Questions tagged [qgis]

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

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4 views

PostgreSQL trigger always shows last modified by “postgres”, even the connection in QGIS is with different user

I've created a role "designer" and assigned it to user: test CREATE USER test_user PASSWORD 'test'; GRANT designer to test_user; then I granted usage of the schema to the role: GRANT USAGE ...
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4 views

Z ordering of Rubberband or QgsGeometry

I'm running some simulations where I have some QgsGeometry that I show with a QgsRubberBand, the code is a little bit messy but this how I add the geometry to the rubberband, is there any way to set ...
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4 views

Why does processing field calculator seems to create new attributes table in PyQGIS?

Why when i call processing.run('native:fieldcalculator') it seems to work as native:addfieldtoattributestable? User case: I need to select one kind of values (those which contains two character to be ...
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in QGIS, how do I map “most recent date”

I have a series of shapefiles indicate locations of controlled burns in an area, which are named using the date of the burn. Many locations have been burned multiple times over the years, so there is ...
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10 views

Mapbox Studio uploaded mbtiles broken?

Using the QGIS "Generate XYZ Tiles (mbtiles)" tool I created an mbtile tileset. My input source was a 3-band RGB raster with CRS: EPSG:3857 - WGS 84 / Pseudo-Mercator - Projected. I used ...
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19 views

Advanced Python Field Calculator Script Error

I am new to QGIS advanced python field calculator. I have the following script that evaluates the results in each feature then gives it a value. Some of the values are null, which is fine, but how do ...
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1answer
15 views

How to obtain buffered polygon area size

I have QGIS 3.16. I have several polygons in one layer, added via field calculator the area_ha field (geometry area$/10000) and then buffered all the polygons (buffer, 300 m). Now I need to know the ...
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13 views

How to add polygons in JSON file?

From this GeoJSON file https://code.highcharts.com/mapdata/countries/fr/fr-all.geo.json, I would like to add some territories (called DOM) to the left of the map and Corsica (at the bottom of the map)....
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10 views

OSTN15 data transformation in QGIS [duplicate]

I have 2D dataset on a layer (currently to British National Grid co-ordinates) and I'm trying to save it as a geojson file using WGS84 CRS and QGIS 3.10.10. This dataset needs to be transformed from ...
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18 views

QGIS expression to expose a list of dict as key: value for each dict of the list in the print composer [closed]

I have a nested JSON object coming from an API into QGIS 3.16 : '[{ "id": 1 , "first_name": "John" , "last_name": "Taylor" , "...
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1answer
20 views

Filtering OSM natural peaks in QGIS

The primary source of data for a map that I'm making in QGIS 3.14 is OSM. There is a layer which contains natural peaks, obtained with a natural=peak query. In order to reduce clutter, I'd like to ...
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1answer
25 views

What is coordinate format on QGIS georeferencing

I watch tutorial from this video https://www.youtube.com/watch?v=THRa2OHpL0k, and found the coordinate from the image are about 7 digits number. e.g. N8352000, N8356500, E247500, etc I want to ...
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8 views

OSTN15 data transformation in QGIS

I have 2D dataset on a layer (currently to British National Grid co-ordinates) and I'm trying to save it as a geojson file using WGS84 CRS and QGIS 3.10.10. This dataset needs to be transformed from ...
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0answers
10 views

How can I change the projection center of a global projection with QGIS? [duplicate]

How can I change the projection of a global map so it is centered on a certain coordinate with QGIS? I know types of maps with varying centers exist, but those centers are (at least on the projections ...
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16 views

Bringing QgisApp & Qgisappinterface to environment using osgeo4w-setup-x86_64

I am using QGIS 3 C++ API. I used osgeo4w-setup-x86_64.exe for installing QGIS. Also, I have installed qgis-dev and Qt5 within QGIS3 SDK. I need to use the QgisApp class in my application, but there ...
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2answers
36 views

Is there a tool in QGIS that has the same functionality as the ArcHydro Tools from ArcGIS?

