Questions tagged [qgis-3]

for questions specific to the 3.x series of QGIS.

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2
votes
1answer
43 views

Where does QGIS save the processing log for a specific project?

After updating to current stable version (3.4.12 Madeira at time of writing), when opening a project, the processing log as described in https://docs.qgis.org/3.4/en/docs/training_manual/processing/...
1
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0answers
19 views

Getting HTML-Values in a QGIS-form by pyQT5

I have created a form for point-objects, that is delivering some values (getting by a database-connection) in the "html-area" in the form. So far the form works well and I´m getting the values that I ...
1
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0answers
25 views

How do I split polygon into line segments?

My question exactly matches with this one : How do I split polygons into line segments? but the solution is outdated, I am not able to find v.type.bl option under the grass dropdown in QGIS 3.8. ...
0
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0answers
10 views

Size of cost raster in Least Cost Path plugin [duplicate]

When I run the Least Cost Path plugin in QGIS, its success is dependant upon the dimensions of the 'cost raster'. If the original DEM or subsequent 'cost raster' it too large then the operation seems ...
4
votes
1answer
60 views

Should I build pyramids/overviews for the source files or for the virtual raster?

I have a virtual raster comprised of a lot of raster tiles of high-res aerial imagery. I wish to build pyramids/overviews to speed up the rendering in QGIS. Should I build them for the source files ...
1
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0answers
44 views

Defining buffer size when labeling text in QGIS?

I need to set label buffer size to near zero but I dont want to overlap labels. How to define buffer size when labeling text? Currently I am using labeling settings which is allowing all available ...
0
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0answers
73 views

Error downloading QGIS 3.8.3 in Windows 10

Been trying to download QGIS 3.8.3 but keep getting an 'Error loading QGIS' message box. And all I have is the OsGEO4W shell and nothing to complete the installation. How can I fix this?
1
vote
1answer
40 views

Change attribute values of multiple fields via pyQGIS

I am starting with pyQIS and I would like to change the values of two fields within selected features: from qgis.PyQt.QtCore import QVariant parent = iface.mainWindow() mc = iface.mapCanvas() myLyr = ...
1
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1answer
26 views

QGIS - Translation problems

I've enabled Processing plugin and provided compiled i8n file but somehow there is a error which causes GUI to create two separate buttons. One of them is translated and one is not. Does anybody know ...
3
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0answers
45 views

Easy way to close open clipped contours with the edges of the clipping mask?

I am trying to programmatically (with pyqgis) clip contour lines that I've generated in QGIS, but make it so that the clipping mask forms the new edges of the contours, rather than leaving the ...
1
vote
1answer
58 views

Error with Least Cost Path plugin

I receive the following error when attempting to find a least cost pathway in a very large dem file (42GB). is this because the file is simply too large? If so, does anyone know the constraints for ...
2
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0answers
60 views

Nearest neighbour analysis from existing Excel sheet

I learnt the Nearest Neighbor Analysis from QGIS Tutorials and Tips. The result of this analysis, see image below I know that after running the distance to nearest hub analysis, it produces hub lines ...
1
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1answer
28 views

Polygon visibility with overlapping polygons QGIS 3.4

I am marking forestry boundaries over google satellite tiles. The forest in question has areas of farmland within the outer boundary. One area of farmland has a patch of forestry within it's ...
2
votes
1answer
42 views

Reference to raster list

I am writing my first Python plugin. There was a problem during work. The plugin is designed to select a raster and calculate the statistics for the area bounded by the vector. I have created a list ...
2
votes
1answer
70 views

SAGA library is not visible in Processing Toolbox

The screenshot of Options > Processing I have SAGA plugin activated in my QGIS 3.8 on a Ubuntu 18 LTS machine. However, it does not show up in my Processing Toolbox. Could anyone help me solve ...
2
votes
1answer
24 views

Saving QGIS form design basic functionality in .ui to modify it with QTDesigner

It is possible to save a classic Qgis form (a drag and drop form) in order to modify it with QtDesigner afterwards ? I have created a form and I just want to change a list value into a toggle button ...
3
votes
1answer
66 views

Add popup images to polygons

I am already having a multi polygon layer of plantations in QGIS 3.8. Now I want to see popup images of the plantations when the mouse rolls over or clicks the polygon shapefile. I have until now ...
2
votes
1answer
58 views

