Questions tagged [qgis]
QGIS is a cross-platform GIS application licensed under the GNU General Public License.
41,111
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Sorting waypoints into groups embedded within single GPX file in QGIS
I am using QGIS 2.18. I transfer the GPS data from my Garmin GPSMAP64s in the form of GPX file format. After opening one GPX file I got many waypoints which I previously marked in the field. Now I ...
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148
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Extracting shapes from vector road data (specifically circles and lines)
I’d like to extract some specific data from QGIS to be drawn in a Garmin application which uses Monkey C but I am unsure of how to do it.
Currently I use many coordinate points to portray roads made ...
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Is there a "gradual style" available in QGIS to do something like this? [closed]
I need to print my map with something like this. I tested several styles in QGIS to represent this idea, but the closest I got was using the shapeburst fill.
The idea is:
The colors represent ...
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66
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Mismatch in point locations between QGIS and my GPSMAP65S
I identified at distance (maps) different points on the island I am working on, Martinique (in the French West Indies). I noted their coordinates in the same system as my QGIS map (WGS 84) as well as ...
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Store QGIS annotations in PostgreSQL/PostGIS database
I have a multiuser QGIS project stored on PostGIS database.
Is it possible to store annotations in a PostgreSQL/PostGIS database so that every user can add annotations directly on the map?
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Long time to load QGIS project in QGIS 3.22.4
I have several QGIS projects which have layers coming from oracle database. Those layers are heavy so I choose to make them invisible in the projects so that I can load the project much quicker. If i ...
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2k
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Building the shortest route through all points in QGIS
How to build the shortest route through all selected points, starting from a given point? Which plugin to use?
There is a point layer and a linear layer for all routes between points.
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180
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Points to Path - creating an expression to group required points
Given two almost parallel lines where points have been added every 5.4m, I want to create a polygon using the point that is on the BL to the BR, to the next one up on the Right to the Next one up on ...
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174
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QGIS how to draw a circular polyline?
I would like to draw a semi-circular pattern (arc) on QGIS as a polyline. I did it before but have no idea how I achieved it. I am on QGIS 3.16.4.
I would like to replicate the black arc lines called &...
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QGIS: Cross-tabulation table full of zero values
I want to calculate the Night Light Development Index (NLDI). For this reason I am using a night-time lights satellite image and a population raster layer, which they have the same dimensions, extent ...
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361
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Solving the error 'Multipart object with only one feature'
I have a single feature county boundary shp file, and when I run Check Geometries on it it says 'Error - Multipart object with only one feature'. However when I ask QGIS to fix this it takes no action....
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131
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TIN Interpolation method in QGIS
I am trying to interpolate 6 vector points in QGIS using TIN interpolation. However, I keep getting an error msg. For some unknown reason, it won't complete the interpolation. How can I fix this?
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220
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QGIS: Can I delete a feature's geometry and keep its table entry?
From an original table of rushed and inaccurate polygons representing geofences around some facilities, I am making another shapefile of appropriately quality-checked polygons. I'm doing this by ...
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709
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Extract multiple raster samples by input vector layer
I am working in QGIS 3.24.0. I am working on a project using the NLCD raster for the contiguous USA. I need to extract 208 circular buffers (10km radius) and have them each saved as a separate raster ...
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276
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Create attribute column with index sorted by coordinates in Point Layer
I have a layer of points and I want to add a column with an index according to the coordinates. I already thought about sorting the UTMX and UTMY coordinates, but still the result doesn't convince me, ...
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101
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Set font with variable in layout
I'm using QGIS 3.16. I have a variable called Projet_font in my projet.
My problem is in the layout composer, it doesn't seem to be possible to use this variable to set the font text?
Here is as ...
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704
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Atlas - Export only certain pages
I would like to export only certain pages from an atlas.
For instance: I have an atlas with 37 pages, and I update pages 3,5,7-10. I would like to export those pages for reprint to a single PDF.
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QGIS - converting categorical raster to polygon includes raster boundary
I am using the QGIS Raster Convert Raster to Polygon tool (which calls gdal_polygonize under the hood), to convert a raster in a netcdf file to a polygon. The raster is a binary mask. The issue is ...
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266
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Highlight polygons using comma delimited text coordinates QGIS
I am new to GIS. I have significant CAD experience and some limited Python knowledge, and am generally familiar with basic QGIS functions.
In short, I will have several CSV files containing co-...
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Extracting lat/long of network vertices
I have created a point from the road network using vector>Geometry tools>extract Vertices tool. But after creating point from the line using this tech I have seen that the lat-long is the same. ...
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Extracting bulding heights from height map into attribute table
In QGIS, I have a layer with polygon outlines of buildings and a height map over the area, I would like to extract the height of the buildings from the map and insert it into the attribute of the ...
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628
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QGIS Offset Points by value
I've got one layer with a line (e. g. a road) and one layer with points (e. g. trees along the road). So far, the points are placed right on the line, but the attribute table of the point layer has a ...
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QGIS - Very slow map rendering and WMS timeout
I am working on a powerful desktop, it was custom made so I do not know the exact specs however ram is 64gb and it was made for 3d modeling.
I am finding QGIS 3.22.2 to be very slow when rendering ...
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140
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QField - Fields automatically filled when supposed NULL [closed]
Here is my issue :
On a QField project, I have few layers depending on from each other.
When "Compartment" is modified, then "ID" is modified and "Compartment value" ...
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269
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QGIS v.net.salesman generates error when restricted to selected features
I'm using the GRASS v.net.salesman in QGIS to find the shortest route between some American colleges on the road network. The network layer comes from Natural Earth Data, specifically ...
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245
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AutoFields Plugin for QGIS 3? Or best way to set up Default Values via PyQGIS?
