Questions tagged [qgis-3]

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

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65 views

Dissolve line intersection in QGIS 3.16

I have two lines I want to disole where the two lines intersect to become like this How to do that in QGIs 3.16? I digitizing two streets. And I modify the width of the lines.
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0answers
23 views

Creating vector gradiants showing magnitude and direction by taking input of two rasters in QGIS

I have two binary rasters and I am focusing on pixels having value 1. Now, I want to know show direction and intensity from which pixels (having value 1) of one raster is shifted other raster. ...
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35 views

Layer layername1 : OGR[3] error 1: REPACK of layer 'layername2' failed. Is there a fix?

Is there a chance to save my data as they disappeared? Geometry is gone, attribute table is empty. I duplicated layer so probably it is where the problem started. MacOs Catalina 10.15.7 QGIS3.10 I use ...
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0answers
18 views

QGIS Styles for MassGIS data

Is anyone aware of a source for QGIS Style Libraries which mimic the MassGIS base map on their Oliver mapping website? I've poked around MassGIS, Github, and a general Google search and haven't ...
5
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1answer
382 views

Candy Cane Style Symbology (Christmas)

I try to make a candy cane style for a line geometry with QGIS I used the hatching and line symbology but the hach are squared. Have you one better idea to do: a more smooth and rounded symbology the ...
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2answers
60 views

How to add BC-dates (age of a continent)

I want to simulate continental drifts using the time tool of QGIS (V. 3.16.0). Turns out I can only insert certain dates into my attribute table. I can't even type in the date 0000-01-01 without ...
3
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1answer
36 views

QGIS 3.4 Spatial Join error message interpretation

I had a problem when spatial joining two polygon layers. The error message says: " Feature (182) has invalid geometry. Please fix the geometry or change the Processing setting to the "Ignore ...
1
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1answer
45 views

QGIS 3: How to iterate in a QgsPrintLayer with pyQGIS

I'm looking for a way to iterate through items from a composer in QGIS 3, with pyQgis. First I create a QgsPrintLayout and add it to the layouts manager in my project. self.newLayout = ...
4
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1answer
90 views

How do I stop the identify results popup window in QGIS 3

I use the identify tool in QGIS3 a lot. When I click a feature it show the results in a identify panel and it gives a popup window that shows the results. I want to get rid of the popup window as it ...
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0answers
21 views

Bad module reference in GDAL — QGIS 3.10.1

Trying to use GDAL with QGIS 3.10.1, I encounter the following error: GDAL command: python3 -m gdal_polygonize contextualWMSLegend=0&crs=EPSG:4326&dpiMode=7&featureCount=10&format=...
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1answer
46 views

QgsExpression cannot get expected result when there is “\” in the string

I hope to use QgsFeatureRequest(QgsExpression) to get desired features. The statement in QgsExpression is: expr = QgsFeatureRequest(QgsExpression("\"planid\" in (48757) AND spi like '0\\...
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23 views

QGIS 3.12 Toolbox Vector Creation - Create points layer from table corrupting field data

I'm fairly new to this I have imported a table from Excel with coordinates and wanted to convert it to a points layer using the above tool. But it appears to corrupt fields that are real numbers for ...
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1answer
23 views

Using “Crtl + C” to copy an item from QTableWidget in QGIS, but get all attributes from a feature

I am using PyQGIS to develop a table as a QGIS 3.4 plugin. The table is created by QTableWidget and looks good. The weird thing is when I try to copy (Ctrl+C keyboard shortcut) an item in the table, ...
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0answers
28 views

Output layers order in QGIS Graphic Modeller (algorithm execution order / dependencies)

I created a simple model in QGIS graphic modeller that takes in input parameters like drive time ranges and start location and outputs 3 styled layers including "start_point", "...
1
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1answer
39 views

How to Access the Current Value of the Scale Factor of a Map as a Variable (eg $map_scale) in Print Layouts in QGIS

Does anybody know how to access the current value of the scale factor of a map as a variable (eg $map_scale) in print layouts in QGIS? I'd love to put the scale factor in my maps...
3
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1answer
40 views

Selecting a point and auto selecting a polygon in another layer in QGIS 3.14

I'm using QGIS 3.14 Pi and here's my scenario. I have a layer of points and each points contain a numerical value code, let's say it's 123. There may be multiple points with the same code value. In ...
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0answers
35 views

