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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28 views

QGIS 3.6 Model works but exported python script gives false results

I would greatly appreciate if somebody can help me out here. As the title says, in QGIS 3.6 i made a model calculating "Forest fire susceptibility index - RC", model works fine and gives correct ...
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52 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 ...
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Rendering styles for output doesn't seem to be working

In QGIS 3.10, setting rendering styles for outputs in processing modeler by right-clicking my model works fine on my computer, but when the model and folder with qml-files is loaded on another ...
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17 views

Running an algorithm based on a condition

In QGIS 3.10, is it possible to only run an algorithm in the processing modeler if certain conditions are true? I'm applying concave hull to a layer, but sometimes that layer is empty and the model ...
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1answer
35 views

QGIS modeler: using input rasters filename for naming columns by expression

I am running QGIS 3.12.3 București on Windows 10 x64; I am building a simple model to reclassify a series of rasters with a 2x3 table, and then count each unique reclassified value within different ...
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25 views

Building a model to standardize rasters in QGIS

I have a little problem, but I think there is a simple solution, but I can't see it. I want to make a simple model for the rasters to standardize them using a simple formula: I want to compare the ...
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22 views

I cannot use Point entry into Graphical Modeler in QGIS

I would like to use a Point entry to get the point coordinates in the map to add in the network analysis as a start point. I have added the Point entry into Graphical Modeler, I can click on the map ...
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28 views

Save processing modeler output layers to project folder/relative path?

I am building an algorithm in the processing modeler which takes a csv file as input and creates a number of vector layers as output. I would like to automatically save these layers in the same folder ...
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2answers
64 views

QGIS Modeler: Extract by location, multiple predicates

I'm creating a processing model and would like to use the 'extract by location' tool, The problem is that when I choose this tool from the 'Algorithms' in the model creator, I cant find the double ...
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27 views

Issue with QGIS modeler raster calculator

I'm trying to apply a formula to scale an NDVI map from a WMS with QGIS modeler, but it keeps throwing me an error. I tried to do this without the modeler and it works. Here are the steps I want to ...
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37 views

QGIS Modeler using File/Folder input paramerter

I would like to use the File/Folder input parameter to set a path for all output layer files. I was trying to connect the File/Folder parameter to my output from a model and set a default folder path. ...
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1answer
39 views

How do I automate the production of a map series?

I would like to produce a series of maps in which each map contains the same layers, with each layer of a given type having the same styling from map to map, but the source of the half of the layers ...
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28 views

If/else condition in Model Builder QGIS 3.10 Batch processing

I have a set of images I need to process - all except one I have to calculate in Raster calculator with one expression, and the only one is the other expression. All following steps are the same for ...
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28 views

Create output folder for merge result of Model Builder on QGIS 3.10

I have export my model builder to python's script and now i would like to save the result to an created folder. But the folder name is based on a layer entity. Example: I have 3 layers (city, store, ...
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29 views

Two task at the same time in Model Builder QGIS 3

I am new to using the graphic modeler and I do not know how to do certain actions. I have several treatments to perform on the basis of a buffer zone. Indeed, I have to polygonize 2 raster (which we ...
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1answer
29 views

Apply Join by Location to a Selection in QGIS Processing Modeller

In QGIS 3.10.2 I have created a process modeler file that takes inputs from 5 input layers and creates a new layer as an output. The output layer is needed by an external program and the processing ...
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3answers
50 views

Dividing shapefile into multiple shapefiles using an attribute value in QGIS Graphical Modeler

I have a shapefile with a column that have project references, I want to create a different shapefile for every project reference there is. Note that the project references are not unique in the ...
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16 views

Automating sqlite to shapefile conversion using QGIS graphical modeler

I have a sqlite database with geospatial tables, I want to extract some of these tables into shapefiles (with all the shapefile files). Depending on an attribute (project name), I would like to ...
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51 views

Extracting several string values by attribute in QGIS graphical model

I am trying to extract several features by attribute within QGIS 3.12 graphical modeler. The values to extract shall be given by an input and not beeing predefined. Currently I am using a string-...
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1answer
28 views

Advanced Python Field Calculation gives error: TypeError: 'in <string>' requires string as left operand, not QVariant

I am using the following function in QGIS 3.10 Advanced Python Field Calculator as part of a Processing Modelling file. The model processed 4 layers and generates a single layer for use in another ...
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0answers
47 views

QGIS 3 modeler: how to use the fields of an intermediate output as input in another algorithm?

I'm working on a model to calculate land uses (usos) in different areas (zonas): I have corrected geometries, cutted the uses layer, corrected geometries again and used the fields calculator to ...
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1answer
82 views

QGIS 3.4 Add vector styles and attribute fields in a model

I made a model, which works like this: from a polygon, it extract its edges coordinates, turns it into lines and add an extra line.shp who will store the distance between the points. Because my ...
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1answer
46 views

Workaround for Mean Coordinates in graphical modeler

I am searching for a workaround to build mean coordinates in graphical modeler since I have noticed a bug which I have reported here: https://github.com/qgis/QGIS/issues/35385 Basically, I just need ...
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21 views

Calculating time difference between consecutive rows does not work within graphical modeler

I have a dataset with time-stamped GPS points. I would like to calculate the time difference in seconds between these rows. I successfullymanaged to do so by running the piece of code below in the ...
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1answer
45 views

QGIS - Automatically find and merge adjacent lines in large data set

I need to merge adjacent lines in QGIS 3.8, but am having trouble coming up with a way to identify and then merge them in a large data set. (3.8 is as far as my Mac can support) I tried to convert my ...
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20 views

Running raster mosaic in batch process in QGIS

I am wanting to mosaic multiple rasters within the same month into a single raster. I am trying to achieve this using the SAGA Mosaic Raster Layers tool within QGIS as part of a model (via the ...
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32 views

Processing Modeller manual / use-case for Multiple Input and Model Variables

Is there a decent manual/examples available somewhere for the Processing Modeller? Official help is very barebones and doesn't explain the different inputs/model variables. Specifically I am ...
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21 views

QGIS Processing Modeller reusing output as input for next step

I would like to run the Sample Points algorithm over 20+ rasters, reusing the sampled result as the input for the next iteration of Sample Points. At the moment I am achieving the wanted result by ...
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2answers
49 views

Why do deactivated layers still appear in the Processing Modeler's wizard in QGIS?

