Questions tagged [qgis]

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

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1answer
49 views

Is it possible to create a custom marker from a vector image?

I am relatively new to QGIS and I am working on an application based on PyQGIS. Right now, I am working on a kind of GPS which gets a set of points and returns the route between these points as a ...
2
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0answers
23 views

QGIS custom form : mixing Qt Widgets and QtQuick QML Widgets

On QGIS 3.16 I am trying to create a custom form with some Python logic for feature navigation and a QML widget to display nicely images. I embedded my QtQuick QML file in the custom form python file ...
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1answer
48 views

Corporate logo added to openlayer web mab created with Qgis2web

I have used the advice from a similar post: <body> <h1>Megacorp Industries</h1> <div id="map"> </div> This works to put in a title at the top but it ...
2
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1answer
30 views

Adding multiple features from GDB files using PyQGIS

I tried to add all features from a GDB with PyQGIS. layer = QgsVectorLayer(r"path.gdb") QgsProject.instance().addMapLayer(layer) This source code, only add one feature from GDB, but ...
2
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1answer
59 views

Merge overlapping polygons to elevation data

I'm new to GIS and need to create a shortest path avoiding buildings. The buildings are represented as polygons in a shapefile. In QGIS I created a buffer polygon for each building, corresponding the ...
2
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1answer
54 views

Compare two layers and find the percentage of the shared areas that are different between them

I have two shapefiles that identify flood zones for the same general area but in different years. The maps, however, do not cover exactly the same geographical areas (e.g., shapefile 1 covers counties ...
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0answers
25 views

I got two different number of items in a merged or dissolved layer

I'm using QGIS and I have the locations toxic waste sites in the U.S. on my map. I also have the weather warnings as a polygon on my map. I want the number and list of toxic waste sites in those ...
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0answers
19 views

Crop API Ordnance Survey map to working area size in QGIS

I'm new to QGIS. I have downloaded the Leisure 27700 Ordnance Survey map. But I want to crop it to just the area I am working on. How can I do this?
3
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1answer
38 views

Repeating labels even if I set to “No repeat” in Placement

In QGIS, I'm working on a map with the contours of a certain location. For the contour labels I used a fixed position with the "Label Toolbar". In the settings of the labels, in "...
3
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2answers
43 views

Making multiple points on single location all visible at once

I am having an issue with visibility of multiple symbols at the same location. The scenario is: I am an archaeologist, dealing with groups of objects all buried together at the same time ("hoards&...
4
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2answers
60 views

PyQGIS Output leads to invisible layers that don't appear in the layer panel or the canvas but can be accessed in Vector tools

I'm working on a Processing Tool in PyQGIS and am struggling with the problem described in the title. Layers are not visible in the "Layers Panel" or on the canvas but can be chosen and ...
2
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1answer
29 views

How do I change extent of shapefile into lat lon of NetCDF file?

I have loaded a shapefile and NetCDF into R, and I want to extract data based on the extent of the shapefile. I have done the following, but when I want to extract it I get NA's as the extent differs ...
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1answer
38 views

QGIS Reports: Create HTML table by iteration through every field in attribute table of layer

I have a QGIS project and I want to generate a report out of this. I am using the report-tool (https://docs.qgis.org/3.16/en/docs/user_manual/print_composer/create_reports.html) as it suits me better ...
5
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2answers
95 views

How to handle the “allow multiple selections” in “Value Relation Widget” results? (QGIS Form)

Using the "allow multiple selections" in "Value Relation Widget" results in {value1,value2,...}. But arrays in QGIS are written like ['value1','value2',...]. How do I handle the ...
6
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2answers
108 views

Rule based symbology rendering order with expression

I want to create a map of origins and destinations as a bubble map. As you can see on the above image (green: origins, red: destinations). I have applied rule based symbology with expression on ...
3
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0answers
37 views

Do not show the label if it is outside the map canvas #42990

I wrote on the Qgis forum, but they suggested to to write here too. I'm having this problem on Qgis 3.16.6 that in 3.10.8 there wasn't. https://github.com/qgis/QGIS/issues/42990 Can you give me a ...
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0answers
15 views

qgis2threejs viewer showing poor resolution

When I open qgis2threejs in preview mode the resolution of the preview is poor. It used to be very good and would render as you moved around eth preview screen.
5
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2answers
99 views

