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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.

4
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0answers
28 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 ...
1
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0answers
29 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 ...
1
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0answers
26 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
57 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 ...
1
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1answer
27 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 ...
4
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0answers
39 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 ...
1
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1answer
29 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 ...
1
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1answer
22 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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0answers
64 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 ...
1
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2answers
31 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
votes
0answers
11 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
votes
1answer
55 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 ...
1
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1answer
31 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 ...
6
votes
1answer
126 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
votes
1answer
72 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
votes
1answer
74 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
votes
3answers
80 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 ...
0
votes
0answers
21 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 ...
1
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0answers
31 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 ...
0
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0answers
42 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 ...
1
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1answer
54 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 ...
1
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0answers
33 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 ...
1
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1answer
92 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
38 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
votes
1answer
63 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 ...
2
votes
1answer
154 views

How to open GPKG layer fo processing in QGIS

I am making a model with QGIS 3.4 graphical modeler that should open and process a layer from the GPKG located in the project folder. Since the folder path may be changed, and QGIS does not allow ...
1
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2answers
63 views

Listing multiple fields to be dropped at once in QGIS modeler?

I'm trying to drop more than one fields at once in QGIS 3 modeler on Microsoft Windows. I'm using the algorithm "Drop field(s)". What is the good syntax to list multiple fields to be dropped? Not ...
1
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0answers
22 views

Pass additional options to GDAL in QGIS v3

I'm using gdalwarp inside a QGis v3 model (using qgismodeler) and I'd like to pass the -tap option to the command. I can't find where to place this. Is it possible to add additional options to gdal ...
1
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1answer
34 views

Fixed QGis modeler vector input parameter

I'm writing a QGis (v3) model and I'd like to have a vector layer input fixed to a specific shapefile. This way, every time I run the model, I don't need to select the file. Is this possible? Right ...
1
vote
1answer
33 views

How do you delete an object or polygon that has been selected in a layer using the graphical modeler?

I wish to create a model in QGIS 3, that can delete a specific polygon that has been selected in a layer. Is it possible to do this? I go through a few different locations in a day and I don't wish to ...
1
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0answers
30 views

Summarize table by group and add logic to keep data

I need to dissolve a polygon layer by group but, at the same time, I need to keep some of the data in extra columns. This is the diagram: This is the logic for the new group: Cod = "Cod" where N1 ...
0
votes
2answers
80 views

How to run the graphic modeler from the python console in QGIS? [closed]

How can I run the graphic modeler from the python console in QGIS?
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0answers
41 views

QGIS problem using join by location algorithm

I am new to QGIS. I have a problem when i use the algorithm "Join by location" in my graphical modeler, it returns me the "uknown error". I think the problem is that the shape i´m using to join is ...
3
votes
2answers
67 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 ...
3
votes
1answer
82 views

File naming iteration QGIS modeler

I am attempting my first use of the modeler from the Graphical Modeler from the Processing menu in QGIS. I made a simple model for cliping species data by sanctuary.It has two Vector Inputs, uses some ...
2
votes
1answer
267 views

Exporting model to Python script using QGIS? [duplicate]

I want to edit a few things to my model in QGIS 3.2.2, but first I need to convert this model to Python script. Is there a way to do it?
1
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1answer
167 views

Access string output of QGIS 3 processing script in graphical modeler

In the good ould days of QGIS 2 I created a processing script, that takes as input a table and a table field (table has only one record) and returns the string attribute value of the table field: ##...
2
votes
0answers
58 views

What to use instead of 'Table' input in QGIS 3 modeller

In QGIS 2 graphical modeler I had an input parameter 'Table' for spreadsheets, csv etc. with no geometry. By now, I'm re-creating all my existing QGIS 2 models from scratch (cp. Using QGIS 2.x ...
1
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0answers
26 views

Converting QGIS Processing Modeler Python (.py) file to (.svg)

A Processing Modeler can be saved in QGIS 2.18.15 as a Python (.py) file. Adhering to good advice by @Spacedman in an earlier thread, I wish to know what are the many ways the (.py) files for the QGIS ...
2
votes
0answers
32 views

Backwards compatibility for QGIS 3.2.1 Processing Modeler [duplicate]

I have created multiple models using the Processing Modeler in QGIS 2.18.15. However, I could not open these .model files in the user interface for the Graphical/Processing Modeler in QGIS 3.2.1, ...
1
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0answers
35 views

Missing toolbar and panel from graphical modeler in QGIS

Does anyone know how I can turn on the toolbars and panels of the QGIS 3 graphic modeler? I closed them and now I do not know how to enable them again, consequently only a blank window appears. I'm ...
2
votes
0answers
19 views

How to make QGIS model result to be a variable?

My model's temporary result is a point layer (one feature) and I need a value from one of its fields because I want to use it in the same model to select a feature on another layer. So for example, ...
1
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0answers
38 views

Set mandatory output format and folder in graphic modeler

I'm working with the graphic modeler in QGIS3.2 Bonn. I have created some models and they work quite well. In order to make them more easy to use for others: Is it possible to set the output format ...
1
vote
1answer
170 views

Vector Fields as Input Variable in Field Calculator

I’m working with QGIS 3.2 Bonn and I try to build a workflow in the graphic modeler. The model aims to build variable buffers depending on values from two attribute fields of an input vector layer. ...
0
votes
1answer
84 views

How calculate vegetation indexes with GDAL raster calculator

I want to calculate a few of vegetation indexes [ example: NDPI (red band-green band)/(red band + green band)] in a model with the GDAL raster calculator but I don't know how put the equation here:
2
votes
0answers
57 views

Convert polygons to lines ignoring redundant vertices in QGIS

Provided the following Polygons layer with 6 polygons (see image below), I would like to calculate each line's segment's angle (amongst other things), so I should convert those six polygons into lines,...
2
votes
1answer
81 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 ...
1
vote
1answer
65 views

Calling a plugin in QGIS Graphical Modeler

I am familiar with Arcmap modelbuilder but struggling with QGIS equivalent. I have installed plugin 'UMEP' and need to run 'sky view factor' module on series of rasters. Inside the Graphical modeler, ...
1
vote
0answers
90 views

Iterating polygons in folder as input in QGIS Modeler like ArcGIS ModelBuilder

How do I iterate polygons in a folder as input in QGIS modeller? Usually, ArcGIS can iterate polygons as an input for functions like union, merge, intersect, etc. But I cannot find the way to do ...
-1
votes
1answer
56 views

Use of model and some tools from QGIS

(repost) This is what I want to do... Data: -raster images with 4 bands (green,red,red-edge and NIR),there are like 30 folders with one zone per folder and the images where taken 3 periods of time. ...