Questions tagged [qgis]

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

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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
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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 ...
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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?
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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
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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 ...
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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 ...
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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....
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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 ...
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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
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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 ...
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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....
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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 ...
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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 (...
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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 ...
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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). ...
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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
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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 ...
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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 ...
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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 ...
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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. ...
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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 ...
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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, ...
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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 ...
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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 ...
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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
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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
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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
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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 ...
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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 ...
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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 ...
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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
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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....
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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 ...
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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
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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
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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
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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 ....
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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" ...