Questions tagged [qgis]
QGIS is a cross-platform GIS application licensed under the GNU General Public License.
38,547
questions
5
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3
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Filtering which points to display using expressions in QGIS
I have a load of points loaded in as a CSV file. I want to show only certain points based on their name, e.g. only value1, value4 and value8, the field name is "Drilled ID".
I have gone to ...
- 193
2
votes
0
answers
64
views
Use VertexTool in QGIS/PyQGIS standalone application
I want to have a simple possibility to edit the geometry of a polygon in a QGIS standalone application. The VertexTool from QGIS would work well.
I am in a standalone application and have therefore no ...
- 549
0
votes
0
answers
25
views
Icon problem when installing QGIS 3.30 and 3.28 LTR on MacOS at the same time
After installing both versions of QGIS 3.30 and 3.28 LTR on MacOS Monterey while in the applications folder the two versions are distinguished with the names "QGIS" and "QGIS-LTR" ...
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0
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19
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I want to change straight line to curve line on my OD analysis
I have an OD analysis of Bicycle stations. But straight lines are overlapping. So I need to convert radial or curved line to solve this problem. How can I do?
Current:
Desired:
3
votes
2
answers
201
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Generating lines at the end of each measurement with plugin in QGIS
It would be very useful to have a tool like this when measuring and even more useful to generate lines at the end of the operation.
I use this plugin which is part of a small GIS program (Map Maker 3....
- 2,365
2
votes
1
answer
77
views
Rename and delete fields in the attribute table
I am using QGIS V3.22.6
I have an attribute table with unnecessary fields that I wish to delete. I also wish to rename some of the fields.
I cannot see how to do this using the Attribute Table Editor.
- 41
0
votes
1
answer
56
views
Select Features by polygon colour
I am using QGIS V3.22.6.
I have imported a set of polygons digitised in Google Earth. They all have the same name but have different polygon colours.
I would like to rename these according to their ...
- 41
3
votes
0
answers
34
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The following layers were not correctly generated grid calculator
I'm doing an assignment for a mapping class and I'm literally stuck trying to create a DEM file using the grid calculator under SAGA. I'm following the directions we were given and I have searched for ...
- 31
5
votes
0
answers
46
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Get rotation and scale of picture after georeferencing using QGIS
How can I access the rotation and scaling information, that is visible during the georeferencing process in QGIS (see yellow marked text in the picture), after the georeferencing is completed and the ...
- 51
2
votes
1
answer
66
views
Georeferenced image not showing in QGis
I am trying to get a Georeferenced image into QGis project, but it does not work.
The georeferenced image has 81 points, and I've set the CRS to EPSG:3035 (the same as the project).
If the QGis ...
- 21
8
votes
1
answer
124
views
Making color from color name in QGIS expression
I have a layer containing color field storing color names as text like red, green. The layer is read-only.
id color
1 green
2 red
3 blue
4 green
I would like to define -using data-defined ...
- 69.5k
1
vote
0
answers
28
views
Managing a great number of reports
In a project I have about 20 different reports. In the report manager, the only presentation seems to be alphabetical order.
Is there any feature or parameter, or plugin that could help manage those ...
- 576
1
vote
0
answers
29
views
QField/QGIS synchronization problem
Using QGIS 3.38.4 (LTR) and QField 2.6.3, I've been having a problem getting one project to synchronize properly by cable (another one I checked seemed fine), one symptom of which is the following ...
- 155
3
votes
2
answers
109
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Is there any way to link the current map scale in the print layout to a text box?
Is there any way to link the current map scale in the print layout?
I know you can do something similar with the the date by entering $CURRENT_DATE(yyyy-MM-dd) into the text box.
- 193
4
votes
1
answer
43
views
For QGIS processing algorithm python scripts, how to limit selectable layers in algorithm input when using @alg decorators
When using the @alg decorator to scaffold a processing algorithm, we use the @alg.input to declare new widgets for the interface. We can declare these as alg.SOURCE for layers we use in the algorithm.
...
- 209
0
votes
1
answer
45
views
How to avoid the negative values in Raster extraction [ example -32767] in QGIS
I 'am trying get a raster values as xyz format for ground terrain analysis using QGIS software,
After extracting raster data,few cells are showing -32767 values, how to get rid of these negative ...
