Questions tagged [qgis]
QGIS is a cross-platform GIS application licensed under the GNU General Public License.
25,398
questions
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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 ...
1
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0answers
33 views
Is there an equivalent to “Build Balanced Zones” from ArcGIS Pro in QGIS?
"Build Balances Zones" was introduced in ArcGIS Pro 2.4 and allows a kind of spatial clustering with the help of genetic growth algorithm:
The Build Balanced Zones tool uses a genetic algorithm to ...
3
votes
1answer
47 views
How to add a time component in a heatmap?
I have a point file extracted from an AIS network. 1 year is about 900 million points. Each point has a timestamp.
I want to make a heatmap for a longer period of time, but I want the heatmap to take ...
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0answers
20 views
Getting less calculated area after merging/dissolving polygons [closed]
After I merge/dissolve polygons together, the area I calculated using the field calculator seems to decrease, in comparison to the calculation of each individual area and then summing it up.
Can ...
2
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2answers
33 views
Create cumulative raster layer in QGIS
I need to create a new raster layer with cumulative values for 16 raster layers. For context, each raster layer represents an 'areas burnt' in a given year - essentially, I want a new layer that ...
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0answers
48 views
Login as another user in PostGIS using QGIS 2.18 without restart
I have a PostGIS DB with three roles: admin, user and readonly.
When I set up a connection to this database via "Add PostGIS layer" this connection is saved as it should be. So I login as admin to ...
1
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1answer
56 views
QGIS geometry generator for marker line
I'm drawing marker line with user defined geometry of the marker (see example on the picture). Markers are placed with interval of screen (not map) units. It's possible to do with svg-marker or font ...
1
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1answer
35 views
Create multiband raster from a single band raster with fields
I have a raster which has a single band containing what is effectively a lookup code. When I open the raster in ArcMap and open the attribute table I can see several fields which I guess come from the ...
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0answers
25 views
Removing addresses / points within certain distance of each other and have the most points remaining?
I have a data set of nearly 2000 points. I would like to find out which points remain and the most possible if no points can be within x kilometers of another point. So, if one point was randomly ...
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0answers
14 views
Giving a unique ID using rules for Streets based on its hierarchy starting from reference point and dispatching from it?
I have streets of my project city which is digitized randomly. I wanna give a unique ID for each street based in rules.
For example, I have a reference point let's say roundabout "001", those streets ...
1
vote
1answer
50 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 ...
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0answers
33 views
How to get a grid 500m x 500m on map composer
I need to make a map on map composer, with a grid layed on it which is 500m x 500m. however the only way I could find of doing this was by adding a grid to my map, found within item properties.
This ...
1
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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/...
0
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1answer
25 views
Delete duplicate label in GeoServer Style
I created complex label style in QGIS 3.8.1 and saved it to SLD file then uploaded it in GeoServer 2.15 as a new style, but I should add centroid function to avoid duplicate labels, I tried to add it ...
4
votes
1answer
59 views
Change drawing order in QGIS?
I have two layers (street name and address numbers). I try to sort layers where street names covers the address numbers. Unfortunately I cannot success because address numbers will always covers ...
0
votes
1answer
27 views
Error Installing sample datasets with QGIS 3.4
Recently tried installing QGIS 3.4 on Windows 10 and somehow it always throws error while trying to install the sample training data sets.
While QGIS itself installed without issues, the data sets ...
0
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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?
1
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1answer
40 views
Problems with dissolving layers [QGiS 3.4.1]
I am currently working on a set of data that defines restricted areas for use of photovoltaic modules.
This set of data amounts to 270.00 polygons in total [with their own geometry].
For simpler ...
1
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1answer
62 views
Using double offset in QGIS Expression String Builder?
I need to dynamically translate points 20 metres from their original point to a suitable cartographic position. I have a rotation value stored in a rotation attribute.
I cannot use this tool right ...
