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

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2
votes
1answer
345 views

Keeping symbology style in a polygon shapefile when converting to KML

I have a polygon shape with 23 classes and have created patterned symbology styles which I will like to have retained when I open in Google earth pro. Is there any how I can achieve this in either ...
1
vote
1answer
108 views

How to fill column with several conditions using QGIS field calculator?

I know the synthax in order to fill one field with only one condition (field calculator): case When "attribut" = 'value' then value End But how to do populate automatically one field with ...
1
vote
1answer
42 views

What's the easiest way to generate many attribute-based depictions of the same layer?

I'm trying to show (in QGIS) how the distribution of 7 or 8 different attributes of a given shapefile vary across polygons within the layer. For a given attribute, this is simple (well, the basics ...
0
votes
0answers
14 views

Why nodes may link to remote ones?

I've noticed that sometimes when creating or editing lines or polygons some nodes may connect spontaneously with nodes in remote areas of the map, creating geometry problems. Why does it happen? Is ...
2
votes
1answer
320 views

Layer properties dialog in my QGIS plugin

I am developing a plugin which should display some information like geometry of the layer, feature count etc. Now those are currently displayed in QMessageBox.information. I want it to be displayed ...
3
votes
2answers
3k views

Connect to postgres localhost in QGIS

I am firly new to actively work with databases. I wanted to try out some stuff on my home computer where I have installed pgadmin and postgres previously. I can connect to my localhost in pgadmin but ...
4
votes
3answers
523 views

Separate a string value in two integers in QGIS

My problem is the following. I have a huge dataset of forest stands. All the information are separated but in many cases the stands have different age and this is marked in one attribute for example ...
0
votes
1answer
131 views

MySQL primary key column not visible in QGIS 2.6

I've tried adding a vector from Mysql table (Mysql 5.1, MyISAM) to QGIS 2.6. All columns are visible except Primary key column(s). Could anyone confirm this behaviour? Could we consider it a bug?
1
vote
0answers
127 views

Extracting the contents of a Google-KML file

I finally found all the datasets I could possibly need from http://globe.six.nsw.gov.au/ ...but a few hours later I'm not sure if it's possible to access this data into QGIS. I've tried MapWindow (w/...
2
votes
0answers
79 views

How to union linestring data distributed on multiple layers?

I have four shapefiles. Each contains a linestring as shown in the image. Each shapefile is represented as its own layer in QGIS. I would like to union these linestrings into one polygon which ...
1
vote
1answer
199 views

Select polygons that contains points in a separate shp file

I am a very new QGIS user and have years of experience using the basic functions of ARCGIS. I am having trouble using the select by location feature in QGIS. I have a point layer with locations of a ...
1
vote
2answers
353 views

Mean values of points within a polygon layer

I have 2 shape files (1x points and 1x polygons). The points have different values (soil sampling results). What I want to do is to calculate the mean values of the points inside the different ...
0
votes
2answers
133 views

Why are my transparent png tiles showing up weirdly in QGIS?

I have Ubuntu 14.04 running QGIS 2.6. I'm loading a raster layer, but the transparent PNG shows up poorly. The black lines along roads aren't showing up and the anti-aliasing looks off. I'm thinking ...
2
votes
1answer
84 views

Obtaining block structure from parcel data using QGIS or ArcGIS for Desktop?

I am trying to analyze the urban form of a city. I don't have the polygon file for streets, so I must derive block structure from parcel data (see image below). What tool could I use to accomplish ...
1
vote
1answer
108 views

Saga:processing resample extent in python editor QGIS

I would like to resample many geotiff layers to another geotiff layer's extent and pixel size. For this I would like to use the QGIS python console (editor). When I run my script it raises the ...
1
vote
1answer
85 views

Is it possible to add multiple labels for each element of a layer?

I want to add different labels for the elements of a layer. Example: One label with the number inside the marker. Another label above the marker with the name of the element, different typography ...
3
votes
2answers
123 views

QGIS (2.4) keeps caching old Python code

I'm fiddling around with a piece of python code to use with form validation. It works fine, but the real problem is that QGIS refuses to acknowledge the changes I make in the script. Here's what I ...
2
votes
1answer
402 views

How to deactivate my custom tool by pressing the Escape key using PyQGIS?

