Questions tagged [qgis]

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

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4
votes
0answers
45 views

QGIS Exporting Line Direction Symbol from Labels

I have set up certain labels to show the Line Direction using the Line Direction Symbol in Label Formatting, with default < and > symbols. It works great, but I now want to export these symbols ...
6
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1answer
65 views

How to use FactoQGIS for Typological Analysis Principal Components Analysis (PCA) for vector features in QGIS?

How to use FactoQGIS for Typological Analysis Principal Components Analysis (PCA) for vector features in QGIS? I have a shapefile of polygons as in the following image: Both visually and as ...
2
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0answers
39 views

QGIS statistical summary gives exponential value

I need the precise sum of areas for a polygon layer, where I have the area values in an attribute. When I use the Statistical Summary window it shows the sum in exponential notation: Statistic Value ...
2
votes
1answer
73 views

Problem exporting shp as CSV

I imported a shapefile into QGIS, made a copy of it, and edited that copy. My edits consisted in changes in the coordinates of a few points. I then exported this edited shapefile as a .csv. For peace ...
1
vote
1answer
48 views

TypeError : can't concat str to bytes

I'm actually using QGIS (3.10 a Coruña) on Mac OS Catalina and I'm having troubles with it. I'd like to use the function "r.reclass" but it doesn't run correctly. It says that there is an ...
1
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0answers
34 views

QGIS animation help ancestral records [closed]

I only have basic GIS skills and wanted some advice or direction. I'm only practising with a smaller dataset at the moment though my other files are much larger 10,000+ so don't know if it's possible ...
1
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0answers
44 views

Putting a point over pixels with highest DN values within grids in QGIS [duplicate]

I have a raster layer in greyscale, and a vector layer that is 3 x 3 m grid. One of the attributes within the grid cell layer is the value of the highest DN number within that grid cell. I just need ...
0
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1answer
76 views

How to draw centerlines of Oriented Minimum Bounding Box in the orientation closest to orientation of all polygons collectively in QGIS? [duplicate]

How to draw centerlines of Oriented Minimum Bounding Box in the orientation closest to overall orientation of all polygons collectively in the layer in QGIS? I have a shapefile of Oriented Minimum ...
4
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1answer
36 views

Creating polygons with “Create shapefile layer” always produce multipolygons instead of polygons when saving in QGIS

Not sure if is a bug or I'm missing something. Every time i'm creating a new shapefile with "Create shapefile layer" i got a multipolygon instead of a polygon (at least is what I'm expecting)...
6
votes
1answer
84 views

Placing point over pixel with maximum value falling in grid overlay using QGIS

I have a raster layer with a Shapefile grid with cells measuring 3 x 3 m overlaid on top. All I want to do is find the pixel with the maximum value within each cell, and place a Shapefile point over ...
3
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2answers
98 views

Get folder path to QGIS processing scripts from PyQGIS

Where is stored path to processing scripts folder in PyQGIS? Version of QGIS is 3.16. I want to get this path by Python script. I suppose then, is stored in processing object: from qgis import ...
5
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2answers
84 views

QNEAT3: Iso-Area as polygons problem

I am using the QNEAT plugin to calculate catchment are/travel reach over a street network. The network is valid and projected correctly. I have tried changing the cell size and topology tolerance ...
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0answers
35 views

How do I solve the problem of the processing plugin, because it marks it as broken? [duplicate]

I am new to using the QGIS program. The processing component tells me that it is broken and therefore does not let me activate a different options that belong to raster.
0
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0answers
38 views

Fixing problem with processing component

How can I fix the problem with the processing component? Since it appears to me that it is broken and I need to activate some functions of the Raster option. When I want to activate the processing ...
6
votes
2answers
60 views

Saving two shapefiles into one GeoJSON

I have 2 shapefiles in QGIS (one point layer and one Line layer as shown in Figure). I am trying to save these two layers in one GeoJSON. I have seen some of the previous answers such as answer [1] , ...
0
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0answers
37 views

QGIS Desktop 3.10.6 works fine when I use my laptop at the office but stops responding when using it at home

I'm stumped on why my QGIS performance is terrible when working from home but fine in the office. I am not using a vpn, all the files being used are on local hard drive, internet works fine at home, ...
0
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0answers
24 views

QGIS style changing

I want choose a properties of a layer and change it's style in QGIS (I have an extension for nautical symbols), but before loading files it's restricted. What I want to load is a huge amount of ...
0
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0answers
39 views

