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

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7
votes
3answers
5k views

QGIS- How to create an “area of interest” polygon mask

I've created a GP tool using ArcGIS that creates an "area of interest" mask from selected features. Effectively it creates a new donut polygon layer where the hole was the previously selected ...
5
votes
4answers
9k views

How do I load a .dbf file into QGIS?

I want to use QGIS to extract lat/lng data from the vertices of polygons. There are about 400 polygons, each with maybe 200 vertices. I am having trouble with step one, getting the data into QGIS. ...
4
votes
2answers
1k views

Misplaced Google Maps with OpenLayers plugin in QGIS?

I was using Google Maps with OpenLayers plugin in QGIS with my vector layer with projection EPSG:4326 with google map projection EPSG:3857 and "on the fly" transformation enabled. It was matching ...
4
votes
2answers
3k views

How to create heatmap (concentration of points) in QGIS?

There was already a question about it in 2010, where the answer was basically "use QGIS Heatmap plugin". I've also read on QGIS webpage that it is now "implemented as a native C++ plugin" My ...
3
votes
1answer
688 views

Hyperlinking in QGIS - Add Data to current window

I am looking to add to my current action in QGIS so that a hyperlinked file will open in the current QGIS window, rather than in a new window. Here is what my action looks like: "C:/Program Files ...
13
votes
2answers
1k views

How to overcome field truncation when converting OSM to shapefile with QGIS?

I am trying to convert an OpenStreetMap file into a shapefile, but I am having problems with the "tags" field being cut-off after 80 characters. With QGIS 1.4, I use the OpenStreetMap plugin to 'Load ...
12
votes
5answers
4k views

Get Raster Values from a Polygon Overlay in Opensource GIS Solutions

I have two layers. A polygon-shape-layer with many tiles and a raster-layer containing CORINE 2006 land cover with many categories in a colourmap. I want to obtain for each polygon in the shapelayer a ...
12
votes
3answers
6k views

How to move 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? Preferably using QGIS.
8
votes
4answers
846 views

assign and move centroids to their polygons

I m using QGIS 1.8 Lisboa. After calculating the centroids from a polygon shapefile, if some of them lie outside the polygon outlines, I'd like to move them on the polygon they came from. The ...
8
votes
2answers
2k views

How to correctly install QGIS with plugins and GRASS-integration from source?

I'm running a Sabayon GNU/Linux (based on Gentoo) at my home desktop system and I want to install Quantum-GIS. I'm currently using the qgis-1.7.0-package from the repositories. But this is somehow ...
6
votes
3answers
446 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. ...
6
votes
2answers
4k views

Using Field Calculator in QGIS to update columns with centroid coordinates

In QGIS I would like to update two columns with the centroid easting and northing of my polygons. I am using the field calculator. I have tried using $x and $y but this only seems to work for points. ...
5
votes
2answers
2k views

Exporting DEM-derived rasters to CSV from QGIS?

I have been able to import into QGIS a set of raster topographic maps and the associated DEM raster maps. It registered the two for me. From there I have calculated the associated slope raster map. ...
5
votes
2answers
1k views

How to automatically add vertices to lines every x meters?

I've made a vector grid using lines; the grid coverage is 100 km x 100 km and the lines are at vertical and horizontal intervals of 1000 metres. Each line in the grid is defined by two vertices, one ...
5
votes
1answer
4k views

qgis to local postgis connection - fails

It seems pretty clear I cannot connect to a local postgresql installation out of QGIS. This is my first experience with PostGIS. I am using PostgreSQL 9.0 on a win7 machine. I can see the successful ...
4
votes
2answers
164 views

Is it possible to edit a layer in QGIS while there is an active query?

I am new to Quantum and I am digitizing polygon layers using the editing features. I would like to apply simple queries ('date > 2012/08/01'), however while the query is active I cannot edit the ...
4
votes
2answers
1k views

How do I split polygons into line segments?

How can I split my polygon file into "segements"? The lines should be broken up like this picture shows:
4
votes
2answers
301 views

Is there a Legend Limiter in QGIS?

