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Questions tagged [qgis-3]

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

784 questions with no upvoted or accepted answers
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47 views

Scale seems incorrect in QGIS 3.4.3 for Mac in the editing window

I've been working on a map for a few months now and decided to export it in Composer to see how it's rendering out elements like creek labels when I noticed the exported scale was vastly different ...
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39 views

QGIS plugin - Works on PC, not on Mac

I'm adding some functionality to an existing QGIS plugin (EcoValuator from Key-Log Economics). After playing with the existing version of the plugin, it works on a PC, but not on a Mac. The issue is ...
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1answer
153 views

Calculating area in the attribute field of a QGIS 3.4.3 project with multiple CRS

The area calculations in my project derived from the attribute field show values way below actual area, because the attribute field assumes the project CRS (EPSG:3857). However, this CRS should remain ...
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227 views

QGIS 3.4 layout: fix extent and scale, let size adjust automatically

I'd like to create maps with a defined extent and scale. Logically, the map size has to adjust accordingly. Since I will be using the maps as pdfs (and not on paper), this won't bother me. Is this ...
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79 views

How to edit manually file geodatabase's OBJECTID column in QGIS?

I'm using QGIS version 3.4.1 with a Windows 10 OS. I'm trying to edit an Esri FGDB folder. Haven't succeeded. So far so I'm using a workaround: exporting specific layer to a new FGDB - with 'Save ...
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1answer
62 views

Loading layers from PostGIS db (populated with osm2pgsql) in QGIS?

I have downloaded some OSM data from geofabrik and used this to create a PostgreSQL/PostGIS database using the osm2pgsql tool: osm2pgsql -G -d <db> -U postgres myfile.osm Examining the ...
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241 views

Unable to get QGIS 3.4 to work correctly with a clean install - Windows Registry Remnants

I installed QGIS 3.4 and I keep getting errors attempting to use certain tools. GRASS r.slope.aspect via QGIS 2.18 vs QGIS 3.4 - not working I uninstalled but it is not removing all traces of the ...
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182 views

Export Layout problem in QGIS 3.4 and Windows 10

I try to export the layout into A0 size- but all size options bigger than A3 are blocked. I working with QGIS 3.4, windows 10. In QGIS 2.18 there no problem export layout to any size. But when i work ...
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182 views

How do you change the value of a Boolean column in a QGIS 3 Attribute Table?

I am editing feature in a PostgreSQL table in QGIS 3 and while I can edit the values in most columns, I cannot edit the Boolean value. I can enter the cell in edit mode, but keystrokes don't work. I'...
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217 views

Distance calculation with v.net.path in QGIS 3.2

I have 3 layers: origin and destination point shapefiles and network line shapefiles. I want to calculate the shortest path on the network between the origin (250 features) and destinations (20 ...
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1answer
112 views

Clip to mask layer not adhering to expected width and height following CRM and resolution changes

I am attempting to take a simple opentopo heightmap and carry out the following in QGIS 3.4.1 - Reproject to UTM 31N - Set cell size resolution to 5mtr - Clip to a shapefile polygon feature exactly ...
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111 views

libqgis_core.so.3.4.1 is missing (ubuntu 18.04)

Wile I was trying to amateurish solve the problem of that post: QGIS 3.4.1 crash without error after opening "options" (18.04. Bionic Beaver) I got a new, much more dramatic problem: /...
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1answer
113 views

Create New field equal to existing field - convert to integer - PyQGIS 3.4

I'm using PyQGIS 3.4, I am trying to add a new field and set the values equal to an existing field. The existing field are population totals but are in string format, I want to convert these to ...
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1answer
454 views

Merge multiple raster .tif in QGIS 3.2?

I'm trying to merge 12 .tif raster layers (raster -> misc -> build virtual raster), but keep getting this error: Loading resulting layers The following layers were not correctly generated./var/...
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18 views

Issue with qgis 3graphcis

I am using the latest installation of QGIS (3.2) in a Macos Sierra 10.12.6 and I get those graphic issues on the top left of the software (see image). Also when I go to full screen the tool tabs get ...
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95 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 ...
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2answers
99 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?
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136 views

QGIS 3.2.1 - 3D rendering causes application to crash

Whenever I try to render features on 3D map, QGIS crashes. Does anybody have any idea why? The 3D map works ok until I set 3D rendering for a layer.
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1answer
230 views

Debugging Error: Algorithm gdal:dissolve not found in PyQGIS?

