Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [qgis-3.0]

For questions about Version 3.0 of QGIS

0
votes
2answers
23 views

How to refresh the HTML, including the linked CSS for a QGIS HTML frame?

I am using a referenced css file in an HTML Frame in a QGIS 3.4.2 layout. <link rel="stylesheet" type="text/css" href="map.css"> It works great until I have to go and edit the css. When I ...
1
vote
1answer
41 views

Compile and load QGIS3 plugin

Win7 x64, QGIS 3.4 installed through OSGeo4W with 'Advanced Install' Here's my workflow: Get the template directory from PluginBuilder3 Navigate to this folder in the OSGeo4W Shell Use call "...
2
votes
0answers
17 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
32 views

How to find intersection polygons in single layer on QGIS version 3.4.2?

I have polygons intersection in single layer. I want polygon in yellow frame and use polygon intersection to calculate area , how to do this?
1
vote
1answer
21 views

Adding points on a map parcel from an attribute in the attributes table

First, my apologies as I am a newbie and may not be using the correct words or I am asking a question that has already been used. I am using QGIS 3.4.2 and a have a map of a subdivision with roads, ...
1
vote
1answer
47 views

Join attributes by location - false information

I've been working on an analysis involving animal vehicle collisions. The data has been passed to r-stats and I keep noticing peculiar things in the cross referencing of the data. I've created highway ...
1
vote
1answer
64 views

UBUNTU 16.04, QGIS 3.4 above Installation problem

I want to install QGIS 3.4 above and did exactly the same as this page: QGIS Installers and tried the codes below having no error at all: (1) add the following lines to /etc/apt/sources.list deb ...
0
votes
1answer
57 views

Attribute table not showing data in QGIS 3.2 (prior answers only apply to QGIS 2)

I've opened a .shp in QGIS 3.2.3 and there is no data in the attribute table. It shows the correct number of rows but no columns. A previous answer recommended choosing "Show All Objects" under the "...
1
vote
1answer
39 views

Creating points along line at ellipsoidal distance

I need to create points along a polyline in QGIS 3 at every 1000m of ellipsoidal distance and have tried several tools, as suggested in other answers: Points along geometry QChainage plugin Convert ...
2
votes
1answer
37 views

QGIS3.4 Madeira crashes when calling print()

I am using the pyqgis template from underdark for showing the crash. Her script is running like a charm, but as soon as I add a print("finished...")-call in her code, QGIS3.4 Madeira crashes. You can ...
2
votes
1answer
64 views

Getting line geometry out of two points using QGIS?

I have one input point layer and out of that, I want to create an output LINE vector layer. For each feature in my output line vector layer, I define a geometry which takes 2 point geometries. ...
1
vote
0answers
40 views

QGIS 3 Python plugin psycopg2 Postgres Notify/Listen Live Connection

I'm developing a plugin for QGIS3 for my company, where my managers can allocate tasks to other users. I have programmed two tables within the python script, witch will be only visible according to ...
0
votes
0answers
24 views

Virtual Fields in PostgreSQL 10.5

I'm having trouble getting a virtual field imported from QGIS 3.0 to PostGIS. The other fields in the layers are importable to my database. We need it in PostGIS to get multiuser-access on the it. The ...
1
vote
1answer
19 views

CAD Editing plugin in QGIS 3.0

Is there a plugin with CAD tools for editing vector entities such as lines and polygons in QGIS 3.0?
0
votes
1answer
32 views

Using v.split in GRASS?

I'm trying to split several lines into bits of a maximum given length using v.split. First, I got this bug: UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe8 in position... , which was solved ...
2
votes
1answer
38 views

Creating VRT or index of large amount of aerial images to create mosaic in QGIS?

