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Questions tagged [qgis-modeler]

An application of QGIS used to develop models utilizing a large variety of powerful Geoprocessing tools via a GUI.

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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 ...
Calidris's user avatar
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18 views

Issue with Iteration/Unique Naming in QGIS Model Building

this is probably a straightforward problem, but I am a beginner at QGIS and having trouble fixing it. The Task I am trying to use a vector of polygons as masks to individually cut out snips of a ...
lGISmor's user avatar
1 vote
1 answer
25 views

How to make a conditional branch in QGIS Modeler based on the raster cell size

I want to make a conditional branch in QGIS modeler based on the cell size of the incoming raster. If the cell size is larger than 10m, I would like to resample the raster to 10m before exporting it. ...
saQuist's user avatar
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QGIS 3.28.15: Model designer - Save output to specific choosable folder

I want to enable users to specify a folder where all the output of the model is to be saved when running it in QGIS. The model was created in the model designer. I have searched far and wide and tried ...
KarlD's user avatar
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Using fields defined from other functions in QGIS Model Designer

I'm creating a rough service map for multiple states and providers based on publicly available FCC Data. I have recently switched over to QGIS and am trying to build a simple model. I need to dissolve ...
Stuart Miller's user avatar
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How to merge rasters with the QGIS modeler

Using the QGIS modeler, I want to automate the following sequence: 1: Filter point clouds, 2: Convert each slab obtained into DEM 3: Merge all MNT with the model below, I only obtain a fusion of a ...
fcka's user avatar
  • 985
1 vote
1 answer
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QGIS modeler adding field with a pre-calculated value but doesn't work after first successful try

Using the modeler, I want to add a new column to my layer. The new column will be used as a label and consists of a number and strings: for example "layername" and "length". Both ...
QGIS-beginner's user avatar
1 vote
1 answer
72 views

Total/sum multiple fields and group by in QGIS

I am trying to build a graphical model. This model takes a vector layer as input. I have the first field as a grouping variable and all remaining fields are numeric. I would like to total each column ...
BKS's user avatar
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Converting shapefiles to GeoJSON with specific structure in QGIS

I work in agriculture and at the moment I'm the only GIS techy in our organisation. Unfortunately, I don't have a lot of programming experience. For a certain applicator we have to convert shapefiles ...
FiftyTwo's user avatar
1 vote
1 answer
48 views

Calculate ratio of 2 polygons using QGIS modeler

Working with QGIS modeler, I need to do some arithmetic operations with some polygon areas. Let's say there are 2 polygons in layer A and layer B. And I'm inputting them into the model using Vector ...
Tolga Evcimen's user avatar
1 vote
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QGIS Graphical Modeler: Dropdown list of strings based on fields values from another Layer

I have a graphical modeler where I need to type the name for a desired region as a string and extract some data matching the name of the region from an layer of another geopackage. In the following ...
Denis Crîlov's user avatar
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QGIS graphical model builder - how to use multiple selected fields

While building a graphical model, I would like to select multiple fields of a vector layer. I am able to select these. As a second step I would like to use field calculator to get a new field which is ...
BKS's user avatar
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5 votes
1 answer
158 views

Accessing layer properties for expression syntax in QGIS Modeler

Overview: In QGIS I want to create a conditional branch in the model designer so that I can pass images with 20m resolution through the 'Warp (reproject)' tool. Images that are already at 10m ...
tds's user avatar
  • 91
4 votes
1 answer
95 views

Model Building - Unable to use output from one tool in the next tool?

I am new to QGIS and would like to set up a model to combine multiple steps into one. The overview: Inputs: Satellite Image, Masking area of interest (shapefile) Tool 1: Clip raster by mask layer ...
tds's user avatar
  • 91
3 votes
1 answer
99 views

Creating & styling a layer and saving an image with it in the modeller

I want to set a layer style in the modeller and afterwards export the map to an image. For that I created a simple layout with just a map and a simple model that sets a style and exports a print ...
bugmenot123's user avatar
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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 ...
bugmenot123's user avatar
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Adding data to existing layer using Model Designer

I am trying to use the QGIS Model Designer to add a count of points within a polygon to the polygon layer. The field existing already in the layer. I can get the Model Designer to count the points OK, ...
Sean K's user avatar
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32 views

"Extract by Expression" works manually, but not in model [duplicate]

I have a QGIS project (v 3.34.0) where I run a model to calculate distances from all building facades to the nearest road. The last step in the model is to extract only those line features (the ...
mtwente's user avatar
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35 views

