Questions tagged [qgis]
QGIS is a cross-platform GIS application licensed under the GNU General Public License.
25,398
questions
0
votes
1answer
62 views
Thematic map made in QGIS [on hold]
I made a thematic map of carbon stock in Russian Federation in 2017 year.
I am not a cartographer and geographer at all.
Tell me please what should I do with this map to make it more professional?
...
3
votes
1answer
75 views
Calculating real length and slope of roads
I have collected points alongside road in form of csv files with z-values. When imported in QGIS I used Set Z value and Points to path to make line. When I use right button in Identify Features tool I ...
0
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0answers
27 views
Creating component Local Government Area from a State Boundary in QGIS [on hold]
I created a State boundary in QGIS but I want to extract the component local government Area out of it. Please I need someone to guide me on the steps to go about this?
1
vote
2answers
146 views
Error adding qgis.org repository public key to apt keyring
The old QGIS key ring qgis-2017.gpg.key is expired and generates a warning during apt update today.
Following the QGIS instructions, I tried to update the key as follows:
wget -O - https://qgis.org/...
2
votes
1answer
32 views
Converting Grayscale GeoTiff to PNG using QGIS results in all black image
I have a GeoTiff in QGIS that I created by merging some images inside QGIS.
It looks like this:
I use Raster>Conversion>Translate. And save it as a PNG.
I then open the image in both, Photoshop ...
1
vote
0answers
19 views
QGIS 3.4.10 for Mac users…Digitzing polygons
I have just installed the LTR version of QGIS (3.4.10) and am having trouble telling QGIS when I have finished a polygon. In fact, I can't.
It used to be in earlier versions that to end a polygon you ...
1
vote
1answer
21 views
QGIS failure in PostGIS connection: “ident authentication failed for user”
I am trying to use the 'ident' authentication of for local PostGIS (2.5) server, so that each user can connect to his/her account without having to provide password.
The local connection (to 127.0.0....
2
votes
1answer
35 views
Shapefile to polygon, then edit the polygon in order to use it as a mold
I am working on QGIS with a shapefile:
I transform it through Raster-> Conversion-> Polygonize
Then I eliminate some parts (Sea), and those that are bigger than one single square of grid but are ...
1
vote
2answers
61 views
Aligning an edge to match another edge
I'm new to QGIS and I wonder whether there is a tool that helps to adjust the edges between two or more polygons; similar to that topology tool that's used in ArcGIS.
http://desktop.arcgis.com/en/...
2
votes
1answer
40 views
Network service area mapping over open ground
Given a timestamped start location, a timestamped end location and a known average speed is there any way I can map everywhere someone (or something) could have possibly been between the two ...
1
vote
0answers
31 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
1answer
28 views
Where has the QGIS2threejs Icon gone?
I am trying to create 3D maps. I am using QGis2threejs. I know I can also create a 3D map using 'New 3D Map View', but I want to try QGis2threejs.
However I have two questions.
When I install the ...
1
vote
1answer
28 views
QGIS: Clip Raster by Mask Layer-permanently remove black edges
I want to introduce geotiff images generated in QGIS by clipping ortho imagery to a shapefile into matlab. However, the clipped raster images come with black borders. I managed to remove them in QGIS (...
1
vote
0answers
25 views
Resampling while drawing rasterfiles in QGIS 3?
I can not find a solution to resample my rasterfiles in QGIS 3. With Arcmap usually I use "resample while drawing" with the method cubic or bilinear interpolation for continuous data to smooth my ...
0
votes
1answer
31 views
Raster smoothing - assigning each raster the average value of its neighbors
I have a raster world map of population densities at a resolution of 30 arc seconds. For each raster, I want to find out the average density of neighbors within a certain distance (e.g. 0.1 degrees). ...
0
votes
1answer
21 views
qgis2threejs window is blank
I have used QGIS2threejs for several years in QGIS2. Now we have upgraded to QGIS3 at work and the plugin no longer works.
The qgis2threejs window is blank and it displays the error “Any 3D objects ...
2
votes
1answer
41 views
Making polygon shapefile from unsorted point shapefile?