0
votes
0
answers
24
views
Fill a column box selection with atlas_pagename in QGIS
I am trying to dynamically fill a box with a column that has the same name as the atlas_pagename. I attempted to use eval(atlas_pagename) but was unsuccessful.
Does anyone have any tips or ...
- 111
4
votes
3
answers
79
views
Categorized symbology with multiple variables (or nested categorization) in QGIS
I have a CSV spreadsheet containing thousands of rows, each corresponding to a georeferenced record of a lizard species. The dataset looks like the following table:
record sex age color ...
- 43
0
votes
0
answers
15
views
Transferring layer with attachments from ArcGIS Online to QGIS
I have an older Android tablet that will not cooperate with ArcGIS Field Maps. I've tried everything, so I'm using QField instead. Everything works great, except I have several layers in a mobile map ...
6
votes
2
answers
114
views
Finding furthest point from origin point using QGIS
I'm using QGIS 3.28 and I need to find the furthest point from an certain origin.
For reference, this is a Fiber to the Home (FTTH) project.
Imported data:
The pink dot on the center is the point of ...
- 69
0
votes
0
answers
39
views
Split line with distance and particular point
I try to split line, or exactly, I want to make a new line between 2 lines.
I try to interpolate point, but it's create 1 point on every node. I need only on start point.
I try to buffer point, but it'...
- 434
1
vote
1
answer
36
views
Rotate photo in Mergin Maps preview
I am setting up a Mergin Maps project and would like an image taken from the QGIS Photo widget to display in the preview. I have been able to get the photo to show up in the preview using the ...
- 11
0
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0
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11
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QGIS QFIELDSYNC failed
When im creating project into QFIELD Cloud, the operation failed, maybe it has something to do with update for qfieldsync, how to solve with problem?
0
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0
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16
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Store the output of qgis-Processing-Algorithm in sourcelayer
I use a lot of QGIS-Processing-Algorithms for my automations.
Often i replace the sourcelayer with the computed layer.
Is there any way to overwrite the sourcelayer with the algorithmoutput? For some ...
- 502
1
vote
1
answer
27
views
Use a conditional raster calculator formula with exponential from ArcGIS in QGIS
I have following formula that works in ArcGIS within the Raster calculator:
Con (("%P%"-"%ETP%)<0, "%RUx%"*Exp (("%P%"-"%ETP%")/"%RUx"), Con ((...
- 425
1
vote
1
answer
25
views
Selecting lastest date per ID in QGIS field calculator
My GeoPackage contains columns like ID, date and number.
There are multiple entries/columns per ID for different dates with different numbers: e.g.
ID date number
1 31.01.22 10
1 31.12....
- 11
1
vote
0
answers
26
views
Population density grid confusion
I have a multi polygons data where red means most populated and white means less populated. I created a gridded population density (image on the right) out of them, but the result seems not quite make ...
1
vote
1
answer
32
views
@atlas_featureid and $id
A project with 2 shapefiles
shapefile road (multiline)
shapefile crossings of roads (point)
I have 2 atlas reports, one about the road and the other about crossings
Both should highlight the ...
- 576
3
votes
0
answers
50
views
How to save a layer to gpkg with user projection that another person can import/ use in QGIS?
Description:
In QGIS, I can create a custom user projections. Create a layer that uses that projection. Save that to a geopackage (gpkg). Then share that gpkg. The layer can be viewed in another ...
- 141
1
vote
0
answers
43
views
Calculate attributes from a polygon layer based on percent within another polygon layer
I have two polygon layers both in EPSG:4269 - NAD83:
One layer is 2020 zctas
The other is 2022 census blocks
The census block layer has two attributes/columns containing counts (int).
I'd like to ...
- 31
1
vote
0
answers
52
views
QGIS - Is it possible to select only features of one particular colour from a georeferenced image?
QGIS 30.0 Windows 10 Pro
I have a project to which I want to add a layer. The source for the new layer is a Tif image on which areas of infestation of a plant disease are shown in an orange colour. I ...
- 915
2
votes
0
answers
23
views
How to merge a selection of layers using the pre-calculated value option from within the QGIS modeler
I have a QGIS model that iterates over features in a polygon layer (see screenshot). The outputs are multiple line layers. I need to merge all these line layers. By nature of the model I don’t know ...
- 173
5
votes
4
answers
629
views
Placing the North arrow
In the picture below, north arrow should be placed, however it's unclear how to do it since north pole is also in the picture.
