Questions tagged [qgis]

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

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Routing algorithm for generating isochrones using open route service

I am looking for a suitable tool for generating isochrones. I need to know the routing algorithm which is used by the tool that I will generate the isochrones using it. so I would like to know what is ...
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qgis 3.16 different results in volume calculation

I am trying to find ways to calculate a volume with : 1 base DEM resolution 1m 1 elevation DEM resolution 1m first method : using the extension volume calculation tool as follows. The result seems ...
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PyGIS Error: Algorithm qgis:joinattributesbylocation not found

i would like to join attributes by location but im getting error. Please help me :) I use QGIS 3.16 from qgis.core import * QgsApplication.setPrefixPath("C:/Program Files/QGIS 3.16/apps/qgis&...
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Data added in the attribute table is not visible as vector data on the referenced map

while adding point data in the map, the data is fed in the attribute table but is not visible on the map. neither is the line or polygon data being shown on the map. I am using QGIS 3.12 (Mac version)....
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Use core code of Qgis in my own python scripts

I would like to know if I can use the code of the default functions that come in Qgis. For example the intersection function. When you click on the help button it redirects you to the user guide where ...
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18 views

GPS points and streets intersection

My goal is to find an intersect between streets and GPS points in QGIS. The output should represent all of the GPS points (GpsLongitude, GpsLatitude) intersecting with streets. So basically in the end ...
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Iso4app parameters in QGIS

In Iso4app QGIS plugin, in the isochrone parameter window, how speed type and speed limit work? do they work based on the maximum allowed speed of the roads? or if we determine a speed level more than ...
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1answer
30 views

How to Group Parameters in PyQGIS Processing Plugin

The PyQGIS Processing Plugin I'm writing has a lot of parameters, most of which are advanced and won't be necessary for most users. I'm concerned that a user will be confused if they see all these ...
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Merge GPX tracks with PyQGIS / Python

I am having problems with my Python script (completely new to PyQGIS). I want to import all GPX-files from an given directory to QGIS, then change the Geometry type from MultiLineString to LineString (...
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24 views

Is a newer version of FlowMapper available? [closed]

I'm trying to use FlowMapper for QGIS. However, upon installing the plugin I get the following error message: My version of QGIS is 3.10.9, and this version of FlowMapper is apparently designed for ...
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1answer
30 views

How to Access the Current Value of the Scale Factor of a Map as a Variable (eg $map_scale) in Print Layouts in QGIS

Does anybody know how to access the current value of the scale factor of a map as a variable (eg $map_scale) in print layouts in QGIS? I'd love to put the scale factor in my maps...
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Setting the Python interpreter in PyCharm 2020.2.3, using QGIS 3.10.11. Error “No module qgis exists”

I'm trying to find out where I'm going wrong in trying to set up PyCharm to make standalone QGIS Python scripts. The very first step in the tutorial is "from qgis.core import *" I've tried ...
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1answer
39 views

Get version of installed QGIS from Windows command line

Tell me please, how can I get current version of installed QGIS from command line (batch-file). QGIS installed with Osgeo4w-installer. Registry search did not return any result.
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QGIS Get maximum sum of a feature subset in Atlas-View

I have a data-layer called data wich looks like this: I also have an atlas-layout with pagenames defined by the column Jahr from the another Layer, representing the unique values from the Data-Layer. ...
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37 views

How does coordinates in QGIS work?

So, I don't really have much knowledge about the coordinate system and sometimes I get stuck in certain things that I just can't get around it. For example, whenever I'm working with a vector that is ...
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21 views

NetCDF projection conversion to EPSG3857 is cropped in QGIS

I am using QGIS and PyQGIS to transform NetCDF files projection to EPSG:3857. My ultimate goal is export it as raster (TIFF or PNG) to display in Mapbox. When first imported, the NetCDF file itself ...
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1answer
51 views

How to create the road center line from the Grid-Polygon Shape file?

