All Questions
6,728 questions
14
votes
1
answer
11k
views
Use QGIS expressions to create geometries: difference between geometry generator and geometry by expression
QGIS has a powerful expression machine that can be used (between other things) to create new geometries, based on existing layers. Basically, there are two options: Geometry generator (introduced in ...
- 74.9k
12
votes
1
answer
7k
views
Changing shapefiles from geographic (WGS84) to projected (EPSG:2263) coordinate system using QGIS
I am trying to calculate service area polygons using the QNEAT3 plug in tool for a project I am doing. However, I got an error before these polygons could be created.
2021-01-04T08:03:38 CRITICAL ...
- 203
184
votes
7
answers
238k
views
Installing File Geodatabase (*.gdb) support in QGIS
I have spent around 2 days to find the way to open GDB (ESRI Geodatabase) in QGIS (or any other open source software) but still without success.
I have downloaded the newest OSGeo4W installer and ...
- 9,794
49
votes
7
answers
48k
views
OpenLayers low resolution and/or shifts in QGIS print composer?
I'm having trouble with the OpenLayers Plugin of Qgis and the map composer:
If I create an OSM-background layer and if I want to export this, the OSM-Layer looks perfectly all right in the normal ...
- 2,331
7
votes
1
answer
2k
views
Understanding Coordinate Reference System of QGIS Project and Layer
I do not understand why there can be in QGIS different CRS for project and for layers. I have worked previously with subsurface petroleum software and there CRS "stuff" was lot more strict ...
- 659
124
votes
8
answers
370k
views
Calculating polygon areas in shapefile using QGIS
How do I calculate areas of an area shapefile in square meters (m²) or in acres (ha)?
I didn't find that functionality in the Vector Tools.
- 2,331
214
votes
7
answers
593k
views
Adding basemaps in QGIS
ArcGIS Desktop has the option of using basemaps from ArcGIS Online.
Does QGIS have any such options?
- 3,409
53
votes
3
answers
76k
views
Reprojecting vector layer in QGIS
I have a series of layers of lines (shapefiles) in My Project. The CRS of some are different and to merge them they all must have same CRS.
When I use Processing > Toolbox > Qgis_algorithims >...
- 531
27
votes
3
answers
17k
views
Displaying world country shapefiles centered on Pacific Ocean using Robinson or Miller Cylindrical projection in QGIS?
I wish to display a map in QGIS (world country shapefiles) showing all countries but centered on the Pacific area.
I am not familiar with Proj4, so is there any way this can be done in QGIS?
- 291
41
votes
10
answers
54k
views
Georeferencing vector layer with control points using QGIS?
I have a non-georeferenced vector layer that I need to be georeferenced. With raster layers the task is easy and straightforward, but I have no idea what should I do with my vector layer. I have a few ...
- 511
37
votes
7
answers
46k
views
Fixing geometry validity errors in QGIS 2
I am working on ownership data at a US county level. I have one shapefile per county that contains thousands of tax parcels. I need to dissolve the polygons representing parcels owned by the same ...
- 993
33
votes
3
answers
36k
views
Understanding "Join Attributes by Location" in QGIS
I wonder if there is somewhere an explanation for the parameters that can be set when running the Algorithm "Join Attributes by Location" in QGIS 2.18.
I had a look here:
Documentation QGIS Testing |...
- 3,480
27
votes
6
answers
26k
views
Finding centrelines from polygons in QGIS
I was wondering if there is a way to create center lines from polygons in QGIS?
I have a polygon layer, but ideally need the centerlines as a separate file.
- 2,483
9
votes
1
answer
5k
views
Layer is not valid error in my standalone PyQGIS script/app
I have written a python class which reads properties of map layers from an XML file and creates appropriate memory layers. I have developed and tested this code with QGIS 2.8.2 on a Windows 7 machine (...
- 4,678
60
votes
8
answers
174k
views
Getting list of coordinates for points in layer using QGIS?
I've got a layer in QGIS that is comprised of points. Its attribute table doesn't have (show) the corresponding x and y coordinates for each point. Is there a way for me to extract a list of ...
- 3,195
48
votes
4
answers
96k
views
Splitting shapefile into separate files for each feature using QGIS
I have a polyline shapefile with about 20 kinds of roads.
I would like to know how can I create automatically a vector file for each one.
I am aware of how to do it using ArcGIS Desktop - see ...
- 489
39
votes
7
answers
64k
views
Performing Raster Reclassification in QGIS
Is there a way to perform a reclassify of a raster image in QGIS?
