Questions tagged [qgis]
QGIS is a cross-platform GIS application licensed under the GNU General Public License.
5,231
questions
174
votes
7answers
184k 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 ...
47
votes
7answers
43k 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 ...
24
votes
2answers
12k 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?
48
votes
3answers
61k 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/...
34
votes
8answers
38k 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 ...
34
votes
7answers
43k 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 ...
171
votes
6answers
395k views
Adding Basemaps from Google or Bing in QGIS
ArcGIS Desktop has the option of using basemaps from ArcGIS Online.
Does QGIS have any such options?
92
votes
5answers
207k views
Calculating polygon areas in QGIS?
How do I calculate areas of an area shapefile in square meters or in acres (ha)?
I didn't find that functionality in the vector tools.
20
votes
3answers
15k views
Problem with import qgis.core when writing a stand-alone PyQGIS script
I am trying to write a stand alone python script in windows 7 that uses qgis.core and various other qgis libraries.
I have found an old question on this subject here: Writing standalone Python ...
29
votes
6answers
36k 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 ...
49
votes
7answers
115k 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 ...
53
votes
13answers
19k views
Seeking QGIS 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 ...
32
votes
6answers
53k 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?
40
votes
5answers
68k views
Splitting shapefile into separate files for each feature using QGIS or SAGA [closed]
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 ...
33
votes
7answers
46k views
Performing Raster Reclassification in QGIS?
Is there a way to perform a reclassify of a raster image in QGIS?
In ArcGIS you can do that in Spatial analyst ToolsāReclassāReclassify
Any ideas?
54
votes
10answers
58k views
Removing small spaces (slivers) between polygons?
I have a set of polygons representing administrative districts. The districts were digitized by hand, and there are small spaces (slivers) between polygons where the polygons should be touching.
How ...
24
votes
1answer
27k 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 ...
60
votes
5answers
97k views
Clipping raster with vector boundaries using QGIS?
I am using 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 ...
22
votes
4answers
16k views
Finding centrelines from polygons in QGIS?
I was wondering if there is a way to create centre lines from polygons in QGIS? I have a polygon layer, but ideally need the centrelines as a separate file.
40
votes
1answer
23k 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=-...
18
votes
2answers
14k 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 |...
96
votes
4answers
220k 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 ...
15
votes
1answer
30k 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'...
17
votes
3answers
59k views
Create buffer in meters?
I'm very new to the GIS world, so my problem could be very stupid, but I'm going to try anyway.
Objective
Given a list of coordinates in longitude/latitude, stored as a .csv file, I want to create a ...
13
votes
2answers
43k views
How to calculate 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
length of the perimeter of each polygon?
21
votes
3answers
31k views
Adding Direction and Distance into Attribute table
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/...
27
votes
1answer
13k views
Filtering features in other layers of QGIS Atlas?
I'm trying to use the QGIS Atlas tools to build student 'scattermaps', ie. display the school and the students that attend that school, for 215 schools.
The schools layer is the coverage layer, and ...
18
votes
2answers
13k views
Accessing `processing` with Python?
I want to access the explode lines function in Python outside of QGIS from a standalone script.
What module do I have to load in order to use it?
How can I access processing?
from qgis.core import ...
5
votes
5answers
8k 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 ...
35
votes
6answers
23k views
Joining attributes from nearest point in QGIS?
I have two layers with points, call them 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 ...
35
votes
4answers
50k 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 ...
39
votes
4answers
62k 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 ...
45
votes
1answer
61k views
How to install a 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 ...
19
votes
3answers
99k 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 ...
3
votes
2answers
6k views
Getting incorrect slope values from an ASTER DEM in QGIS?
I have a DEM layer from ASTER satellite and I want to get the slope information from it.
I use terrain analysis > slope, but the output is so wrong. Why is that?
Here is the DEM:
And here is the "...
13
votes
2answers
19k views
How to completely uninstall and remove QGIS 2.8.1 on Windows Vista?
I want to uninstall and completely remove QGIS installation from my computer(windows vista). I have uninstalled it and when i try to reinstall it says it is already installed on the system.
19
votes
2answers
12k 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 ...
6
votes
4answers
7k views
Dissolving ploygons 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 ...
24
votes
9answers
50k views
Calculating latitude and longitude of points using QGIS
I'm trying to figure out how to calculate the lat/long of points using the QGIS Field Calculator.
Is there an easy way to do this?
I saw a previous related question (Using QGIS API and Python, to ...
43
votes
5answers
65k 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 ...
34
votes
8answers
42k views
How to set all pixels with value <= 0 to “nodata” in DEM raster?
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 calculations and to reduce the ...
11
votes
3answers
16k views
Installing ECW for QGIS in Ubuntu 12.04?
I have followed various online help guides on how to make ecw for QGIS 1.8 work in Ubuntu 12.04. I had it all working in Ubuntu 10.04 but since migration to 12.04 no such luck.
Is there a guide that ...
47
votes
9answers
61k 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 (eg vector overlay, analysis, etc). They do appear in the processing toolbox but there's no sign of them in the Vector menu. ...
25
votes
5answers
41k views
Creating fishnet grid Shapefile in QGIS?
How do I create a fishnet shapefile using QGIS?
The equivalent task of "Create Fishnet" in ArcGIS.
7
votes
2answers
4k 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 ntem ...
4
votes
1answer
2k views
Failed to create memory layers in QGIS application on Linux
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 (...
65
votes
5answers
45k views
Building effective heat-maps?
Using ArcGIS, QGIS, Grass, and/or GVSIG:
What are some of the tools and processes involved in building effective heat maps?
What are the plugins involved?
What are the major data requirements?
What ...
42
votes
7answers
24k views
How to create svg symbols that have modifiable fill color, stroke color and stroke width?
I want to create some svg symbols for Qgis using Inkscape, those symbols must have attributes as described in the question. For the last two days, I have been experimenting as instructed by Sourcepole ...
64
votes
3answers
89k views
Installing latest QGIS version on Ubuntu? [closed]
I am relatively new to Linux, so can you indicate the exact commands (step-by-step) that I need to type to get the latest QGIS installed on Ubuntu 14.04.
I have tried to follow the instructions ...
53
votes
2answers
97k 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 QGIS a lines layer, a points layer and a polygon layer.
What I'm trying to do is to select a polygon in the polygon layer ...