I have about 1600 aerial images that I want to create a mosaic of. I tried doing about 400 at a time in a VRT, it's extremely slow (been building polygons for about 15 minutes now + the 20 minutes it ...
3
votes
1answer
84 views

Styles with parameters

I'm using QGIS 3.4 , and without going into python scripting, is there a way I can create some kind of rule based styles where I can add a parameter? I have a number of layers, each with between 1 ...
1
vote
0answers
24 views

Batch processing DTM with Hillshade in QGIS 3

I'm using the Hillshade tool from GDAL library [Raster analysis] in QGIS 3.4. I can't use the batch process with creative options like compress=LZW or profile=Geotif. It doesn't work. The tool works ...
1
vote
2answers
51 views

Output layer from PyQGIS 3 processing script is empty

I've created a processing script in QGIS 3, and although my output layer has shows a feature count greater than zero when using the feedback command, the resulting feature layer that appears in QGIS ...
0
votes
0answers
14 views

How to export a GPX that is ingestable by the ridecommand.polaris.com GPX import?

I am attempting to export a GPX file from a PostgreSQL line table to a GPX file using QGIS and/or OGR. And then upload that to https://ridecommand.polaris.com. For the most part, this seems to be ...
1
vote
0answers
27 views

Failed to load python Qgis 3.4 add-ins

I installed Qgis 3.4 Madeira and it worked fine, but now it throws me two errors The first is the following: The second is: By omitting the two errors that load with several defects, such as: a ...
3
votes
0answers
26 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 ...
1
vote
1answer
40 views

Compute 3D seismic fold with QGIS and Python

Computing 3D seismic fold is quite straight forward, for those unfamiliar with the concept, below is a brief explanation. Background information (Seismic 101) : Seismic Fold: Basically, I have (...
1
vote
1answer
83 views

QGIS 3 - Online POSTGRESQL database error “undefined symbol: GEOSFrechetDistanceDensify”

Using QGIS 3 on mac book air and set up a POSTGRESQL database with Acugis 6 days ago. Everything's been working fine and no issues. The yesterday everything went off and was unable to see the layers ...
1
vote
1answer
34 views

Polygon geometry suddenly disappeared/deleted from shapefile in QGIS

I was editing a polygon shapefile in QGIS (3.0.1) today when suddenly 966 out of 5382 polygons disappeared from the map. I had been changing attribute information in the table, cutting polygons, etc ...
1
vote
0answers
21 views

How to remove last created QgsRubberBand by clicking in Map Canvas area where doesn't exist any feature?

By combining information from these posts: Get the identified feature How to create and remove multiple QgsRubberBands in PyQGIS? I produced following code for getting feature attributes and ...
3
votes
0answers
22 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 ...
2
votes
1answer
58 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 ...
2
votes
1answer
106 views

Defining fields and adding features to output layer using QGIS?

I have two input vector layers (one point and one line layer). I loop through every feature in the input-line-layer and calculate some things (with help of the point layer). What I am trying to do ...
2
votes
1answer
34 views

KeyError when trying to set attribute in QGIS?

I have two input vector layers and I want to create an Output vector layer by doing some calculations. But somehow, the setAttribute method does not work. In QGIS 2.18, I was able to set an attribute ...
1
vote
0answers
18 views

How to make a QGIS 3 Layer refresh after a joined data source is updated

I have a layer of ZCTA features that is sourced from a SpatiaLite table that is joined to an Excel spreadsheet and rendered with categorized symbology. That all works fine. The join configuration is: ...
1
vote
0answers
26 views

Data-defined size legend QGIS and Map Unit symbol

In QGIS, I am making maps of the same project in different scale (global and local). To make my symbol looks alike in all scales, I've choose to use proportional symbol with a size in "map unit". ...
2
votes
0answers
28 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
1answer
44 views

How to create a symbol with directional arrows in QGIS 3?

