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

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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 ...
6
votes
2answers
751 views

How do you calculate lat/lons from a PostGIS table which has a projected coordinate system?

I have a PostGIS table in a projected coordinate system (EPSG: 28355 or MGA94 Zone55). In QGIS (with the PostGIS manager plugin) I calculate a coordinate by performing the following SQL "UPDATE ...
2
votes
2answers
420 views

Error when setting projection of a tif file in QGIS. Any ideas to solve this? [closed]

I get this error when trying to define a projection for a tif file in QGIS: ERROR 1: Too many points (3249 out of 3249) failed to transform, unable to compute output bounds. How do i work this out? ...
14
votes
1answer
2k views

Voronoi polygons that run out to infinity

I have been working on implementing the voronoi.py script (Bill Simon's translation of Steve Fortune's code). According to the QGIS link it is basically the same code that I am working with, but the ...
1
vote
1answer
220 views

What is the shell command for the tool 'simplify geometry' in QGIS?

I was wanting to batch the tool 'simplify geometry' for a set of shapefiles, in the osgeo shell.
1
vote
1answer
778 views

Last edited information missing when used QGIS - Dxf to Shp

I am doing as constructed drawings which require the information to be in a GIS system and more specifically drainage as constructed drawings. I must have a separate file for Pipes and Pits. First I ...
2
votes
2answers
389 views

Shapefile CRS changed after exporting from QGIS. Are they equivalent?

I added a shapefile as a vector layer in qGIS 1.7 so that I could join in additional attribute data (not geodata) from another DBF file. The Shapefile that I added has this CRS (as far as I can tell ...
7
votes
2answers
2k views

QGIS and Raster Mapping in 'Seamless' layer

I would like to use Ordnance Survey base mapping in QGIS. I would like to set up something like a seamless table in MapInfo. I think that the equivalent in QGIS is a Virtual Raster Table. The files ...
2
votes
4answers
4k views

Export to new projection in QGIS 1.7

Suppose I have layers A and B. I don't know their projections but by the looks of the map I know they are not the same. In QGIS 1.6 I would use one of my favorite features: Vector> Data ...
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. ...
4
votes
2answers
309 views

Total newbie. Creating map from aerial photo of golf course in QGIS

I have a aerial photo in tif with a tfw file of the golf course that I work at. I would like to create vector data of different features on the course such as greens fairways tees, etc. to calculate ...
12
votes
3answers
4k views

How to join attributes from nearest point in QGIS?

I have two layers with points, call them A and B, each with different attributes. For each point in A I want to join all the attributes from the nearest point in B. Ideally this would also include ...
22
votes
5answers
4k views

How to identify clusters in vector point data?

I have a vector dataset of rural broadband data-points (how fast, etc.) and I'd like to explore if there are clusters of points with similar characteristics, and to plot polygons encompassing them. ...
0
votes
2answers
1k views

QGis import partial PostGIS layer using query builder

I'm sorry, but I'm terribly new to the GIS scene (and PostGIS & QGis). I have loaded a whole bunch of OpenStreetMap data into a PostGIS database and successfully drawn a map using Mapnik. Now I ...
10
votes
1answer
935 views

Is there a way to access QGIS plugins in Python?

Is there a way to access QGIS plugins in Python? I'd like to write a script to do some geoprocessing, and I'd like to use the clip, regular points and convex hull tools in fTools, as well as the Road ...
3
votes
2answers
2k views

How to Zoom in QGIS Print Composer Without a Scroll Wheel

I am attempting to print a simple map from QGIS in portrait orientation. When I use the "Add New Map" tool it brings the map in at an extent which matches my original data frame if I were to use ...
1
vote
1answer
378 views

Python console not loading with QGIS1.7-Ubuntu 10.04.2 LTS lucid,

Any tips on how to get the Python console working on Q-GIS (Quantum GIS)? (Its not working from the software's menu.) System: Python 2.6.5 QGIS1.7 OS Linux: Ubuntu 10.04.2 LTS lucid Error ...
21
votes
7answers
17k views

Removing small spaces (slivers) between polygons?