Computing concave hull from points using PostGIS and display in QGIS

I'd like to create a boundary of a set of point using ST_ConcaveHull function in PostGIS My query works fine and I can see the polygon through the geometry viewer embedded in the pgadmin. CREATE TABLE ...
2
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0answers
39 views

QGIS 3.18.2 Print Composer/Layout map legend vanishes/goes blank when layer/theme is changed

Using the print composer/layout in QGIS 3.18.2 I have the following problem ... Starting point: I had a print layout set up with a map and legend. The map layers were set by 4 themes. The layout used ...
2
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0answers
50 views

Using ctypes for QGIS Python plugin to bind DLL

I'm trying to build a Python plugin in QGIS which does some raster image processing. The processing itself is done via a .dll. Hence, I'd like to bind it with ctypes. First of all: is it possible to ...
1
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0answers
28 views

QGIS doesn't recognize BETA2007.gsb for Transformation from GK3 to UTM

I want to transform data from GK3 (EPSG:31467) to UTM(EPSG:25832) unsing the transformation grid BETA2007.gsb. BETA2007.gsb is already in the C:\Program Files\QGIS 3.10\share\proj directory. I ...
4
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1answer
105 views

Limit the number of features rendered in a map

I have a layer of village points and I want to limit the number of features rendered to a maximum of 50 points. I tried using Layer Properties > Labels > Rendering > Limit number of features ...
2
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1answer
42 views

Stacked bar chart in QGIS

I have seen several videos of being able to do stacked bars as diagrams to represent atrributes in QGIS (e.g. https://www.youtube.com/watch?v=Ras5y6TpECk&ab_channel=WiseGIS) However I do not see ...
3
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2answers
48 views

Visually differentiating raster pixels in area of same value QGIS

Given a discrete band, and say an area that for example all has the value 5, is there a way in which I can highlight or differentiate where pixels start and stop? This doesn't have to be some ...
7
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2answers
268 views

Making an ellipse based on an ellipse-like polygon in QGIS

I'm using QGIS. I have a layer that contains ellipse-like polygons as in the image. I need to convert them to ellipses. They come from a different data sources. These are all actually regular shapes ...
0
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1answer
32 views

Understanding Analyse > Slope function of QGIS

Playing around with QGIS I discovered the tool 'Analyse > Slope' and I wondered what it actually tells me. Is it an additional information to let's say contourlines, which already provide info on ...
5
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1answer
94 views

Disjoint is very slow in Virtual Layer but fast on symbology

In QGIS, take a polygon grid (named 'grid') and a multipolygon layer (named 'surfaces'). For each feature in surfaces, I want to union all features of the grid that are disjoint (not intersected) with....
2
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0answers
28 views

QGIS qgis2threejs color points and set radius expression

I use Terrain from Google Maps, then I have an import list from csv with earthquake location, depth and magnitude. As I'm not familiar with this tool I managed as much as I could with trying options ...
2
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1answer
30 views

How does QGIS calculate slope?

There are several ways to calculate slope in qgis using a DEM layer, but how does it actually work? My results show pixels with a slope of 40°+, this seems like a lot (in my DEM, one pixel is 25*25 m)....
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0answers
23 views

Slope calculated with QGIS vs slope in GoogleMaps

I want to calculate the average slope in percent of a vector line in QGIS. I have a DEM layer, converted it to a slope layer and then I use the plugin Profile Tool to calculate the slope of the line. ...
4
votes
1answer
57 views

QGIS - Python Action Error

I am using QGIS 3.18.1-Zürich and I am trying to create a Python action. Although I have installed the required packages, I get an error as shown below. Traceback (most recent call last):   File "...
4
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0answers
80 views

In QGIS my expression aggregation in attribute forms slow works

There are two layers: Parcels and Parking. In parking has attribute: parcels_objects, this is lists of parcels intersect of parking. When I create a parking object, I want to calculate all parcels ...
1
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0answers
14 views

Using QGIS Histogram & Bars for import as GeoJSON polygons

I am trying to visualize data as histograms in Mapbox. The way that QGIS displays the same data is perfect, but I can't figure out how to export a file that would render the same effect with ...
0
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0answers
7 views

