New answers tagged qgis
0
votes
Create vector layer/virtual layer with dynamic number of features in QGIS
Assuming you want each of the points to have an identical geometry, you could use a recursive CTE and generate a row (with unique id) for each layer as such:
WITH seq AS (SELECT 1 AS n UNION ALL ...
- 7,574
0
votes
Exporting project with all files, properties and dependencies using QGIS
I tried Project Packager by Tarot Osuji - https://github.com/tarot231
Although it doesn't have a rating yet it seems to have more than 2,000 downloads. So, I risked trying it.
It seems to be working ...
0
votes
QGIS clipping virtual raster into tiles using grid layer (polygons)
Are you willing to try a solution in R ?
library(sf)
library(terra)
grid <- st_read(dsn = "polygon_grid.gpkg")
nr = nrow(terrace_grid)
r <- rast("uas.vrt")
lapply(1:nr, ...
- 14.6k
0
votes
QGIS auxiliary label locations: determining their storage locations
When you move the first label, you must select the primary key to use for joining with internal data storage.
Solution 1
When this is created (as it is the case with you), you automatically find two ...
- 45.1k
1
vote
Adding multiple points using Excel data in QGIS
If you have a text file (removed the spaces from the one you provided):
Name,Latitude,Longitude,A1,A2,A3
City1,44.499232,23.651273,1,1,1
City2,44.199232,23.251273,1,0,1
in data.txt, you can proceed ...
- 356
2
votes
Accepted
SVG or PNG image from web as maker symbol (QGIS)
It works but you have to make sure to use the correct URL.
You have a link that points to a website (html file) containinge a link to the SVG:
https://commons.wikimedia.org/wiki/File:LDB-blau-OSM.svg,
...
- 45.1k
1
vote
Deleting vertices inside polygon area in QGIS
To identify the vertices to delete, you can check the interio angle at each vertex and where this angle is very high (near to 360 degrees), you can delete the vertex.
To measure the interior anlge, I ...
- 45.1k
0
votes
Download of QGIS Version 3.24 'Tisler' not available
Here are the direct download links (2022-10-01):
dmg: https://download.qgis.org/downloads/macos/pr/qgis_pr_final-3_24_0_20220223_132611.dmg
md5: https://download.qgis.org/downloads/macos/pr/...
- 7,063
0
votes
Accepted
Download of QGIS Version 3.24 'Tisler' not available
You can download older QGIS point releases (pr) for MacOS from https://download.qgis.org/downloads/macos/pr
- 54.2k
1
vote
Deleting vertices inside polygon area in QGIS
Try these geoprocessing tools:
Snap geometries to layer and snap the layer to itself
Buffer with 0 distance
Snap points to grid
- 55.4k
1
vote
Accepted
Copy/Paste of features into existing PostGIS table
One way to do it, from the postgis side, is to add a new serial column and set it as the primary key:
alter table your_table add column pk serial primary key;
This will provide QGIS the next sequence ...
- 6,584
4
votes
Deleting vertices inside polygon area in QGIS
If the vertices immediately before and after the ones that are within the polygon are coincident, the solution could be running the Processing > Vector geometry > Fix geometries tool from the ...
- 141
5
votes
Accepted
Display both edges of adjoining polygons in QGIS
This is probably very "tuned" for my data and not optimal, but using a small negative buffer that is roughly the width of your outline should give you the impression you might be after. Here ...
- 54k
2
votes
Creating Square Buffer in QGIS?
I recently wanted to do the same thing as the OP, but rather than irregular-shaped buffers of irregular polygons, I wanted actual squares. Here is an approach I used in QGIS 3.16, I hope it might be ...
- 511
1
vote
Rank values in a row with QGIS field calculator
Here's my convoluted QGIS expression answer - but it only takes the top 5 as in it cuts off after #5, it cannot actually rank the numbers where there are duplicates. In which case, if your #5 position ...
- 7,574
3
votes
How to show points on LineString in QGIS?
