views

Reduce raster file size during QGIS Python script processing

I wrote a Python script based for QGIS that is using the raster calculator to create a new raster based on two existing raster inputs. My problem is, that each output file is 35 GiB and I do have not ...
1 vote
1 answer
72 views

Creating polygon layer (road border) from line layer (road) and polygon layer (buildings) using QGIS [closed]

Picture 1 showing a line layer representing road and a polygon layer representing buildings. How can I create another polygon layer for the road with the edge touching the buildings e.g. thick orange ...
5 votes
2 answers
3k views

Multi-thread processing in QGIS 3.8

I have an I7 quad-core processor in my laptop. I use QGIS 3.8 to do dissolve jobs on large polygonsets. The biggest set takes 131 minutes. If I look a the load monitor I see my system on a constant ...
6 votes
2 answers
765 views

Added raster layers with PyQGIS do not show up

I have a list ("datList") with names of raster layers which I want to add. When I add raster layers in the Python Console everything works fine: for da in datListe: layerDir = "C:/[...
2 votes
6 answers
5k views

Why input layers do not have the same grid extent in the processing, hydrological analysis?

I'm trying to generate the hydrological analysis using processing and I have already done some terrain processing using the DEM. In this moment, I'm working in he channel network but, when I assign ...
0 votes
1 answer
64 views

How to add OpenStreetMap layer as bottom layer via QGIS processing script

I want to add an OpenStreetMap layer as the bottom layer of my project via a script. This works from the console: project = QgsProject.instance() root = project.layerTreeRoot() all_layers = root....
13 votes
3 answers
22k views

Missing processing menu in QGIS

I'm sure there is a really simple explanation to this but haven't found any pointers on this site or elsewhere. I seem to have lost the 'Processing' menu from QGIS and can't figure out how/why! Any ...
0 votes
1 answer
221 views

PyQGIS feature field of type float not setting attribute

I am trying to set a feature in a PyQGIS processing script Its fields are defined like so: interp_fields=QgsFields() interp_fields.append(QgsField('X_int', type=QVariant.Double)) ...
0 votes
1 answer
175 views

QGIS - QgsProcessingParameterFeatureSource - Filter input layer

In QGIS, I try to write a script for a custom toolbox. I'm using the processing framework logic and following official documentation. I add an input vector layer, but I can't handle it has a ...
2 votes
1 answer
3k views

ModuleNotFoundError: No module named '_gdal' ... but I have GDAL

I'm really at my wit's end with this. I'm on a Macbook running Sierra 10.12, so I used the KyngChaos installation of QGIS 3.8. I followed the instructions in the ReadMe (added the PATH variable), and ...
2 votes
1 answer
373 views

Checking SAGA version from a Python plugin in QGIS 3.4.0

I use QGIS 3.4.0 on Windows and I want to verify SAGA version with processing.algs.saga.SagaUtils.getSagaInstalledVersion(). But I get an error: module 'processing' has no attribute 'algs' This was ...
4 votes
1 answer
359 views

Error: Algorithm not found using grassprovider in PyQGIS standalone script

With QGIS 3.22 the GRASS algorithms got its own provider (grassprovider.Grass7AlgorithmProvider) and are no more part of processing.algs. Knowing this, in a standalone pyqgis-script I am trying to add ...
0 votes
1 answer
1k views

Semi-Automatic Classification Plugin Error on install required python library remotior_sensus

I have been trying to install the semi - automatic classification plugin but it results with the following error: semi automatic classification plugin : Error, please install the Python required ...
0 votes
0 answers
42 views

Issue with Google Earth Engine Plugin in QGIS

I am trying to resolve an error from using the Python console on QGIS. I have QGIS version QGIS version 3.34.4-Prizren on my linux Ubuntu 22.04.4 LTS, Codename-Jammy. Then I successfully installed ...
4 votes
1 answer
336 views

Which output data type to choose in QGIS SAGA Raster Calculator in Batch Mode?