QGIS wrong filter result when using "." instead of ","

I am using the graphical modeler in QGIS. I need to extract all water objects within a county which are bigger than 5,133 ha. After clipping the nationwide OSM water objects to the county. I let the ...
BAE_23's user avatar
  • 677
1 vote
1 answer
85 views

QGIS -> Model designer -> using Shortest Path (Run in Batch Process)

I'm using QGIS 3.34.0, and making a litle model using Model Designer. I have lots of tractor roads and I need to calculate distances from each crossing of two roads to the highway road. I make points ...
sttipa's user avatar
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1 vote
1 answer
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QGIS: Modeler: conditional branch & case dependent input fail

I have this model attached here wich has the left side (osm1) where the points input are beeing buffered - bounding box and the osm_highway is beeing downloaded. The left side (osm2) should be an ...
Denis Crîlov's user avatar
3 votes
1 answer
135 views

How do you iterate through raster bands using model designer in QGIS?

I am processing atmospheric data and I need to convert my raster input into polygons so I can find the intersection values between my pixels and other polygon features. I used the Raster Pixels to ...
steglitz's user avatar
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0 answers
28 views

QGIS calculated area output as CSV

I have used the graphical modeler to extract polygons. I calculate the areas of each polygon in the attribut table. Since I have multiple layers, I do not want to use the function Field Statistic for ...
BAE_23's user avatar
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1 answer
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Assign a specific color to the results in the QGIS graphical modeler

During the photovoltaic analysis using QGIS and the graphical modeler, the results are saved as shapefiles in a specific folder. It is possible to assign a specific color to each shapefile within the ...
BAE_23's user avatar
  • 677
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0 answers
47 views

Not required input layer in QGIS Graphical Modeler

I would like to know how can I use an optional (not required) input layer (used with other input required or not) in a graphical modeler of QGIS. Obviously, I uncheck "required" in the panel ...
Mark's user avatar
  • 975
1 vote
1 answer
39 views

Write a Project Variable from a Modeler result attribute in QGIS

I am trying to set a Project Variable with QGIS Modeler with values as the modeler calculates them. In this case I am trying to get the calculated area from a process "Fire_Area" written to ...
Mikeoramma's user avatar
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63 views

QGIS append layer in one geopackage output of modeler

I would like to append new layer (created with model builder) to a new/existing geopackage in a batch processing. Tried with 3.36RC and 3.34.4 LTR. Every line is a csv converted to point Every line ...
john mega's user avatar
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0 answers
53 views

Adding iterative group of algorithms to QGIS model

In a QGIS model, I have a section in the workflow where a certain group of algorithms (let's say: do A, then B, then C, then D: see below for details) has to be re-run until a condition is met. So ...
Babel's user avatar
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1 answer
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QGIS model algorithm "Load layer into project" wont allow layer to be loaded more than once

I am creating a model which saves a polygon layer as geopackage in a project folder. I then want to load that layer into the project several times and apply different style files to each layer to show ...
Greengadget's user avatar
1 vote
1 answer
42 views

Adding raster file name to attribute table of polygonised version of raster file using QGIS Modeler

I have a polygonised output of a raster file but need to add the raster filename to the attribute table of the polygon (vector) file. I can do this manually using the command 'base_layer_name' but I ...
wj68's user avatar
  • 13
1 vote
1 answer
63 views

Recursive model in QGIS

I needed to do an algorithm in the modeler and wanted to try (and also because I couldn't see any other solution) to make it recursive. Unfortunately, now every time I try to just open the model to ...
Biorix's user avatar
  • 31
0 votes
0 answers
25 views

Use output of an algorithms with another algorithm in QGIS Graphic Modeler [duplicate]

I have Processing Algorithm of Explode Lines and I need to use the output of the layer to create a field calculator Processing Algorithm, so i have entered the filed name that i need to create and ...
Abdullah Muthanna's user avatar
1 vote
1 answer
60 views

Using QuickOSM in model designer QGIS

I am trying to create a model in QGIS using the model designer but having difficulties with the QuickOSM features. My goal is to: Create three buffers (2km, 3km, 6km) around a multi point feature. ...
GeoCharm's user avatar
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0 answers
59 views

QGIS select by expression Modeler

I'm trying to build a model which should select polygons based on selected polylines. The polygons share attribute values with the polylines. In this case the field "Outlet" (polygon) ...
user237984's user avatar
1 vote
1 answer
54 views