This is the same as this question for ArcGIS: Creating Directional Flow Arrows for sewer lines? but for QGIS. I tried to follow the same approach as in ArcGIS, but I keep missing the mark. I think I ...
1
vote
0answers
29 views

Calculating number of pixels with different values

I have a tiff where each pixel has a value in megagrams for biomass. I'm trying to get a count of the pixels for all the pixels with diffrent megagrams values so that I can get an estimation of ...
0
votes
0answers
37 views

PyQgis How could I open the “identify results” dock using “onSelectionChange()”

Using iface.mapCanvas().selectionChanged.connect(function) I'd like to open the Identify result dock for the selected feature as shown below: it could be manually done by selecting the feature with ...
0
votes
0answers
40 views

QGIS Girona 3.0.3 : CSV File and Georeferencing

I installed version 3.0.3 because I have to give lessons on this version but I meet several bugs compared to version 2.18. I would like to import a csv file. I do not have an error message but my ...
1
vote
0answers
39 views

QGIS3: How to set an attribute value?

I have written a python script which has one output line-vector layer. The python script should calculate some value and then the script should set the attribute (with that value) of a newFeature (...
0
votes
2answers
49 views

Getting field index from input vector layer in PyQGIS?

I am very new to QGIS3 and I am currently trying to convert a python script from QGIS 2.18 to QGIS 3. Therefore, I am trying to integrate my python script into the template from underdark -> see here ...
0
votes
0answers
11 views

Raster-Projections-Plugin - Extract Projections not loaded

I am trying to generate a .wld file for a GeoTiff I have georeferenced in the GeoReferencer, but cannot see the 'Extract Projections' option in the menu or in the plugin list. Any ideas?
1
vote
0answers
17 views

Curved labels with data defined coordinates in QGIS

My goal: I want to have curved labels placed in the center of a linestring. I define the label position with the expression x: $x_at( num_points( $geometry)/2) y: $y_at( num_points( $geometry)/2) to ...
3
votes
1answer
71 views

Project CRS not being respected by QGIS

I have a button in a QGIS (3.4.1) plugin that should: create a new project; set it's CRS to EPSG:4326', then import various maps. However, when I run it for the first time after QGIS has loaded, the ...
1
vote
0answers
28 views

Creating a flow graph in QGIS 3.4

I attempting to make flow graph in QGIS 3.4, some thing like I have found several 'ways to do it' in QGIS 2.xx eg QGIS2.0 method I known its possible to get a line with arrows by just change the ...
0
votes
0answers
17 views

Custom QGIS CRS for transformation - MGA50 to Local Grid

I'm not sure how to define a custom QGIS 3 CRS for a local grid. I have the equation for transforming a projection system (GDA94/MGA zone 50) to the local grid but I don't know how to define the ...
1
vote
0answers
31 views

Vector Grid shows big difference between cartesian and ellipsoid measurement

I am using QGIS 3.4.1 on Windows 10. Project CRS is EPSG:3857 (WGS 84/Pseudo-Mercator). I have defined a vector grid. Type is Rectangle (polygon). Horizontal and vertical distance is 50 m. Overlay is ...
0
votes
0answers
33 views

Is there a QGIS 3 Implementation of Gravity/Huff model?

I tried to implement Jake's answer, but it depends on a plugin(rasterlang) that didn't port to QGIS 3. Is there QGIS 3 Implementation of this Huff model implemention? or Is there something ...
1
vote
3answers
33 views

Attribute errors with selectbylocation algorithm

Could anybody tell me what is wrong with execution of processing.run('qgis:selectbylocation', layer2, layer, u'intersect', 0) layer2 and layer is QgsVectorLayer object. This is error message I got
2
votes
0answers
21 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 ...
0
votes
0answers
90 views

ECW raster support for QGIS 3.4 and Ubuntu 18.04

I want to add ECW support to QGIS 3.4 on Ubuntu 18.04. I have not found a method to successfully add it.
1
vote
1answer
27 views

Changing txt layer Data Source in QGIS only using Python console?

I want to change the data source of a layer (non geometric, just a table of fields) created from a .txt file. I know how to do it manually but I want to do it with the Python console. I have tried the ...