I need a tool in QGIS that has the same functionality as the ArcHydro Tools from ArcGIS.
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1answer
30 views

pyQGIS: How to retrieve only type of the geometry error by using validateGeometry()

I have a polygon layer and I am trying to catch the geometry error by using validateGeometry(). The following snippet is working and finding the reason for the error as well as the location. layer = ...
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41 views

Error when running QGIS graphical modeler: output of several vector layers

In order to intersect a grid according to hundreds of communes, I used the graphical modeler in QGIS to automate the process. I separated my district layer from the insee field to have as many layers ...
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2answers
40 views

Auto-complete polygon in QGIS

I am missing auto-complete in QGIS. From other answers I understand that you need to snap around the hole and you can't just let QGIS fill the hole, is that correct? It's bothersome when it's a lot of ...
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28 views

Creating maps in QGIS from Drone Videos

If it is possible to create maps in QGIS from Drone Videos, then how do I do it? I've found software like DroneDeploy but QGIS being so long in this race, I feel more reliable. I have drone video ...
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0answers
27 views

Interpolate an attribute value along poyline in QGIS

I have a river as polyline with several vertices. Also I have stage and bottom level information for the start and the end point of the river. How can I interpolate the value for stage and bottom ...
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1answer
14 views

Keep line attributes in QGIS Network Analysis - Shortest Path

I'm running a simply Shortest Path task from the Network Analysis toolbox in QGIS, but it seems that the output doesn't transfer the line attributes, only the start layer attributes. I need the road ...
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1answer
79 views

Formatting coordinates from Google Earth georeferencing for projection on QGIS

I have XY data from a .csv sheet without any metadata. Presuming WGS84 or UTM CRS, the points won't display correctly on a Google Earth basemap with QGIS when imported as XY data points. My data was ...
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12 views

Semi-Automatic Classification Plugin MacOS operational issue

I am using MacOS Big Sur. I have QGIS 3.18.x installed on my system. At another place in my office, I have Ubuntu Linux 21.04, and with QGIS 3.18.x installed. As an additional information, both the ...
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1answer
48 views

Extracting nearest point inside and outside of polygon in QGIS

I have multiple storm track data with unique storm track IDs in point data format; Below is example of one track data (all has common storm ID). I am looking to extract the landfall point i.e. came in ...
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24 views

Using variable field and extracting field by attribute in QGIS Modeler

I have a problem while creating a model. I want to extract certain polygons based on a field value (chain of character). The problem is the name of the field might change depending on the origin of ...
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0answers
27 views

K-Mean Clustering of Rainfall

I am currently clustering a region based on monthly rainfall. Should I check the "Normalize attribute"? I already did both (checked and unchecked), but the results are totally different, so ...
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20 views

Analysing spatially irregular data [closed]

I am not a spatial analyst or an expert in a related field. Data (2 trials) - routes crossing the study area (about 1250 sq. km.), about 1000 points along the lines represents an event of occurence of ...
1
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1answer
44 views

Getting the mean value of each row for the final column in QGIS

I am trying to calculate the mean/average of all the values in a row to obtain the final value i.e., "IRAT". How can I calculate it automatically using a field calculator in QGIS? for e.g., ...
1
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1answer
23 views

Change type of QGIS message bar with widget

I followed the following tutorial to create a QGIS message bar with widget, but it is being shown as a warning message (orange color). https://docs.qgis.org/3.16/en/docs/pyqgis_developer_cookbook/...
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16 views

Elevation Above Stream from WhiteBox problem

I'm having problems with the results of the Elevation Above Stream tool from WhiteBox. The input data has been fixed (Raster DEM and Stream Raster), but the generated image has NoData issues in ...
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1answer
38 views

How to load OSM highway values in QGIS

I want to extract the rest areas along highways using quick OSM in QGIS. But I'm facing an issue that there is no value for rest_area. Does anyone else have this problem?
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38 views

Reproject polygon from 3857 TO 4326 with R or QGIS

I am trying to reproject a vector from EPSG:3857 to EPSG:4326. The data is originally available as an ArcRestful API Canadian population tiles When I bring in the layer into QGIS and save it out as a ...
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0answers
26 views

