Questions tagged [qgis-3]
for questions specific to the 3.x series of QGIS.
1,765
questions
0
votes
0answers
19 views
Additional No Data Value Raster Pyqgis 3
I would like to improve way to adjust histogram of Sentinel 2 images in Qgis 3. I am using pyqgis to do the first task to it (create histogram rightly). So I have images that 0 is a no data value. To ...
2
votes
1answer
43 views
Copying and pasting features using PyQGIS?
I have created a table join between two shapefiles which I've named 'OSMM' and 'Mastermap'. I want to copy and paste all features (polygons) without a match from the target layer (Mastermap) into the ...
2
votes
1answer
12 views
Dynamic oriented grid using QGIS 3 layout view (grid borders parallel to paper borders)
I use QGIS 3 to create maps with coordinate grid. Often, when I change the extent of a map, my coordinate grid tilts and becomes not parallel with the paper borders. This looks very awful, and I have ...
1
vote
0answers
18 views
QGIS dissolve/merge features by all attributes
I have a vector layer with thousands of features and over ten columns (attributes). I would like to dissolve/merge features with identical attribute combinations and keep the attributes. I think it ...
1
vote
0answers
36 views
Loading multiple CSV in QGIS? [on hold]
I tried to use the same coding from Loading Multiple CSV Files into QGIS 2.10 to load multiples CSV in QGIS but in QGIS 3.6 and it does not work. The code provided in the above link was used and the ...
2
votes
1answer
34 views
Reading label positions from attribute fields with Python in QGIS 3?
I'm trying to label a shapefile with coordinates from attribute table with pyqgis.
I've been messing around with labeling shapefiles with python, I can do most things that I need, but the main ...
0
votes
0answers
9 views
GDAL Rasterize (Vector to Raster) not working with any extent
I am attempting to rasterize a road layer and neither the GRASS nor GDAL routines for this are working in QGIS 3.8.2.
All of my data is in UTM.
Here is my input (GDAL):
{ 'BURN' : 0, 'DATA_TYPE' : ...
0
votes
0answers
23 views
ST_Intersects and PostgreSQL geometry problems
I updated PostgreSQL to version 11.5 and some strange things are happening. I added some layers from QGIS into a PostgreSQL database, with PostGIS enabled.
Here is what one layer looks like in QGIS. ...
2
votes
0answers
25 views
Split selected feature with selected line from another layer in QGIS LTR 3.4.9
Can't seem to find that tool since I switched from QGIS 2.14 to 3.4.9
It doesn't seem to be included in the Advance Digitizing Toolbar like before.For now, I re-installed 2.14 since I need to use this ...
1
vote
0answers
29 views
QgsVectorLayer.IsValid() always returns False?
I'm writing a standalone Python script which involves some geoprocessing using qgis libs. Unfortunetely, I couldn't manage to properly instantiate a vector layer - every time i run .isValid() on ...
1
vote
2answers
31 views
Exporting layout in .pdf A3 size using PyQGIS?
I am using PyQGIS with GGIS 3.
I'd like to export my map in a A3 size .pdf (so that my printer prints it directely in A3).
How do I do that?
I did not find the right settings for exporting the ...
0
votes
0answers
26 views
Generating a building vector layer from aerial photography, DEM or point cloud? [on hold]
I'm assessing a ~200km long, 1km wide, corridor of mixed land uses (agriculture, conservation land and suburban) as part of a preliminary environmental assessment. I have aerial photography and ...
2
votes
1answer
33 views
Load layer From Oracle using QgsDataSourceUri in QGIS3 always return Invalid Layer
I'm tring to load spatial layer from Oracle but when i called function QgsVectorLayer(uri.uri(), "LAYER" , 'oracle') it still inValid layer
This is my code
> def LoadFromOracle(tablename):
> ...
0
votes
0answers
9 views
“Driver not loaded Driver not loaded” when trying to connect to MSSQL database in QGIS 3.8 on MacOS
When trying to create a new MSSQL Connection, I get an error saying: Error opening connection: Driver not loaded Driver not loaded.
I have tried both QGIS 3.8.0 and the newest pre-compiled QGIS 3.8.1 ...
1
vote
0answers
41 views
Stop QGIS opening multiple taskbar items?
I have QGIS pinned to my taskbar, right clicking shows that it's named "QGIS Desktop 3.8.2". When I run it and open projects some of them open a new taskbar item called "QGIS 3". This also happens ...
