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
votes
5answers
11k views

Seeking model builder for QGIS?

Like the ModelBuilder of ArcGIS Desktop to run simultaneous geoprocessing tools, is there any model builder available in QGIS?
20
votes
1answer
463 views

Performing QGIS modeler multiple raster calculations with data from external CSV?

I need to perform multiple calculations on a set of rasters based on values in a CSV metadata file. I'm using the QGIS graphical modeler and can call a specific field in a CSV with the Table and ...
13
votes
1answer
14k views

Syntax of conditional statements in QGIS Field Calculator(s)

I have a shapefile which I need to modify. There is one column "CLASS" with the attributes: "A", "B" and "C". I need to change "A" into "1", "B" into "2" and "C" into "3". I tried it with case when ...
13
votes
1answer
4k views

Simplify repetitive tasks in QGIS Graphical Modeler

Are there iterators that can be used in QGIS graphical modeler to simplify the model shown above. If not, is there any better way of simplifying the model? The first column represents my input layers,...
11
votes
1answer
341 views

Using Layer Parameter variables in Field Calculator within QGIS Model?

If I define a Vector Layer as an input parameter to a QGIS model, then the parameter name is exposed as a variable in a Field Calculator within the model, however I am unable to use this variable as I ...
10
votes
1answer
335 views

Why is QGIS graphical modeler modal?

I often switch between graphical modeler and the main QGIS application and wonder why I am not able to operate QGIS when modeler window is open. Saving my models and closing / reopening modeler annoys ...
10
votes
2answers
14k views

Why “Export as Python script” button is unaccessible in QGIS 3.0/3.1 Modeler by default?

In QGIS 3.0, "Processing Modeler" window has no "Export as Python script" button unlike QGIS 2.x. If you look at the codes (in DlgModeler.ui and ModelerDialog.py files), you see the code lines ...
10
votes
2answers
164 views

Using Viewshed Graphical Modeler

I am trying to create a viewshed using the graphical modeler, the first part involves creating the viewpoints which works fine, however when I create the viewshed I get the following error. Also, when ...
10
votes
1answer
2k views

QGIS Modeler if/else condition, custom script for Modeler

I want to make a simple if/else function inside my Model and I wanted to know if it's possible or not. I want this thing to do that if an Input for 'Segment Layer' is selected that it doesn't have ...
9
votes
2answers
2k views

Saving processing results in a file using QGIS modeler?

From a model, I would like to save processing results in a file. In my model I have some Extract by location algorithms (with two vector inputs) producing reasonable results but only as temporary ...
9
votes
1answer
430 views

Conditions in modeler field calculator

I want to check a vector file if there is a column "Source". If yes, nothing to do. If there is no column "Source" it should be created and filled up with '0'. Is this possible to do via the ...
8
votes
1answer
392 views

Extracting features with equal field value using graphical modeler of QGIS

Is it possible to automate the following procedure with graphical modeler in qgis 3.4 or is it easier to perform such action with a python script using PyQGIS? Identify a feature (a line) in a vector ...
8
votes
4answers
435 views

Arranging GUI elements in QGIS 3 processing model user interface

Using QGIS 3 graphical modeler I created a model with a variety of input parameters (> 10). When starting the model, a nice user interface is generated. But the arrangement of the GUI elements is ...
8
votes
4answers
1k views

Clipping line layer to every feature of polygon layer in QGIS?

I have a line layer (roads) and a polygon layer which represents districts/counties. I want to clip the roads according to every one different county. That means that I must repeat the procedure sixty ...
8
votes
2answers
568 views

Using Calculator in QGIS Graphical Modeler

Since QGIS graphical modeler calculator did not lead to an answer, I'll try my luck here again. I created a simple model in QGIS 2.18.16 that shall calculate a distance based on the extent of a raster ...
8
votes
1answer
322 views

Order of parameters in QGIS 3.6 graphical modeller [duplicate]

When using graphical modeler in QGIS 3.6 I have added additional parameters to the model inputs for the buffer tool. The model looks like this: When running the tool the order of the parameters in ...
7
votes
1answer
235 views