Fine-tuning curved text positioning

I'm trying to label features using the geometry generator (QGIS 3.8). I used the following expression to build a simple circle : buffer(centroid($geometry), 500) In Placement i used Using Perimeter (...
4
votes
1answer
173 views

Creating standalone application with same directories and qgis-auth.db

I try to have a standalone QgsApplication (api documentation), but, instead of a lot of code samples found like this one below (I'm on Ubuntu): from qgis.core import QgsApplication QgsApplication....
3
votes
1answer
152 views

QGIS 3.6.1 problems with CRS

After I have created a new QGIS project, the project CRS is set automatically to WGS84 (EPSG:4326 - WGS 84 - Geographic). The layer (.shp) which I loaded to the project has already a predefined CRS (...
1
vote
1answer
80 views

QGIS QNEAT3 AttributeError by creating isodistances/isochrones

Trying to generate isodistances/isochrones in the QNEAT 3 plugin I got the following error: > Traceback (most recent call last): File > "C:/Users/User/AppData/Roaming/QGIS/QGIS3\profiles\...
3
votes
1answer
38 views

Arrow shape with text in it

I have been trying to solve this for hours and I haven't found a way to do it. I am working with the print composer on QGIS 3.4 to design a map and I just want to add an arrow with some text inside, ...
0
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0answers
24 views

Snapping value = 0 in Qgis

I am building pipes network, I need check connection between of pipes. I want to pipes must snap and tolerance has value = 0. Is there any tool to check and fix this things. I know Topology Checker ...
2
votes
1answer
50 views

QGIS Action commands in 3.8

In earlier versions i was able to open pdf files by using an action command like this one: cmd /c [%path%] this function no longer works on version 3.8. Any ideas why and what an alternative could ...
4
votes
1answer
67 views

Failure importing CSV file lines

I'm trying to import a CSV file in QGIS 3.4 using the common method of "Add Layer" > "Add Delimited Text Layer". But QGIS is reading every row of the dataset as a column title, and nothing is in a row ...
2
votes
1answer
56 views

Iterating over layer features, zooming fully on map and exporting them as PNG images in QGIS

I have 2 layers in QGIS map, One is raster layer and other is a vector layer having location of sites. Both are having same CRS. I want to zoom in to each feature in the vector layer and save the map. ...
2
votes
1answer
24 views

Opening KML with preserved raster symbology for icon

I have a KML file where the Icon is a png image of a generated coverage, and the idea is to overlay this in a layer over a basemap background, below is the KML file: <?xml version="1.0" encoding="...
8
votes
4answers
619 views

Labeling lines that are not within polygons using field calculator [duplicate]

I have two features. One line feature and another polygon feature. I want the line feature label not to appear when it is within a polygon similar to the one in the figure. That is, I want the label ...
1
vote
1answer
51 views

Auto populate fields with different values from another field in QGIS?

Is it possible to populate a number of fields in a shapefile in QGIS with different values based on the values of one other field? Essentially what I want to be able to do is to populate fields to ...
1
vote
1answer
65 views

QGIS 3 save project to geopackage

I am saving all layers of my map to a geopackage. This works fine so far. Now I want to save my project into the same geopackage. I select Project Save to Geopackage and now QGIS 3.8.3 (OS: windows ...
1
vote
1answer
45 views

Display labels set from within QgsProcessingAlgorithm in QGIS 3.x?

I'm writing a simple QgsProcessingAlgorithm and I need to set some labels (to display the azimuths of the sides of a polygon). I can set the labeling expression alright (the expression is properly set ...
4
votes
1answer
71 views

Deleting all custom CRS from QGIS

I am using a custom CRS for a project and whenever I load a .shp file, QGIS (3.8.2) creates a new custom CRS entry. As of today, I have about 10000 entries that are all the same and would like to ...
1
vote
0answers
39 views

Separating 50 duplicate points by limit in buffer zone using QGIS

I am building a customer database in QGIS. I get GPS coordinates for customers from my staff. Then I convert those GPS coordinates into shapefile points in QGIS. I get a lot of duplicate points. I am ...
3
votes
2answers
68 views

Updating layer extent after changing source in PyQGIS?

