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Questions tagged [qgis-3.0]

For questions about Version 3.0 of QGIS

6
votes
0answers
285 views

Editing Layout-Items after loading a QPT-Template in QGIS 3 with Python

I am facing a problem with the new Layout API while implementing a plugin for QGIS 3. Starting point is a layout template in qpt-Format, which contains different elements like (attribute) tables, map, ...
5
votes
0answers
495 views

Join attributes by location very slow on QGIS 3.0

"Join attributes by location" is very slow on QGIS 3.0. I have tried it with a CSV file and also with a shapefile (point layer) and a grid (made of polygons). On QGIS3.0 it takes about 3 hours to ...
5
votes
0answers
155 views

Point cluster symbology for different categories without overlapping symbols

I'm trying to visualize crimes based on if the crime happened during day or night time. I've tried using the point displacement tool but I'm not satisfied with the results because the readability for ...
4
votes
0answers
143 views

qgz-projects can't be opened in QGIS 3

I have recently switched to QGIS 3.4.0 and currently, I can't open projects saved in .qgz-format. No error message, no crash, they simply don't open. When I try to load the project a second time, I ...
4
votes
0answers
41 views

Setting grid in QGIS that automatically adjust its intervals?

I am setting a template for multiple maps in QGIS 3 Layout and i was wondering if there is a way of automatically adjusting the grid's interval as a function of the scale of the map? I did a bit of ...
4
votes
0answers
128 views

Graphical modeler in QGIS 3.0.3 - Access Vector Field in Calculator

I want to create an algorithm with the graphical modeler in QGIS 3.0.3 where i define one Vector Layer and a Vector Field from this Layer as my inputvariables. Then i want to access the field-values ...
4
votes
0answers
144 views

Unable to connect to postgres server in Database Manager

I try to connect to my postgres server, hence I got this failure And following error: 2018-04-26T18:02:05 WARNING Traceback (most recent call last): File "C:/OSGEO4~1/apps/qgis/./python/...
3
votes
0answers
41 views

Updating Algorithm list in pyqgis3?

I am attempting to run a union operation in a standalone pyqgis script and I'm receiving this error: Algorithm qgis:union not found The union operation fails with this code: params = { 'INPUT' ...
3
votes
0answers
32 views

How to view layers by data source in QGIS 3?

Is there a tool or panel in QGIS 3 that allows a user to view the map layers by data source? Similar to the List By Source view in the ArcMap Table of Contents? I thought I had come across it, but ...
3
votes
0answers
26 views

How to render features that are just outside the map canvas extent in QGIS 3.4?

I am trying to generate a cloudy mask, following the recipe in "Qgis Map Design 2nd ed. Edition". For the most part, I have it working. But when panning around, the mask changes. And I think that ...
3
votes
0answers
144 views

Developing QGIS Python plugins using Jupyter?

Is it possible to run PYQGIS commands using Jupyter notebook and, if so, is there any documentation to develop QGIS plugins using Jupyter?
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 ...
3
votes
0answers
115 views

How to read out which map theme is used in QGIS 3

I'm using QGIS 3.2.2 and Python. I would like to read out which map theme I currently use. I know the following method provides me a list of defined map themes ('Theme1', 'Theme2'): QgsProject....
3
votes
0answers
196 views

Using Python to set text for a label in a QGIS3 print layout label

I am able to assign a QGIS 3.2 print layout label item to a Python variable using: MyMapLabel = MyPrintLayoutObject.itemById('MyLabelName') Which is all well and good but I need to be able to change ...
3
votes
0answers
138 views

QGIS 3.0.3 (and 3.2.0) crashes on start. Ubuntu 16.04, conda environment

I am trying to QGIS in a conda environment, python 3.6.5, conda 4.5.8, Ubuntu 16.04 Xenial. It crashes upon start-up without even loading all the way. I have tried both QGIS 3.0.3 and 3.2.0 (3.2.0 is ...
3
votes
0answers
131 views

Wrong length values on QGIS 3.0.3 and 3.2

While using QGIS 3.x today I noticed that length values were not calculated and measured correctly on EPSG:32611. Calculating and measuring the same data on QGIS 2.18 latest LTR and 2.2 on EPSG:32611 ...
3
votes
0answers
48 views

QGIS rule based symbology for rasters in Atlas?

I'm making species distribution maps and have got the Atlas working perfectly using a polygon layer to show the quarter degree grid cells for species observation records. I have ~ 250 species. Problem ...
3
votes
0answers
205 views

Removing duplicate labels in QGIS3

I have a layer (streets) where I want to remove duplicate labels and then set a display interval for the labels. This is relatively easy in ArcMap because removing duplicates is based on the label ...
3
votes
0answers
99 views

PyQGIS 3.0: cannot make it work under Windows

I've just tried to install QGIS 3.0 package in my Anaconda (Win7x64, Python 3.6 x64). I wanted to use QGIS widgets in my PyQt application. Alas, QGIS works incorrectly: at first, when I just tried to ...
3
votes
0answers
87 views

Changing point cluster symbol color by expression (color ramp with manual intervals)

I am working on cluster map (QGIS 3.0). My map display both "not clustered" markers with color attribute based on manual brackets ( [1-1.9); [2-4.9]; (5+ ) and clustered markers (red color). What I ...
3
votes
0answers
419 views

Difficulty using ordinary kriging in QGIS 3

I have a shapefile with 65 data points. Each data point has a value for NO2 pollution. I would like to use kriging to create a grid of NO2 pollution values for the whole area. I have tried using ...
3
votes
0answers
46 views

Where does qgis store calculated field from field calculator?

