Questions tagged [qgis]
QGIS is a cross-platform GIS application licensed under the GNU General Public License.
28,969
questions
-1
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0answers
31 views
Raster values change after any kind of operation/calculation in ArcGIS, QGIS, R to -3.402823e+38 and new maximum [closed]
I have a single band raster file (.tif) with pixel values indicating the water depth (in meter) of a flooded area. The pixel size is 1m. My general objective is to extract these values for a given ...
0
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0answers
15 views
SCP Plugin for QGIS 3.10 on Mac
I'm using the semi-automatic classification (SCP) plugin in QGIS on a Mac OS Catalina 10.15.5. I've tried it in multiple versions and I'm having issues with saving files. Whenever I click the Run ...
0
votes
1answer
41 views
QGIS: Converting a QVariantlist from a GeoJSON to a List with some prefix removed
I have some problem seeming to converting a QVariantList from a GeoJSON file to a list in a new shapefile.
Every time I just do the expression "Column" and just put the type of data as List ...
0
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0answers
20 views
QGIS export 3d view / vector layers of 3d model to cad/blender friendly format
I am loading vector layers in .gml format that create 3d models on a map. I'd like to save that model out of those layer using either 3d rendered map or other method. Is it possible, and If so, how?
0
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2answers
59 views
Spell Check in QGIS [closed]
Does anyone know if QGIS is going to have an in-built spell check as standard in future versions? It is one complaint I get from staff is lack of a spell check.
If not has anyone successfully found a ...
3
votes
1answer
47 views
QGIS: How do I combine/summarize information from several attributes to one specific attribute?
I have a pretty specific question and I dont know how to approach this.
I have a polygon layer for subbasins in the Danube area (HydroShed) which also contains information for water discharge.
The ...
5
votes
0answers
109 views
Naming clipped layer according to the attributes of the mask layer in QGIS
I have calculated the dnbr for a fire season across a whole region, and I've clipped it using a mask.
The mask is a layer of ground survey plot locations because I want to find out the dnbr for each ...
-1
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0answers
24 views
Extract common area from raster layer in QGIS
I have raster layers of satellite images (4 bands R,G,B and NIR) in GeoTIFF format. These images have been taken by a single satellite and consequent images have a small area of overlap between them. ...
0
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0answers
13 views
Legend in map atlas anchored to bottom left or bottom right will not correctly reposition in PDF
I submitted this as a bug but I'd like to know if anyone here has experienced or has a solution.
In a map atlas, if I anchor a legend to either the bottom left of bottom right and if the legend is set ...
0
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0answers
18 views
Save a QGIS project as a “no-setup” package containing the project itself, all the layers loaded, and the layer styles?
In ArcMap, you can do this by saving it as a Map Package. When you open the package, the layers are loaded already and is styled the way you saved it. No setup nor finding of necessary files needed.
I'...
0
votes
1answer
56 views
Donut shape related to concentric circles in QGIS
I would like to get an area between 10 miles and 20 miles from the center of counties. To do that, I wrote the code and got the following image. But, as you can see, there are some empty points, as ...
0
votes
1answer
26 views
Has anybody else experienced having issues opening QGIS or .gqz project files on macs?
I have an old Macbook pro with QGIS 3.10 installed. I have not been able to open any QGIS projects I have saved because of this error -> There is no application set to open the document “test ...
0
votes
1answer
34 views
Documenting workflow and processing in QGIS-project
I want to include a documentation about the steps I undertook to create a QGIS-project to be able to understand how my data was prepared and processed, which steps I performed in QGIS. I'm not sure ...
1
vote
0answers
31 views
How is Topographic Position Index calculated?
My understanding of how topographic position index is calculated is:
TPI = cell value - (mean of cell values within defined neighborhood)
But, I see that Weiss' original poster (http://www.jennessent....
1
vote
0answers
28 views
TIN interpolation to construct DEM shows strange triangulation
I'm working with QGIS and I am trying to create a DEM starting from a DXF containing the grid of points located at 5m from each other. The following picture shows the points imported:
I used a TIN ...
1
vote
0answers
24 views
QGIS can output shapefiles larger than 2 GB [duplicate]
I have read that shapefiles are limited to 2 GB, yet I have found that QGIS can go beyond that limit. In this case, I was generating contours from DEMs. The output would have been greater than 2 GB, ...
