Questions tagged [qgis]

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

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3
votes
3answers
4k views

How to refresh MapCanvas while PyQGIS-script is running?

I try to write a PyQGIS script similar to this: Use of python console to prepare offline map from WMS (tile downloader). Basically there are two loops to pan the mapCanvas, refresh the mapCanvas and ...
24
votes
1answer
3k views

Creating sector lights in QGIS?

I'm using QGIS 2.18. I need to create sector lights for navigational purposes on a map. I have the light sector data as fields giving becon_id, start degree, end degree and color in a shapefile with ...
39
votes
5answers
16k views

Calculating average width of polygon? [closed]

I'm interested in examining the average width of a polygon that represents the road surface. I also have the road centerline as a vector (which is sometimes not exactly in the center). In this example,...
62
votes
4answers
35k views

Visualising WKT geometry string in QGIS

A very simple question: Is there a simple tool in QGIS to graphically visualise geometry formatted as text? Example geometry: "POLYGON((571178 6337246,571178 6402217,598061 6402217,598061 ...
57
votes
12answers
124k views

Creating point features with exact coordinates in QGIS?

How do I create point features with exact (manually entered) coordinates in QGIS? I get precise GPS coordinates from a survey team which I need to add to a point layer. What I want: -Add point, type ...
14
votes
1answer
5k views

Writing a python processing script with Qgis 3.0

Following the update to Qgis 3.0, it has become very difficult to find any information concerning the writing of processing scripts in Qgis 3.0. @Underdark (see here ) has provided a basis for the ...
17
votes
4answers
47k views

How to export Polygons to CSV with coordinates?

I am very new to QGIS, so please bear with me. I have a ".shp" file, which is contains a set of boundaries for suburbs of Australia. I opened it to QGIS and I would like to export it into a CSV file ...
26
votes
2answers
54k views

Joining several raster files using QGIS?

I'm new to QGIS. How can I combine multiple raster layers into one layer? The raster images are of different areas with very little overlap. The goal is to bring numerous town plats into one ...
11
votes
1answer
2k views

How to automatically populate fields instantly?

I am looking to create an attribute table where the first field is a drop-down menu (I have achieved this by using the 'value map' edit widget), but I'm struggling to find a method for the next part; ...
10
votes
2answers
13k views

Rotating a vector layer in QGIS with qgsAffine (or other method)?

I would like to rotate a set of vector points in QGIS an arbitrary number of degrees around a central point (or arbitrary point). This is similar to a recent question about creating a regular grid; ...
31
votes
4answers
29k views

Where does QGIS write its error log messages?

I want to read and copypaste the error log for the crashes I am experiencing in QGIS 2.0. The error I am getting freezes QGIS so I have to ctrl-alt-del. I can see the last message in the panel, but ...
8
votes
5answers
11k views

How to calculate distances in a point sequence?

I'm looking for help calculating the distance between a sequence of points that are in a single Shapefile in QGIS. Below is what my data look like and a blank distance column I've added to show how I'...
8
votes
2answers
15k views

Is there QGIS plugin to allow 3d visualisation of geological borehole data similar to functionality of Target for ArcGIS?

I'm very new to QGIS, I have started using it as my new company is not willing to pay for ArcGIS and Target at this stage so I'm hoping QGIS can substitute not just in the interim but for good. What ...
7
votes
1answer
4k views

How to evaluate raster calculator expressions from the console?

How can I execute from the console an expression that should be used with the raster calculator? I'm searching for something like this: qgis.someRasterCalcClass.evaluate("boh@1 + boh@2", "outputfile....
33
votes
2answers
16k views

Does QGIS have the equivalent of ArcGIS's Layer (*.LYR) file?

Using ArcMap, it is possible to add a dataset (eg a shapefile) to the map, and configure the layer's properties (such as the symbology, table joins, switching some attributes off in the Identify ...
33
votes
8answers
24k views

Creating shapefile showing footprints of Rasters?

I have around 1,000 satellite images in tiff format, and I want to create a shapefile which will serve as an index to the rasters. This is something similar to a raster catalog, but I do not want to ...
17
votes
2answers
14k views

How to check Topology in QGIS?