GRASS init error when opening QGIS

This error has prevailed through many installations and now is about time to get rid of it. I get the following error message each time I open QGIS. I only install stable versions of QGIS. (No ...
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0answers
33 views

AADT points into lines [closed]

I have AADT (Annual average daily traffic) points shapefile that I want to turn into lines. Problem is that shp doesn't contain length and direction of road segment that one point covers. Is there any ...
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3answers
109 views

Counting points in polygon and printing out what each polygon contains

Here is my sample table for further description: I have a original point layer: ID Name X(latitude) Y(longtitude) ID1 Dog A 1 ID2 Cat A 1 ID3 Bird B 1 ID4 Cat A 2 ID5 Cat B 1 ID6 Dog A 1 Those ...
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1answer
33 views

Area/perimeter calculations in table

In ArcView3.2 I used Xtools a lot, just click and it calculated area/perimeter for every polygon, in QGIS I am choosing column and write $area after the "Epsilon" + update. Is there some ...
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2answers
33 views

QGIS randomly rotates images stored as Geopackage BLOB

BACKGROUND: At 3.18.3, this is my first experience with BLOB fields. I have created a standalone Geopackage table that contains a BLOB field (I'm not sure why Layer Properties calls it a QByteArray, ...
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2answers
30 views

Precipitation Interpolation Resolution Setup in QGIS

I am trying to interpolate rainfall data using the GDAL's Grid (Inverse Distance to a power) in QGIS 3.16. Is there a way to specify the resolution of the result/change the size of pixel? The ...
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0answers
26 views

Creating large base map quickly

I'm new in map. I try to create map tile. I start with GeoJSON and using QGIS 3 to parse it into PNG tile. But when I add more data in layer, I have to run it from beginning. It very slow in zoom ...
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1answer
102 views

Finding scale of map in QGIS

In QGIS I want to know how can I find the scale of a map. I have state boundaries with me, and when I calculate the length of the boundary, it comes out to be something like 245.854. This most ...
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0answers
33 views

During use program, QGIS suddenly down, How can I fix the problem?

When I use QGIS program, suddenly down. I use QGIS program that connected to GeoServer. And there isn't something special else There is two case when program suddenly down program notice message that ...
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2answers
45 views

Performing interpolation using QGIS

I measured chemical concentration for different types of soil, and I have a picture or map of the distribution of different soils for my studied area. I assume that the concentration will be similar ...
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2answers
29 views

Calculating road travel distance between point and polygon layers [closed]

I am trying to calculate the top three shortest distances from a point file (buildings) to a polygon file (designated natural areas) via road networks. I basically need the "Join attribute by ...
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0answers
16 views

Splitting line by raster or vector attribute - Transect classification

I have a point, from this point I made 3 lines to the closest polygon with certain attibute. Now I want to determine over what classification values ​​my line passes and the distances considering the ...
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0answers
29 views

No/incorrect rendering of background-color for vector tiles using QGIS

I'm trying out vector tiles in QGIS: It works great, with one exception: the background-color defined in the style should be #F2EFE9, but in QGIS, it just renders as white. You can see the difference ...
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1answer
23 views

QGIS Atlas - pages all exporting same extent

I am trying to export multiple map pages from QGIS using Atlas, I am used to doing this in ArcMap using Data Driven Pages so applying similar concepts to the Atlas but all the exported pages are ...
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0answers
26 views

Transforming to NED coordinate system

I’m working with a map that I've downloaded from OSM (EPSG:4326, using geopandas). Ideally, I would like to convert to a locally predefined NED (North-Ease-Down)/ENU(East-North-Up) coordinate system ...
3
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1answer
42 views

Auto-naming temporary layers in QGIS

I get a lot of temporary layers called 'Union' or 'Singlepart'. And then I lose myself in which layer is which in when for example I want to check geometry. Can I do so that QGIS is naming them '...
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0answers
31 views

How to make polygonal buffers with the criteria of being 100m close to a point in QGIS?

I am trying to create buffers around transit stations (which already is a vector layer with points) in QGIS. However, I've only been able to make round buffers of distance from each point, rather than ...

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