I'm developing a QGIS plugin and I have created a custom tool. Once the process is over, if the user presses the ESCAPE key, I want my custom tool not to trigger mouse events on the map anymore. How ...
2
votes
2answers
105 views

How to disolve lines from same layer?

How can I dissolve lines from the same layer so there are no borders in the junction? For example, a crossroad shouldn't have any border (not as seen in the picture). Can you help?
1
vote
1answer
2k views

Overlapping polygons in the same layer

I am working in QGIS on a vector layer where areas are classified using an attribute "typo". The problem I'm encountering is that many polygons are duplicated or overlapping, with the result that some ...
1
vote
1answer
364 views

Continuous raster legend in QGIS map composer

Is it possible to make continuous raster legend in QGIS? Something like in ArcGIS???
1
vote
1answer
85 views

Unable to find a specific GRASS add-on in QGIS

I would like to use the r.xtent add-on made for GRASS GIS (http://svn.osgeo.org/grass/grass-addons/grass6/raster/r.xtent/description.html) in QGIS using the GRASS plugin, but I can't seem to find it. ...
2
votes
1answer
161 views

How to calculate the sum of virtual fields

I have a set of data on track creation in a large forest, my job is to explore the cost implications of various layouts. I have a virtual field for track length and one which multiplies length by cost ...
2
votes
1answer
233 views

How to iterate over features and abort iteration with keypress in PyQGIS?

I would like to run a loop with PyQGIS, it should wait for the user to press a key either SpaceBar or Escape to continue. canvas = qgis.utils.iface.mapCanvas() aLayer = canvas.currentLayer() feat = ...
0
votes
1answer
55 views

How to snap already digitized polygons in different layers using QGIS?

As a newbie, I have digitized a lot of polygons without snapping them. Is there any way that I can add snapping to them aftervards? They are in different layers?
1
vote
0answers
216 views

Distance Matrix QGIS [closed]

I'm trying to get a distance matrix though QGIS, I have two different point layers to run the distance matrix and have input and target layers correct, output matrix type is Linear(n*k x 3) Use only ...
1
vote
1answer
128 views

Adding PostGIS raster to QGIS via database manager

When I attempt to add a PostGIS raster to QGIS I get a GDAL error saying I need to set PGHOST. I have set PGHOST with export PGHOST=localhost but still get the error. How can I resolve this problem?...
1
vote
1answer
200 views

Globcover 2009v2.3 Legend Qgis

How can I add a legend to a raster to the Globcover land cover dataset in QGIS without plugins? The data can be found here http://due.esrin.esa.int/globcover/ Unfortunately, as far as I know, QGIS ...
1
vote
1answer
208 views

Multiply whole column with the field calculator in QGIS

I have a layer with the field size. I did some mistake with the value and now I need the values multiplied by 16. But instead of going through 500 lines and recalculating them I would like QGIS to do ...
2
votes
1answer
135 views

How does fTools' Distance Matrix compute the distance and in what units?

I am new to GIS in general, and QGIS in particular. I am trying to find information about fTools' Distance Matrix function in QGIS, but am having trouble finding documentation…I managed to make a ...
0
votes
3answers
320 views

Exporting QGIS polygon shapefiles to Trimble Juno or similar

I am considering buying a Trimble Juno or similar hand-held field computer to assist with vegetation survey. My main need is to be able to see on it shapefile polygons drawn on my home PC in QGIS. I ...
1
vote
2answers
71 views

Splitting polgons in QGIS produces topology errors

I am trying to split existing polygons but when I do, gaps and overlaps are created between the polygon I am cutting and adjacent polygons. I have snapping switched on and have enabled topological ...
1
vote
2answers
280 views

QGIS opening file - Very slow on POSTGIS databse with many layers

When opening a qgis file with many layers (20 or so) it takes +5 minutes to load. All the layers come from a single PostGis database. When looking into the server logs, i see that there are many ...
2
votes
1answer
470 views

How to link my QGIS plugin main class to mouse events from a custom Tool?