Graphical modeler calculator missing in QGIS3

There used to be a calculator in the modeler-only tools in QGIS graphical modeler. But I notice that it is missing in QGIS3. How do I do numerical calculations as part of the model? For example, take ...
7
votes
2answers
133 views

Dropping all fields exept one with QGIS 3 Model Builder

Is there a way to remove all but one of the fields in the attribute table (with a pre-known name) using QGIS 3 Model Builder? The problem is, I don't want to include all of these names in the model ...
7
votes
1answer
103 views

QGIS graphical modeller joining input layers to processing algorithms

I am trying to learn how to use the graphical modeler application in QGIS 3.14 I have encountered a problem early on. If I pull vector layers into the modeler canvas and then add in an algorithm to ...
7
votes
1answer
955 views

Using QGIS 2.x processing model in QGIS 3.0?

Is it somehow possible to convert a QGIS 2.x processing model (*.model) to a *.model3 so i can run them in QGIS 3.0 without having to redo mine from scratch?
7
votes
1answer
415 views

QGIS Graphical Modeler Add Specific files

When I create a model in the Graphical Modeler Tool I need to add layers using ‘Add File’. When I run the script, I have to add the same files each time (Which can lead to adding numerous files). ...
7
votes
1answer
326 views

Two Selections from one Layer in Processing Modeller

I have the following problem: I try to do two parallel selections. For this I have applied before the "extract by location" algorithm. Now I would like to execute in the next step from this layer two ...
7
votes
2answers
1k views

Referencing another layer in Field Calculator inside Graphical Modeler

I want to use the Field Calculator inside the Graphical Modeler to create a new column in an input vector layer (LAYER1) using data in another layer (LAYER2). LAYER2 is the output of another algorithm ...
7
votes
1answer
489 views

Interpolating Daily Values from Monthly Grids using QGIS?

I am currently performing a bioclimatic analysis using monthly averaged climate grids. One particular calculation, Growing Degree Days, relies on daily maximum/minimum temperature and a threshold ...
7
votes
1answer
441 views

Processing modeler Output Order

I have a model running on the processing framework it produces a serie of vector layers as output(alt-0, alt-1, alt-2, alt-3, and so on). I have prepared the model keeping the order of these ...
7
votes
0answers
362 views

Merge Raster Layer Specific Order in Graphic Modeler [closed]

I'm using the Graphic Modeler/Processing Modeler to automate a process. The last step in this process is Merging three different Raster Layers. I'm using the "Merge Raster Layers" from Saga 2.0.8. Is ...
6
votes
1answer
661 views

Using variable in graphical modeler for raster calculation? (QGIS 3.8)

I am trying to create a flow in the graphical modeler using a variable in a raster calculation. Is there a way to use a variable directly in the raster calculator (SAGA or GDAL)? I know there was a ...
6
votes
1answer
282 views

How to use optional inputs in model processor for QGIS 2.18/3.0?

I have developed a processing model in QGIS 2.18 where all my inputs are optional and I need them to be truly optional. However, the model will not run unless I have all inputs present. I have tried ...
6
votes
1answer
208 views

QGIS equivalent of Calculate Adjacent Fields for Atlas

Is there a QGIS plugin available or a processing model to calculate and populate fields that can be used to label the adjacent pages in a map book? Although there are tools to create vector grids, I ...
6
votes
1answer
970 views

Adding date field to attribute table using QGIS processing modeler?

I want to add a date field to my output layers attribute table, using processing modeler. I want the Date field to be a parameter in my model, because I want to manually input the Date everytime I ...
6
votes
1answer
1k views

Defining “Style file” of QGIS modeler process “Set style for raster layer”?