2
votes
1answer
53 views
Open .qgz files to edit file paths
I have hundreds of QGIS projects that have been built over years and many different QGIS versions. Now I need to move them to another server and I want to be able to edit the project files to show the ...
3
votes
1answer
47 views
Custom renderer crashes QGIS because “renderFeature” is called in a different thread
I am trying to implement a custom renderer with Python in QGIS. I have put together a small toy example based on the code from the Creating Custom Renderers section of the PyQGIS Cookbook.
To get ...
3
votes
1answer
58 views
Adding CSV file with lat/long to map in different CRS in QGIS
I'm very new to QGIS, so I'm sure the solution to this is common sense.
I have a map in the WGS 84 zone 58S CRS and am trying to add lat/long coordinates from a text file to it. The issue: the WGS 84 ...
2
votes
0answers
33 views
Calculating lacunae of MCP to calculate home range?
I'm using QGIS 2.18.26 and I am trying to calculate the home range of howler monkeys I was tracking. Using the AniMove plug in I have managed to produce Minimum Convex Polygons (MCPs). However, I ...
1
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1answer
56 views
Adding Vector File Server Layer In QGIS w Plugin?
I'm using QGIS 3.8 and trying to connect to the following vector tile server layer using the latest version of the vector tile reader plugin: https://www.arcgis.com/home/item.html?id=...
1
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1answer
42 views
Coordinate system confusion in QGIS 3
I'm using QGIS 3.4 to consult the Italian cadraste maps, using the Government's WMS service available here: https://wms.cartografia.agenziaentrate.gov.it/inspire/wms/ows01.php
As the technical ...
2
votes
2answers
46 views
Summing Area of polygons within vector layer within zone using QGIS?
I have one vector layer with multiple polygons (purple). I also have a number of other vector layers which are catchment zones (I also have a layer where these catchments are merged).
Is there any ...
1
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1answer
67 views
Buffering in WGS 84 / Pseudo-Mercator 3857 using QGIS?
I have read all the buffer issues topics but haven't found solution to my problem.
I have two layers:
Border layer of Tokyo ward - WGS 84 / Pseudo-Mercator 3857
A CSV text layer with x,y ...
1
vote
1answer
60 views
Use points to clip a polygon
I have a slight issue I just cannot solve. I use QGIS 3.6
I have multiple layers:
layer with multiple points with milage numbers;
a layer containing one or more polygons (let's call them ...
-1
votes
1answer
54 views
Import ArcGIS Esri_style to QGIS [closed]
I want to add esri_styles (ArcGIS) to QGIS. I went through the web but I haven't found any solutions yet.
2
votes
0answers
27 views
Making a delimited text file for my data in QGIS?
I am using QGIS 2.8 and I want to make a mesh file for dam break simulation. I am following a tutorial of BASEmesh for it. BASEmesh is QGIS plugin. My data is in form of dam dimensions, geometry and ...
0
votes
0answers
37 views
QGIS Rule-Based styles fail to render
I'm working with some Ordnance Survey data, specifically the VectorMap Local (in GML format, October 2018) set and attempting to style the layers using the very handy OS provided stylesheets (here: OS ...
0
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0answers
25 views
Pyqgis import non-spatial CSV to Qgs project
I'm trying to upload a .csv file to my QGIS project via Pyqgis. According to the following thread Using non-spatial CSV with PyQGIS it should work that way:
uri = 'file///C:/Users/denni/Desktop/test....
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0answers
22 views
Making clickable hyperlink from URL with QT Creator for QGIS custom forms?
I am creating custom forms for QGIS with QT Creator.
I want to know how to make a clickable hyperlink from an URL.
It is said that QT Creator can handle them directly in a QLabel if the "...
1
vote
1answer
47 views
Locating features along route in QGIS?
I have a polyline and points layer. The points lie on both sides of the polyline at some distance. I want to calculate the minimum distance between all the individual points and the polyline.
I can ...
