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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22 views

Copy all features and attributes to a new dataset based on a template in QGIS Modeler

In QGIS desktop I can merge a template spatial file that has no data but all the attributes I need with another spatial file that has the spatial data where some of the attributes aren't in the ...
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1answer
52 views

Compare two columns using Graphical Modeler in QGIS

I have a layer with several columns. One of them is called 'cod' and the other is called 'cod_2'. 'cod_2' is null, except for one row. I want to know if the numerical value of 'cod_2' is present in ...
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0answers
18 views

Including metadata on QGIS 3 models?

Models on QGIS 3 are stored following a XML schema. Do you know if it is possible to embed metadata, may be using Dulin Core or ISO? I have noted that the modeler's help take in account subjects like: ...
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1answer
44 views

QGIS 3.4 Modeler: Select a band of a raster layer for processing

As model input data I select a raster stack with three bands. The first processing tool just needs specific bands of this stack which I like to select in the input dialog. I create a 'Raster Layer' ...
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1answer
74 views

Why QGIS3 is not running processing models and scripts in background?

I have a problem with QGIS 3.6.0 on macos and QGIS3.2.3 on Windows7 with running processing scripts and models in background. According to QGIS3 docs they are run in background thread by default (if ...
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1answer
183 views

Incorrect result while adding points along geometry in QGIS

I'm trying to add points along lines every 3 metres but I'd like the starting/ending point at certain non fixed distance. When I use the tool 'Points along geometry' inside Graphical Modeler. I don't ...
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1answer
213 views

Model works for single layer but errors for batch process

I have a pretty simple model in QGIS that I am trying to use as a batch process. The model takes a line shapefile input, creates a temporary buffer, extracts by location using that created buffer, ...
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1answer
28 views

How to enter text into attribute tables with QGIS graphical model?

I am using QGIS 2.14 to open NC files for chlorophyll satellite data with the end goal of compiling chlorophyll values for many dates (each its own initial file) in a spreadsheet. I know how to do the ...
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61 views

How to chain multiple field calculators in QGIS Modeler with pointers on next or previous feature?

I have a Model that I use to filter a chain of points that have extracted values form a DEM (digital elevation model). I want to smoothen the hights with a filter that takes the average of the ...
3
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1answer
103 views

Using input layer as output in PyQGIS for QGIS Modeler?

I have written a simple Processing script to rename a given field. It works successfully, changing the input layer's field name. However, I have not been able to produce an Output. This is a problem ...
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1answer
102 views

Python script from graphical modeller of QGIS 3.4 gives KeyError?

For several tasks in QGIS 3.4 I need a python script. As I am not used to use python I created the script with the graphical modeler (I modeled the tasks in the graphical modeler and exported the ...
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1answer
47 views

Inserting string without ' ' in QGIS modeler?

QGIS 3.4.7 I have a lot of Models where there are some string inputs. In all of them, I have to enter the string between quotation marks ''. I understand the meaning and pourpose of them in any ...
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41 views

Open attribute table script in QGIS 3.6 graphical modeler

I am looking for a script which will allow me to open an attribute table of the final output of a graphical model in QGIS. I know that you can use the following lines of code in the console but ...
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0answers
26 views

Merge Vectorfile Outputs from Model Batchprocess in QGIS

I have written a model in QGIS 3.6 that allows to vectorize the outlines of raster layers containing measurement data. I run this model as a batch process to vectorize several field outlines in one go....
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1answer
64 views

Define multiple fields to copy in graphical modeler in QGIS 3.6

I am looking to find the correct syntax for copying a defined set of fields when using the "Join attributes by field value tool" in the graphical modeler in QGIS 3.6. I would like to know how the ...
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1answer
153 views

Sort inputs parameters in QGIS modeler

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 ...
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1answer
37 views

Using fixed vector layer parameter in QGIS?

How can I set my input layers to be called as defaults is QGIS Modeller? I am sure I am missing something simple but as it is I need to pull them down from the list every time. I want to set them as ...
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35 views

Using relative path in QGIS 3.x processing modeler? [duplicate]

I try to use a relative path for the algorithm "Set style for vector layer" in the processing modeler, but it works only with absolute path. A similar request is here, but the answer doesn't suit me. ...
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59 views

Selecting polygon as Input in QGIS Modeler?

I need to create a model where I select two polygon and the first one is clipped with the second one. Difference function is doing it. But asks for two input layers. How can I add as Input a Polygon ...
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144 views

How to import xyz data in QGIS 3.0 Processing Modeler for creating points and raster?

I want use dsm data in QGIS 3.0 Processing Modeler. This data are in xyz-format. I want to convert xyz data into points to create a raster. Later I want also apply this modle for the a folder with ...
3
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1answer
133 views

Issue with “Join attributes by field value” on QGIS 3.4.7

I have a shape file with polygons and a xlsx sheet, and I need to join their tables using Join attributes by field value in the modeler. At QGIS 2.18 it works perfectly, but in 3.4.7 the join doesn't ...
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1answer
65 views

QGIS: Graphical Modeler (Python?) task

I'm a complete newb when it comes to things like Python, however I'm keen to learn more. I have some experience with ArcMap's Model Builder and have started playing around with QGIS Graphical Modeler (...
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42 views

Create buffer based on the size of a line's length (QGIS) [closed]

I need to create a buffer around a point, witch has to be 1.3x bigger than the length of a given line. I want to automate this process with graphical modeler or pyqgis. So the program should ...
2
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1answer
41 views

How to change the Help Description in Modeler?

