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

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6
votes
2answers
1k views

Raster generalization - buffers in rasters, expand pixels?

Is it possible to create buffers for pixels of raster files? Actually I need to expand the pixels classified as 1 (in white in the figure) with a spatial range of 1 or 2 pixels, in order to perform ...
6
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...
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
645 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
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
5k 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
811 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
336 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
2answers
913 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
767 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
881 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
4k 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
2answers
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 ...
3
votes
4answers
1k views

When labelling polygons, not all labels are displayed - QGIS 1.7.0

I am trying to create a simple map of Mexico showing the state polygons and their label. The state shapefile is from here, and the specific file is the first one from the top (Áreas Geoestadísticas ...
2
votes
2answers
69 views

Is there any way to 'clean' up ASTER v2 DEM data?

I downloaded all the tiles I needed, then plotted them to find that they don't all seem to have the same quality. Basically, you can see all the edges of a lot of the tiles. Is there any way to clean ...
2
votes
0answers
142 views

Problem loading output layer QGIS

Every time I run operations with temporary file output from the graphical modeler, I get the following error message: Oooops! The following output layers could not be open CLIP: ...
2
votes
2answers
2k 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 ...
2
votes
1answer
366 views

QGIS rounds up the coordinates to six decimals when saving layer changes

I have the problem that when I create a new point (in a point layer) or a new line (in a line layer of course) and I save the changes to the layer (so NOT the project save) then QGIS rounds up the ...
2
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. ...
2
votes
1answer
363 views

Flattening JP2 files to single band (i.e. averaging bands)?

I have created thousands of png tiles using ArcGIS and have merged groups of them into large jp2 files for serving via GeoServer. I need to flatten these to a single band so that I can apply a colour ...
2
votes
1answer
2k views

Convert area from square meters to degrees globally

I have a global raster file with 3600x1800 pixels. I don't have any information about the projection used. The raster contains one band with a quantity with the unit "per square meter". How can I ...
2
votes
0answers
777 views

OSGB36 to WGS84 reprojection 'error'

First off, I am a recent convert to QGIS and am greatly impressed with its ease of use and speed compared with the ESRI products with which I am more familiar - my congratulations and thanks to its ...
2
votes
1answer
4k views

Import MySQL Spatial vector layer in QGIS

I have a spatial table called 'places' in MySQL, with a spatial column 'pt' (point). I tried to import it in QGIS and no points appear. I created a view 'places_as_text' which reproduces the table but ...
1
vote
2answers
538 views

Qgis server on Ubuntu Server 14.04: Permission denied

I'm trying to install and configure Qgis Server (2.0.1) on a virtual server with ubuntu 14.04, Apache 2.4.7. After trying to install normally, the server gave me 404 error, so I tried to add ...
1
vote
5answers
1k 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 ...
1
vote
1answer
153 views

pgrouting unexpected output

Thats my ways.shp file. I loaded this to PostgreSQL DB using PostGIS shape file loader. I ran pgr_anlayzeGraph() on it and found it had a lot of isolated segments. Next I ran pgr_nodeNetwork() to ...
1
vote
1answer
542 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 ...
1
vote
2answers
429 views

Any QGIS 2.0 updated RPM for Fedora?

I'm very excited about the new release of QGIS (2.0), and would like to install it on my Fedora 18 machine. I couldn't find any relevant RPMs, and the documentation on the QGIS main site for Fedora is ...
1
vote
3answers
769 views

Can I use QGIS with Qt5?

I want to use QGIS with Qt 5.But i don't know the exact relationship between Qt and QGIS.Will there some problems if i use qgis with qt5 or it will not depand on it...
1
vote
1answer
178 views

QGIS Crashes when writing to PDF

8 Lisboa. I have a very large mapper. Formatted to A1 size with a large area and constraints laid across it. Everytime i try to write to pdf it crashes. It is just due to the size of the file. I ...
0
votes
2answers
964 views

How to Join Attributes by Location in QGIS 1.8.0

I have a points layer with site attributes and a polygon layer with region attributes. I'd like to join the names of the regions to the point site locations using QGIS 1.8.0., on Windows XP. ...
-3
votes
1answer
242 views

How to extract drainage line network from GRASS GIS and QGIS [closed]

Giving DEM as input is there any way to get drainage network? I am newbie to GRASS and QGIS ,provide any working examples in GRASS GIS and QGIS with procedure.
21
votes
3answers
3k views

What do I need to know, to develop a plugin for QGIS?