2
votes
0answers
36 views
Include only selection of a layer in a QGIS aggregate formula in field calculator
The following collects the chainage along a road at the start of a segment.
aggregate(layer:='DSC_Roads_10m_Chainage.tab', aggregate:='max', expression:="distance",
filter:= intersects(...
1
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0answers
25 views
Calculating percentage/fraction of thematic pixels with coarser resampled pixels in QGIS/GRASS
I am using QGIS 3.4.9 on Mac OS10.13.6.
How can I edit raster data type to change it from thematic to continuous/quantitative?
details:
I am trying to calculate the fractional (percentage) ...
0
votes
0answers
30 views
Rasterize Vector (polygon) ERROR 1: Wrong value for -outsize parameter [closed]
I intend to rasterize a vector polygon [a land cover shapefile] to a grid [ in GeoTIFF format] through the QGIS3.8 version. It is really important to get a cell size [pixel] of 0.0008333333. As shown ...
-1
votes
1answer
33 views
Extracting data from ASCII file? [closed]
I have ASCII files for a country that map altitude. I'd like to extract information on slopes for specific cities in my country. My goal is to have at least a rough idea of physical constraints in ...
2
votes
1answer
40 views
Circle around all points of a layer
I want to draw a single circle which includes all points in a layer, but is as small as possible (so the two outermost points are exactly at the line). Is there any way to do this in QGIS (3.4) or ...
1
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0answers
45 views
Solved - QGIS Measurement
Solved.
In QGIS I turned off CRS. It then read the data of the image correctly.
I have brought a tiff photo of a side of a building into qGIS. It is about 300 images that were put together in ...
0
votes
0answers
20 views
Export layers in QGIS to one shapefile [duplicate]
I have a group of shapefiles already loaded into QGIS.
How do I export them to a .shp, .dpf, and .shx file that I can put into a folder and load onto another instance of QGIS?
1
vote
1answer
19 views
SVM object based classification QGIS with Orfeo Toolbox. Model outputs incorrect/ invalid
I am trying to run an SVM object based classification on QGIS with Orfeo Toolbox. I have 5x Spectral Tif images of bands; blue,Green, red, Infra-red and Rededge, these were generated from a UAV survey ...
2
votes
1answer
37 views
Control scale dependent visibility of symbols created using geometry generator in QGIS
I am using QGIS v3.2 "Bonn".
I currently have symbols that have labels and call-out lines created using the geometry generator. I can make the labels follow scale dependent visibility rules, and ...
1
vote
1answer
46 views
Labeling features in a given order within QGIS?
I want to sort the address numbers where would show only the bigger number and smaller value should be suppressed away.
I have used earlier ORDER BY -method when using PostGIS but now it isn't ...
0
votes
1answer
29 views
Using QGIS to create a GeoTIFF raster of Google Earth import
I've managed to link QGIS3 to Google Earth via XYZ tiles. I would like to convert the Google Earth map shown to a GeoTIFF raster (to save on memory?). I try and export the Google Earth layer to a ...
3
votes
0answers
56 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 ...
1
vote
2answers
47 views
Sum attribute from overlapping polygon
I have a number of bus stops (green points) and a layer of population data (square polygons) containing information on the number of households.
I want to know how many households are within the ...
2
votes
2answers
112 views
Get latitude and longitude differences by clicking in two locations on the map
Is it possible in QGIS 3.x to click in two places on the map and to get back the X and Y distances between these two locations (latitude and longitude differences).
I was hoping there is a plugin ...
1
vote
1answer
42 views
ERROR: Could not find a version that satisfies the requirement qgis
I want to use the RQGIS
library(RQGIS)
# set the environment, i.e. specify all the paths necessary to run QGIS from
# within R
set_env()
Trying to find QGIS LTR in C:/OSGEO4~1
$`root`
[1] "C:/...
2
votes
0answers
43 views
QGIS degrees - meters
I have point data in GDA2020. shapefile *.prj file says units are meters. when I load the data in QGIS the layer units are degrees nd the buffer tool is always degrees. I have searched for every ...