Add a new symbol layer of type marker line and opt to show a marker on every vertex. Eventually click on the said marker to customize it.
- 36k
3
votes
Accepted
How to show points on LineString in QGIS?
Add a new symbol layer () of type Geometry Generator and select the geometry type to Point / Multi Point use this expression: nodes_to_points($geometry).
- 1,796
1
vote
QGIS split HTML code table into different fields
A robust solution that fully parses any syntactically valid HTML table, extracting whatever field names are within it, will probably require writing a Python script which uses an XML converter like ...
- 6,533
2
votes
Accepted
How can I transform a StringList to one String
If you want to replace texts inside a list, you will need to loop throw that list.
array_foreach(
array:="field-name", -- set inside double quotes the StringList field name
...
- 1,796
1
vote
Layer just for annotations
In QGIS >= 3.22 there is the possibility to create an annotation layer. You need to activate Annotations Toolbar in View\Toolbars. You will see something like this:
Use the first button for ...
- 1,978
4
votes
Importing CSV or Excel file into QGIS to make shape file (polygon)
You dont need to specify what coordinate represents which location and not that it is a Polygon because your datasource is already provided as WKT where these are specified. Try this query:
Select ...
- 27.3k
0
votes
Text annotation scaling
Has there been any development on this issue? I am having the same problem coupled with scaling issues between a Microsoft surface and external display.
I managed to solve the scaling issues but the ...
- 1
1
vote
Accepted
How to permanently combine rasters in QGIS?
One way to do it is to export your desired visualization as an image
(Project/import/export/Export map to image).
Just make sure of the following
a) calculate the extentent. If you want the whole ...
- 2,942
0
votes
Vector Bender in QGIS 3.10 not aligning
Make sure that Vector Bender Layer is on the same Coordinate System as the layers on your project.
When creating a "Pair Layer" using the plugin interface - the Coordinate System of this new ...
- 1
1
vote
Clip raster by extent creating Band 1,2,3 from Band 1 (Palette)
I suppose that your raster is not really converted into RGB but the GeoPackage raster driver has a peculiar behavior in how it reports the bands. See https://gdal.org/drivers/raster/gpkg.html#opening-...
- 54.1k
0
votes
Attribute aggregation - from line to point
this one also worked.
if("diameter_valve" is NULL,aggregate(
layer:= 'waterpipe_pipe',
aggregate:='concatenate',
expression:=to_string("diameter"),
concatenator:=', ',
filter:=...
0
votes
Attribute aggregation - from line to point
This expression worked for me, thanks for help
if("diameter_valve" is null,
overlay_nearest('waterpipe',diameter_pipe,max_distance:=0.01)[0],"diameter_valve")
1
vote
Finding where to close polyline using QGIS technique that resemble how US Census Geography's Inland Water is calculated
Hypothesis
There is one continues line representing edge of water - both for open waters, and inland water
The line has known direction, and the water is on the known side in regards of line ...
- 9,296
0
votes
@row_number with virtual layer in QGIS
You can use ROW_NUMBER() to generate a row number as long as there is some other field to use in the OVER parameter, doesn't matter if it's non-unique. Apparently, using geometry field works (tested ...
- 7,574
0
votes
I am importing layers from a DWG file into QGIS, and they are visible in the "Layers" panel, but they are not visible in the layout
A lot depends on how the original dwg was set up. Sometimes features that appear to be in a specific layer in CAD will end up on another layer because the block itself is on that other layer. ...
- 7,574
0
votes
Searching for single Layer in Layers Panel of QGIS?
For QGIS 3.>
for layer in QgsProject.instance().mapLayers().values():
if 'Municipal_Boundaries_of_NJ' in layer.name():
iface.setActiveLayer(layer)
iface.legendInterface()....
- 1,537
1
vote
Accepted
Aggregating points within certain distance and keeping all points info using QGIS
I'm not sure if this is best, but I think it will work. I wasn't able to find a plugin or other way to accomplish all your requirements.
DBSCAN
Calculate field with a value of Name plus CLUSTER_ID. ...