I want to add "Set style for raster layer" to QGIS processing modeler but I have no clue how I need to define the "Style file" field. I have a layer style document and I assume, I need to define a ...
6
votes
1answer
528 views

Interpolating a string input into an output layer name in QGIS' Graphical Modeler

I believe that the answer to my question is 'no' but am hoping that I missed something in my Googling and trawling of StackExchange... I have a simple Graphical Model built in QGIS (2.12) that asks ...
6
votes
1answer
551 views

Cannot find layer error with Execute SQL in QGIS Graphical Modeler

I'm trying to sort a shapefile by one of its attributes using "Execute SQL", in the QGIS Graphical Modeler. Using a vector as input is working fine, but when I use a layer generated by an algorithm ...
6
votes
1answer
461 views

QGIS modeler - use input filename in output filename

I need to use the input filename in the output filename in a QGIS model. I have spent a couple of hours trying to find a solution but can't. If the input is contourXY.tab and I want output to be \...
6
votes
1answer
757 views

Adding field to table using QGIS graphic modeler?

I was wondering if anyone could help as I'm struggling to get anything out of the QGIS graphic modeler. I need to be able to add a new field to an attribute table and update that field with a value ...
6
votes
0answers
68 views

Referencing an output in an expression in process modeler

In the process modeler, I'd like to reference an output of a previous step as one of the parameters of an algorithm. In this case, the previous step was clipping a large raster and I want to use the ...
5
votes
2answers
650 views

Execute a field calculation on just selected records from Processing Toolbox in QGIS 3?

When I try to do a field calculation from the Processing Toolbox in QGIS 3 it performs the calculation on all records instead of the selected records. Is there a way to have the calculation performed ...
5
votes
1answer
281 views

Syntax for “fields to keep” of Intersection tool in graphical modeler

I'm working with QGIS 3.2 Bonn and try to set up a workflow with the graphic modeler. The model uses the Intersection Tool from the QGIS Geoprocessing Tools. The model works, but I don't want to ...
5
votes
1answer
4k views

Split a vector layer based on attribute value?

I have read the question and comments on: Splitting shapefile into separate files for each feature using QGIS/GDAL/SAGA? that can be seen here: Splitting shapefile into separate files for each ...
5
votes
2answers
1k views

Programmatically naming outputs from the QGIS Modeler?

I am attempting my first use of the modeler from the Graphical Modeler from the Processing menu in QGIS (2.18.3). I made a simple model for using meanshift segmentation. It just has a raster input and ...
5
votes
1answer
55 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?
5
votes
2answers
984 views

Run QGIS Model on selected features only?

Would it be possible to run a script in a QGIS model so that it only runs on selected features from an input layer? I don't want to use the option in the toolbox options as I have other models that ...
5
votes
1answer
3k views

How to connect input parameter to the field calculator algorithm within the graphical modeler?

I am building a model in the graphical modeler of QGIS 2.8.1 Wien and I would like to give the option to the user to enter a number in the model with which a selected field will be multiplied, but I ...
5
votes
2answers
275 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 ...
5
votes
2answers
320 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 ...
5
votes
1answer
266 views

How to use Replace function in a custom script?

I would like to use Replace function in a QGIS model but it doesn't work as I wish. I was working with Joseph's brilliant solution (using a custom script in a model) but I couldn't find out how to ...
5
votes
1answer
687 views

QGIS Count lines in polygon ( to be part of a graphical model )

My problem is very easy to understand but I can't find a solution. I'm actually working on the spreading of a local optic fibre network. These fibres will be contained in plastic tubes buried in ...
5
votes
1answer
2k views

QGIS processing default output vector layer extensions

You can set the default output-extension of a model in processing > options > general. The intermediate transactions in a model are processed in that default file format. After installing QGIS, the ...
5
votes
1answer
360 views

Sort inputs parameters in QGIS modeler [duplicate]

I created a model in QGIS 3.6 with three inputs parameters (two vector layer and one vector field). When I run the model, the inputs are not sorted in a correct way: the vector field is requested ...
5
votes
1answer
323 views

Processing modeler to update table

Not sure if I'm missing something very basic or not, but I have 6 or 7 shapefile vector layers in a dozen or so models that I need to update a single field with a rather simple formula. I could spend ...

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