Is there in QGIS a function or a plugin that works similar to Legend Limiter in ArcGIS? The attribute I want to show in my legend has many possible values, I want my legend to only show those values ...
3
votes
3answers
815 views

How to add QGIS Python API Intellisense support in Aptana Studio3/Pydev

I'm developing QGIS plugins using PyDev in Aptana Studio 3 and I would like to know if it's possible to make it aware of the QGIS API and add some "intellisense" functionnalities when programming. For ...
3
votes
2answers
1k views

How to find the middle point of a line in QGIS

I am trying to locate the coordinates of the middle point of a line feature in QGIS. I tried searching online but can't seem to find an easy way to do this.
3
votes
3answers
6k views

Calculating the minimum distance between points and polygons in QGIS

I have two vector layers: one point and one polygon and I want to calculate the minimum distance of each point from the polygons (ie the distance from the closest point of the closest polygon). Is ...
1
vote
2answers
539 views

installing older version of QGIS on Ubuntu

I recently installed the latest version of QGIS (2.0) on my UBUNTU 12.04. But am not very satisfied with it. I would like to uninstall it and reinstall QGIS 1.8 v on Ubuntu. Am unable to do so. It ...
1
vote
1answer
3k views

'Couldn't load PyQGIS' after upgrade to Raring Ringtail?

I upgraded my Ubuntu to Raring Ringtail. After that, when starting QGIS I receive a message: Couldn't load PyQGIS. Python support will be disabled. Traceback (most recent call last): File "", ...
1
vote
3answers
2k views

Using QGIS with a pre-existing installation of Python 3.2 and matching GDAL

I need to have GDAL/OGR working with Python 3.2 because of another dependency. However, I also want to have QGIS for convenience. However, QGIS - FWTools in particular is built against Python 2.5, ...
1
vote
1answer
837 views

psycopg2 error with QGIS 1.5

So I just installed QGIS 1.5 using the windows installer not the osgeo4w one and now any plugins that need access to PostgreSQL databases don't seem to work, they all throw a: "Couldn't import Python ...
14
votes
3answers
2k views

Rubber sheeting in GRASS or QGIS

We are in the process of getting our property boundaries corrected and a side effect of this is that we need to move any assets that have been drawn relative to the property boundaries, so they are ...
7
votes
1answer
2k views

How to delete fields in QGIS?

When is the option to delete field in an attribute table enabled in QGIS? I'm in editing mode and still am not able to delete a field...
5
votes
4answers
140 views

How to Unsplit/Dissolve multiple touching lines in Stream Network?

I am trying to dissolve multiple lines for stream networks into individual features. The dataset contains many stream networks so a complete dissolve of the whole dataset wont do as I would like to ...
5
votes
4answers
8k 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 ...
4
votes
5answers
1k views

How to fix quickly a lot of geometry validity errors in QGIS?

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 ...
4
votes
2answers
891 views

QGIS relations widget in custom form

I've just begun exploring QGIS relations option, now in version QGIS 2.2, details here: http://blog.vitu.ch/10112013-1201/qgis-relations This is a great implementation of something I've been ...
4
votes
2answers
2k views

Installing qgis 2.0 and saga 2.1 on ubuntu 13.04

I have been trying to get this working for a few weeks now. I am trying to install QGIS Dufor (2.0.1) and Saga GIS from the Unstable branch of the UbuntuGIS PPA. When I attempt to do this I get the ...
4
votes
3answers
765 views

no Get More in Plugin Manager in qgis 2 + ubuntu 13.04

After upgrade of qgis 1.8 to qgis 2.0 I couldn't find the choice "Get more" in Plugin Manager and I can't install plugins.
4
votes
1answer
1k views

Why does Google satellite layer change the project CRS?

