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Questions tagged [qgis-3.0]

For questions about Version 3.0 of QGIS

1
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1answer
26 views

Keep only endpoints of line with Extract Vertices

Using QGIS 3.2, I can use the "Extract Vertices" tool to generate a layer of vertices for each line segment in my data. My data is split into line segments of between 400-500m in length (using the v....
2
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0answers
42 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
91 views

Datum transformation in QGIS 3

I have an Esri shapefile with following in the .prj file (broken into multiple lines for comprehension): PROJCS[ "SGL_Stereo", GEOGCS[ "GCS_SGL_GEO", DATUM[ "D_SGL", SPHEROID["...
0
votes
1answer
58 views

GML axis order problem in QGIS

Is there any reason why QGIS swap axis order if CRS (EPSG:3908) is defined inside GML, for example: <au:geometry> <gml:MultiSurface gml:id="_42d05737-123d-4a52-a655-aef968cd9511" srsName=...
1
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0answers
55 views

Polygon Centroids working for only some Polygons in PyQGIS?

I have a building Layer(Full of Polygons).I want to get centroids of polygons and save them as point layer.I am using python console within Qgis 3.0. I have tried below code.I got my Centroid Layer(...
1
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2answers
131 views

Issues with QgsTask and task manager

I am trying to use the task manager to run a long operation (uploading layer to a GeoServer instance, for the Geoserver Explorer plugin), but I am finding some issues. Here is the code that I am ...
1
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1answer
87 views

next method for FeatureIterator object in QGIS 3 seemingly not working?

How do we get the next feature from a QgsFeatureIterator object in QGIS 3? I tried the following with no success: l = QgsProject.instance().mapLayersByName('Dissolved')[0] f = l.getFeatures() f = f....
1
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1answer
113 views

Error using QGIS 3.2.2 Warp (Reproject) tool with custom coordinate system

I'm using the QGIS Warp (Reproject) tool to reproject a raster from WGS84 to a Lambert Conformal Conic custom projection in QGIS 3.2.2. The call to the GDAL/OGR console is the following: gdalwarp -...
1
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1answer
44 views

Snapping in PyQGIS3.0

The following expression enables snapping for PyQGIS 2.0 : QgsProject.instance().setSnapSettingsForLayer(layer.id(), True, 2, 1, 10, True) What is the equivalent expression in PyQGIS 3.0?
1
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1answer
83 views

QGIS Attribute table - How to merge the values of $area field of several elements by the same attribute (point ID)?

I have a land use vector layer with polygons representing forest, farming, urban aggregates, etc. Each polygon has a field with its area. I was trying to intersect it with buffers of different ...
0
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0answers
51 views

QT Designer: Cannot load library C:\…\designer\pyqt5.dll: The specified module could not be found

I have a standard network installation of QGIS3. When I open QT Designer from the standard location where it installed with QGIS, I see the following error by selecting the menu "Help" and then ...
1
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0answers
54 views

Why are random characters (e, ?, `, … ) appearing in my text field (attribute table) of the shapefile in QGIS 3.0?

I have a shapefile that I have created which has a few features (about 10) and I have input attribute information for each feature and each attribute (set to text). For example, one of my fields is ...
5
votes
1answer
72 views

What happened to the changelog on QGIS 3 plugin info page?

In QGIS 2.X the changelog from the metadata.txt was/is displayed on the plugins info page (and besides, the info whether a plugin is trusted or not): In QGIS 3 I miss both informations: Users are ...
1
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0answers
14 views

How to get last added layer in pyqgis?

Can we find last added layer in pyqgis? I use Data Source Manager | Delimited Text at the end of the process it creates a layer and adds it layers panel: However, I can not know what the Layer Name ...
7
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1answer
186 views

'native' vs. 'qgis' geoprocessing algorithm provider in (Py)QGIS 3

In QGIS 3 processing toolbox among all the algorithms with the QGIS 3 icon there are some with Algorithm-ID starting with qgis: and some starting with native:. What is the difference between ...
0
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0answers
18 views

How to use qgis customization.xml code in my gui?

