Questions tagged [qgis]

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

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18
votes
3answers
12k views

How to snap lines to points automatically?

I have two vector shapefiles: One file is points representing manholes and the other is a polyline file representing pipes leading to and from the manholes. I need to snap the lines within a ...
17
votes
6answers
32k views

Calculate bounding box coordinates of a selected polygon with QGIS

I just manually (and somewhat inaccurately I'm sure) retrieved the bounding box coordinates for a county polygon, which is a selection from a larger layer of county shapes. I'd like to be able to use ...
21
votes
2answers
28k views

Resample GeoTIFF images to the same resolution?

I have two geotiff images that I would like to resample the same resolution. If I use ArcGIS this would be easy to do. But using QGIS I don't know how to do this. Some help will be very appreciate. ...
17
votes
4answers
28k views

How to group and count attribute data?

I want to group and count features with the same code attribute value. I can classify the data and enable feature count in the layer list but I cannot get counts in the attribute table.
16
votes
4answers
6k views

How to create an OD road distance matrix in QGIS?

I'm looking for the steps required to produce an origin-destination (OD) cost matrix. What I'm looking for is a matrix of road distances. The distance matrix tool only produces euclidian distances. ...
14
votes
2answers
5k views

Moving points onto lines (~neighborhood)

I do have two vector layer, of which one is a point layer based on "events" by remote sensing and the second one is a line layer from local research. In my case these are earthquakes and tectonic ...
7
votes
3answers
5k views

High resolution, printable alternative to OpenLayers plugin for QGIS?

Are there any alternatives to OpenLayers plugin to have Google / Bing maps for QGIS projects? I need an high quality cartography (both aerial and street view) but OpenLayers plugin does not allow ...
29
votes
5answers
16k views

Change style properties of several layers simultaneously?

I'm working on bulk data. I have a few hundred GeoTIFF images imported into a QGIS project, and I'd like to modify their layer properties - things like the no-data-value, transparency of certain pixel ...
10
votes
1answer
12k views

Handling Many Raster Files in QGIS?

I have a project with a large number of raster files, but it is becoming very slow. I wonder which is the best way to handle all this. I'm simply georeferencing these files creating .wld file (geoTiff ...
9
votes
2answers
6k views

What are valid values for “data defined” labeling settings?

I'm using QGIS 1.8. I'd like to customize label features on an existing shapefile using the new label engine and it's "data defined settings" option. I'd like to know what the attribute table field ...
18
votes
5answers
38k views

Convert Shapefiles to GeoJSON?

I'm trying to convert Shapefiles from the State of Texas Senate Districts website into a GeoJSON file for use with Google Maps API. I'm using QGIS to facilitate but I can't get the projection/...
9
votes
3answers
12k views

How to configure Orfeo toolbox in QGIS 2.18 on Windows 7 32-Bit?

I had installed QGIS 2.18.3 using OSGeo4W and then the OTB standalone binary. In QGIS, I had manually entered the directory of the OTB applications folder (C:\Program Files\QGIS 2.18\apps\OTB-5.10.0-...
8
votes
2answers
2k views

Seeking purge function to remove layers from qgs file which are not present in Layers pane of QGIS?

I have some QGIS projects that I've been using for long time, adding and removing layers, updating reference to deleted or moved files etc. Opening the qgs file with a text editor I see that it ...
6
votes
1answer
5k views

Performing Ordinary Kriging in SAGA via QGIS SEXTANTE Plug-in?

I'm trying to learn how to apply the kriging analysis in QGIS using the SEXTANTE plug-in and SAGA tools. It appears that I have my SEXTANTE and SAGA folders configured properly according to the user ...
29
votes
2answers
53k views

Draw lines from points in QGIS

I have a point layer and need to draw a line passing through or in the vicinity of the points (up to 0.5m ditance between the point and the line). The nodes of the line will recieve the attributes of ...
11
votes
7answers
11k views

QGIS 2.14.1 LAStools install error: “wrong value for parameter 'Msys folder'…”

I went to step 4 from How to install LAStools toolbox in QGIS guide and extracted LAStools to my C drive and just made the folder there. I can't do step 8 because it seems to already be in "advanced ...
11
votes
2answers
6k views

Running QGIS from flash drive?