I am running a python script in QGIS 3.8.3-Zanzibar where I am changing the source of a GeoJson file. I am calling layer.reload() but subsequent calls to layer.extent() still return the old extent. ...
0
votes
0answers
12 views

How to mosaic and clip multiple sentinel 2 bands together using shape file as masked layer in QGIS 3

I am using sentinel 2 for LULC mapping. My study area contains three sentinel 2 tiles: T46RDN, T46REN and T46QDM. Using my study area shape file as masked layer, I want to mosaic and clip these bands. ...
2
votes
2answers
42 views

Routing a consecutive set of points on a network

I need to generate routes based on a consecutive set of points exactly as given in this routing script by Anita Graser. As given in this image, I have a layer of consecutive points as well as a ...
2
votes
0answers
36 views

Print composer too many row in attribute table how to split in multiple frame?

In the print composer, I've only added an attribute table and different attribute columns. As I have too many row to display in a single page, I would like to split the table between different pages ...
7
votes
1answer
71 views

Can gradients be applied to lines in QGIS?

Is it possible in QGIS to apply a gradient to linear features? I'd like for some roads to fade from opaque to transparent as they get further away from some set of points. I can measure the distance ...
5
votes
4answers
109 views

Find the maximum value for a point among several overlapping vector layers in QGIS3

Dataset 1: around 80 vectorlayers with polygons. Each polygon has a value for a noise measurement. Some of the layers (up to ten at at time) are intersecting at some locations. Dataset 2: a ...
1
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0answers
33 views

Remove dark background around clipped image in QGIS 3? [duplicate]

I used QGIS 3 for clipping a satellite image using a shapefile. The output raster gave a clipped image with dark background. How to fix this issue?
0
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0answers
56 views

Error when unzipping LiDAR data with LAStools

I try to unzip LiDAR data (.laz) with LAStools under QGIS 3.4 but I get following error message : Traceback (most recent call last): File "path\to\LAStools\laszip.py", line 61, in processAlgorithm ...
1
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0answers
34 views

QGIS 3.8 Python Code for calculate area

Is this the the best solution to calculate the area of the features? parent = iface.mainWindow() mc = iface.mapCanvas() fldname = "m2" #field which has the values for squaremeters myLyr = mc....
3
votes
1answer
38 views

QGIS 3.8 Python merge files

For a merge operation I need a list of all my layers in the TOC with path and filename. How can I achieve that? layers = QgsProject.instance().mapLayers() # dictionary myLyrList[] for layer in layers....
0
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0answers
10 views

How to I get square pixels from r.resamp..stats in QGIS3.8? [duplicate]

I am resampling a geotiff from 0.75 arc seconds to 3 arc minute in QGIS, but after I resampled, the x and y value of the pixels are not the same, how do I solve the issue?
3
votes
1answer
146 views

Basic script for Raster Files - PyQGIS 3

I am trying to make a script, to run at the toolbox, that receives a raster file and has an identical output to it, following the idea from here. I couldn't find a complete script that works ...
2
votes
1answer
42 views

QGIS 3.4 set transparency only for some layers below

I‘m working on a geomorphological map of a river and its sourroundings. As a base I have a topographic map and a DEM for the pre-mapping. The topographic map is not accurate enough in the river gulley,...
1
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0answers
17 views

QGIS 3.4: Why does DEM not appear after 3D configuration?

I have a problem with the 3D map view of my DEM in QGIS 3.4. When I open the 3D map view, the DEM is there. Then I go to 3D configuration and choose the DEM for elevation. When I click ok, the map ...
1
vote
1answer
99 views

Simple way to add a legend in QGIS 3.8.2?

I'm making a simple map using QGIS 3.8.2 and data from OSM. The maps looks good, but I'd like to add a legend. It seems like there used to be an "add new legend" button in older versions of QGIS, ...
5
votes
1answer
258 views

Exporting result of QGIS model to CSV

I am trying to output the result of a QGIS 3 model as a CSV file. At first I came across How to export csv/excel in QGIS3.0 model processor? but the accepted answer is not satisfying to me. Further ...
2
votes
3answers
106 views

How to draw a Polygon in QGIS 3.8 on Mac?

My apologies, this is quite certainly a duplicate of an old question, but I cannot find the answer. I am struggling with drawing polygons in the new QGIS 3.8.3 on Mac. In QGIS 2 drawing polygons was ...