I want to use the code under customization.xml file to use in my gui designed in QtDesigner. For instance in Data Source Manager | Delimited Text in QGIS there is a window: I want to use this ...
2
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0answers
79 views

Displaying cross sections/3D volumes in QGIS 3.X

Is there is a way to display vertical images (cross sections) in a 3D view window in QGIS 3? I want to display some cross sections underneath a geological map overlain on the topography. I can do ...
2
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0answers
115 views

PyQGIS Layout export

I have some problems with PyQGIS while generating a layout. Here is a minimal (non-)working example in which I first load some layers with their styles. Then I would like to export them using a ...
1
vote
1answer
48 views

No module named 'mmqgis'

I have two layers in my Project 1)Points Layers 2) Polygon Layer I need to apply nearest neighbour Analysis between point and Polygon, but i am unable to get . I tried the below code.I am using ...
1
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0answers
42 views

Activating snapping with PyQGIS?

I would like to construct a map tool application that allows only to add some point features. How do I complete the following code to activate snap mode while editing a layer with PyQGIS 3? from ...
0
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0answers
34 views

Customizing the legend with a column attribute sum or a custom string

What I am trying to attempts is to get the sum of all areas of all features in the extent and separated by the categories in the legend.And all this in an Atlas. So that I would have all the total ...
1
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1answer
108 views

Disappearing polygons when zooming in QGIS 3.0

I am using QGIS 3.0 and loaded a polygon layer from a shapefile containing more than 300,000 polygons. When zooming in some polygons are not drawn (not the entire layer).
6
votes
2answers
126 views

Finding which side of closest polyline point lies on in QGIS?

I would like to find on which side of the line (left or right) my points are located with respect to the direction of the line (like knowing the rivers bank along a meandering river). But, if there ...
1
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0answers
82 views

QGIS 3.0.3 takes a lot of time to save selected features

I'm editing a large .xml layer with over million points and 2GB of data. I'm trying to save selected features (about 100 000 points). After an hour of saving, I have just 77 kb of data saved. With ...
1
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3answers
216 views

QGIS 3 shapefile clip issue

I was clipping vector layers yesterday with no problems, and now all of a sudden it doesn't want to work and keeps giving me an error stating: Feature (2) has invalid geometry. Please fix the ...
1
vote
2answers
172 views

QGIS does not load OSM data completely

I used QGIS 3.2 to load OSM data obtained from Geofabrik as Layer/ Add Layer/ Add Vector Layer The problem is that QGIS does not show roads completely compared to the OpenStreetMap website. I ...
5
votes
2answers
176 views

Dividing two or more rows in single attribute table?

I want to divide rows in my attribute table. I need to divide the lengths of rows having specific IDs. For instance the length of ID 21 divided by the length of ID 11. An this calculation execute for ...
1
vote
1answer
42 views

Error in executing clip with polygon from another layer

I have used clip with polygon from another layer with the Digitizing tools toolbar successfully before but I am running into an error recently. I have selected one polygon in the layer to clip and ...
1
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0answers
84 views

What happens when you press cancel on a QgsTask?

I'm trying to get the "cancel" to work for my QgsTask, I have created a simple example to illustrate, When I press the "x" i want it to print reslut: None values: False, hence it just finishes without ...
1
vote
1answer
87 views

Error in executing Voronoi polygon algorithm

I am trying to create Voronoi polygon on point layer of my project. I need to save this new layer as .shp file. The following is the code I have written in Python console, using QGIS 3.0 import ...
1
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0answers
39 views

Cutting TIFF in QGIS 3.0.2 produces an empty Raster

I am currently trying to cut a georeferenced TIFF image by using a Polygon as cutting boundary. Both are saved in EPSG 25832. When running the algorithm from the Raster - > Extract menu it runs and ...
0
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0answers
36 views

Breaking LineString into MultilineString group by distance between two points and it's time

This is line string of my geometry column that created by postgis and shown in qgis: This is multiline string like above: I am new on gis and How can i do break line and convert it into multiline? I ...
1
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0answers
46 views

Saving outputs of “proccesing” to temp file in PyQGIS

I'm trying to save the output of a "proccesing" algorithm executed in PyQGIS as a temporal file, and then re-using it with another algorithm. The desired result is to write the output only at the end ...
0
votes
1answer
53 views

Adding vector layer and newly created layer always in Top- Down Order Panel using Pyqgis 3 [closed]

I have two layers in my project Point Layer Building Layer I recently created Voronoi Polygon on Point Layer say (vor-points layer) But as soon this Happen, the newly created vor-points layer ...
2
votes
1answer
82 views

Rasterise polygon layer using QGIS 3.0.3

I am trying to rasterise a simple polygon layer this file using QGIS but cannot get a sensible output. The documentation doesn't appear to have been updated for version 3 yet, and does not match. ...
2
votes
2answers
130 views

How do I declare a QGIS custom expression function and use it in a single python script?