When adding a (computed) field for a PostGIS table, where is the new field stored? I thought it would be with the original table, but it does not seem to be the case for QGIS 3.0.1/3.0.2 (Ubuntu 16.0....
3
votes
0answers
55 views

QGIS 3 Plugin Cancel Edits is crashing plugin

I was using, this method in QGIS2. self.iface.actionCancelEdits().trigger() This method was used, on canceling the edits in the iface. But this method is crashing my plugin on QGIS 3. What is the ...
3
votes
0answers
266 views

Using QGIS 3 Plugin Builder on a Mac

Now that I have QGIS 3 running nicely on my Mac. I am having another go at building some plugins. I have installed the plugin builder plugin and run it without problems and it has generated a source ...
3
votes
0answers
63 views

How to transfer QGIS configurations to latest version?

I have QGIS 2.18.11 on my machine. There are saved wms, wfs and DB connections. After installing QGIS 3.0 I can see saved wms connections but no DB connection is listed in 3.0. Collegue's problem is ...
3
votes
0answers
149 views

Connectors do not appear automatically in easy custom labelling

I'm using the easy custom labelling plugin in QGIS 3. When I move a label away from its associated polygon a connector does not automatically appear as in QGIS 2.18. How do I get connectors to appear ...
2
votes
0answers
31 views

Does the Clipper plugin for QGIS work for Shapefile layers?

I created 2 overlapped polygons in one Shapefile layer, run the intersection tool with another layer and then run the Clipper plugin. This causes the error: TypeError: MultiPolygon geometry cannot be ...
2
votes
0answers
23 views

Showing split polygons in different layers in QGIS

I used the split feature to split a polygon into two parts. Is it possible to show the split parts in sub-layers in the layers panel, so that I can hide them individually? I am using QGIS 3.
2
votes
0answers
27 views

How to create a valid QgsVectorLayer from a PostgreSQL view?

I am attempting to create a QgsVectorLayer with the same code as I am using for a PostgreSQL table, which works correctly and the isValid() method on the layer returns true. uri=QgsDataSourceUri() ...
2
votes
0answers
68 views

Unresponsive MessageBar in QGIS 3

I created a little plugin to geocode addresses using the HERE API and QGIS 3. Especially in batch mode, I can see that the plugin is iterating over my features in a table and my messageBar progress ...
2
votes
0answers
30 views

Rendering Google Terrain in QGIS Layout Manager

I am using the Google Terrain map (via XYZ Tiles). This seems to make the system very slow, and when making a .jpeg through the Layout Manager, the Google Terrain will not display (render) when ...
2
votes
0answers
25 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
0answers
34 views

QGIS 3 downgrade on Ubuntu

I updated to QGIS 3.4 on Ubuntu, but there are some functions that are not working so I want to downgrade. Therefore, I have several questions: How to downgrade or reinstall to some older version ...
2
votes
0answers
28 views

Using QgsExpression in a custom validation?

We use our own validation in QGIS, which can be called from different areas of the plugin. In addition, reports can be generated from the results. Now we have switched to our own attribute forms in ...
2
votes
0answers
163 views

How to Enable the QGIS Official Plugin Repository in the 3.4.1 Version?

I am using QGIS version 3.4.1. Recently, I cannot install new plugins. I have looked in the plugin setting. It seems that the link is blocked. The address is "https://plugins.qgis.org/plugins/plugins....
2
votes
0answers
35 views

Redrawing raster layer after file changed in QGIS?

I'm trying to find a way to redraw a raster layer after the original source file has been changed in QGIS 3.2+. However, it redraws only sometimes (~10%), which means there is some deep caching that I ...
2
votes
0answers
241 views

QGIS 3.4.0 Madeira: unresponsive

I "upgraded" from 3.2.3 to 3.4.0 and it's so unresponsive it's unusable. The startup time is the same as 3.2.3, then it needs half a minute to build its UI. When I click on the UI, the reaction is ...
2
votes
0answers
38 views

Copy polygons to another layer with different attribute

I am working in QGIS 3.0.2-Girona. I am digitizing images in which there are rocks that can be encrusted, totally or partially, by algae. I want to have a polygon for the rock and one for the algae. ...
2
votes
0answers
41 views

Changing the Location of Python Expressions QGIS3

I've recently started using QGIS and I've written a few custom functions to use with expressions in the Function Editor (see image below) From what I can find these appear to be saved in: C:\Users\...
2
votes
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 ...
2
votes
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
votes
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 ...
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
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 ...
2
votes
0answers
37 views

r.series GRASS algorithm in QGIS 3.2 output no-data image

I'm trying without success to calculate a standard deviation image from 4 input images. I already used the r.serie algorithm in 2.18 to calculate an averaged image. Know after upgrading to 3.2.2 on ...
2
votes
0answers
19 views

How to stick plugin widgets for ever to its own position?

Every time I'm starting Qgis my custom widget disappearing. Is there a way to stick plugin to keep it all the time at the same place in the screen layout ?
2
votes
0answers
77 views

How to use QGIS plugins functionality in standalone application

I'm new to QGIS 3 Library to develop standalone map application in qt4, C++ language. I was wondering if there is any way that I can use QGIS plugins such as Advanced viewshed analysis, Contour plugin ...
2
votes
0answers
148 views

Creating heat map with fixed max color value in QGIS?

I am trying to create a heat map using raster data in QGIS 3.0. I have made them previously in ArcGIS pretty easily, but I am having difficulties in QGIS. The difficulty I am having is setting a fixed ...
2
votes
0answers
61 views

No attribute table or values in QGIS 3.2 Grass toolbox plugin output files

Using the Grass toolbox within QGIS 3.2 (and previously 3.0) when I import any files and overlay them, then use the "View Output" option (button), the resulting file has the correct polygon areas ...