Creating DXF from WFS Saves Slowly

I'm currently required to periodically pull cadastral lines from a WFS server and my current methodology is resulting in slow saves. I first query a very large layer within the WFS with a known ...
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2answers
45 views

Splitting feature into layers which are overlapped in same layer in QGIS

My script needs to select each feature in layer. While selecting features I found some of feature are overlapped. Feature can be selected but cannot highlight in map canvas. Is there any plugin or ...
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0answers
22 views

QGIS custom forms cache

I am using QGIS 3.14. I'm using an *.ui file for a custom form in the layer properties dialog and everything works fine. Once the form is open, i change the size of the form with the mouse from the ...
2
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1answer
88 views

Add scale bar to canvas using PyQGIS

Is it possible to get the decorator scale bar onto the map canvas inside a standalone PyQGIS application? It is possible to get a scale bar on the QGIS Desktop version by View -> Decorations -> ...
3
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2answers
115 views

Select polygons containing particular attributes from points layer

I have thousands of polygons (buffers) in a single layer and I have a points layer containing tree species. The tree species points shapefile has an attribute called Tree_Type. I need to select only ...
4
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1answer
80 views

Overwrite existing raster layer using PyQGIS

QgsVectorFileWriter allows you to overwrite an existing layer with your output, but I have not found a similar option with QgsRasterFileWriter. Here's my code that is writing a raster layer out to a ...
2
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1answer
45 views

Filtering out attributes fields of a vector layer using PyQGIS

I have a vector layer with 50 columns/fields. I have been trying to find a way of selecting 6 columns of particular interest (by name or index) and then creating a new layer from that selection, such ...
1
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0answers
32 views

Error while exporting data through Mappia Publisher in QGIS 3.14

I installed Mappia Publisher in QGIS 3.14 and try to share some data. It works until almost the end. It gives me a Python error. I do not know why. Also, it takes me almost two hours to run. Finished ...
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0answers
49 views

JPEG file wont open in QGIS 3.10 but does in QGIS 3.4

I recently made the upgrade to QIGS 3.10 from 3.4 and I am having trouble loading a JPEG image that previously worked fine in 3.4. In the georeference window when I try to open the raster I am given ...
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0answers
56 views

V.Clean is not giving output In QGIS 3.14 Pi

I was trying to clean by removing sliver lines between set of polygons in my KML file. But unfortunately I am getting following error: QGIS version: 3.14.15-Pi QGIS code revision: d5114d2cfa Qt ...
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0answers
26 views

Setting the 3d view function for a polygon layer

I am trying to create a 3d model of an archaeological site on QGIS. I had some contourlines, I made them polygons using the "polygonize" plugin and I categorized the polygons with a colour ...
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0answers
34 views

Importing CSV (downloaded from Google Drive) with polygonal geometry data, into QGIS

I formerly used Google Fusion Tables but due to the product downturn I had to bulk-download a backup copy of my data. Right now I have them all saved in CSV format. I have attribute columns in these ...
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0answers
27 views

Different scale for x and y in a QGIS map layout

I'm making some geological cross sections with the geoscience plugin. I have been able to do this and I can make a print layout where I have my cross section (which the plugin makes in x-y space where ...
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0answers
24 views

Moving the View during Temporal Animation in QGIS 3.14

I'm very excited about the native support for temporal elements in QGIS 3.14. I have enjoyed the detailed tutorial by developer Nyall Dawson here, which gives nice overview of its many possibilities. ...
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1answer
39 views

Detect yellow spots on an image [closed]

I have a big raster image (12 GB) and I would like to detect yellow stains on it. I did try the Zonal Statistics but it is almost impossible to find the right parameters in order to detect the stain. ...
2
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0answers
77 views

No transform available between EPSG:2100 and Unknown CRS

After upgrading from 3.04 to 3.10 my QGIS projects keep reporting "No transform available between EPSG:2100 and Unknown CRS" although the project settings dictate that EPSG:2100 should be ...
1
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2answers
184 views

Problems with loading Plugins (processing and other plugins)

I have the following python errors when starting the QGIS 3.14: 2020-10-21T09:21:57 CRITICAL Traceback (most recent call last): File "C:\OSGEO4~1\apps\Python37\lib\site-packages\osgeo\osr.py&...
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0answers
20 views