I´ve created some Models in QGIS 2.18 and the help in the Model shows only what is in the description field. Thats the way I want it. But I migrated to QGIS 3.4, and now when I type something in the ...
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56 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 ...
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0answers
46 views

QGIS Modeler - Select by expression error

QGIS Modeler works fine with my data if I store the layers as temporary layers, but soon as I will save the output in the selected folder (as shapefile or geopackage) I get a wrong result. The select ...
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70 views

Modeler with optional inputs or none?

I have a need for a model that all the input may be optional and allow the "Selected features only" option. So, I developed a model that fakes it all as seen in the example below I realize that some ...
2
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0answers
71 views

Method in QGIS to do a select by radius but ignore “islands”

I am looking for a process in QGIS to run a selection from a given point based of a radius that ignores "islands". For example you may have a body of water which acts as a natural barrier past which I ...
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1answer
116 views

Getting QGIS Model Processing Raster Calculator Error?

I am using "raster calculator" tool of the saga in my model. The tool correctly executes raster operation like "a * 2" in value formula option but the same expression is not executed pre-calculated ...
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0answers
140 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 ...
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1answer
141 views

Batch processing not available in Graphical Modeller QGIS

I'm currently running QGIS 3.6. I'm trying to set up a model that uses the GDAL 'Clip Raster by Mask' tool to extract individual rasters from a DEM. I'm using geopackage polygons as the mask layer. I ...
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1answer
26 views

Error with categorized render tool in model builder QGIS 3.4.3

In my model, I'm trying to color my polygon layer using an xml file through categorized render tool (under cartography toolset). However, when I run the model the output file has the attribute data ...
2
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1answer
274 views

Join attributes by value in QGIS 3.4.3 Processing Modeler

I want to add only a few specific columns from the join table but there is no drop down list. When selecting manually I'm able to select only 1 column when trying more than 1 I'm not getting the ...
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2answers
106 views

Error when using vector field parameter in field calculator with graphical modeler in QGIS 3

When trying to divide a vector field parameter with an output calculated during the model process I get a No root node, parsing failed! error at the point in which the field calculator in the model ...
2
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0answers
22 views

Error in Graphical Modeler when converting raster to vector

I'm building a model where, among other things, I use r.watershed, from which I only keep the "stream segments" output. In addition I would like to convert that raster to vector lines. When I do that ...
2
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1answer
70 views

Converting QGIS Algorithm from history to a plugin / tool

Rather than going through the process of creating a plugin is there a way to take algorithms from the history and put them together to create a quick tool like in ArcMap? For example I have ...
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1answer
42 views

Filter options are not saving in Dissolve algorithm window through Graphical modeler in QGIS 2

I am working on my project in QGIS 2.18 through Graphical modeller and using some basic algorithms for polyline objects. However, I do not understand why specification for Dissolve algorithm cannot ...
7
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1answer
182 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 ...
3
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1answer
419 views

Modeling iterative processes in QGIS 3

In the QGIS version 2.X, there was an Iterative Button from the algorithm also available for the algorithm used inside the processing modeller. Actually, I use version 3.2 and 3.4 and can not find it....
4
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1answer
218 views

Geometry by expression in QGIS Modeller

I want to use 'Geometry by expression' in a model I'm working on but I couldn't figure out how to pass the layer name parameter. Basically I have two polygon layers (A and B) and I want to do a ...
3
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3answers
163 views

Automatically populate r.reclass rules based on table values

In QGIS I have a raster map showing land, snow and cloud zones, having resp. pixel values 1, 2, and 3. I extracted the mean altitude values (in m) of each zone on the basis of an underlying DEM and ...
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0answers
27 views

Making QGIS model that iteratively creates several constant grids at once?

I'm looking to calculate the volume of a virtual reservoir from a DEM. I would use a constant grid (SAGA) to represent the ceiling, and I want to see the change in volume for each 1 metre interval. So ...
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73 views

Unable to select table in “reclassify by table” algorithm in QGIS Processing Modeler

In the Processing Modeler (Graphical Modeler) for QGIS 3.4.3, the "reclassify by table" tool seems bugged. I cannot select a Reclassification table, even though it's an obligatory field. Am I doing ...
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1answer
94 views

Raster calculator giving a different result in processing modeler Qgis 3.2.3

I'm running Qgis 3 processing modeler and I am trying to invert the values of a raster file. I had previously asked this question and the answer I came up with works with the raster calculator ...
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0answers
100 views

Download OSM data with QuickOSM and QGIS Modeler example and/or tutorial to share

I would like to automatically search and save my results (11 layers) via the QuickOSM plugin using the Qgis Graphical Modeler. Could anyone help me with some already prepared example or some tutorial ...
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1answer
169 views

Inputting CSV in QGIS graphical modeler and defining its geometry [duplicate]

Is it possible to have a model in QGIS graphical modeller which accepts a CSV with geometry fields and then allows you to use them for the rest of the model as if it was a vector file? This is ...
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0answers
36 views

Way of viewing attribute table of layer at end of model without loading layer in QGIS

I have created a model in QGIS 3 graphical modeler, with the final output being a shapefile. I was wondering if it is possible to have the final result as a pop up of the data table just to view the ...
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1answer
198 views

How to extend QGIS Graphical Modeler with Python Scripts

I'm trying to extract lat longs from my centroids, then feed the lat longs to the Google distance matrix API using another python script. I exported the graphical model as a python script: ##Drive ...
2
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0answers
54 views

In QGIS 3 Graphical Modeler can you add a check box to allow for different model path

In the Graphical Modeler in QGIS 3 is it possible to add a check box to the model GUI that if selected takes you down a different path of the tree so to speak. Example: Within a model I want to have ...
2
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1answer
204 views

Change attribute table value using graphical modeler?

So I have a buffer layer with an associated attribute table. This table has a column called "value" that I want to change to "x" based on previous selection. I can select the buffers in the layers I ...