I have difficulties with the processing package. I try to run a simple QGIS dissolve in pyQGIS 3. When I run the line : from qgis.core import QgsVectorLayer import processing from processing.core....
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127 views

Making 3D choropleth map in QGIS 3 with native tools?

This is similar to this question Is it possible to draw a 3D Choropleth Map in ArcGIS?, but I just wanted to know if the same could be done with the new release of QGIS 3 without the use of the ...
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1answer
470 views

QGIS API 3.2 and PyQT5 in Ubuntu Fails: Native Qt signal is not callable

I'm trying to migrate from QGIS API 2.18 to 3.2 in Ubuntu18. Several changes are made, including the update from PyQT4 to PyQT5. This is the very beginning of my code: from qgis.core import ...
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26 views

Reduce or heighten a DTM with overlaying polygons

I am using QGIS 3.01. I have a DTM over a historic area. There has been done archaeological surveys there, which suggest that the ground was several meteres below todays surface many hundred years ...
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189 views

QGIS 3 - load point layer from Geopackage doesn't render points

I am trying to load a point layer in QGIS (3.0.2) using DB Manager. I have a non-spatial table, which I imported to the Geopackage from CSV (and needed to implement the .csvt approach to import the ...
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80 views

Read the band value and Write the band value in Raster(.tif) using QGIS python

I have written a plugin in QGIS 3 to read the band value of a pixel or from a textbox and update the value to the selected pixels. When I'm updating a single pixel or smaller group, the script is ...
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49 views

Displaying rasters in a folder | QGIS 3.0.3

I have a satellite image. And in the folder where this picture is stored, it is well displayed. But when I divide it with the help of script into parts and save in a separate folder, then get such a ...
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117 views

loading satellite image in qgis3

Hi I had loaded a satellite imagery in PostgreSql using command "raster2pgsql -s 4326 -I -C -M E:\20Mar\55M1_Geo.tif -F -t 100x100 public.55M1_Geo | psql -d rasterdata -p 5437 -U postgres" and ...
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281 views

Self-Contact Topology Errors?

I've been trying to clean up some vector data sets so that I can reproject them to WGS84 but I keep finding topological errors that fail the process. The one error I can't resolve involves a node on a ...
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63 views

Mangled table names and choice of geometry when there are multiple geometry columns

I have a PostGIS (2.4) table tt with multiple geometry columns, geom, geom1, geom2. When loaded into QGIS (3.0.1), the table is displayed with the table name plus a geometry column name, such as tt....
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264 views

how do I enter start point in shortest path algorithm in QGIS 3.0.1?

Are the x and y values displayed by the Vertex Editor (bottom left of image) not the same as the x and y values in my TestNetwork layer required by the Shortest path algorithm?
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137 views

QGIS crash: delete column in GeoPackage

QGIS crashes without error or log massage as soon I try to delete a column in a GeoPackage using the attribute table: How could I find out, what's going on in background of QGIS? Installed QGIS3 on ...
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1answer
39 views

Attribute table of GPKG layer does not allow to edit

I created a GPKG layer whose name is Grid 1. In database, I wrote a trigger,because when attribute table of layer is changed, another table value should be changed also -They have common id's. ...
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59 views

apt-fast errors with installing qgis3?

I am using apt-fast to install and upgrade QGIS-3 (2.99) under Ubuntu 16.04, which is a much faster method than the default apt-get. This works well until recently. I begin to get errors about SSL/TLS ...
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1answer
95 views

QGIS one to many join issue

I already asked in previous question QGIS table join issue, how to join shape file data and CSV data which contain multiple SAME ID for one object? Shape file contains columns: object id, area, ...
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1answer
139 views

r.stats output parameter error

The "r.stats" tool gives "ERROR: r.stats: Sorry, is not a valid parameter" error and it creates empty file.