I have a set of polygons representing administrative districts. The districts were digitized by hand, and there are small spaces (slivers) between polygons where the polygons should be touching. How ...
3
votes
2answers
718 views

Overlaying GPX data on rasters in QGIS

I have a series of raster map images that I would like to use in QGIS and overlay some simple GPX routes over the top to produce a custom map image. This is all quite new to me so please bare with ...
2
votes
2answers
1k views

Problem reprojecting data from personal geodatabase using QGIS

I have a dataset in the form of a personal geodatabase (mdb) and am interested in using certain feature classes for further processing. My problem is - I am using USGS data orthoimagery which comes ...
7
votes
5answers
8k views

How to join multiple records to single feature?

apologies for what I'm guessing is a really easy problem to solve. GIS user, not programmer here. I'm trying to create a join/relate in QGIS where I have a shapefile of buildings and to that I would ...
6
votes
1answer
718 views

How to force QGIS Centroid Fill inside the Polygon?

I would like to use a centroid fill to enable me to place a letter inside a polygon. The advantage of using a centroid fill is that it also shows up in a legend, whereas labelling the layer would mean ...
5
votes
1answer
749 views

Vector Legend item names in QGIS Map Composer

Is it possible to get the text for a legend item to go over multiple lines? I have some long item names and I have a set legend width that I have to use. Without being able to make the text go over ...
5
votes
2answers
274 views

How to deal with multitype data sources in QGIS?

Today I was trying to import a DXF to Qgis, the result is that qgis displays everything LINES and POINTS but it only displays options for the POINT objects. When I try to export to a shapefile, it ...
2
votes
3answers
472 views

Has QGIS 1.7 been released as a stable version yet? [closed]

Has QGIS 1.7 been released as a stable version yet? I see on the QGIS site the windows download on the is still referring to 1.6 and the OSGEO4W install has 1.6.0-7 as the stable release. I had seen ...
25
votes
2answers
8k views

How to style beautiful road maps with QGIS?

I am trying to design a beautiful map using Qgis. As I'm a software developer not a designer, I was hoping that this will be easy, but it isn't! There is a similar question here Qgis tutorials and ...
5
votes
1answer
973 views

QGIS Data Management: How to calculate Standard Deviation?

does anyone know of a way to find the standard deviation of an attribute lying within any given polygon? The plugin dialog "Join Attributes by Location" gives only the options Mean, Min, Max, and Sum. ...
4
votes
2answers
274 views

How can I make my data efficient and “light” to do 3D Visualizations in Google Earth?

As a test run, I'd like to visualize population on census blocks for a few states (New England for example). I assume that the kml to do this will be huge, when you factor in the census boundaries and ...
3
votes
1answer
726 views

How to Solve the error - “Python Plugin is Broken”?

I tried following the steps to build a python plugin for QGIS. (step 3 is where I am stuck at) 1) I used the Plugin Builder plugin to build the initial set of files. I call my plugin ...
1
vote
1answer
289 views

How to get a composition name in Qgis python console?

In Qgis python console: I want to populate a list with compositions names, like in Composer Manager, but I can't figure out how to get the names (titles). So far: composerlist = ...
3
votes
1answer
1k views

How to import qgis.core in a Osgeo4W installation?

when I try to import qgis core module from python: from qgis.core import * I get this error: ImportError: DLL load failed: The operating system cannot run %1. Searching the web I found that I need ...
5
votes
1answer
760 views

How to insert 3d line into postgis database?

I have 3D line which I exported from GRASS in .shp format. When I try to insert this line to Postgis database with QuantumGIS, it gives an error: ERROR: Invalid type name - valid ones are: ...
6
votes
1answer
755 views

Can I specify a point and get all features within a certain radius of this point?