I wish to develop a simple plugin for QGIS, which will open some data, and some specific processing. I have quite a it of development experience with ESRI's Arcojects, but haven't developed with QGIS ...
18
votes
3answers
4k views

How to easily edit attribute data using Regular Expressions?

I am writing a tutorial for MSc students that uses QGIS. One of the tasks requires the attribute data to be modified (see pdf draft of tutorial here if interested ). The question is how to get them ...
13
votes
6answers
929 views

Which topics are essential for a crash course in QGIS?

What topics do you think are essential in a 25-hour "crash course" introduction for Quantum GIS? What topics do you think are nice extras to be included in such a course? Target audience: Zero or ...
10
votes
2answers
10k views

How to Add OSM Layer to QGIS

How can i add OSM layer in QGIS? The help says there is an OSM plugin i can use. But i don't see it the list of plugins. Or maybe there is a WMS URL for OSM i can use? QGIS version ...
10
votes
2answers
2k views

How do you display related records in QGIS?

Coming from an esri background I have always used relationship classes in a gdb to display records related to a feature. Eg. Relate 1 survey point to many documents, photos etc. Does any one know how ...
5
votes
2answers
5k views

How to connect to Postgres with QGIS?

Oddly, it should be simple, but I can't connect to a local PostGIS database. My installation is with Mac OS X (10.8), Postgres.app (in doc it's said to have PostGIS included) and Quantum GIS 1.8. ...
4
votes
1answer
2k views

QGIS on Mavericks

I have been trying to install QGIS on Mavericks and I have failed. Prior to installing QGIS, I installed GDAL using homebrew. I also installed Numpy, SciPy and pyqt using the detailed instructions ...
10
votes
1answer
2k views

How to create desire lines in QGIS?

How can I show the flow coming from an Origin-Destination matrix as desire lines? I need a result like the one in the picture below. I need to scale them proportionally to its value (coming from a ...
8
votes
1answer
2k views

One to Many Relationship in QGIS with PostGIS

Does anyone know of any tool that can do a One-to-Many relationship in QGIS. I have my data in a PostGIS database. I would like to be able to query spatial layers that are related to spatial or non ...
5
votes
3answers
1k views

Developing Web Application For Map

I have huge data of maps usually most of the table are co-ordinates and the other are raster maps stored in SQL server 2008 and PostGres Server. I am using desktop application to analyse the data. ...
15
votes
6answers
1k views

Can I transfer custom QGIS settings from one computer to another?

Can I export custom general settings from my QGIS installation to a file so that I can transfer the settings to QGIS on a different computer? Does QGIS have them already saved to a file located ...
9
votes
3answers
3k views

Divide a complex shape file into a grid

I have a decently detailed shapefile with polygon/multipolygon features (the file is about 500mb). It's actually a shapefile of the entire world, with the features representing coastlines. I need to ...
6
votes
1answer
971 views

Open source tool for point/node conflation/matching?

The Question Are there any open source tools for conflating (matching) two layers of point (node) data? Motivation I'm particularly interested in using such a tool to sync data with OpenStreetMap, ...
2
votes
2answers
1k views

How to create a map with states by attribute value?

I'm using Qgis, but I am quite familiar with R and python. So I could use any of these. I want a map of mexico but want to color the stats according to a certain variable. It goes from 0 to 100. So ...
14
votes
2answers
2k views

Creating Thiessen (Voronoi) polygons using lines (rather than points) as the input features?

I have a set of line features inside a particular polygonal boundary. For each line, I'd like to generate a polygon inside which every possible point is closer to the given line than to any other line ...
13
votes
1answer
2k views

How to have a drop down list for feature editing (attributes) in Quantum GIS?

I'm editing a lot of polygons of a shapefile in QGIS and i need to classify them, so i have to write the classes a repetedly a lot of times. In ArcMap there is an option to have domains set for the ...