Adding point features by machine learning in QGIS 3.16

I've got several georeferenced traditional maps and there are circles on it. (these are the studied points) So I want to add point features to the middle of the circles. I could do it manually, but I ...
0
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1answer
24 views

Extract data from one shapefile based on another [closed]

I am using QGIS 3.16.1. I'm trying to find a way to have it tell me what the most common soil type is in a field boundary. I have downloaded the soil information from NRCS's web soil survey site and ...
0
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0answers
26 views

Mapping origins and destinations to the created isochrones

I created isochrones in QGIS with an interval of 30 minutes. I have some coordinates related to some origins and destinations as well as travel time from the origins to the destinations. I need to map ...
1
vote
1answer
45 views

How to Share a QGIS Project

I want to share my QGIS project to someone else who also uses QGIS, how would I do this? I am very new to QGIS and am not very tech savvy.
4
votes
1answer
120 views

Calculating dominant angle of a polygon in QGIS without main_angle function

How can I calculate dominant angle of a polygon in QGIS without main_angle function? I have a shapefile of Oriented Minimum Bounding Box rectangles (accessible from the following link: https://drive....
3
votes
1answer
48 views

QGIS 3.10.13 (64-bit) on a Asus laptop with Windows 10 is running EXTREMELY SLOW - looking for suggestions

I am using: QGIS 3.10.13 (64 Bit) My machine: OS: Windows 10 Home, version 20H2, OS build 19042.746 Installed RAM: 12.0 GB ( 11.9 GB usable) Processor: Intel(R) Core(TM) i7-8750H CPU @ 2.20GHz, 2201 ...
4
votes
1answer
41 views

Creating custom categorized symbology and coloring based on two fieldNames

I am developing a plugin in PyQGIS 3. Within this plugin, I want to change the symbology of a layer to categorized. I want to categorize based on the column Collecti_2 in PyQGIS 3. This step has been ...
1
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0answers
27 views

Construction mode multiple points

Is there a way to define multiple points to snap in the construction mode in advanced digitizing? Let's suppose I want the value -26- from point 3 to 4 but also want a value -31- from point 1 to 4. ...
0
votes
1answer
42 views

Completion in input form works on QGIS but not on QField [closed]

I created an attribute form for a shapefile layer. For one of the fields ("NAME") that I want to fill in, I have opted for an entry by relational value. I selected "the layer", the ...
2
votes
0answers
17 views

Getting accurate length for custom dash pattern in QGIS 3.4

I try to set a custom dash pattern for simple line using QGIS 3.4. Both my project and layer are in a projected CRS using meter as unit (EPSG:2154, layer are stored as Multilinestring in a geopackage)....
2
votes
1answer
24 views

Create a polygon to match non-white (or non-empty) part of a raster

I have a irregular raster with empty spaces as seen in the attached image, which is the southwest corner of my raster. I would like to create a polygon or a mask that matches the non-white regions of ...
3
votes
1answer
37 views

How to do a “many-to-one” join

I have used the distance matrix tool for a large point set (100 000+ points) to find three closest POI's from another layer and their distances. The distance matrix outputs a table much like this: ...
5
votes
2answers
53 views

Populate legend items with values from another layer

I'm using QGIS 3.10. I'm trying to label my map with values taken from a different layer (meaning not my atlas coverage layer), which is intersecting the atlas cover layer. This layer named "...
1
vote
2answers
32 views

QGIS: Legend not displaying symbology of items

I'm making a plant including power plants in a country. I plotted the plants and their symbology shows up in properties in the legend items but it does not in the legend itself as you can see in the ...
1
vote
1answer
36 views

Error in rasterizing a shapefile

I tried to convert a polygon shapefile of classified land cover to raster using 'Rasterize (vector to raster) tool in GDAL. I chose the DN field, set output ratser size unit to pixels and chose the ...
8
votes
1answer
115 views

Opening old QGIS model in current QGIS versions

There is an older answer by @underdark to this post: Finding centrelines from polygons in QGIS? She links a QGIS model that apparently was created in QGIS 2.12. It has the file extension .model When I ...
1
vote
1answer
17 views

Topography - represent result in WKT as polygons with rings or multipolygon without rings?