I have a point Shapefile with unsorted feature ID's (FID). I want to convert the same point file into polygon Shapefile by using python gdal/ogr. I got the help from link1 and link2. I'm able to make ...
1
vote
1answer
20 views
Clipping a raster from quickmapservices or XYZ tiles
I'm trying to clip a google satellite XYZ tile over a layer mask of my DEM layer to make a 3D map.
the problem is that after making the connection and adding it as a layer to my project, im unable to ...
1
vote
1answer
27 views
PostGIS: ST_Azimuth between Points in same Table
I've seen the questions and answers about ST_Azimuth, but didn't find a specific example for this case:
I need to calculate the azimuth from point id 1 to id 2, id 2 to id 3, id 3 to id 4, ...
Table ...
2
votes
0answers
43 views
Saving what is inside a polygon coordinates as an image?
I am trying to get an image from inside a polygon.
TLDR;
What I am trying to do: save what's inside a polygon as an image.
What is happening now: I am only able to save the canvas as an image. ...
1
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0answers
24 views
Creating a tile layer for a polygon for use in QGIS Atlas?
I want to create a series of plans at a set scale that covers a large area defined by a polygon. The polygons are a buffer for a water network, so is very irregular with sections that are long and ...
1
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1answer
77 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
13 views
Automatically assigning bins for vector graduated classes within a given range (QGIS 3)
Is there a way to assign graduated bins automatically for vectors within a given range in QGIS3?
I am trying to produce a series of maps which share a same legend, but do not necessarily exhibit all ...
-1
votes
0answers
15 views
qGIS Embedded Layers Not Persistent [closed]
Documentation asserts "The Import button allows adding layers loaded in the map canvas into the Embedded layers list. This allows to later remove those layers from the Layers panel without breaking ...
1
vote
1answer
28 views
Difficulty with Scaled Visibility for Labels in QGIS 3.4.9
I am having great fun getting to grips with QGIS (fantastic). I have set myself a "project" to try to learn the techniques.
This project refers to 2 Layers (geographic areas for Telephone Exchanges ...
3
votes
1answer
36 views
Where is attribute form widget saved
When i create widgets for the attribute form in the properties of a layer:
Is this stored in the geopackage layer or in the QGIS project file?
3
votes
1answer
39 views
QGIS: Split with lines does not fully work
I'm using QGIS 3.8 and I've got two shape files which I would like to cut in pieces using Split with lines
Both times I used the algorithm the first two lines did not cut through my shapes, while the ...
1
vote
1answer
28 views
How to get the intersected region(s) of multiple polygon layers
I have multiple layers with polygons.
I want the regions that are intersected by all the polygons. The shared, common regions.
An example use case would be finding the shared area of multiple raster ...
1
vote
2answers
62 views
Tools for georeferencing PDF's [on hold]
5 years ago I exported all our PDF record drawings to TIFF and georeferenced them using Esri Arc Desktop. This added the .tfw file associated with georeferenced images without modifying the original ...
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
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0answers
14 views
Show QGIS layer definition (qlr) filename in my project not the source file it was created from
I have a QGIS project with multiple qlr (layer definition files) in it which all source the same original data but all have different styling, labeling and filters applied. But when I bring these qlr ...
0
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0answers
24 views
When re-saving a GeoJSON file to a shapefile, the .dbf significantly increases in size
When re-saving a GeoJSON file to a shapefile, the .dbf significantly increases in size to the point where the file size becomes unmanageable.
For example, I re-saved a 250 MB GeoJSON file to ...
1
vote
1answer
28 views
Extracting vector information from a .dwg file into a QGIS environment?
I have a few CAD files in the .dwg format and I am trying to extract the data into a QGIS environment. The CAD files have a large number of different layers that represent different types of assets eg....
0
votes
0answers
41 views
QGIS 3.4 Layout composer tool bars are too small to see
I'm at a loss. I just updated to QGIS 3.4, and it was working fine, but now my Layout window has only tiny tool bars and the move item content tool is non-existent. Can anyone help? The same thing ...