I have the shape files for the polygon part which are colored as yellow but there is no any specific shape file for the white parts( roads). Note: I have seen the same question here as below but it ...
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24 views

Including QGIS in QT on Windows

I am trying to include QGIS in Qt on my Windows system. I downloaded OSGeo4W and run this. It created OSGeo4W folder in my C drive. My Qt version is Qt 5.5.1 (MSVC 2013, 32 bit). When I try to run ...
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Cannot mannage to intgrate QGIS in QML/QUICK application

I turnaround to try make QML version of QGIS work. I manage to compile, but integration doesn't work. Even if the .dll is inside module, compiler always say that it's not reachable... How can I fix ...
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1answer
33 views

Join Attribute by location (Summary) not capturing all inputs

I created a 0.1 acre hexagonal grid and am trying to produce a heat map based on the respective polygon area that are found within a hexagon. I am using the Join Attribute by location (Summary) tool, ...
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Filter Feature Service layer by current extent [closed]

I'm trying to build a plugin to quickly add two feature server layers to QGIS. These are soil maps that are built up from a crapton of polygons. I'd like to be able add the layers from a python plugin ...
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2answers
70 views

QGIS How are data points of the same value classified for Equal Count (Quantile)?

For example, I have 100 data points and am classifying them using the Equal Count (Quantile) method. I want to have 5 classes, and in the ideal situation I will have 100/5 = 20 values in each class. ...
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1answer
32 views

QGIS Attribute Table on print layout not sorting

I've added in an attribute table to a print layout and am trying to sort numerically ascending using Plot Order For some reason it doesn't change order whatever field I use to sort the items in the ...
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21 views

Using glob to select all shapefiles in a subfolder within a for loop

I want to iterate a script through a number of subfolders within the folder TQ. Within each subfolder are a number of shapefiles that I need to merge and then rasterize. I created a for loop to ...
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21 views

QGIS refresh layer at interval

I am trying to understand the behavior of Layer->Render-> Refresh layer at interval in QGIS I sat up a flask rest api which serves a geojson. I added the geojson to QGIS via Add Layer-> a. ...
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1answer
25 views

Can you use Landsat 7 to make studies of land surface temperature, even though it has the scan line problem?

Is it recommended to use Landsat 7 to study the temperature of the surface? If you fill the gap of the scan line errors, would that gap filled give you different results from the original image?
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1answer
46 views

Convex hull that follows irregular points distribution

Based on an irregular distribution of points (longitude,latitude), I obtained the convex hull below (I use saga_cmd with polygon convexity in 1). Would you have a way to create a convex hull that ...
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32 views

Dissolve line based on same id and same value keeping the order from start to end

I have the solution for doing this in R but would like to avoid using other tools. Is it possible to dissolve lines with the value sections/features while keeping the start to end order and avoid ...
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1answer
23 views

Reading output of QNEAT3 plugin in R

If I create Iso-Area polygons using QNEAT3 plugin in QGIS, is it possible to get an output and read it in R for doing further data analysis? If yes, how can I do it?
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2answers
78 views

QGIS Geopackage export of layer symbology

I want to save several layer as one geopackage. That works fine. My problem is, that the layers in the geopackage have a different symbology than they had before. I found a video where you could ...
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1answer
24 views

QNEAT3 plugin and Iso-Area polygons

I need to generate isochrones considering emergency vehicle’s speed. I have checked several packages in R and different plugins in QGIS. I found QNEAT3 (Iso-Area as polygons) as the only tool that the ...
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18 views

GeoServer 'layer does not exist' exception (but everything works)

I have set up a simple GeoServer (2.17) isolated workspace with a store and corresponding layer. This is being taken from a simple GeoTIFF file. I am accessing this from QGIS for simplicity currently. ...
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22 views

QGIS 3.10 and data dependencies

I have one table call "LR - Données", with 2 attributes: 'LR nom français' and 'LR nom latin'. I have a point layer in a geopackage call "Observations" with 2 attributes: 'Nom ...
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32 views

Is it possible to fix Quick Maps layers not displaying properly when zoomed out in WGS84 in QGIS?