In ArcGIS Desktop you can do that in Spatial analyst Tools→Reclass→Reclassify
- 3,464
32
votes
7
answers
44k
views
Joining multiple records to single feature using QGIS
I'm trying to create a join/relate in QGIS where I have a shapefile of buildings and to that I would like to join a non-spatial table (.csv-file) containing people who work in each building. So I have ...
- 321
37
votes
7
answers
63k
views
Changing CSV layer attribute value from text to number in QGIS?
I read in a CSV file for linking to a .shp file.
All the variables that are just numbers came in as text.
How do I change the text variables to numeric in QGIS?
- 1,015
70
votes
5
answers
140k
views
Clipping raster with vector boundaries using QGIS
In QGIS I would like to clip a raster precipitation layer using an admin boundary layer that is vector data. However the Geoprocessing tools seem to be usable only for vector data.
How can I clip this ...
- 701
116
votes
5
answers
302k
views
Merging multiple vector layers to one layer using QGIS
I've imported several shapefiles which where exported from a Mapinfo .tab. Several .tab-files are imported resulting in 20+ layers.
Afterwards I want to export it to GeoJSON; but I'm reluctant to ...
- 2,329
25
votes
1
answer
31k
views
Understanding QGIS buffer tool units
I have had no luck getting the buffer tool to accept anything but degrees as units of measure.
I have found lots of stuff saying the layer needs to be reprojected and saved but it hasn't worked at ...
- 353
53
votes
13
answers
20k
views
Seeking QGIS user interface tutorials and web resources
I wish to familiarize myself with the capabilities of QGIS up to and beyond QGIS version 3.0.
Can you recommend some good web resources and tutorials that would show me QGIS' capabilities?
I am ...
41
votes
1
answer
24k
views
Defining new custom projections in QGIS?
I'm trying to define a projection in QGIS. I want to add North America Albers Equal Area Conic. From the spatialreference site I copied the proj4 line:
+proj=aea +lat_1=20 +lat_2=60 +lat_0=40 +lon_0=-...
- 16.3k
33
votes
2
answers
25k
views
Filtering features in other layers of QGIS Atlas
I'm trying to use the QGIS Atlas tools to build student 'scattermaps', i.e. display the school and the students that attend that school, for 215 schools.
The schools layer is the coverage layer, and ...
- 18.9k
39
votes
9
answers
101k
views
Calculating latitude and longitude of points using QGIS
How do I easily calculate the lat/long of points using the QGIS Field Calculator?
I saw a previous related question (Using QGIS API and Python, to return latitude and longitude of point?), but it ...
- 16.3k
25
votes
4
answers
130k
views
Changing projection of shapefile in QGIS
How do I change the projection of my shapefile using QGIS?
The default projection is set to EPSG:3003, I want to change it to WGS84 EPSG:32632. When I do a reprojection or I change projection in the ...
- 513
25
votes
6
answers
53k
views
Filling holes in polygons using QGIS
Is there an option in QGIS to fill holes in polygons automatically by setting parameters e.g. maximum area, distance between borderlines?
I want to delete/fill holes that a very "thin"/small....
- 259
24
votes
4
answers
102k
views
Creating buffer in meters
Objective
Given a list of coordinates in longitude/latitude, stored as a .csv file, I want to create a buffer with distance of x km around those coordinates. (In case this is relevant, these ...
- 343
22
votes
3
answers
41k
views
Adding Direction and Distance into attribute table in QGIS
I just want to add direction (Bearing: i.e N 25 35 E) and Distance (Length: 125 meters) as my new field in polyline/line data.
Is there a Plugin to generate these fields?
I tried to used Export/Add ...
- 306
17
votes
1
answer
34k
views
Using Elseif Conditional Statement in QGIS Field Calculator?
I am trying to write an ELSEIF conditional statement in QGIS Field Calculator (version 1.8.0). I have used an example I found online:
CASE WHEN val < 0 THEN 'negative'
WHEN val = 0 THEN "neutral'...
- 9,549
59
votes
10
answers
98k
views
Missing Processing Tools in Vector Menu of QGIS
I'm missing all the usual processing tools in the Vector menu in QGIS 2.16 (e.g. Vector Overlay, Analysis, etc). They do appear in the processing toolbox but there's no sign of them in the Vector menu....
- 926
14
votes
2
answers
59k
views
Calculating polygon areas and perimeters using QGIS
Using QGIS, if I load a polygon layer and make a new column, how do I fill that column with the area of each polygon and another column with the length of the perimeter of each polygon?