Please advise on the arrow placement and position, hopefully with ...
- 153
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votes
0
answers
26
views
Cost distance QGIS similar to ArcGIS
I want to create the cost distance raster using a tool from QGIS. I see a lot of old questions about this, but I could not have the answer. When I use the cost distance tool in ArcGIS, the resulted ...
- 1,459
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0
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31
views
What CRS should I use to georeference a map from 1857 (North America)?
I am trying to georeference a map in QGIS from Beale's Expedition of 1957-1858, using coordinates he recorded for camps in his daily log.
Here is the map: https://digitalcollections.nypl.org/items/...
0
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0
answers
16
views
QGIS layout template font appearance
I've made a layout template in QGIS 3.26.2-Buenos Aires. When my colleague opens the layout on their PC the font appearance seems to have reverted to default. This is happening for text and dynamic ...
- 1
4
votes
2
answers
153
views
QGIS: Compare two concatenate fields and add similar strings to new column
I am doing research on how planned improvements in urban green will likely affect biodiversity using QGIS. Each form of urban green has a list of so-called references species, species that are ...
- 49
0
votes
1
answer
19
views
QGIS .tiff to shapefiles by extracting colours
So I have the following raster file:
I would like to edit it so that I export all green, blue or purple areas as a single, new .tiff. Afterwards I would make a vectorization to be able to process the ...
- 78
1
vote
0
answers
27
views
Python Script tool not supporting Selected features only option in QGIS
I'm create a python script tool in QGIS that is working perfect. However when I use the "Selected features only" checkbox to run my script in just one polygon feature it returns the ...
- 1,000
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votes
0
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12
views
How do you change the shape of a point based on an items category and change its color based on price?
I am working with generation data. I want to have different symbols for each technology used to generate power such as coal, wind, natural gas etc. I also want to change the color of that symbol to ...
0
votes
0
answers
23
views
Measure length in pixels over raster in QGIS
In MATLAB there is a simple tool called imdistline which measures length in pixels over an image.
I can't find an equivalent tool in QGIS (3.26.3) for measuring the length between two pixels on a ...
- 123
1
vote
1
answer
57
views
PostGIS import error
I need to import some shapefiles into a database. PostGIS has successfully imported several small files.
But an error occurred with large files. It shows this error:
"Unable to convert data ...
- 21
2
votes
0
answers
43
views
Expression writing in QGIS/Select by expression
I'm trying to write formulas/expressions for selecting purposes. I want to create a fixed table in a report layout, and for let's say one particular cell, I'd like to retrieve data from a SELECTED ...
- 21
0
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0
answers
35
views
Inset map in Print Composer in QGIS using irregular shapes
I have been trying, unsuccessfully, to create an inset map in the Print Composer (via the Add New Map button) but, instead of it having the shape of the viewport main canvas, I would like it to have ...
- 393
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0
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21
views
Draw a line as part of a QGIS model and rotate a grid accordingly
I am generating a grid based on a polygon extent. I want to be able to draw a line on the canvas as part of the model. The line indicates the direction of the grid. My thought was to create the grid, ...
- 173
0
votes
1
answer
33
views
Local coordinates into global coordinates - QGIS
Since there aren't any georeferenced points on the site, we're creating a local grid using a few close locations as references as I use a total station to do some measuring.
Aerial photographs can be ...
4
votes
2
answers
117
views
QGIS: Create rectangular grid from point grid
I would like to create a grid of rectangles from this grid of points using QGIS 3.16:
I want the rectangles to be 8km by 8km in size. My points are 8km apart. I tried using the Rectangles, ovals, ...
- 425
2
votes
1
answer
48
views
Make the aggregation function in the form menu more versatile for different projects?
I have expressions for a table field that has a map layer named as a data source file (building_ex.shp). I plan to save this setting as a style and use it in other projects, but in other projects the ...
- 303
0
votes
0
answers
18
views
Analysing distance matrix data
I am trying to analyse this distance matrix data I created from QGIS (see picture) of the distance of all crimes in one month to the coast. A is crimes and B is the distance from the crime to the ...
1
vote
0
answers
17
views
Fix gaps in xyz tile basemap with QGIS
I'm making a map and want to use the Stamen terrain background basemap because it looks good. The issue is that there are a number of tiles that appear to be missing at the higher resolution (i.e. ...
- 11