I have a project and a topomap in WGS84 (EPSG4326). On the fly CRS transformation is activated. I open Google satellite layer from the OpenLayers plugin. The Google layer is WGS84 / Pseudo Mercator ...
4
votes
3answers
1k views

Convert an arbitrary meta-data-free map image into QGIS project

My background: experienced programmer, amateur historian, complete beginner to GIS (so I'm using QGIS). I did learn to use the QGIS georeferencer tool though. The input: suppose I have an image like ...
4
votes
2answers
6k views

How to use Distance Matrix tool in QGIS?

I have a point data set. Now there are cluster of points based on a field. So I take out one such cluster which has points with same field.I want to find distance between all the points in cluster and ...
3
votes
2answers
92 views

CRS reprojection

I am trying to change the CRS of one shapefile that is originally in NAD27 to WGS84 in Qgis 2.6. When I proceed to make the change, I still continue to see the file in UTM coordinates... I've tried to ...
3
votes
2answers
1k views

QGIS GISBASE specify location

I am just a beginner at this QGIS and GRASS and I am using this QGIS 2.0.1 Dufour which throws a error at the startup that "QGIS couldn't find your GRASS installation. Would you like to ...
3
votes
2answers
797 views

keep the same field headers after joining a table to a shape file in QGIS

I noticed that after joining a table to a shape file the headers of each fields in the table used for the join are changed by QGIS and they are attributed to a different name. For instance, i had a ...
3
votes
2answers
462 views

QGIS DB manager Import layer/file tool won't allow me to choose “Append data to table”

I want to append some data to a layer in my PostGIS DB using a shapefile, but when I use the Import layer/file tool in QGIS, it doesn't allow me to choose the append option. Why is this and how do I ...
3
votes
1answer
317 views

How to update data from external table in real time?

I have been trying for a long time to connect a external table data[csv] through Excel (for exmaple) with QGis with the objective to each time i change any data in table(for example data location - ...
3
votes
2answers
3k views

How to install the Python module shapely for QGIS use?

I'm using QGIS 1.8.0 on a Mac with OSX 10.6.8 (Snow Leopard). I've installed QGIS including GDAL, GSL, UNIXImageIO, Freetype, and Matplotlib all from www.kyngchaos.com. When installing the plugin ...
3
votes
2answers
1k views

How to calculate the area of rasters in QGIS?

I have been working with some rasters and would like to know how to calculate the area occupied by one element of a raster in Qgis.
3
votes
1answer
839 views

Does anyone have a shapely install for python “dummies” guide?

I have read both questions in regard to installing shapely on a Mac (OS Mountain Lion) and haven't been able to figure it out. I'm not familiar with python syntax and am just trying to get shapely ...
3
votes
1answer
2k views

find polygon corner coordinates

I am trying to get the coordinates of each node of the polygon I create. I would like the attribute table to display the name of the polygon (ex. address) and then the coordinates of the nodes (ex. ...
3
votes
1answer
1k views

How can I save the label style as SLD in QGIS?

In QGIS there are 2 options to style labels. Using the style properties. Using the label in the toolbox When I dbl click layer -> styles -> save as SLD , the style of the label isn't saved in ...
3
votes
3answers
5k views

How to install Python libs for XYtools to read Excel files

I need to use the XYtools plugin to read an Excel file. After choosing the XYtools incon and indicating an Excel file to read in, a message appears "there is a problem with loading a python module ...
3
votes
3answers
2k views

Why is QGIS not launching?

I've got a problem using qGIS. Always when I try to launch the programme with the desktop icon, nothing happens. I also checked the Task Manager and it doesn't show any process running regarding qGIS. ...
3
votes
1answer
2k views

How to draw a cross section in QGIS

Given my enthusiasm for QGIS, does anyone have a simple workflow for drawing cross sections of earth features? My thing is that QGIS is being used to present the plan view, but we have a little ...
3
votes
1answer
2k views

How to install SDA4PP plugin for Kriging in QGIS?

I am trying to do kriging in QGIS. I have loaded the SDA4PP plug in. Almost all of the items in the SDA4PP dropdown menu are not highlighted and are unresponsive when clicked on - including the ...