I have 5 years of MODIS13Q1 NDVI .tiff images for time series analysis. I want to multiply all the images with the scale factor of 0.0001 before using them. In order to process all at once I try to ...
4 votes
3 answers
83 views

Snapping line on grid / cell edges

What I want to do : This question is about finding an equivalent path on a grid to a given line. The following image shows what I am trying to achieve : Starting from a generic line (in red), I want ...
1 vote
1 answer
452 views

Not able to create memory layer while running processing algorithms

I am trying to run processing algorithms in Python code editor inside QGIS. Here is my code: zones = QgsVectorLayer('C:/Users/pamidiashoka/Downloads/OP_Pen/boundaries.shp', 'zone boundaries', 'ogr') ...
0 votes
1 answer
1k views

Converting TotalStation native field data to coordinates

I'm trying to convert field data from an older Sokkia TotalStation machine, to coordinates. I've looked at Copan but as far as I can tell it doesn't support the file format. There are some outdated ...
0 votes
0 answers
92 views

Issue with custom QGIS process algorithm

I have a written a custom processing algorithm which iterates features within one vector layer and eliminates polygons in the second that are within each feature from the first under a specific size. ...
-1 votes
1 answer
54 views

Removing 0 and NULL columns in a geopackage [closed]

I have multiple geopackages with columns containing a mix of 0 and NULL fields. I want to remove these columns where there is no value above 0. I cannot do this manually as each geopackage has 90-100 ...
0 votes
1 answer
592 views

'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&...
0 votes
1 answer
27 views

Empty Metadata table in Semi-Automatic Classification Plugin of QGIS

I am working on Landsat 8 images using QGIS 3.36.2 When I want to convert clipped images to reflectance in Semi-Automatic Classification Plugin, nothing is displayed under the metadata table even ...
5 votes
3 answers
721 views

Usage of QGIS Dissolve geoalgorithm in QGIS Graphical Modeler (2.18.19 LTR)

When I use QGIS Dissolve geoalgorithm as a standalone tool from the Processing Toolbox, the GUI looks like shown below. By selecting the Input layer I am able to chose from its attributes on wich to ...
0 votes
1 answer
59 views

How do I speed up selection of a large number of features

I'm looking for ways to speed up selection of a large number of features (10k+) from a list of attribute values. I'm developing a plugin to trace a pipe network, and select the tranversed pipes. The ...
7 votes
2 answers
364 views

AttributeError when counting entity number using PyQGIS

I'm trying to count the number of entities but each time I have this error: `AttributeError: 'dict' object has no attribute 'featureCount' while I have only one selected layer uri = r"C:\...
1 vote
1 answer
60 views

Using PyQGIS zoomToSelected(...) in QGIS Python processing script freezes map canvas

I am currently struggling with the zoomToSelected(...) function in my QGIS Python processing script. Users should select a city district via the GUI and then the tool should zoom to this feature and ...
0 votes
0 answers
31 views

QGIS Processing Tools - IDW Grid not recognising point file

I'm trying to convert my point (PointZ) layer into a grid using the Processing algorithm, Grid (IDW with Nearest Neighbor Searching, but whenever I run the algorithm, I get the error: ERROR 4: `file://...
1 vote
1 answer
283 views

SAGA difference tool in QGIS 3.4

I am using QGIS 3.4 Madeira. I want to use difference tool from SAGA from the processing tool box since my data has some invalid geometries and want to fix the issue later after using difference tool ...
3 votes
1 answer
122 views

Using QgsProcessingParameterEnum in QGIS Python processing script

I am currently working on a processing script for QGIS. In the function def initAlgorithm() I am defining several parameters. One of the parameters is using QgsProcessingParameterEnum with a pre-...
1 vote
1 answer
471 views

Using the "Selected Features Only" checkbox with QgsProcessingParameterFeatureSource in PyQGIS script

I'm working on a custom QGIS Processing algorithm, and I'd like to include an option for the user to process only the selected features in the input layer by using the checkbox "Selected Features ...
6 votes
3 answers
1k views

Using relative path in QGIS 3.0 Processing Modeler?