1
vote
1answer
20 views
Assigning points to all bends on polyline in QGIS 3.6
I have a series of polylines representing water pipelines that I want to clean up. I want to split the pipeline polyline at key locations where there is a fitting such as a stop valve or hydrant.
...
1
vote
1answer
24 views
PyQGIS: Importing own modules results in ModuleNotFoundError or KeyError
I've installed QGis 3 on Mac using osgeo4mac and wrote a script in the Processing Script Editor. The script works fine but when I try to divide it into several modules, I get an error when importing ...
1
vote
2answers
33 views
PYQGIS 3: Change layout scalebar item to a round scale (e.g. 1:5000)
I'm loading a layout template to a .qgs project and would like to set up the scale bar so that it has a round numeric scale (e.g. 1:5'000, or 1:25'000 but not 1:12'500). How do I do that?
Here is my ...
2
votes
2answers
119 views
Filtering multiple fields in QGIS 3
I am working with QGIS 3.8.1 Zanzibar.
I have a layer with Offshore Licenses holders. The attribute table has separate fields for "Participant 1", "Participant 2", ..., "Participant 13".
I'd like to ...
0
votes
0answers
16 views
Collecting metadata using Google Forms and converting to xml? [duplicate]
Background
Currently i'm working on a project that aims to standardize some data from several sources. It's my first "semi-professional" job on the GIS world (a summer internship, kind of), and i only ...
3
votes
1answer
46 views
Nearest line to polygon based on equal attribute
I have a polygon shapefile and a line shapefile with several thousand features each. I want to get:
The nearest distance between a polygon and a line that have the same attribute (e.g. ID). Example ...
0
votes
0answers
37 views
QGIS 3.8 labels placement
On my layer the setting of the labels is:
But all the labels do not appear, as if there was a limit on the number.
Sample with some features
Sample with all features:
some labels have disappeared ...
2
votes
1answer
34 views
3D View is not available in QGIS 3.4
I'm running QGIS 3.4 Madeira on Linux Mint 17. The upgrade to 3.4 seemed to go smoothly, but there is no "3D View" option in my "View" menu.
Is there something else I need to do? FWIW QGIS 3 J's ...
2
votes
1answer
39 views
Quickly change my current location in the QGIS 3 browser
I use Windows Explorer to manage the contents of the folder, and the fastest way to change my current folder in different applications is to copy the folder path and paste it into the browser tab of ...
1
vote
0answers
14 views
MapProxy : possible config issue?
I created a yaml config file and ran it with mapproxy-util serve-develop my-config.yaml
The file contains this:
services:
demo:
tms:
kml:
wmts:
capabilities: http://localhost:8080/wmts/1....
0
votes
0answers
41 views
Getting complex CAD drawing to right location in QGIS?
I have a complex CAD drawing from a city with many layers..hatches, points, poliylines..and I need it to georeference because when I import the DWG file into QGIS it turns out to be at the wrong place....
1
vote
0answers
13 views
QGIS 3.6.0 when shutting down hangs with 'Running checks' message [closed]
When I have used the Layout Manager to print several different layouts, then go to exit from QGIS (Windows 10), I get a message that the shutdown cannot complete because QGIS is 'Running Checks' and ...
2
votes
0answers
19 views
Clipping interpolation layer to a coastal boundary in QGIS 3.6?
I have created an interpolation layer and want to clip it so I don't see the area outside the coastal boundary. map showing area to be clipped:
1
vote
0answers
32 views
Plotting CDF of the values in a raster (.tif) file, using Python or QGIS?
I have a tiff file with some values and I want to read those values and plot a CDF (Cumulative Distribution Function). So far I only know how to get the mean value
from osgeo import gdal
gtif = gdal....
1
vote
0answers
18 views
Custom legend with concatenated fields on QGIS 3.8.1
I prepared a map with a custom legend on QGIS 3.8.1, combining a classification of several concatenated fields. However, when creating the layout compouser and including the legend, the descriptive ...
3
votes
2answers
86 views
QgsGeometry.length() giving wrong result?
I have a vector layer with Multilinestrings and used the field calculator to add a field ("length") with the calculated $length of each feature. I know the field values are correct. Now, if I ...
1
vote
1answer
32 views
Projecting as USA_Contiguous_Albers_Equal_Area_Conic_USGS in QGIS?