0
votes
0answers
23 views
Labeling contour lines through script [closed]
I've been working with QGIS I have a file with contour lines. I can easily label them through the UI but I can't seem to find a way to label them with a script/program. Is there any tool I can ...
2
votes
0answers
56 views
Running QGIS on GPU [on hold]
I have a QGIS application running on Linux and I added a heavy vector layer. Every user operation like zooming or panning, takes almost one minute. I installed NVIDIA graphics card but it didn't ...
1
vote
0answers
21 views
Pyqgis Set the field value of a dynamically created vector layer in QGIS 3 before user saves to database
I am quite new to both QGIS and Python.
I have inherited a project that needs to be upgraded from using QGIS 2.0 DUFOUR to 3.8 Zanzibar.
The way it works is, there is a separate application written ...
2
votes
2answers
58 views
Change path to help in QGIS 3.4.8 LTR
I want to use the offical help from qgis, which I can open with the F1 button.
But it doesn´t work. I always get this message:
I checked the Settings → Options →System, the path is right. And in the ....
1
vote
0answers
38 views
QGIS3.8 Hotspot Analysis Plugin not installing
I'm hoping someone on here might be able to help me. I'm fairly new to working with QGIS I'm completely lost. For my PhD project I have to use QGIS to produce georeferenced heatmaps based on ...
-1
votes
0answers
29 views
ESRI-GRID data or ASCII GRID data [closed]
I'm trying to make a poster with different climate projections for a river basin in Thailand. I would like to make a box & whisker plot for each month in 2030 (will repeat this for other years).
...
0
votes
0answers
42 views
Error when trying to run simple algorithms [QGIS 3.4.1] [closed]
I am trying to Cut two simple .shp files in QGis, both of which have a supposingly correct geometry, and are the simplest forms of polygon Layers. (Picture 1)
Both layers are also in the same ...
1
vote
0answers
35 views
Using Raster Dataset in QGIS?
I've been trying to convert all my ArcGis projects into QGIS 3.4.10.
I have a problem with my raster data sets. They're all .tiff data and have the right projection but they still won't fit to my ...
1
vote
1answer
29 views
Defining index for scattered polygons
I have 50m X 200m polygon which has several small polygons inside. I would like to define how scattered small polygons inside a big polygon. I was wondering if there is a tool which can calculate some ...
2
votes
1answer
45 views
Shifting a set of points and get new coordinates?
I have a transect that I've added as a delimited text layer that has UTM X and Y coordinates for about 300 points all within a river meander.
They currently do not line up with the channel shown in ...
0
votes
1answer
42 views
Creating random points from attribute field
In QGIS 3.6, I wanted to create different layers of random points reading different fields of an attribute table. For example:
City #cinemas #malls #stores
A 15 10 12
B ...
1
vote
1answer
37 views
QGIS: Joining data from multiple road lines onto polygons by location
I'm looking to add traffic data linked to a polyline shapefile of road centerlines to a multipolygon shapefile of land parcels. I want to join this data using proximity to roads instead of by matching ...
2
votes
1answer
29 views
Cutting/ exporting multiple terrain profiles to CSV files with QGIS?
I am trying to cut multiple terrain profiles and export them to CSVs (individual or combined).
I have a shapefile of the profile lines, and a DEM to cut the profiles from.
I can do this manually ...
-3
votes
0answers
44 views
QGIS Madeira: crash when export map [closed]
After install QGIS Madeira on a new Win10 PC, QGIS crashes when exporting a PNG file, the crashlog:
QGIS Info
QGIS Version: 3.4.10-Madeira
QGIS code revision: 3d97aaae88
Compiled against Qt: 5.11.2
...
2
votes
1answer
42 views
Setting a buffer around a road and visualizing it in QGIS
So i need to set a 30 meter Buffer around a road in a Layer and visualize it in QGIS. The road is split in 8 segments( don´t think it makes a difference).
Tried this code:
select a.ref, a.geom, ...
1
vote
0answers
31 views
Polygonize each object in layer individually (QGIS)
Running the polygonize algorithm from the processing toolbox doesn't seem to work if you have a layer with several line objects that you want to polygonize individually. Think two "polygons-to-be" ...