QGIS: spatialite error: no such function: st_functionname() in specific qgis project

From one day to another I can't import any queryresults that contain a spatialite function as layer from DB manager anymore despite the query concluding successfully in DB manager. select * from table ...
4
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1answer
110 views

Processing tool to invert/switch selection in Graphical Modeler

I want to switch/invert a selection in Graphical Modeler so I'm looking for a processing tool to do so. In ArcGIS, this can be done with "Select Layer By Attribute" with Selection type: ...
5
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1answer
149 views

QGIS Temporal Controller with raster data

Starting from QGIS 3.14 TimeManager is dead, long live the Temporal Controller! There are a lot of tutorials out there how "Temporal Controller" deals with vector layers, which looks nice. ...
3
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1answer
95 views

Converting list into field with PyQGIS

I am trying to convert a few lists into fields. I have no problem creating the fields. I just don't have any idea on how to fill them. if result: layer = self.dlg.comboLayerLine.currentData() ...
1
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1answer
28 views

Query Result message returns 0 rows but browser shows results

I am using the Layer filter tools in QGIS version 3.14.1 Pi. (Right Click on layer > Filter) The source data is a Mapinfo .tab-file on a Server. When I put in my filter query, "Field_name"...
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0answers
34 views

Using geography cast as geometry in QGIS No SRID in Airports table. Other table have geom and is 26986

I trying to add a layer into the map in QGIS. It will execute the SQL and show the answer but will not add it to the map. It states there a geometry error. I type cast geom::geography it should allow ...
1
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1answer
47 views

How to put QgsCheckableComboBox() into standby

I'm trying QgsCheckableComboBox() in my simple python script in QGIS. How to pause code execution while a comboBox-window is open (like a dialog box)? In my example, I want to ensure that the print() ...
1
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0answers
26 views

Refreshing VRT raster layer using PyQGIS

I'm working a lot with GDAL VRT raster layers in QGIS 3.14, often changing the file content while viewing the rasters in map canvas. When I zoom or refresh the canvas in QGIS 2.18, all modified VRT ...
5
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2answers
186 views

Align existing points along a line with even spacing

I have a number of existing points which are snapped to a line, however they are unevenly spaced along the line, like this: How do I align them so they are evenly spaced out along the line like this: ...
1
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2answers
52 views

Buffering river but it came out as circle

I'm buffering a river using QGIS 3. I am using 30 meters for my buffer. My problem is the buffers came out as a circle, not following the lines. This is what happens during my buffer
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0answers
22 views

QGIS 3.10 Layout Manager not printing Google Satellite background

I am trying to compose a layout with Google Satellite as background. I am trying to add such background both with XYZ tiles utility and with QuickMap Services plugin. In both cases the layer is ...
2
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1answer
51 views

No Plugins available in QGIS on Mac

I downloaded the 3.10 version of QGIS onto my Mac (version 10.15.6). There are no Plugins available in the programme. Do I have to download plugins from somewhere else? Also, in the Raster Menu, the ...
2
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1answer
36 views

CRS for Ellipsoid Measurements

I noticed within the "Project Properties" there's an option for, Measurements --> Ellipsoid. What should this setting be configured to? From what I read online, if this is set incorrectly,...
1
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1answer
45 views

Shortest path (point to point) when filling out coordinates in boxes

I am using the processing toolbox interface to launch the "Shortest path (point to point)" command to connect two points using a line network layer (see attached photo). If I fill out the ...
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0answers
13 views

Why is ArcGIS Feature Service layer incomplete once added to QGIS?

I'm running QGIS3 and I'm trying to a add property cadastre layer from a publicly hosted ArcGIS Feature Service connection. The connection works ok, but when I add the cadastre layer, not all polygons ...
5
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2answers
54 views

Map extent matching permanently main canvas extent

Refreshing the map extent on QGIS's composer requires to click on Set map extent to match main canvas extent I was wondering if there was a possibility to have a map extent (in the composer) that ...
0
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0answers
20 views

Vector Tiles: do the zoom levels depend on the projection?

For Mercator Projection I found a table of zoom levels and their corresponding scale. I suppose that the number of zoom levels and the corresponding scale change when using another projection for Map ...

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