0
votes
1answer
33 views
QGIS: Turning a string into “relative” hyperlink
I have a few columns in my shapefile that to refer to certain folders and files (PDF, JPG etc.). Because these are intresting in a form for each object, so that people can open them. I want to make a &...
0
votes
1answer
32 views
Trouble importing coordinates
I'm having trouble importing coordinates. I have a map over Scandinavia, and I need to import sampling coordinates that I've downloaded. The CRS I'm using is SWEREF99 TM EPSG:3006, and the format I'm ...
0
votes
1answer
51 views
Disconnect editingStarted in PyQGIS
I am creating a Plugin, where on addFeature button, first user will get a dialog box to select the type of feature user wants to draw. On the basis of users choice, other editing constraints will get ...
0
votes
0answers
20 views
How to integrate a Python Script into Processing Modeler in QGIS
I have a model in QGIS and I've generated a Python Script to calculate the matching between two strings (Levenshtein Distance with the FuzzyWuzzy Package) for one of the OUTPUTS.
#####################...
1
vote
0answers
22 views
Joining attributes between layers based on proximity of features [duplicate]
In QGIS 3.12 I have a Layer Y that has a specific attribute and my objective is to fill this attribute with information from Layer X regarding the proximity between the features of Layer X and Layer Y....
0
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0answers
53 views
Enable QGIS Core Plugin with Python Code
Kind of a follow on from this related question:
Installing QGIS Plugin with Python code
Within QGIS, how using Python can I list the keys of the core plugins and enable/disable them?
When listing the ...
-2
votes
0answers
27 views
Merge polygons to fixed number of equal attribute size [closed]
I have polygons containing data of 60 parishes. I would like to merge these 60 polygons into larger ones according to the number of people. The overall population is 35 916. I would like join ...
3
votes
3answers
69 views
Creating inset of the polygon
How to create inset of a polygon?
Not just visually but as a new polygon. For example - I have yellow polygon and need to create green one:
Looking for solution in QGIS.
0
votes
1answer
36 views
How do I get the layer from a featureSource within a QGIS plugin?
I'm writing a QGIS processing toolbox plugin 3.14 and need to modify its features:
So am doing something like this:
source = self.parameterAsSource(parameters, 'LAYER', context)
features = source....
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votes
0answers
26 views
Weighted Voronoi polygons in QGIS
I want to build weighted Voronoi polygons in QGIS, as in How to draw weighted voronoi polygons (thiessen) from points in QGIS?? but the aforementioned answer and code (https://github.com/HichamZouarhi/...
2
votes
0answers
29 views
Changing color symbol legend by field
I changed the color of the polygon symbology with a specified field. Now, I need to categorize the symbology for better data management and to be displayed on a map. But, this not change the legend ...
0
votes
0answers
39 views
module 'qgis.processing' has no attribute 'run' [duplicate]
I am using Python for my postgraduate studies and I am having
trouble running my code when I try to use processing in Qgis using the command-line interface.
I think the error is really easy to fix it ...
0
votes
0answers
32 views
Shapefile incompatibility between ArcGIS Online and QGIS 3.4 for a point feature layer
I created a hosted feature point layer ('Threatened Plant Locations') in an ArcGIS Online webmap, collected some data using Collector for GIS app on my iPad, synced data back to my ArcGIS Online ...
1
vote
1answer
26 views
Stop QGIS on Windows from recentering on single-click
I'm using QGIS on Windows 10. In Windows, the normal UI is that when you want to bring an application forward, you can click on it. And that tends to select what you clicked on, but single-click ...
0
votes
0answers
12 views
How to display contour labels within QGIS using Maptiler
How can I display contour labels within QGIS using the Maptiler plugin?
The contour elevation (height) displays 440m in the Identify Result pannel. Can the Layer Properties be reconfigured to display ...
0
votes
0answers
26 views
Exporting layer to GeoJSON the result is in the wrong coordinate system
I have a layer with MultiLineStringZM features that was imported in EPSG:4326 - WGS 84.
This I want to export to geojson in EPSG 25832 (UTM).
However even if I specify EPSG:25832 in the export it ...
1
vote
0answers
20 views
Save categories of graduated symbols, but not their values in QGIS 3
I have about 100 vector layers of different months and years showing EVI anomalies based on county boundaries in Germany. When I use graduated symbology (equal count, 5 classes) for each layer I get a ...
0
votes
1answer
36 views
Does anyone have had a similar problem regarding extracting contours?