Is it possible to project EPSG: 6350 (NAD83 (2011)) as WKID: 102039 (USA_Contiguous_Albers_Equal_Area_Conic_USGS) in QGIS?
There is no EPSG code and I'm unsure how to create a custom CRS.
1
vote
1answer
79 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, ...
0
votes
1answer
29 views
How to create an editable personal copy of a read-only PostGIS layer in QGIS 3.4
I have a few vectory layers in a PostGIS database. I want to give the other users of the database read access to these layers. I don't want them to be able to alter them, though. Instead, if anybody ...
-1
votes
2answers
51 views
Getting position of point in PyQGIS?
How to get position of QgsPoint objects in pyqgis/ python console using QGIS 3.x?
For example:
1 points in vector layer TEST_P
migeometria = f.geometry()
posicion=geom.asPoint()
print(posicion.x()) ...
3
votes
0answers
36 views
QGIS 3.4.6 Cannot create fields in new shapefiles
Running 3.4.6 on Windows 10. Until today I have had no problems creating new shapefiles and fields. Now when I create a new shapefile everything in the new dialog box works as usual when I create ...
1
vote
1answer
24 views
PYQGIS 3: Save custom layout in .qgs project
I iteratively create .qgs projects, load different layers in them, create a layout and export the maps. The .qgs projects are created but when I open them, my custom layout is not there! Therefore it ...
2
votes
0answers
25 views
QGIS3 application not there after installing
I installed QGIS3 on my computer at work. The installation was completed without errors. But there is no QGIS application on the computer. The folder exists though, and it also contains all the other ...
0
votes
1answer
40 views
Getting maximum extent of 2 different layers for map display using PyQGIS?
In the QGIS 3 layout, I would like to display two layers and for this I need their combined maximum extent. So far I've got:
import os
import processing
from qgis.core import *
from qgis.gui import *
...
1
vote
0answers
44 views
QGIS 3 running slowly
I've been using QGIS 2.14 pretty successfully for about two years. I do also have Arc but tend to use Q more primarily because it did run considerably faster. I then installed QGIS 3 as I noticed it ...
1
vote
0answers
22 views
Generating MBTiles in QGIS3.4?
Similar to this question: Generating map tiles with QGIS 3.6?, how is it possible to create MBTiles from a raster ? (I operate QGIS 3.4 LRT)
I have tried Save As.... and selecting format: MBTILES, ...
2
votes
1answer
13 views
QGIS3 - Fast jump to another feature
I am looking for a method (plugin) to choose next feature of my vector layer really fast. I need to edit a lot of polygons and fast choosing next record is really necessary (using arrow or something ...
0
votes
0answers
30 views
Broken PostgreSQL layers?
I'm adding some layers from a PostgreSQL/PostGIS database. They worked fine yesterday, but today nothing is working and I really have no idea why.
Here is my process to connect to the database:
Now ...
0
votes
0answers
55 views
Using map themes in PyQGIS? [closed]
I have one big QGIS project including several vector and raster layers. I use map theme names to differentiate between different model variations and results.
For some reasons when I remove a layer ...
1
vote
1answer
26 views
How do I change style/colour of a few selected features?
We have features which represent the locations of pupils within the local area and would like to change the colour of these features to represent whether they reside within the catchment area of a ...
0
votes
0answers
21 views
Can't add layers to new PostgreSQL database
I made a new PostgreSQL database and am trying to add layers/tables to it in QGIS using the DBManager. And I am failing.
Here is the error message I'm getting:
However, I can add layers to other ...
1
vote
1answer
51 views
Convert decimal degrees to meters QGIS
I am working in QGIS 3.4.8-Madeira on MacOS 10.14. I simply want to create a buffer on a point shapefile, but the layer is not being read in UTM but in degrees. I understand this is a common question ...
1
vote
1answer
35 views
Run processing algorithm from CSV
I'm trying to run the following algorithm which runs fine when I select a layer I imported from the CSV file in question but not when I just try to run if from the file itself.
input = '/media/path/...
2
votes
1answer
69 views
Display two different maps with different layers in one layout in PyQGIS? Problem with .pdf export
I would like to export a .pdf with 2 maps (with different layers).
However, some layers do not appear in the map items!
I'd like:
In the first map: the shapefile over the raster 1, and these two ...
0
votes
0answers
14 views
Using Model Builder for QGIS? [duplicate]
I'm looking for a "model builder" for QGIS 3.2.1.
If that kind of tool exists, could someone share some related topic showing how to use it?