I have recently shifted to QGIS from ArcGIS and am looking for some help/pointers with the following: Does QGIS have a method by which I can specify a lat-lon coordinate (or a utm x,y coordinates, ...
20
votes
3answers
17k views

How to clip a raster with vector boundaries?

I am using QGIS. I would like to clip a raster precipitation layer using an admin boundary layer that is vector data. However the geoprocessing tools seem to be usable only for vector data. How can ...
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 ...
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 ...
19
votes
6answers
3k views

Creating a small web-mapping/map-tiling service

I am looking for a small-scale and easy way to present one or more polygon shapefiles online (on a municipal website without any existing map-server infrastructure, to be precise). Right now, I'm ...
5
votes
6answers
661 views

Southern hemisphere projections for Landsat upsets GRASS

Hi All does anyone have the last word on why Landsat scenes don't project in the southern hemisphere. This causes no end of trouble in GRASS, less so in QGIS. What I mean is, take an original scene ...
3
votes
0answers
867 views

How to create point labels from midpoints of road polylines in QGIS?

Heres what i want to achieve: i have a roading polyline layer (singlepart ie has several features per road, grouped by an id field), and i want to (after merging the parts) find the mid point of the ...
20
votes
5answers
4k views

How do I get the best print quality from QGIS (and is Arc better)?

QGIS exceeds my expectations by a country mile. I am impressed. But; I work with people who use Arc and they have found the best resolution output images are made by creating PDFs. They tell me that ...
9
votes
5answers
8k views

Can QGIS read an ODBC connection?

I have a co-worker who manages a large MS Access database that contains X & Y fields for various locations he tracks. We have previously exported the data to CSV and used the QGIS Delimited Text ...
1
vote
2answers
309 views

Is it possible to save PostGIS connection string in OGR add-in to QGIS?

In QGIS I've saved a couple of PostGIS connections for adding data. This works fine. I've been unable to save the connections in the OGR layer converter add-in though. Has anyone found a way to do ...
4
votes
2answers
915 views

Qgis is slow with complex 'postgis query' layer. How to speed up?

I have a postgis layer in Qgis that is a result of a complex query. Every screen update, Qgis runs the Query again and that's slow. Any suggestion on how to speed up? EDIT - Here is the query: ...
19
votes
3answers
3k views

How can I switch line direction in QGIS?

Something that is hopefully pretty easy. I would like to be able to swap the direction of a polyline/line in QGIS. I made a custom tool to do this in MapInfo a couple of years ago, however I can't ...
3
votes
1answer
198 views

SVN Version of GRASS and QGIS

I have GRASS6.5 SVN installed and wanted to go for SVN installation of Quantum GIS in Ubuntu 11.04. So as instructed in QGIS Wiki, I added the qgis repository to my sources.list file. Now I am able to ...
1
vote
2answers
3k views

Hyperlink relative paths to files in points layer in QGIS?

I would like to add hyperlinks to each point in a points layer in QGIS 1.7.0 running on Mac OS X 10.6.7, but I have several requirements: (1) Each hyperlink has to be a relative path to the linked ...
6
votes
3answers
407 views

Grass v.rast.stats returning null values

I have a vector layer (polygon) and a raster layer. The raster layer holds values for height above bald earth in a field called "value". I'd like the vector layer to inherit either the mean or the ...
4
votes
1answer
834 views

Can QGIS resample Rasters during display?

When I was using ArcGIS a user could resample a raster during the display (I think via layer properties under the display tab). This would smooth the appearance of the raster so it wouldn't appear ...
6
votes
1answer
566 views

In QGIS, how do I remove a band from a raster?

When I process a raster in QGIS it creates a second band. It appears that band has no useful data. I like to use the Raster Colours Tool and it will not accept a raster with anything more than on ...
3
votes
2answers
915 views

Change output file type in QGIS georeferencer?

I have successfully georeferenced a raster file via the Georeferencer plugin (Georeferencer GDAL Version 3.1.9) in QGIS 1.7.0. However, I noticed that the output georeferenced raster file is in TIFF ...