I would like to create and populate a virtual field in a QGIS vector layer attribute table using a python script. I think the easiest way to do this is to create a custom expression function, and, ...
0
votes
1answer
170 views

Adding multiple layer on Map Canvas using pyqgis

I am facing issues on adding Multiple layer in Qgis3.0. I tried below code but its not working. I am unable to detect what wrong since its not giving error. Both Layers are valid, but cant be added ...
1
vote
1answer
88 views

Constructing Voronoi Polgon and Applying Nearest neigbour in it

I am learning QGIS 3.XX and currently working on Voronoi Polygons. I have three layers Point layer Building Layer Population CSV file. These points layer are basically water tanks and building ...
1
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0answers
45 views

QGIS API Label expression for vector layer

I'm using QGIS 3.3 C++ API (python dev should be able to answer too as both C++ and Python API share the same elements names) I'm trying to display a label on each point of the layer with this ...
3
votes
0answers
324 views

OTB-QGIS plugin does not appear in QGIS 3.2 after manual installation

I have followed this instruction to connect the qgis-otb-plugin manually. But after completing all the steps, OTB does not show under Settings > Options > Providers. I cloned the qgis-otb-plugin ...
0
votes
0answers
29 views

Specify output data type from TIN interpolation

Is it possible to specify the output data type when running a TIN interpolation in QGIS 3.0? I don't see any options I can use to specify the data type, it is defaulting to float64. I need the ...
2
votes
0answers
389 views

Python processing script with clip in QGIS 3.2

I have been following the QGIS scripting templates, but have been unable to get vector processing to work with input and output layers. Working with QGIS 3.2.2. The following script is my attempt at ...
2
votes
1answer
69 views

mapCanvas.saveAsImage() doesn't work properly within loop in standalone script (only .PGW)

I have a problem with the export of QGIS 3 interface screenshots. I run stand-alone scripts and one of them launches QGIS and runs script.py with the following code : mapCanvas = iface.mapCanvas() ...
1
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0answers
26 views

How can I install a python 3 module for its use in QGIS3 in Windows?

I've been struggling to install BeautifulSoup4 for a Python script I want to share with Windows users, but I just can't get it installed for its use in QGIS, I've tried pip install BeautifulSoup4 ...
0
votes
2answers
61 views

Table with overlapping areas of 2 maps?

I have a base map with various land use. to this I have to superimpose a shape with the polylines that delimit the areas. How can I get the surfaces of each ground use that fall within each polyline?
1
vote
1answer
31 views

Map eastings in QGIS 2:18 Print Composer alternate between correct values, then negative values

Using CRS OSGB 1936 (ESPG 4277) at various map scales in Composer, I find that the northings are all correct, but the eastings alternate between two or three correct values, then two negative ones. I ...
2
votes
2answers
81 views

Converting 0 values to 1 in QGIS 3 using r.mapcalc GUI

I'm using GRASS 7.4.1 in QGIS 3.2 and would like to change 0 values of a slope raster to 1. I've been following this video tutorial and my r.mapcalc function looks exactly the same. However the output ...
1
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0answers
50 views

Editing features in PyQGIS3 application [closed]

I would like to complete the following map tool application that allows only to add some point features, by other functionalities like prompting the user to fill attribute form while editing for each ...
2
votes
0answers
53 views

Georeferencing xyz layer from Griffiths Valuation of 1850s?

I have made progress on my project to map land and property owned by individuals in 1850 in Ireland using Griffiths Valuation maps. I used http://griffiths.askaboutireland.ie/gv4/single_layer/tiles/{...
2
votes
0answers
42 views

Available snapping points for advanced digitizing?

In QGIS, the Advanced Digitizing tools have some snapping features that I don't see mentioned in the documentation. We know that we can digitize new segments that are perpendicular or parallel to ...