I Have two files one is mouseevent.py and the other one main.py. class MouseClick(QgsMapTool): canvasDoubleClicked = QtCore.pyqtSignal(object, object) def __init__(self, canvas,layer,...
2
votes
1answer
312 views

Generate new geometric network from intersection between curent network and polygons

I have generated a stream network using the "Strea Reach and Watershed" tool from the TauDEM toolbox. Within the stream reach dataset there are fields that give an ID to the stream segment and ...
0
votes
1answer
381 views

export to GeoJSON coordinates in the reverse order

This question has been asked before, but I don't understand how to use the answer given by cengel. I want to make a GeoJSON file with lat long coords, not the default of long lat coords. I have a ...
4
votes
0answers
111 views

Integrating numeric scales into a text or HTML box in QGIS print composer.

I am trying to embed the scale of a map in the print composer expression builder or HTML frame. Effectively the value of the scale in the map item properties would come through into the text and be ...
11
votes
3answers
15k views

Installing the latest QGIS version on Ubuntu 14.04

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 ...
1
vote
1answer
55 views

What's the letter and word spacing unit in QGIS labeling?

I just want to know if letter and word spacing, in qgis labeling, are expressed in points, and if the value its absolute or relative to the font. I have searched a lot, but I can't find any ...
5
votes
3answers
664 views

great circles in QGIS and export in 3857 webmap

My plan is to visualize great circles in a leaflet webmap. So coming from this great postgis article and R version I thought it would work like this in QGIS: create line from two points, store ...
1
vote
0answers
45 views

“mapinfo qgis style converter” : error message

I would like convert a big point layer from .Tab toward .QML thanks to the plugin called "mapinfo qgis style converter" . The symbology of my layer is quite complexe (variables of coulours, shape, ...
1
vote
2answers
582 views

How to delete a shapefile from a directory using QGIS?

I am using the following code to clip a shape file using processing tools via Python and would like to delete the clipped file from the directory. Here is my code. from PyQt4.QtCore import * from ...
1
vote
0answers
578 views

qgis-bin.exe has stopped working after changing symbol selector?

i am having troubles with QGIS 2.6.1. It crashes when i try to change the symbol selector within each vector layer. If it doesnt crash it seems that the changes i have made in symbol selector do not ...
1
vote
0answers
19 views

How to fix the links clipped by an unconnected area in QGIS?

I'm trying to clip my target shape file with a given example area. The given example area looks like the following pic: And there is a river separating two areas. However there are links ...
2
votes
2answers
66 views

Why do I get green crossed circles instead when I try to move a point?

It's really horrible I must say. I sometimes have geometry issues and then try to go one by one through them and fix these cases. Therefore I mark the area points and delete them for instance. After ...
2
votes
1answer
114 views

Is there a way to give the drawing red polygon a higher alpha channel

Is it possible to set the alpha channel a bit higher when drawing? I don't mean the alphachannel of a already finished polygon, that's possible for sure! I mean the red area. It's really stressful ...
4
votes
1answer
1k views

How to clip a single layer of overlapping polygons in QGIS

I have a single layer of polygons. Some of the polygons overlap. I wish to make a new layer of just the parts of the polygons that overlap. What is the best way to do this in QGIS seeing it's ...
2
votes
2answers
150 views

Is it possible to redefine a projection in QGIS?

Is it possible to redefine a projection in QGis? It seems like the shape files offered by Agiv (a Flemish agency) differ slightly from the definition that QGis has of EPSG:31370. I'm NOT looking to ...
4
votes
3answers
597 views

Calculating file name with field calculator

Is it possible to calculate the file name in an attribute table? My shape file has a name like "cities.shp". In this shape file I want to have a attribute "cities").
2
votes
2answers
60 views

Clipping polygons within a certain range

I have a map consisting of polygons and a line. I need to a new shapefile of polygons that are to the west of the red line, and are between the northmost and the southmost ends of the line. How can I ...