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

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12
votes
2answers
3k views

How to create a new empty vector layer programmatically?

I am new to python and QGIS. I have looked at a few tutorials of python scripts for QGIS. All of them create new vector and raster layers with some existing data source. eg. shapefile or geotiff or ...
11
votes
1answer
2k views

How do I build a custom form for entering attributes in QGIS

I've done this many times in ArcGIS and ArcPad but I don't even know where to start building a custom form for data entry in QGIS. I would like to do this for field operations--QGIS would make a good ...
8
votes
1answer
216 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; ...
6
votes
1answer
12k views

QGIS - Change unit of measure from degrees to meters

I am running QGIS 1.7.0 on windows, and I donwloaded a shapefile of census block group boundaries from TIGER. This file appears to be in the WGS 84 coordinate system, and when I open it in QGIS the ...
8
votes
1answer
5k views

Create a csv with geometry as WKT in QGIS (and choosing the field delimiter)

Is there a way to choose the field delimiter when exporting to CSV with geometry as wkt in QGIS? I have a shapefile with donut holes and I'd like to export it as a CSV. It's for a partner whose DB ...
4
votes
4answers
2k views

What is the projection of WGS84 in GIS software?

WGS84 is a reference ellipsoid that determines coordinates of every point on Earth using latitude, longitude and height about the its surface. This ellipsoid is often used as a base to make maps. ...
13
votes
1answer
715 views

How to setup QGIS Master and Stable in parallel on one Linux system?

I mainly use the QGis Master (nightly build) for my Debian Linux and I'm quite happy with it. But for educational and demonstration purposes, I now have to work with the Stable(1.8) version. How can ...
4
votes
1answer
521 views

Is there a purge function to remove layers from a qgs file which are not present in the Layers pane?

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 with a text editor the qgs file I see that it ...
4
votes
2answers
2k views

Adding a hotlink to an attribute field in QGIS

How to add hotlink to QGIS? I saw this but had some problem. I want to open network location like \\fileserver\filefolder\file1.excel but it ends with error. Edit: The network location is stored ...
11
votes
5answers
3k 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 ...
9
votes
1answer
440 views

How to render a table with mixed geometry types in QGIS?

I created a table with geometry type "GEOMETRY" AND inserted data of point, line and polygon type. My question is how to show this spatial data Qgis not supporting for geometry type "GEOMETRY".
9
votes
2answers
12k views

How to enable projection transformation in QGIS

My QGIS project has two layers, one layer is retrieved by Google layer plugin which fetches the static Google map image whose CRS is +proj=merc +lon_0=0 +lat_ts=0 +x_0=0 +y_0=0 +a=6378137 +b=6378137 ...
8
votes
1answer
416 views

How to address the new “Task-Completed” QgsMessageBar in Python?

I am really amazed what huge steps the QGIS development has taken in the last months. The new iconset, the improved Print composer and many more changes to be seen in QGIS 2.0 are really awesome! ...
7
votes
4answers
2k views

How to close watermarks window in QGIS Openlayers plugin?

I'm using Quantum GIS Ver. 1.7.4. I have upgraded openlayers plugin 0.7 to 0.9. However when I open google satellite, a watermarks/copyright dialog box "Data Peta@2012 ..." appear in the middle of the ...
7
votes
3answers
5k views

How to calculate raster statistics for polygons?

how can I calculate sums, averages etc of raster-points (multi-band) per polygon of a vector-layer. I was told that this is called "zonal statistics". I tried that with QGIS first. There is a way to ...
7
votes
3answers
4k 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 ...
6
votes
2answers
5k views

Is there a way to manually place labels in QGIS?

Is there a way to manually place labels in QGIS? I have a map which has almost-duplicate labels in some places (e.g. E 1st St and 1st St) and I'd like to remove some of them. Also, I'd like to move ...
4
votes
3answers
1k views

Finding centrelines from polygons?

I was wondering if there is a way to create centre lines from polygons in QGIS? I have a polygon layer, but ideally need the centrelines as a separate file. Thanks, Alan
3
votes
1answer
648 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 ...
1
vote
3answers
375 views

How to get shapefile of river from OpenStreetMap?

I dont want to download whole map of an area. I just want rivers and other waterbodies present in an area in shapefiles so that I can use them in Qgis. I tried geofabrik but it is giving whole map and ...
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 ...
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 ...
7
votes
4answers
670 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 ...
7
votes
3answers
5k views

How to access QGIS Plugin Repositories from behind a proxy?

I have been trying to teach myself QGIS by using this forum and others to help. Most of my questions can be answered by downloading plugins that are available through 3rd party repositories but for ...
6
votes
2answers
3k 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
1k 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 link to external files with relative path in QGIS actions?

Objective: I have point layers with attributes contain paths to external files (visio, autocad dwg...). I want to put them all in one folder together with the project file, compress the folder into a ...
5
votes
2answers
907 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 ...
4
votes
2answers
994 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
259 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 ...
4
votes
2answers
640 views

QGIS affine - form of equation

I am at the mercy of a govt authority who have provided utility information in a cad format with a 0,0 origin and a nonsense grid. About a dozen files, the grid and origin are entirely arbitrary. To ...
3
votes
2answers
841 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.
2
votes
3answers
656 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 ...
2
votes
1answer
1k views

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 ...
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
827 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 ...
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
3answers
595 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
656 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
291 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
3answers
1k views

QGIS 2 Python error on Mac OSX

Have just installed newly released QGIS 2.0. I installed the gdal package available at the official kyngchaos site. It seems to run ok, but when the program loads up I get a lengthy error message ...
3
votes
2answers
848 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
731 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
789 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 ...