How can I setup a portable QGIS to run from a flash drive / USB-Stick? In the userguide for QGIS 1.7 Wroclaw there is only mentioned the option of "--configpath". But to me it is not clear how to deal ...
11
votes
2answers
12k views

How to change the value of an attribute using QgsFeature in PyQGIS?

I would like to update one attribute of a feature. However, I don't know to update it using the feature object. I have to use data provider to update it. layers = QgsMapLayerRegistry.instance()....
10
votes
1answer
10k views

How to reproject a raster file in QGIS with datum transformation?

I want to reproject a tiff raster file from projection A (ETRS89/UTM Zone 32) to projection B (DHDN/Gauss-Kruger zone 2). The two projections have a different datum so I have to use a datum ...
8
votes
1answer
10k views

GDAL scripts not found in QGIS 3 on OSX

I installed QGIS 3, and tried to execute tools like "sieve" "merge" and "polygonize". All of them gave me the error message: GDAL command output: /bin/sh: (scriptname).py: command not found I found ...
8
votes
1answer
1k views

What is the purpose of some functions and files in QGIS Python plugins?

I'm just trying to understand the architecture of a QGIS Plugin created with the QGIS Plugin Builder, as well as the workflow and the linkage among generated files. If possible, I'd prefer a diagram. ...
18
votes
1answer
4k views

Voronoi polygons that run out to infinity?

I have been working on implementing the voronoi.py script (Bill Simon's translation of Steve Fortune's code). According to the QGIS link it is basically the same code that I am working with, but the ...
16
votes
4answers
14k views

Extracting raster values and creating new raster in QGIS?

I want to extract certain values of a raster image in order to create a new raster which then should only contain the extracted/chosen values. How to do this in QGIS?
14
votes
5answers
18k views

Concatenating fields in field calculator of QGIS?

Is there a way to concatenate fields in field calculator of QGIS? (e.g. hectares + ' ha')
12
votes
5answers
13k views

Split a polygon layer with a line layer?

I am drawing administrative regions that have boundaries follow streets in another layer. As these streets are pretty long with many vertices, I don't want to re-trace them. I am looking for a way to "...
11
votes
2answers
8k views

QGIS calculate distance of point along a line

I have a polyline (movement path) and points recorded along the line. I would like to calculate for each point the distance along the line in Quantum GIS. I hope for a result which will add a new ...
6
votes
4answers
6k views

Finding middle point (midpoint) of line in QGIS?

How can I locate the coordinates of the middle point (midpoint) of a line feature in QGIS?
6
votes
3answers
8k views

How can I specify the CRS of a raster layer in pyqgis?

I manipulating netcdf raster data from the QGIS python console. The metadata of my netcdf file does not provide the Reference system. However I know it is 'EPSG:4326' I am writing a python script to ...
5
votes
1answer
3k views

Linear Referencing in QGIS?

I work for a survey company doing gas lines GIS. We use QGIS. We create hand drawn sketches of pipelines containing all sorts of information including: materials used, skew numbers of equipment ...
5
votes
2answers
2k views

How does QGIS calculate distances when the data is not projected (WGS84)?

I am playing a bit around with Qgis 2.14.6 to understand how it deals with distance measurement. I took a line-shapefile that I saved in 3 different coordinate systems (4326, 32642 and a national one ...
17
votes
2answers
8k views

Is QgsMapLayerRegistry removed in QGIS3?

Is QgsMapLayerRegistry going to be availabe in pyqgis with QGIS3 When I typed it into the QGIS python console (2.99), python seems to recognize it because it auto-completes qgis.core....
16
votes
4answers
61k views

How to Split Features in QGIS?

I am new at using QGIS. How can I simply split features in QGIS? The manual tells to simply draw a line through the polygon you want to split. But it doesn't work. The line disappears when finishing ...
13
votes
6answers
7k views

Georeferencing in QGIS 3.0?

I just upgraded to QGIS 3.0 (OS X as well on Windows 10) and can not find out how to do some georeferencing. I am told by the software, that GDAL georeferencing is still installed and that I could not ...
11
votes
1answer
3k views

Where is composition tab in QGIS Composer to change page size?