I'm quite new to the graphical modeler of QGIS (version 3.10.1). It's a great tool, still, something has been bugging me for a while. I've created a fairly long model, saving the outputs of some tools ...
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2answers
48 views

Adding multiple fields in join attributes by location in graphical modeler

I want to add multiple fields in "fields to add" using the join attributes by location algorithm in the graphical modeler. It works if I add only one field, like DISTANCE, but when I want to add ...
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1answer
92 views

Accessing Vector Field Parameter Value inside Python Script

I have created a QGIS Graphic Model using the built-in Graphic Modeler. My model is supposed to ask the user for an input layer, an overlay layer, and a field from the overlay layer. The model then ...
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12 views

Boolean parameter redirect in a Model

For a very basic situation where you have a Boolean parameter in a model and you want to specify if value="Yes" go-to algorithm A in the model if value="No" go-to to algorithm B, for example, how can ...
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113 views

SQL 'insert into table(values)' using QGIS-modeller

How can I run a precalculated SQL query using QGIS-modeller to insert values in an existing PostgreSQL table? I know I can use import layer in DB-manager to load features in an existing table, but I'...
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1answer
98 views

for iterator in QGIS3 Graphical Modeler

I´d like to integrate the for loop in my model in ModelBuilder in QGIS3 (similar as the for interator in ArcGIS ModelBuilder). data: testdata: point layer with different classes (assignment to ...
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1answer
38 views

How to keep an edited layer edited in graphical modeller QGIS?

I'm new to the graphical modeller of QGIS, and was wondering how to keep a line shapefile which has been edited and some of its parts deleted? For example, I have a country polygon that I have changed ...
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1answer
50 views

Obtaining the average red, green, blue values within grid cells in QGIS?

Is there a way to obtain the average red, green, blue values within grid cells in QGIS?
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1answer
48 views

How to edit a model that is saved in project?

I have a model saved in QGIS Project which i can find under "Project models". But how can I open and edit it? I have tried dragging and dropping it to the empty canvas, and using open Icon in toolbar ...
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1answer
84 views

Transform Excel into vector in the Graphic Modeler

I have a graphic modeler with two inputs, a shapefile and an Excel file. I would like to make a join by attribute between the two. But I am confronted with a concern, the join can only do this between ...
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1answer
40 views

Attribute stats query with Execute SQL tool in QGIS Modeler

I'm trying to get a simple temporary table with the surface of different categories of a polygon shapefile, classified by category. My final aim is to hide an SQL query in a tool with optional ...
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1answer
106 views

Using input vector field in QGIS python script

I have created a QGIS Graphic Model using built-in Graphic Modeler. My model is supposed ask the user for an input layer, an overlay layer, and fields from the overlay layer. The model then should ...
2
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1answer
43 views

Select multiple fields in Modelbuilder

I am trying to make a model in the Processing Modeler of QGIS. I need a step where a layer with polygons is dissolved based on two fields. At the moment I do this manually. When I open the dissolve ...
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1answer
78 views

Connecting number parameter to Field Calculator in QGIS Modeler

I intend to develop a model with field calculator processing using the QGIS Modeler. How do I include the number input by the user to be as a value in Formula of Field Calculator? This is the model ...
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2answers
164 views

Definitive list of QGIS multiprocessing tools?

This question is not as straightforward as it seems, but can be summed up with the following: Is there a definitive list of geoprocessing tools for QGIS that currently support multithreaded ...
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15 views

Processing Modeler QGIS Issues With Interpolation Step

I am trying to interpolate Sampled Points with IDW Interpolation in the QGIS processing modeler. For some reason I am not able to select the Sampled Points with the IDW Interpolation. Anyone know ...
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1answer
61 views

Using QGIS Processing Modeler to split polygons with lines

I am trying to use the QGIS Processing Modeler to split polygons with lines. Here is the workflow I have so far. It is sucessful. I then add "Grid" and "Split With Lines" to split the polygons. ...
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21 views

Calculating percentage overlap in graphical modeller

Can anyone help me calculate the percentage overlap of a polygon with multipoint attributes (I.e fragmented pieces of polygon overlapping) in graphical modeller? I need to calculate the area of my ...
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1answer
85 views

Exporting map layout from QGIS modeler

I am trying to write a processing script that takes a template file as input and writes out the current canvas content as a PDF. The processing script works fine. But when I use the script in a model, ...
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0answers
36 views

Dealing with empty parameters in QGIS

I'm building a graphic modeler in QGIS. I need to model adding multiple fields/columns to a layer and then importing values from other fields/columns into those new fields. Example : Existing field ...
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1answer
68 views

Using Python Code from QGIS modeler with if and else

I am using QGIS 3. The following script code is generated from a model. At the end the code has to create a field Fl_m2, if the blnFl is true. if ['blnFl'] is True: If it is not true the ...
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1answer
52 views

QGIS custom script to run one process or another depending on input

[QGIS 3.10] I have two processes I have created using the graphic modeler. I'm trying to create a script that would run one process or another depending on the inputs. But I'm getting an error in line ...

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