RGB Alos AVNIR 2 composition shifted in QGIS

Recently I started messing with the alos avnir 2 images, as they are old images with 10m resolution. However, I had a problem, when I open the separate bands in QGIS I notice that they are well ...
1
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0answers
15 views

QGIS QFieldSync project cannot copy layers in config settings

In this one particular project which I tried to recreate from another project that will not sync with QField but just crashes QGIS. When I try to configure the project for QField packaging I only see ...
0
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0answers
36 views

QGIS cutting tile with shapefile [duplicate]

I already have a Sentinel-2 tile imported in QGIS and a shapefile corresponding to the area I want. How do I cut the Sentinel 2 file?
0
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0answers
13 views

Unable to import QGIS after setting PYTHONPATH and LD_LIBRARY_PATH on Mac

I've set my environment variables on Mac to: export PYTHONPATH="/Applications/Qgis.app/Contents/Resources/python" export LD_LIBRARY_PATH="/Applications/Qgis.app/Contents/Resources/lib&...
2
votes
0answers
30 views

Geometry Type error preventing saving of layer after editing - geometry type is correct under layer information

I have a problem with a linestring layer that doesn't want to be saved after editing. The layer itself shows 'LineString' under the information tab. When I add a line with the tool by snapping the ...
10
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3answers
266 views

Filling a field with a random string from a list in QGIS

I need to fill a field with false string data from a given list randomly. There are rand and randf functions generating random numbers. There is a similar (not identical) question: Updating attribute ...
4
votes
2answers
114 views

Clustering spatial data based on categorical attribute

For a project I'm doing, I want to cluster parcels together based on their specific land use category. As an example, a small part of the data looks like this. Spatial Data with different categories ...
0
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0answers
27 views

WFS layer load problem in QGIS 3.16

Using QGIS 3.16.6, adding WFS layers (names start with 'Base Map 2017:***') from open WFS server "https://moldova-map.md/geoserver/maps/wfs". Usually work at 1:1000 to 1:5000 scale. When WFS ...
1
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0answers
30 views

Cutting off polygon splinters in QGIS

There is an analysis about the potential of solar areas in Germany. When I finished the project I realised, that there is one polygon with a huge value for its area. By looking closer it gets clear ...
1
vote
1answer
36 views

Can I draw a new irregular polygon in QGIS 3.16?

I have a geotiff raster of Indonesian landsystems which I need to clip to the Papuan provinces in New Guinea. Unfortunately, I can't use a rectangular extent (as this would include some of the nearby ...
0
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0answers
16 views

2D and 3D in the 3DMap CityJSON

When I load CityJSON with the CityJSON plugin (QGIS 3.18) I also see the 2D ground in the 3DMap. Is that a setting in QGIS? I can set the 2D symbology to "No Symbols". But this way, I have ...
1
vote
1answer
44 views

How to smooth the DTM?

I had a point file of an area around 70 km^2 collected through field survey using Auto Level. The survey was carried out in the lines 25 m apart. I converted the readings from auto level into point ...
1
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0answers
35 views

Rendering PostGIS layers in QGIS

I am running QGIS Desktop 3.18.2 on Ubuntu, but I have observed this issue on other operating systems. When I query a relatively small table (~300 simple polygons) from PostGIS on a remote server, it ...
1
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0answers
16 views

Exporting results of supervised classification using Ecognition

I am trying to export the result of the classification. I set the parameters as below. However, when I open the shapefile in QGIS, there's no category called "class name". Thus, I can't ...
1
vote
1answer
37 views

How to load JSON with image link and extents into QGIS

One of the ways to get data from ArcGIS REST API in image format is this. https://services.twdb.texas.gov/arcgis/rest/services/Base/BaseLayerQueryService/MapServer/export?bbox=-11360770.018835%...
3
votes
1answer
44 views

Detecting cliffs higher than X meters from DEM

Using QGIS, and the 'Raster > Analysis > Slope' tool, I could easily detect cliffs from my DEM. I can identify all cliffs, and can color areas where slope is above a certain threshold. Since ...
0
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0answers
16 views

QGIS - Export raster layer to SVG with maximum detail

I'm trying to export the "Stamen Terrain labels" raster shapefile to an SVG. So I added it to a new QGIS project then I'm trying to use print composer to export the SVG. I want the entire ...