Using QGIS 3.0, we are working on creating a tool that will allow people to check that their snapping is correct with several linear features stacked on each other. A co-worker of mine figured out how ...
2 votes
1 answer
87 views

"Could not load source layer for INPUT: memory: not found" error in Processing Script using PyQGIS

I have a workflow where a raster should be polygonized and afterwards simplified. The simplified vector should be saved as a shapefile. I am using the template script from QGIS to create a processing ...
0 votes
0 answers
25 views

QGIS: "Export Mesh on Grid" not working with "Export Vector Option" enabled?

I need to sample the vector data from a Mesh to a grid, and was hoping to use the Processing Script Export Mesh on Grid, with the Export Vector Option enabled. (pic. 1) Unfortunately the whole ...
4 votes
2 answers
995 views

Fill nodata holes in discrete integer raster with majority value of adjacent pixels QGIS

I have a large land cover raster with classified integer values from 2-22. There are some single or double pixel no-data gaps where I merged 2 adjacent tifs together. If this were a continuous raster ...
0 votes
1 answer
43 views

GRASS r.viewshed not working with elevation? - PyQGIS

I'm making a QGIS plugin that uses grass:r.viewshed to analyze the area of terrain visible from different points. However, I've noticed, that when using a viewpoint where the elevation between the ...
3 votes
1 answer
735 views

How to close open files after processing.runalg() command (Qgis: Error No 24)

I'm creating a pyqgis script. In this script I use the processing.runalg command several times. The problem is that these processes are within a for loop. After several iterations, the error number 24 ...
0 votes
1 answer
27 views

QGIS model designer field name as variable in expression

I am trying to use Extract by Expression in Model Designer with the following: @SearchField ilike concat('%', @SearchWord ,'%') but it returns an empty layer. If I specify the field name like so: &...
5 votes
1 answer
4k views

Creating buffer based on Field attribute value in QGIS Modeler

Working under QGIS 3.16.4 and using the Modeler, I would like to create buffers for a polygons layer. The polygons layer includes the buffer size as an attribute (e.g. "BUFFER_M") resulting ...
2 votes
2 answers
263 views

QGIS polygonize issue: GDAL DLL load failed

I am using QGIS Desktop 3.10.0 and I have some issues with the polygonize tool. When I run the polygonize tool, a warning shows up saying that there is an “Import Error: DLL load failed” (see Figure 2)...
-1 votes
1 answer
35 views

QGIS "Create Vector Grid" code

I need to create code in a plugin to create parallel lines at a given heading and spacing within a polygon. This is very similar to what the "create vector grid" function does. It's found ...
5 votes
1 answer
1k views

r.viewshed Raster map not found

I wanted to test the r.viewshed module from grass via the Toolbox in QGis. But no File is generated. This is the log output: Algorithm r.viewshed - Computes the viewshed of a point on an elevation ...
1 vote
1 answer
41 views

Inconsistent Vertex Counts with native:simplifygeometries Algorithm in QGIS 3.22 vs QGIS newer versions

When applying the native:simplifygeometries algorithm to the same polygon features in QGIS 3.22 and QGIS newer versions (3.28, 3.34), the resulting geometries can have a different number of vertices. ...
0 votes
0 answers
55 views

Accurate small-scale mile/km markers in QGIS. Qchainage and "Points along geometry" are inaccurate

Looks like Qchainage has been integrated into QGIS as "Points along geometry" and they're basically the same. But they only work in projected units so they'll be inaccurate for any small-...
3 votes
0 answers
457 views

Extract TIN mesh [closed]

I have a shapefile that I convert into TIN. The result is following: Now I want to extract a mesh based on this TIN to reach this: However I do not need TIN itself, I need only to save the mesh. I'm ...
0 votes
0 answers
23 views

Allowing File/Folder modeler input as input for a QgsProcessing algorithm

I have a simple QgsProcessingAlgorithm from qgis.core import ( QgsProcessingAlgorithm, QgsProcessingParameterFileDestination, ) class TestAlgorithm(QgsProcessingAlgorithm): def ...
0 votes
0 answers
27 views

Correct way of calling processing algorithm multiple times with different parameters

I have a processing algorithm that loads layers, applies styling, and adds to the project. I would like to call the processing algorithm simultaneously with different parameters (batch loading). I ...

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