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Questions tagged [qgis]

QGIS is a cross-platform GIS application licensed under the GNU General Public License.

5,682 questions with no upvoted or accepted answers
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1answer
66 views

Changing degrees to meters

I'm using QGIS 3.4.9. When I try to create a heatmap the only radius option is degrees. Can you tell me how to change this to meters?
3
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0answers
31 views

Changing Map Tip popup direction dynamically

Is there a way to dynamically (or semi-automatic) change direction of a popup? Default direction is 'right-down', which in some cases, where hovered feature is at the bottom of a canvas, Map Tip is ...
3
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0answers
40 views

Extracting the polygons from a multi-polygon shapefile where they intercept with points from a multipoint shapefile in QGIS

I have 2 shapefiles, one multi polygon shapefile (a) and and one multi-point shapefile (b). I would like to extract the polygons from (a) only where they contain points from (b). I can do this pretty ...
3
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0answers
43 views

Offset Expressions Dynamic QGIS - Unique non-repeating Numbers

I am trying to create a layer style that shows line features that share the same geometry, an exploded view for line Features. What I have done so far via the Offset expressions in QGIS 3.6 ("...
3
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0answers
64 views

No Vector Menu Available QGIS 3.4

I've installed QGIS 3.4 on my Mac. I don't have any vector or processing menu. In the "plugins" menu under settings, I have the following: "The settings on this tab are only applicable for Python ...
3
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0answers
105 views

Error using 'Clip raster by mask' in QGIS v3.8.2

I am attempting to clip a raster to a shapefile boundary (country boundary, 1 polygon) using the 'clip raster by mask' tool in QGIS v3.8.2. Both layers are in WGS84, so projection mismatch shouldn't ...
3
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0answers
37 views

QGIS Transforming from ETRS89 to WGS84 - why are Helmert parameters 0?

If ETRS89 (EPSG:4258) is tectonically fixed and WGS84 (EPSG:4326) isn't, the Helmert coefficients shouldn't be zero, right? In fact these parameters should diverge more and more with every new release ...
3
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0answers
34 views

Problem with QGIS GDAL Fill Nodata

I have been using the 'GDAL Fill Nodata' function in QGIS in order to rectify downloaded Landsat 7 images, having created a relevant mask. Whilst said function has been successful in resolving bands 1 ...
3
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0answers
26 views

Batch Processing and Raster Calculators in QGIS

As of right now I have two sets of raster files. The first and second set are of differing sizes. I am attempting to use set to clip the other, using the process outlined in this question here Clip ...
3
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0answers
81 views

Refreshing QGIS project after updating MS Access Database?

I already connected the MS Access DB to QGIS via ODBC. Moreover, I applied the tool "create point layer from table" and I got all points from the DB (longitude/latitude coordinates) on my map. And ...
3
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2answers
234 views

QGIS 3.8 not running GRASS

I am having trouble initializing the GRASS plugin.I've tried un-installing and re-installing QGIS already. But the following message keeps appearing. GRASS init error : GRASS was not found in '/usr/...
3
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0answers
56 views

Displaying QGIS's “Map Tips” in OpenLayers?

Still a little new to QGIS and Openlayers. How would you display QGIS's "Map Tips" into OpenLayers? I am currently using QGIS 2.18 and have the latest update in Openlayers. In QGIS, I have created a ...
3
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0answers
64 views

QGIS Value based arrows

Although i've seen some similar treads, I don't manage to quite solve my problem. I've added a delimited text layer that includes coordinates of 2 points. I want to make arrows between these points ...
3
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0answers
73 views

Get Isochrones for Public Transport in QGIS

I'm using QGIS and trying to get public transportation isochrones in Montreal for 20, 40, and 60 minutes. I was able to use the ORS plugin to do the same for cars, walking and cycling in the area. I ...
3
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0answers
76 views

Exporting to QField from QGIS?

In creating an export from QGIS 3.8.0 Zanzibar to Qfield using the sync plugin, I am encountering a strange error. Each time I run the export, several of the layers I have in a geopackage in QGIS ...
3
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0answers
65 views

Removing noise selectively from DEM using QGIS?

I am looking for a processing tool that can remove noise selectively from a DEM (Mostly SRTM). My current workflow includes "Fill sinks" and "r.neighbours". The problem is that the tool is blind to ...
3
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0answers
25 views

Can I save a batch process as a default within a project?