I am working on transitioning my workflow from QGIS 2 to QGIS 3. I was using the AutoFields plugin in QGIS 2 to setup automatic adjustments to the attributes for lines and points (namely their length, ...
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553
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Unsupported geometry type 'Unkown type' in Layer - Unable to load project in QGIS
This is a seemingly simple issue but I can't seem to fix it. When I load my project in QGIS, I get an error message that says: "Unsupported geometry type 'Unknown type' in Layer ''. When I click &...
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169
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Transformation of negative ordinate values from a .itiff file
I have multiple iTIFF files which were georeferenced by another person (CRS EPSG 31468, 3 degree GK Zone 4). The problem is that the ordinate (northing) comes with a negative sign while it should be ...
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401
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Expression for extracting specific parts/geometries from dataset in QGIS
Solution below worked for a small subset with a filesize <<1 gb, for larger file sizes another solution would be needed
I'm trying to formulate an expression which extracts specific parts/...
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145
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Spatial clustering with areas in QGIS or Python
I am working in QGIS with shapefiles containing several polygon features with various areas.
I would like to cluster neighbor polygons in a way that results in clusters of approximately the same total ...
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126
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GDAL Warp Using QGIS from AK_IFR to EPSG:4326 looks odd
I am using QGIS for converting tiff from AK_IFR to EPSG:4326 (CRS), but in QGIS tiff looking perfect
but while exporting it looks like this
Source Image Details: FAA IFR Chart
Extent -3738773....
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49
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Unwanted canvas title in QGIS
The main map canvas shows a plain text title or label at the top left. It behaves like a decoration from View > Decorations but it is not accessible from there. The text is relevant to the project, ...
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Convert TIF file to CSV/ASCII format using QGIS v. 3.24.1-Tisler
I have DTM data in the format of .tif and I need to export this as CSV or ASC for point cloud data input into Leapfrog.
I've read other walk-thrus that are outdated now (2014/2017) that came close to ...
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73
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Trying to make vector line data into a polygon in QGIS
I am using Open Street Maps in QGIS to make a map. I have generated "highways" or streets to find all the streets are vector lines. I am trying to add a width to each line/street and have an ...
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Importing layers from DWG and they aren't appearing on my QGIS map
I am extremely new to QGIS and havent been able to find a solution to this problem I ran into when trying to upload a .dwg file I was given.
I imported the file using Project > Import/Export > ...
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2
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196
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Calculate area of adjacent pixels
I have a raster layer of seasonal lakes created from snowmelt runoff. I would like to calculate the size of the lakes that are created. So I want to basically calculate the area of pixels clustered ...
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7k
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Creating polygon mask in QGIS
In QGIS 3.22.5, is there possible to use polygons for the masking layer?
I want to use numerous little polygons to mask lines (only layer which consists of lines).
In ArcGIS that works just by ...
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327
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QGIS - set custom default legend symbol for a layer
I am aware that I can change the symbol representing a layer in the legend manually.
In order to save time I want to prepare a style which includes the changed legend symbol, while preserving the ...
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215
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Clip WFS layer with QGIS on import
I have a large WFS polygon layer and I want to use query builder to clip it before importing to desktop app.
To do this, I have created predefined polygon ( QGIS layer named: clip_boundary ) which I ...
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274
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Symbolizing line thickness by M-values
Is there a possibility in QGIS 3 to render line thickness by M values on every vertex?
The new Interpolated Line symbol layer type introduced in version 3.20 seems suitable for the task, but so far ...
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493
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gdalwarp - ERROR 2: gdalwarpoperation.cpp, 2401: cannot allocate 839889004 bytes on QGIS 3.16
I have two Int16 DEMs of 129600x64800 cells that cover the entire globe. The projection is WGS84 [EPSG:4326]. One contains only the elevation above sea level (no data cells above oceans), and the ...
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54
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Variable resolution across DEM in QGIS
I am try to build a contour map from this DEM but I've noticed that the resolution varies across it resulting in orthogonal contours and 'choke points' where contours are sharply forced together. How ...
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855
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Aggregating child features with parent attribute values in QGIS
I found this question when looking for my answer Referring to the parent layer with aggregate functions in QGIS
I need to do something similar. In another words I need to join attributes by field ...
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83
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Labels Background - one per letter and not one per label when using curved placement in QGIS 3.20.3
When using Background on labels I expect it to show one homogeneous background, but instead I get one background per letter. It only occurs when I use "Curved" placement for the label.
Is ...
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138
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Exporting Geopackage converts milliseconds of QDateTime to zero
I use this solution to display actual QDateTime value with milliseconds in a temporary memory layer. And I use another solution to export as CSV the value including the millisecond value.
But then, I ...
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175
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Callout lines drawn under other layer's labels
I'm using QGIS 3.22.4 and struggling with labels.
I'm having quite a headache trying to avoid callout lines to cross each other but now a new problem arise and it is that they are drawn as any other ...
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126
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QgsRasterFileWriter in QGIS gives blank output
I am trying to export the new Mapzen terrain to a local tiff for offline use (licence is open so no copyright issues).
I can easily do this in the interface by using Export -> Save As..
This allows ...
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177
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Connection errors with PostGIS database
I am trying to import vector data into a managed PostGIS database with QGIS and I get this error:
server closed the connection unexpectedly This probably means the server terminated abnormally before ...
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1k
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Calculate average value of raster within polygons based on type
I have seen How to calculate the average value of a raster within polygons?, which helps me a bit but not completely.
I have a raster of 16000 by 12000 (country-size) and a vector which indicates ...
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44
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Extend a line network from only its open ends [duplicate]
I want to extend a dissolved (one single feature) line network from its open ends with the help of either QGIS, PostGIS or any other python package available to use.
Edit: When I run extend tool in ...
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