I have two Shapefiles with Polygons ( City and Forerst) Is there a Plugin who is able check the topology (QGIS)? Like "Knots do not overlap" or something like that? I dont want that they overlap. ...
9
votes
3answers
5k views

How to load memory output from QGIS processing?

Many processing algorithms have an option to save output as memory. If ran from toolbox, this works fine, because you can tick the "Open output file after running algorithm" box. Looking at the ...
8
votes
2answers
2k views

Plugins crashing with “No module named qgsprojectionselectionwidget” in Windows?

My Python QGIS plugin works on Ubuntu (at least for me, and all fatal bugs reported so far are solved), but when I run it on QGIS installed from the official 2.10.1 64-bit installer for Windows (on ...
18
votes
2answers
11k views

Is it possible to create Thiessen polygons around nodes in QGIS?

Is it possible to create Thiessen polygons around nodes in QGIS? e.g. http://en.wikipedia.org/wiki/Voronoi_diagram
16
votes
3answers
10k views

Calculating sum of parts of column based on another column using QGIS Field Calculator?

I would like to calculate the sum of values in one column, based on values in another column. To illustrate my question I uploaded the picture below. The second column consists of zipcodes, the third ...
11
votes
2answers
13k views

Google Maps not Showing in QGIS 2.12

The Google Maps in my OpenLayers plugin in QGIS 2.12 does not show anymore. The other maps do show, that is: OSM Bing MapQuest Stamen Apple Maps I tried in QGIS 2.8 and Google Maps does not show ...
11
votes
1answer
6k views

Displaying multiple fields as labels if one field is null in QGIS?

I am having some issues trying to show multiple fields for a single label in QGIS. In QGIS2.6, attempting to display labels for a feature consisting of multiple fields results in an empty label if one ...
6
votes
5answers
17k views

Measuring the distance between lines and points in QGIS

Using QGIS - I have a vector of fault lines. I have point data in the form of a csv which I have also loaded into QGIS. I need to know how far each point is from the nearest fault line then enter ...
12
votes
5answers
22k views

Is there a Rotate Tool in QGIS?

I can see the move tool. But coming across versions, i did not see any Rotate tool in Quantum GIS. As a hardcore feature editor myself, i have found it rather difficult. Am i missing something obvious?...
10
votes
3answers
22k views

How to create contour lines from point data using QGIS?

I'm using QGIS 2.4.0 and I have a shapefile of points with elevation data and X and Y coordinates. I'm using windows 7 OS. The idea is to create a contour line SHP using my point data. My question ...
10
votes
5answers
14k views

How to display special characters German “ÄÜÖß” in a map?

I have a shapefile with names for Regions. These don't seem to contain special characters but ugly hieroglyphs. What can I do do display them correctly. If I import the shape as UTF-8 it doesn't work.....
7
votes
2answers
4k views

How to move layers in the Layer Order Panel using PyQGIS?

Related to the following question but looking for a PyQGIS method: QGIS Layer Order Panel - add layers at top of layer order The following is a simple setup containing a group with three layers. ...
5
votes
5answers
9k views

Importing 3D DXF file into QGIS with z information as attribute value?

I have a dxf file of 3d contours. after import it does have only layer,x,y attribute and doesn't have Z attribute. How can I provide Z attribute to create a TIN file?
5
votes
1answer
689 views

Activating 'missing' standard GRASS utilities in QGIS Processing toolbox

I have been using QGIS and Grass for ages and while I've noticed this issue before, I've not been bothered by it until now. It is (hopefully) a bit of a noob question but when I open GRASS in the ...
5
votes
1answer
2k views

Is it possible to programmatically add calculated fields?

In the Memory provider described in PyQGIS Cookbook or in question How to create a new empty vector layer programmatically? I can see how to create a vector layer programmatically using standard ...
3
votes
1answer
5k views

How to round pixel values of a raster in QGIS?

I have a raster with float number values for example: 2.544459104537964 and I want to round these up to integers. I have seen other posts on ArcGIS like this one but when I use Raster Calculator in ...
9
votes
3answers
15k views

Change Shapefile data source encoding?