I am trying to change the page size in the QGIS 3.0 Composer but I am not able to see the Composition tab. I have right clicked an empty space in the toolbar but did not see anything about ...
11
votes
4answers
13k views

Converting/using ArcGIS *.style file for/in QGIS (QML or SLD)?

I have downloaded a dataset from a government organisation. it comes with a .style file. I use QGIS 1.8 on windows 7. Is there a way to use the .style file as a qml or sld? I have tried simply ...
7
votes
2answers
20k views

Why can't I edit attribute table imported through 'text as layer'

I imported the coordinates from an Excel table. They show as single points as intended. Now I want to add columns to the attribute table, but I'm not able to edit it. I wanted to import the following ...
6
votes
2answers
645 views

Odd behavior in a QGIS plugin: my function is triggered twice

I have a plugin with a function (triggered by a button) that selects a specific layer by name, then shows its attribute table. When I close the plugin and open it again, the attribute table pops up ...
5
votes
1answer
653 views

Error using grass v.clean: “ 'utf-8' codec can't decode byte… ”

I try running the v.clean tool using QGIS 3.4. As input I use a vector line layer (I checked the validity and everything is fine), but running the algorithm I get the following error: Traceback (most ...
4
votes
4answers
3k views

Installing QGIS on Ubuntu 14.04?

Following the QGIS installation guide I have tried both UbuntuGIS and QGIS stable, but both fail with the error message: The following packages have unmet dependencies: python-qgis : Depends: python-...
12
votes
1answer
23k views

How to filter features in a layer?

I am trying to display certain features in a shapefile-based layer using QGIS. I have found the subset function in the properties panel, which does exactly what i want, but is too tedious given that I ...
8
votes
3answers
3k views

How to set a default value for attributes in shapefiles?

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 explicitely sets the value. Is there a way to ...
5
votes
1answer
1k views

Qgis polygonize problem - DLL load fail

I have a raster file and I want to perform the method "polygonize". Then the problem occurs, that is shown on the screenshot. It doesn t have anything to do with the rasterfile format, I veryfied. ...
4
votes
2answers
7k views

Workflow for creating line features between two coordinate pairs in QGIS

I have a table of stream reaches with XY coordinates for their respective tops and bottoms. I'd like to convert the table to a feature, using the XY coordinates as the endpoints of the line. Any ...
4
votes
3answers
3k views

Join table field with shapefile programatically (via PyQgis)?

The following is currently unsuccessful at fulfilling a table field join to a point shapefile in Qgis. All instances of the join object will print the proper values, and no error is flagged when ...
4
votes
1answer
5k views

Getting GRASS plugin working in QGIS for Windows?

I've installed QGIS 2.16.3-1 on Windows 10 via the OSGeo4W 64-bit installer and also selected the following packages: grass (7.0.5-1) qgis-grass-plugin7 (2.16.3-1) qgis-grass-plugin-common (2.16.3-1) ...
3
votes
2answers
762 views

How to restore a scarp surface grid to calculate material loss

I would like to calculate the volume of material lost from a scarp like the one shown in the following image: Is there a way to do these calculations with open-source software such as GMT, QGIS and ...
3
votes
2answers
4k views

Making overview with linked detailed maps in QGIS?

i want to create 4-5 detailed maps, and then an overview map that has rectangles that markes the locations of the detailed maps. Best case would be if the rectangles were links to the detailed map. ...
2
votes
1answer
3k views

Setting QGIS Python version?

I have brewed python 2.7.3 onto my Mac (Lion), and installed shapely via pip install shapely. The Polygonizer plugin, however, does not find the shapely library. I see when QGIS loads a Python console,...
2
votes
4answers
3k views

How to get ECW support on QGIS 2.16 - Ubuntu 16.04?

after several attempts I am still not able to enable ECW support on QGIS on Ubuntu Xenial. Before updating to latest version of Ubuntu, solution proposed here worked for me on the same machine, but ...
16
votes
4answers
3k views

How to create a label combining different font sizes or types?

I would like to place the elevation-number of a point in a different front size and centred under its name: Is that possible? (That is my actual labeling: label || '\n' || elevation)