QGIS create vectorlayer based on project axis and data table

I have a project where I need to mark ongoing and planed projects along a river on a map. I have a list of the projects in form of a table with multiple attributes including the start and end point ...
Markus Lang's user avatar
1 vote
0 answers
49 views

Linking Point input data with SAGA Upslope input in QGIS Modeler

I have a model set up with a point input. I need the point's x and y coordinate data to populate the x-value and y-value fields required as input for the SAGA upslope function. I have tried various ...
Louw's user avatar
  • 11
2 votes
1 answer
89 views

Picking Input Layer according to attribute string in QGIS Graphic Modeler

My model is based on a vector layer which contains a Field with layer names. The Plan is to pick the input raster (from a directory or directly from the project layers) according to an attribute value ...
farmgis's user avatar
  • 45
0 votes
1 answer
67 views

Using Python script inside QGIS Graphic Modeler

I created a model that combines two vector layers and outputs a single layer with aggregated data. I have a Python script that calculates the Chi-square, and I would like it to be executed at the end ...
Tony Sampaio's user avatar
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0 answers
56 views

QGis-Modeler: Using "Basic statistic" values for "Extract by expression" - Outliers

I'm working on Qgis 3.34.0. with Model Designer. I'm working with soil data (Organic matter for example). I have 2 data sources, "cal OM" and "lab OM". The data I'll use will be &...
Matias Z's user avatar
3 votes
1 answer
76 views

Grouping sum by user provided field name in graphical modeler

I want to sum and group some percentages as a part of a model in order to check whether the percentages are exactly 100, or if there is a small rounding error. When using the field calculator outside ...
Erik's user avatar
  • 16.5k
3 votes
0 answers
128 views

How to update a field in a layer with the DBSCAN algorithm using the Graphic Modeler QGIS

As you can see in the screenshots, I have a vector layer 'POINT_LAYER' with an "IDCLUSTER" field ready to be updated. I am also using Graphic Modeler to prepare a processing workflow to ...
Acperience's user avatar
  • 1,142
2 votes
1 answer
58 views

Transferring QGIS Algorithm settings/properties to modeler

When creating models I often first run a toolchain step by step on a small example dataset to test whether each tool does what I want and if I get the desired result. I then use this to build a model, ...
Honeybear's user avatar
  • 2,524
0 votes
0 answers
83 views

Selecting polygon based on value present in field using QGIS Graphical modeler

I have a layer (polygons) of municipalities and I need to select just one polygon based on their name (e.g. 'venice' this value is present as a value in the field "COMUNE" ) because this ...
Checco68's user avatar
4 votes
0 answers
38 views

Don't re-use previous model run's user inputs

I have a QGIS model with a Number input (though this applies to many if not all inputs) When users enter a number in the model's dialog, run the model and then re-open the model dialog to run it again,...
bugmenot123's user avatar
  • 10.9k
1 vote
1 answer
119 views

QGIS: Model Designer: Specify the order in which algorithms are run

I am trying to build a complicated model in the model designer. It will have, once I'm done, probablyy around 20-30 conditional branches. The branches select and extract points from a point layer with ...
Andy Baader's user avatar
5 votes
1 answer
346 views

Using Conditional branch algorithm in QGIS Graphical Modeller

I have a question regarding using the Conditional Branch algorithm in the Graphical Model Builder. I am building a rather complicated model with many branches but not every branch needs to be used ...
Andy Baader's user avatar
0 votes
0 answers
36 views

In QGIS modeler I get SQL query syntax error - in Database Manager SQL window is working fine

I have SQL query which add record to several related tables. When I run query in Database manager, it works fine. But when I use PostgreSQL execute SQL from algorithms in Model Designer, I get error. ...
Tomas's user avatar
  • 1
3 votes
1 answer
138 views

Creating dummy (random) vector layers of different geometry types, with random attributes

Problem In QGIS, one sometimes needs some layers with dummy data just to test something: the functionality of an expression, the syntax of an SQL query in a virtual layer, creting quickly an animation ...
Babel's user avatar
  • 73.2k
1 vote
1 answer
115 views

Using QGIS Model Designer to rotate points but it moves the points location

Using model designer to automate a process and I would like to be able to rotate points whether it be using the affine transformation tool or the rotate tool. I have gotten both of these tools to ...
Max's user avatar
  • 31
3 votes
0 answers
135 views

Removing memory layers as you go in QGIS Graphical Model to avoid running out of memory

I run a lot of graphical models to automate the workflow of complex tasks. Often, my workflows have 40 or 50 steps that manipulate attributes in a complex way. The graphical modeller is powerful and I ...
Cameron Blackburn's user avatar

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