I tried to change the only the shapefile datasource encoding through properties and also How to encode shapefiles from LATIN1 to UTF-8? but it doesn't change it. Without saving the QGIS project can'...
8
votes
2answers
4k views

How to automatically reload raster layers if source is changed in QGIS?

How to automatically reloaded raster layer if source is changed? (The path is the same but inside source file are changes) I use: qgis.utils.iface.mapCanvas().refresh() but layer not refresh. # #...
8
votes
2answers
6k views

Cost Distance Analyst In QGIS?

Are there any tools, plugins or methods in QGIS which allows for an analysis of the best path between two points using least cost path method? As shown below ArcGIS has several distance tools.
7
votes
1answer
7k views

How to create a point along a line given distance

I have been given a non-spatial database which contains the names of lines which I have a shapefile for. The database also has names of points and the distance of each point from the origin along the ...
6
votes
1answer
782 views

How to generate multiple maps where one highlighted attribute changes?

I have a layer that contains counties within the state of Washington. I need to build one map (jpg) for each county. For that specific map all counties will show as light grey, but the specific ...
20
votes
5answers
23k views

Moving vectors to specified coordinates in QGIS?

I have a layer of vectors located around, say, (100, 100), and I want to move them to new coordinate like (1000, 1000). How should I do it using QGIS?
9
votes
3answers
2k views

Four color theorem for QGIS? (4 colour)

I recently looked at some other posts relating to this topic but as far as I can tell there is currently not a working plugin or script for QGIS 2.0 to achieve a four color theorem for styling polygon ...
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 ...
7
votes
2answers
813 views

How does QGIS Zonal Statistics handle partially overlapping pixels?

There are a couple Stackexchange posts asking this question, but neither of them were sufficiently answered: How does Zonal Statistics work exactly? How does Zonal statistics handle pixels that are ...
2
votes
3answers
12k views

Calculating slope in percentage with QGIS

I'm working with QGIS, v. 2.0.1. I have several soil types. They are (amongst others) described with slope indications. I already calculated the slope from the DTM in degrees, but as description of ...
9
votes
1answer
7k views

Enable 'on the fly' CRS transformation in QGIS 3?

In QGIS 2.8 there is a clear button to 'enable on the fly CRS transformation' in the "project properties" for a new project. Seen here: But in QGIS 3.0, I cannot find it to save my life. Can ...
7
votes
1answer
4k views

QGis Save Raster as Rendered Image

In QGIS 1.9.0 Master, when you right click on a raster in the Layers Panel and select "Save As", you can select the output mode to be "Raw Data" or "Renedered Image". When selecting the Rendered ...
6
votes
3answers
3k views

Unable to stylize raster data as pseudocolor render type on MAC OSX

In a raster layer's Style Properties, I can choose pseudocolor render type, and choose a color ramp and classify the raster. However, when I click the 'Apply' button, or click 'OK', the ...
5
votes
1answer
2k views

WMS layer in a QGIS 2.4 stand alone Python script

What is the best way to add a WMS layer on a map, in a stand-alone Python script with QGIS 2.4? The methodology explained at the bottom of the official QGIS documentation page seems to be outdated ...
44
votes
5answers
18k views

Smoothing DEM using GRASS?

I have a SRTM DEM and I want to create a shaded relief from it. I created the shaded relief in GRASS and the result is very nice, but a little rough because the area is near flat and the DEM is 90m in ...
24
votes
10answers
34k views

Installing QGIS on Ubuntu?

Has anyone had any luck with getting QGIS working on Ubuntu 12.04? I have tried the stable and unstable versions and with not luck. I also get the following: "Some packages could not be installed. ...
12
votes
2answers
14k views

Calculating shortest distance from point to line using QGIS?

What is the best method to calculate the distance from the nearest road for a series of address points in QGIS, having a very big dataset? (QGIS 2.0.1, Win XP) I read the answers to previous similar ...
31
votes
2answers
27k views

Handling multiple map frames with different layers in one print layout?

Often I need two (or more) map frames in map layout to present different data next to each other. It is easy to make multiple map frames in QGIS Print Composer. BUT... It is in the nature of my work ...