I'm new to GIS vector, especially for GIS tools like ArcGIS, QGIS,... My question is, for this image below with poylgon 1 and polygon 2, typically how a WKT (Well-known text) is represented in GIS ...
4
votes
2answers
84 views

Connecting points with line in a specific sequence

I have 6 points in one layer as shown in the first image. I am trying to: connect points with lines in a required sequence. Save data of line connections (From_point and To_point) in the seperate ...
-1
votes
0answers
11 views

Creating Maximum Value Composite of MODIS NDSI images using Erdas Imagine , QGIS, Arc GIS? [duplicate]

I am working with MODIS Snow Cover Daily L3 Global 500m Grid product (MOD10A1) and I am trying to generate MVC(Maximum Value Composite) on series of monthly composites of each year for a study area ...
3
votes
2answers
51 views

QGIS coordinates not displaying correctly

Making my first Print in QGIS, and for some reason the coordinates are all over the place (see image). Does anyone know what would be causing this? All of my settings seem quite standard, I will post ...
0
votes
0answers
21 views

Raster formats that support colormaps for floating-point data in GDAL?

I am writing a program to overlay a raster image over a map in a KDE Marble project. I am using a combination of QGIS and GDAL to convert non-standard NetCDF data to a raster file. I began using ...
2
votes
1answer
30 views

GRASS plugins not loading on Qgis 3.10.13 Coruña LTR

I have QGIS 3.10.13 LTR installed with the stand alone installer on a Windows 10 machine. In this machine I have also a QGIS 3.16.2 OSGeo installation. I can work perfectly with GRASS in my OSGeo4W ...
3
votes
1answer
67 views

Data conversion between Shapefile and Geopackage: does it affect accuracy of data?

I use Shapefile as interchange format and Geopackage as the format to to processing. So I convert file format at least twice between Shapefile and Geopackage. Does/can this somehow affect the data ...
8
votes
2answers
179 views

Converting geometry to WKT format by using QGIS Expression

I have a gpkg file and I am changing the geometry to wkt format by using expression geom_to_wkt( $geometry ) in the Field Calculator. The output looks like this in the image. The geometry type is not ...
2
votes
1answer
35 views

Toggle a non selected layer via hotkey

I am trying to do some annotation in a layer (layer 1) where I draw many single polygons within a specific ROI. To do this I toggle a second layer (layer 2) on and off to compare it to the "...
2
votes
1answer
27 views

r.watershed error in QGIS (3.16.2) for MAC

I'm trying to use the r.watershed tool, here is the error that is arising. I've tried changing the GRASS path to custom /Applications/QGIS.app/Contents/Resources/grass78 and it doesn't seem to work ...
6
votes
1answer
88 views

Creating grid with PyQGIS

I cannot create correct grids with PyQGIS. When I create grid with PyQGIS, the grid shape is not correct, i.e. rotated grid. But it's correct when I create it with QGIS > Vector > Research Tools ...
3
votes
1answer
56 views

Clipping shapefile – QGIS vs Python

Which algorithm does QGIS use for clipping shapefiles? When I use ogr2ogr to clip a large shapefile (approx. 3gb) it takes 77sec. When using QGIS it takes approx 5 sec, clipping the same dataset (and ...
3
votes
1answer
77 views

Mapping polygons into lines and projecting lines on road network

I have a layer with polygons that describe road damages. I have then another layer with road network lines. The layers are shown in the picture. I need to project the polygons as lines to the road ...
4
votes
1answer
52 views

Create star map with polar projection from Right Ascension and Declination

I'm hoping this is the right place to find help with this. Here's a brief description of what I have so far and the context for what I need. I'm creating a star map within Unity 2D, consisting of one ...
8
votes
1answer
103 views

Connecting points with lines and saving starting and ending points in new layer

I have 3 points in one layer as shown in the first image. I am trying to connect a building points with junction point by 2 lines. For demo, I have manually drawn a lines in image 2. Here, I am trying ...
0
votes
0answers
21 views

Accessing a non spatial table in an ArcGIS Map Service in QGIS

I have a client who wants some information that is stored in a non-spatial table on an ArcGIS Map Service. When connecting to that service via either the Map Service Connection or Feature Service ...
1
vote
1answer
42 views

Calculating the percent of binary values in grid of 1 km by 1 km across the entire raster

I have a raster of the entire united states with 30 meter by 30 meter pixel size. Each pixel has a value of either 0 or 1, with 1 defining a certain type of landcover. I need to find the percent of 1'...