I often want to display some global point or polygon data over a base layer, to provide some context. Quick Maps layers like OpenStreetMap are handy for this, but these layers are usually in EPSG:3857,...
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1answer
30 views

Splitting feature into layers which are overlapped in same layer in QGIS

My script needs to select each feature in layer. While selecting features I found some of feature are overlapped. Feature can be selected but cannot highlight in map canvas. Is there any plugin or ...
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1answer
25 views

Does QGIS support WMS/WCS Connections that use path variables?

With QGIS, I have added and configured WMS and WCS connections for parameter queries as per the applicable specifications and I am able to add the layers and view imagery. However, I have a need to ...
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16 views

Add a CQL Filter to a WMS Layer in QGIS

I have a WMS Layer published by a geoserver instance. It has the capability of being filtered by a CQL Filter via GetMap CQL_FILTER query parameter. Adding it to QGIS works, but I can't find a place ...
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21 views

Error causing proximity not able to compute layer QGIS Command Line [closed]

enter image description here I've been struggling to create proximity (raster distance) within QGIS and I was wondering if anyone knew how to fix this problem, I'm also on mac.
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2answers
141 views

Moving multiple points using QGIS

I worked with a photo that is apparently a bit offset. Now I have more then 10,000 points with that offset. Now that I have the correct map I would like to move them all to their new location. Is ...
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19 views

Layer fields refactoring does not work for CSV export file

In my graphical model does not working refactoring layer fields. Entry layer has two fields, which first is string and second is integer. My Refactoring functions change first column to int and second ...
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1answer
23 views

Optimal Sentinel 2 Bands combination for NDMI

I want to calculate NDMI (Normalized Difference Moisture Index) using Sentinel 2 bands on QGIS. I am not sure if right formula is B8-B11 or B8A - B11. Band 8 seems to give better results but on the ...
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1answer
23 views

Selecting features by characters contained in a text string

Is there a way to select the features of a map by finding text within an attribute table? For example, if several features are listed as "Nature preserve" under a column called "...
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13 views

GeoServer Basic Auth Login Failures (but everything works)

I've set up GeoServer to use basic auth (oauth/oidc is a can of worms I dont like opening). I am testing it using QGIS. Everything seems to work fine in QGIS however I am getting a phenomenal spam of ...
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1answer
24 views

Using Points to Path Plug-in of QGIS

I was able to use the Points to Path plugin to create a simple line with a label in the middle: Here is the very simple text file I used: ID;GEOM "BL2990";"LINESTRING(490206.73 214102....
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29 views

Clipping raster is taking too long in 3.16.0-Hannover

Okay so I wanted to clip [this][1] raster with this [JPN_adm0.shp][2] file. It's been more than 6 hours and it's still on "Processing algorithm part." I have a decent PC that has 12GB of RAM ...
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1answer
28 views

PyQGIS image exporter adding scale

In QGIS I'd like to add scale to my PyQGIS image exporter. Similar to the Project -> Import/Export -> Export map to image where you can add the scale to the image as in the picture below. ...
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19 views

QGIS: prepare data for timeline animation

I have a data-spreadsheet containing a value-attribute that changes over time for a number of administrative units. I have a polygon layer as well with features for each of the administrative units. ...
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38 views

Isochrones for emergency vehicles

I need to generate isochrones for emergency vehicles. Is there any possibility of QGIS to do this? I checked TravelTime and QNEAT plugins but unfortunately, I could not find any way. With TravelTime ...
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15 views

Model designer issue, QGIS 3.14 on iMAC

I tried to make Model in Model designer but I don't see my new fields in designer window, but only the offer of the existing layers. What's wrong and what did I miss? There is no connection lines.
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3answers
198 views

Sorting text column by numbers with letters

I have a text column. It's made up of the numbers 1, 2, 3 up to 1650, which are currently not in increasing order. However, it also includes text such as 520a, 639a, 639b, 639c. Sorting on increasing ...

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