- 3,050
2
votes
Calculate mean in Qgis filter
In version 3.22 this worked for me. Open the Attribute Table, choose the Filter button and then use this formula in the field you want to filter.
mean("SHAPE_AREA")
Make sure to change ...
- 3,050
2
votes
Accepted
Python script in toolbox
You need to actually get the layer from the context argument of the function with QgsProcessingContext.getMapLayer(identifier) -> QgsMapLayer (source)
I have also changed ...
- 1,816
3
votes
Extract QGIS text label position as polygon feature
Not 100% what you are looking for but hopefully a start. This will only work for labels which are in Curved placement mode. You need to select the layer from which you want to calculate the polygons ...
- 1,215
0
votes
Creating a map of only a specific region with OpenStreetMap
If you're looking for OSM-derived vector data of British Columbia, I think that the best option is to download it entirely from Geofabrik in a GIS compatible format. Here you could find the entire ...
- 141
2
votes
Accepted
Attribute aggregation - from line to point
Use the following expression on the point layer and adapt it to your needs. It checks whether the point layer's attribute named value is 0:
If not, the current value of value will be returned.
if ...
- 45.1k
2
votes
Normalize images for Sentinel
There are several product levels for Sentinel-2. For vegetation indices, I would recommend using bottom-of-atmosphere products (level 2A). No need for normalization as far as I know.
Please note that ...
- 437
0
votes
Accurate way to show values of each classification range in the legend in QGIS?
I would write it as follows, if accuracy is important for the cut-offs:
Legend_Category_1: >= 1000, < 2700
Legend_Category_2: >= 2700, < 9200
This would let you know, if we are not talking ...
- 1
0
votes
Joining attributes by location where percentage of polygon feature is more within a polygon in QGIS
For a Python answer without QGIS, it is possible to do this with geopandas as well. Given two GeoDataframes, A and B:
geom_b: str = 'geom_b'
geom_b_area: str = 'geom_b_area'
B[geom_b] = B.geometry
B[...
- 7,893
1
vote
Joining attributes by location where percentage of polygon feature is more within a polygon in QGIS
QGIS has a "Join attributes by location" process that includes the METHOD parameter, option 2: "Take attributes of the feature with largest overlap only (one-to-one)", use it with ...
- 7,893
0
votes
Error when clipping raster by mask layer (polygon) in QGIS
Maybe you are clipping the temporary file. try to save the file then clip
- 1
2
votes
modify symbol/stroke of digitized line used during digitizing?
Options --> Digitizing --> Rubberband
- 1,215
0
votes
Accepted
How to uncheck no data value option in Python
If you need to disable nodata value I believe it means that the nodata is set wrong in the source data. Therefore I suggest to correct the source data with gdal_edit.py https://gdal.org/programs/...
- 54.1k
0
votes
Joining attributes by location where percentage of polygon feature is more within a polygon in QGIS
Add an $id to your small features
Run intersect with the small features as first and the large features as second input. This a) splits your small features at the borders of the large ones, and b) ...
- 13.4k
1
vote
Getting all symbols to render when using Point Displacement in QGIS
I think you would be better of by using a single symbol composed of two half circle and control the fill color of each half using data defined override. You may just use a CASE WHEN expression ...
- 12.4k
0
votes
Extract subset of linestring based on distance
...found the Service Area function, which does the trick
- 197
-2
votes
Python script in toolbox
Processing give you access to the layer features data only, but not to the layer instance itself in project. So, you have to create your own little python plugin, not algorithm. Create ui form (run ...
- 475
1
vote
Create polygon from a raster in specific areas
This amounts to translating the values contained in the pixels to obtain a layer vectorized thematic information.
It is a work of classification. There are several methods.
You can do it with QGIS (...
- 723
0
votes
QGIS Triangle marker size control
Use the SVG triangle.
Select the equilateral SVG triangle, unlock the lock in the right of Width and Height settings, then set the expression in Width and Height.
This are my expressions:
Width: &...
- 1,796
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