I have been working on QGIS 3.10, I am using DEMs files that come originally from Lidar data, so they are large files with high resolution. I have been trying to create contours using the: Raster, ...
0
votes
0answers
16 views
Making KMZ file permanent
On QGIS I have my recorded trails saved as KMZ files and applied with the “Add vector layer”. I have edited these to corresponding colors etc. All have been saved, but when I exit and return a select ...
2
votes
1answer
32 views
How to easily toggle outlines and fills for polygon layers (in QGIS 3.x)?
So I want to be able to easily toggle outlines and fills for polygon layers in the Layers List.
I managed to make two rules (both with the rule 'true') and then they will show up in the Layers List:
...
2
votes
0answers
38 views
Distance buffer from point, with obstacles
In QGIS is there a tool or technique that would draw a fixed distance buffer from a point, taking into account obstacles in the buffer field?
I want to illustrate the maximum distance a ship can ...
5
votes
0answers
109 views
Determining which QGIS layer has a spatial index?
I would like to loop over all layers within a QGIS project and determine which layer don't have a spatial index and cause QGIS to slow down.
I tried the method hasSpatialIndex() but this always ...
0
votes
0answers
17 views
Modify an extracted Python code from the graphical modeler to save and open the output raster on QGIS 3
I used the graphical modeler to extract flow paths from a DTM, it works fine so I exported the model as Python code. However, I would like to save the output raster in a file and to open it on QGIS.
...
3
votes
0answers
42 views
Update virtual field on demand (not permanently) (QGIS)
I quite often use virtual fields. Some of them are relatively complex aggregates. Since virtual fields updates on every input, by moving the map, open the attribute table and so on, it can cost a lot ...
3
votes
1answer
56 views
Custom CRS for historic “site” grid
I have a set of historic drawings which show a local site grid. I'd like to setup a custom CRS for this grid in QGIS so i can convert layers to/from this grid and MGA94 Zone 56 (EPSG:28356).
...
0
votes
0answers
32 views
Calculate Percentage population from Vector Grids
I have a vector grids layer of population (shapefile). Each grid represents population in that grid and have the following attributes:
Area
Population
I want to calculate and display the percentages ...
0
votes
0answers
19 views
Orfeo Toolbox error
I'm using segmentation (mean-shift) tool in Orfeo Toolbox with QGIS
I used a subset of pansharpened image from Worldview3 after orthorectification.
But, I got same error whenever I tried:
2020-07-02 ...
0
votes
0answers
23 views
Exported QGIS 3.12.3 maps not wysiwyg [duplicate]
Hoping folks are tolerant of rank beginner questions.
I recently downloaded QGIS 3.12.3 running on a pc with windows 10.
I have my first project and map which looks good in print layout, but it looks ...
0
votes
0answers
31 views
Does QGIS have Generalization toolset like ArcGIS Desktop?
In ArcGIS Desktop there are Generalization tools like:
Merge Divided Roads
Collapse Road Detail
Resolve Road Conflicts
Does QGIS have this toolset or is it possible to run these algorithms on QGIS?
0
votes
1answer
26 views
Making categorized symbols mutually exclusive using PyQGIS
Hello, I am wondering if there is a way in PyQGIS to automate the process of selecting/deselecting the check marks for each categorized symbol in the included picture. I am writing a plugin and would ...
1
vote
2answers
29 views
QGIS add new field for each value in exisiting field on a vector layer
I have a vector layer containing around 17000 polygons with a field named 'theme'. Each polygon of the layer has one of 30 unique values (e.g. buildings, roads etc.) assigned to this field. I now want ...
2
votes
0answers
11 views
Is it possible to make “Project Bookmarks” the default when adding a bookmark in QGIS?
Whenever I add a new bookmark in QGIS (3.14), I have to change the Saved in dropdown from User bookmarks to Project bookmarks. Is it possible to make Project the default?
The User bookmark doesn't ...
1
vote
0answers
23 views
Strahler calculation ignoring large rivers
I have a DEM of a portion of the Yukon. I merged numerous DEM rasters then selected a subset for my AOI. I filled the sinks and then calculated the Strahler, but it seems to be ignoring large streams ...
1
vote
1answer
31 views
QGIS 3: How to count the mean of shapefile attributes that lie in a specific area
so I have a shapefile with buildings and the shapefile has the height of the buildings in the attribute table. I have a second shapefile with the districts the buildings are located in. Now I would ...