I have a clip batch process saved as 'project-abc-clip.json' and would like it to be the default batch process for clipping when I open 'project-abc' The batch is project specific so I don't need or ...
3
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0answers
59 views

PyQgis 3 - Add New Layer to Spatialite Database

For the most part, working with QGIS layers has been a pleasure, but I've run into some difficulties recently when trying to create a new vector layer in the SQLite database I've been using. I've ...
3
votes
2answers
96 views

Is there any way to reorder layers in GeoPackage and change the default naming in QGIS?

I have successfully saved several layers in one GeoPackage in QGIS 3.8. This is how it looks like in DB manager: I found out that the ordering of the layers is somehow strange when loading the GPKG ...
3
votes
1answer
73 views

Handling projections with QGIS?

I know this may sound like a silly question, and it is, but I've read lots of questions and tutorials, watched a few videos and still can't properly understand what I should do... I am trying to work ...
3
votes
0answers
98 views

“Clip Raster by Mask Layer” produces zero values (and not Nodata) outside mask boundaries

This is my first question here. I have a big raster of the world's nighttime lights and want to clip it down to the Adm0 of a country: In order to do so, in QGIS 2.18 what I do is using the Clipper ...
3
votes
1answer
127 views

Multi-thread processing in QGIS 3.8

I have an I7 quad-core processor in my laptop. I use QGIS 3.8 to do dissolve jobs on large polygonsets. The biggest set takes 131 minutes. If I look a the load monitor I see my system on a constant ...
3
votes
1answer
117 views

Merging many rasters with Python script within QGIS using GDAL?

I have many rasters that im trying to combine in order to produce contours. They are in the .bil format so I understand that i need to translate them using gdal first but none of my attempts have ...
3
votes
2answers
92 views

Symbol in layers panel not visible

I have a layer with symbology that includes geometry generators. It would appear that because of these the symbol is not visible in the layers panel. Is there a way to show the up most symbol (green ...
3
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0answers
42 views

Can QGIS remember the state of open tables?

Is there an option to choose while saving a QGIS project,to save the state of the table views and their location on the screen? I am on 3.6.3-Noosa
3
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0answers
145 views

Why do the Heat Map (QGIS) and Kernel density estimation (SAGA) tools provide different results?

The Heat Map tool (QGIS) and the Kernel Density Estimation tool (SAGA) provide different results for the same data as shown below. Why is this happening? Is one of them more conceptually correct? ...
3
votes
2answers
167 views

Automatically fill gaps and merge freshly generated polygons with the longest adjacent polygon

I get polylines automatically generated from AutoCAD from a colleague. Converting them into polygons with QGIS 3.6, I find out some sliver polygons and gaps in between, as shown in the picture below : ...
3
votes
0answers
78 views

Saved QGIS Project is empty!

I worked a complete night in a project involving a research of my group. When I tried to open it today, it's blank, there are no layers at all. As you can see in this link the thumbnail in the home ...
3
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0answers
91 views

Slow loading of QGIS project?

I have a number of standard projects set up for QGIS users. Some of them take more than 5 minutes to load. Things recently got much worse suddenly - and I want to track down why. Are there any ...
3
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0answers
60 views

Calculating number of different colored pixels in multiple polygons at once

I have a raster with 17 different colors. I need to find the count of pixels in each colour. I could use Zonal statistics for one polygon but I have to find the count in multiple polygons at once. How ...
3
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0answers
53 views

Lines length plugin - QgsVectorLayer error

Several similar questions have already been made, but none of the is helping me. I have a layer of polygons and I want to known the length of each line of each polygon. And based on the length I ...
3
votes
0answers
26 views

Suppress legend item scaling (layers panel QGIS)

Is it possible to suppress the legend item scaling in the layers panel of QGIS 3.4.x? I'ts a nice functionality, but confusing when using the magnifier > 100%
3
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0answers
79 views

How to import QGIS layer definition files without losing value relation settings?

QGIS allows groups of layers to be saved as a 'layer definition file'. Where one layer in that group references another - using a 'value relation' widget on its attribute form - these setting are ...
3
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0answers
57 views

How to chain multiple field calculators in QGIS Modeler with pointers on next or previous feature?