- 1,015
5
votes
1
answer
2k
views
Fill attribute-table on feature-creation based on intersection with other layer
I am digitising line-features based on WGS-84 point-coordinates from a PDF which cannot be copied from.
The final line layer should contain lines which each connect two points and have the following ...
- 17.1k
43
votes
8
answers
76k
views
Setting all pixels with value <= 0 to "nodata" in DEM raster using QGIS
I am using QGIS.
I have a DEM raster with pixel values between about 3000 and -0.0003.
I need to set all pixel with a value of 0 and smaler (<=0) to "nodata" (for later raster ...
- 8,406
42
votes
5
answers
72k
views
Creating DEM from contours in QGIS
I have a shapefile with contours and their heights.
Is it possible to make a DEM from contours in QGIS without using GRASS?
I found Creating DEM from contours using ArcGIS Desktop? but the answer is ...
- 3,464
28
votes
6
answers
44k
views
Nearest distance between point and line layers in QGIS
I have two layers, a line and a point layer.
I need to make a line layer which connects all the points to the nearest line feature. How can I do that?
Is there a plugin available for QGIS?
This is a ...
- 2,425
50
votes
5
answers
98k
views
Smoothing/generalizing polygon in QGIS
Is it possible to smooth or generalize a polygon in QGIS, perhaps by using a plugin like the Generalizer Plugin for lines?
I could convert my polygons to lines, smooth them and convert them back to ...
- 8,406
46
votes
1
answer
65k
views
Installing QGIS plugin when offline
Due to various IT policies at my workplace, QGIS is installed on a machine that is not connected to the Internet. I wish to install a couple of QGIS plugins on this system.
I have downloaded the ...
- 41.6k
33
votes
5
answers
51k
views
Creating fishnet grid Shapefile in QGIS?
How do I create a fishnet shapefile using QGIS?
The equivalent task of "Create Fishnet" in ArcGIS.
- 3,563
20
votes
3
answers
24k
views
Splitting all lines in layer at vertices using QGIS
I want to automatically split all lines in a QGIS layer at their vertices (like this).
I've done a Google search and found this article, which is quite close but the workflow is complicated. Because I'...
- 2,024
15
votes
4
answers
10k
views
Setting default value for attributes in shapefiles using QGIS
In QGIS 2.14.6 I would like to define a default value for an attribute in a shapefile (or spatialite layer as well) which is applied if the user doesn't explicitly sets the value.
Is there a way to ...
- 14.9k
10
votes
2
answers
10k
views
Calculating proportional area of polygon within another layer's polygon using QGIS
I have two polygon layers, 'model' and 'ntem', whose features overlap and intersect one another.
I would like to calculate the proportion of the area of the 'model' polygons which fit within each '...
- 497
10
votes
4
answers
8k
views
Dissolving polygons in QGIS or GRASS to new polygons of defined population sizes
I have a shapefile with 3800 polygons representing the smallest administrative areas in Ireland. Many of these, in rural areas, have tiny populations, under 100 people. In urban areas, all would have ...
- 249
5
votes
5
answers
9k
views
Unable to install ECW support on lubuntu 14.04
I try unsuccessfully to install the ECW support (mainly to use ECW file in QGIS 2.2).
We attempt to follow and adapt the howto provided by makina-corpus.
My first supprise was the repository ...
- 53
66
votes
2
answers
159k
views
Selecting features within polygon from another layer using QGIS
I'm using QGIS 1.8 with a PostGIS database and I have three PostGIS layers in QGISL: a lines, a points, and a polygon.
I'm trying to select features in the polygon layer and mark all points within ...
- 661
41
votes
4
answers
66k
views
Loading OpenStreetMap data in QGIS?
In QGIS 1.8 I used the openstreetmap plugin to request data from the server, or open a .osm XML file, which produced 3 layers (polygons, polylines and points) in QGIS.
This was great (give or take ...
- 533
41
votes
6
answers
31k
views
Joining attributes from nearest point in QGIS
I have two layers with points, A and B, each with different attributes.
For each point in A, I want to join all the attributes from the nearest point in B.
Ideally, this would also include a field ...
- 692
23
votes
3
answers
20k
views
Accessing raster attribute table in QGIS?
I have some Python code that makes Raster Attribute Tables for GeoTiffs using GDAL.
In ArcGIS I can see these attribute tables fine and they behave how I like (as classifications) but in QGIS the ...
- 1,599
23
votes
2
answers
25k
views
Finding Georeferencer in QGIS
I'm using QGIS 3.26 and I can't find the Georeferencer.
I've basically looked everywhere. It should be in the raster section, but it isn't there. I checked all of my plugins if there was anything, but ...
- 231