I have a Model that I use to filter a chain of points that have extracted values form a DEM (digital elevation model). I want to smoothen the hights with a filter that takes the average of the ...
3
votes
0answers
25 views

How to eliminate lines that are added when “join multiple line” plugin is used?

I'm new in QGIS. I have three road shapes. If I merge them, I cannot use "network analysis" (shortest path) because the merged lines are not continuous. I tried to use "Join Multiple Lines" and, ...
3
votes
0answers
48 views

Plugins that works with high resolution screens

I've written a plugin for QGIS (GeoDataFarm) and I've been using QT creator for all ui files of the plugin, which have worked fine for me. However, I just got an email from someone that tested my ...
3
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0answers
43 views

Using QGIS widget value-relation with PostgreSQL tables?

I am trying to implement types and subtypes to a layer of points that is stored in PostgreSQL and I wonder if it is possible to use Value Related Widget of QGIS, in PostgreSQL? I followed the ...
3
votes
0answers
112 views

EPSG:4326 being saved as CRS:84

I am trying to save a GeoJSON file in QGIS as EPSG:4326, but it keeps being saved as CRS84. EPSG:4326 and CRS84 are the same except CRS84 saves coordinates as long, lat - and EPSG:4326 saves them as ...
3
votes
0answers
116 views

Pyqgis 3: Trying to Update Attribute with Value but Getting Index out of Bounds

I'm able to successfully add attributes with an expression to my vector layer using: #Add fields to get evaulated based on an expression vectorLayer.addExpressionField("'R'", QgsField("rtype",...
3
votes
1answer
112 views

3-D Terrain effects for vectors in QGIS?

I'm a bit new to QGIS, and making a few maps of roads through mountains. I'm looking to have a 3-D effect within my 2-D map. I got a DEM, made a hillshade, and blended a basemap over it. Nice ...
3
votes
0answers
56 views

Adding source and target fields in attribute table

My issue is I want to export a CSV-file from QGIS 3.6.2 to Gephi (network analysis software) the layer I want to export is the edges layer for Gephi. However, when importing into Gephi I am missing ...
3
votes
0answers
175 views

Aggregate functions in QGIS using spatial intersection

I am trying to compute a virtual filed using aggregate functions in QGIS (3.6). I want to compute the average on a field in the child layer based on the spatial intersection with the parent layer. ...
3
votes
0answers
59 views

Create foldable section in QGIS tool using R script

I am developping a GUI tool in QGIS using an R script and I am wondering how to add this kind of foldable section in the graphical interface.
3
votes
0answers
143 views

Find / select / delete dangles in QGIS

Via Topologie Checker I'm able to find dangles, but there is no way to select them to edit or remove. Is there an other way to find and select?
3
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0answers
75 views

How to refresh cached join layer using PyQGIS

I have exactly the same problem like Kory Roberts in his unanswered post on osgeo.org: http://osgeo-org.1560.x6.nabble.com/Help-with-cached-join-layer-refresh-using-PyQGIS-td5352190.html This is the ...
3
votes
0answers
42 views

How to plot distances distances in meters in QGIS?

My goal is to plot circles on QGIS canvas by taking distances in kilometers from MySQL base. This is code I use: from PyQt4.QtCore import * from PyQt4.QtGui import * from qgis.core import * from qgis....
3
votes
1answer
70 views

Fixing self-connect polygon in QGIS 3.2

I'm trying to clip a soil map layer and am getting invalid geometry that affects my clip result. The problem appears to be a self-intersecting polygon. I've tried using the 'check geometries', and ...
3
votes
0answers
69 views

Displaying Legend for Variable Width Line in QGIS

I am using QGIS v3.4 to display a simple line as a line of varying width using the variable line width attribute facility of QGIS (please see screenshot below). The layer displays correctly within ...
3
votes
0answers
95 views

QGIS tile cache not working

I'm new to QGIS and work on an air-gapped system where I have access only to QGIS 2.14.9-Essen. I create a WMS layer, which "works" but performance is abysmal. So I enable caching (Settings > Network) ...
3
votes
1answer
320 views

Error : Could not load source layer for INPUT

Very simple piece of code. I'm trying to run this as a stand alone Python script, not in the console. Keeps giving the error "Could not load source layer for INPUT" , shape not found. But the os....