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

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7
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1answer
1k 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 ...
6
votes
1answer
861 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, ...
6
votes
3answers
1k views

Is it possible to create 3D dxf with OGR?

Does anyone know if it's possible to create a 3D dxf with OGR. I would like to assign our contour lines a z value and export them to dxf for some cad work. PS I know FME can do this, however I would ...
4
votes
2answers
4k 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. ...
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 ...
9
votes
2answers
366 views

How do I generate a large number of maps?

I have to make a large number (hundreds) of distribution maps of species. I have a shapefile that contain the distributions for each species, and for each one, I would like to get a map as an image ...
8
votes
1answer
1k 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

How to display geoJSON from an URL in a layer?

I am looking for some type of plugin or code which would allow me to add a geojson URL, define the areas to input the lat/long variables from the visible Qgis canvas map and call/render the results ...
5
votes
4answers
3k views

How to change field length in QGIS

I have a shapefile I made in QGIS 1.7.4. One of the fields is a String of length 80. I'd like to make the field accept longer stings, but I can't figure out how to change its length. How do I do this? ...
4
votes
2answers
677 views

How to use map composer in a stand-alone script?

I'm trying to follow the map rendering section from the pyqgis cookbook, but I'd like to test this as a standalone application. I can do the first part, using simple rendering, but I'm a bit stuck ...
4
votes
5answers
5k views

Why can't I add most plugins under Ubuntu 12.04?

I loaded QGIS into 12.04 with much trouble but it works. Although I do not seem to be able to load most plugins. I go to fetch plugins and most are not loaded so I try to load some and they will not ...
4
votes
3answers
722 views

How do I specify a CRS for a fictional game map in QGIS?

I am about to start playing a steampunk RPG game called The Iron Realm, which uses a fictional world map. I have recently started using QGIS v1.7 and have no real experience with GIS sysstems. I have ...
3
votes
2answers
2k views

How to split a line at point positions?

I am a rooky with QGIS and i am stuck from a basic problems. I have a polyline and i have some points (2) on the polyline. I would like to know if there is a tool or script that i could use to ...
3
votes
3answers
2k views

Missing tools (icons) QGIS

I lost selection and navigation tools from the GGIS 1.8 toolbar when I tried drag then to different place. I can't get them back anymore. Where they disappear? All these tools are checked but are ...
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 ...
2
votes
2answers
1k views

QGIS Server Capabilities Response doesn't contain any Layers

This question is similar as this one QGIS Server not working (problem with fast CGI), but with more details: I installed the latest QGIS from trunk on Linux (Ubuntu 11.04) in the non-default location ...
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 ...
11
votes
5answers
4k views

Is it possible to connect to ArcSDE using QuantumGIS?

Is anyone aware of any plugins, or any other way to connect and view data from an ArcSDE database in Quantum GIS desktop?
9
votes
1answer
331 views

Is it possible to edit layers from a FGDB - File Geodatabse in QGIS?

I think I've found the answer (you can't edit FGDB's) but there seem to be few reports around that it is possible to edit FGDB files in QGIS. Can anyone advise if it's possible to setup QGIS ...
9
votes
4answers
7k views

Is there a SVG symbol library for qgis?

Im currently using default simple symbol capabilities or dingbat fonts for point objects. Is there maybe a SVG symbol library for qgis that is a bit more extensive than that which is included? I've ...
6
votes
1answer
7k views

How to crop Shapefiles in QGIS?

I need to clip a large and very detailed .shp file in QGIS showing environmental data similar to a temperature map. Is there something like the very simple crop tool alike in photoshop where you can ...
6
votes
2answers
4k 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 ...
5
votes
2answers
890 views

How to create curved labels in QGIS

I added an image, that explains my demand (see Schiefelsbach river). How can I do this? thanks
5
votes
4answers
6k 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
1answer
1k views

What is the best way to connect spatial data with attributes in Excel table?

I have many attributes which are stored in an Excel table. They refer to USA counties. I need to somehow connect those attributes to polygons in some format (don't know which is the best) and ...
4
votes
3answers
998 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
4
votes
1answer
1k views

How to perform Ordinary Kriging in SAGA via QGIS SEXTANTE Plug-in?

I'm trying to learn how to apply the kriging analysis in QGIS using the SEXTANTE plug-in and SAGA tools. It appears that I have my SEXTANTE and SAGA folders configured properly according to the user ...
4
votes
2answers
2k 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 ...
4
votes
1answer
917 views

Why does QGIS's Clipper tell me “Computed -srcwin falls outside raster size” and how do I address it?

I'm trying to clip a heightmap to a small area that I'm interested in. When I attempt to use Raster > Extraction > Clipper I get an error dialog with the message ""Computed -srcwin falls outside ...
4
votes
1answer
2k views

Loading a raster using QGIS into a PostGIS2.0 enabled database

Following on from my attempt to install a postgresql 9.1 db with postgis 2.0 on windows 7, I am trying to figure out how to load a raster. I have successfully loaded a shapefile, and am trying to do ...
3
votes
3answers
688 views

Auto-calculate field (area or formula)

I'm wondering if anyone has any insight into the potential to auto-calculate the value of a field, either area or distance (ideally) or a formula (based on the values of say 2 other fields, or an ...
3
votes
1answer
457 views

Getting dataProvider from vector layer outside QGIS

I'm using PyScripter to explore PyQGIS API because of it's very handy auto-completion function. I've managed to get a handle on a PostGis vector layer by: >>> from qgis.core import * ...
2
votes
2answers
232 views

Calculating elevation profile of a trail?

What would be the best way to calculate an elevation profile of a trail remotely (without using altimeter/gps tracking your steps)? For example, to do it in the most rudimentary way you might take a ...
1
vote
2answers
170 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
768 views

Polygon gradient fills / tint bands in QGIS

Is it possible to use a gradient fill on a polygon in QGIS? I would like to have my polygons with a colour at the edges, fading to clear/white as it moves away from the edge. The majority of the ...
7
votes
2answers
342 views

How do I use the Natural Earth SQLite DB with QGIS?

I just downloaded the Natural Earth data in SQLite format from http://www.naturalearthdata.com/downloads/. I had assumed that this would be a SpatiaLite database, but it appears not to be! QGIS is ...
7
votes
2answers
557 views

Easiest way to create historical street maps using QGIS

I want to make some historical street maps using QGIS. I understand how to upload a historical OS map from DigiMaps to QGIS, but I want to actually 'draw' the streets myself in order to have some ...
7
votes
2answers
1k views

How to use a field-to-RGB mapping for symbology in QGIS?

Using QGIS version 1.7. I have a plain text file that lists a set of rgb values against a code. I want to use this colour table to colour a polygon layer by mapping one of its attribute fields ...
6
votes
1answer
196 views

Why will QGIS only import the first 20 lines of my delimited text file?

I have a file of bird species and counts with Lat Long that I want to put into QGIS (2.0). However, when I add the file it only shows the first 20 entries (excluding the field titles). This is the ...
6
votes
3answers
974 views

How to fill a hole in a multi-polygon layer on QGIS 2?

I need to fill a hole in a multi-polygon layer on QGIS 2.0. I've set the snapping option for the layer as follows : mode: to vertex and segment tolerance 4 pixels avoid intersection "enabled" ...
6
votes
1answer
231 views

how to aggregate the rates, represented by points, within X radius

the point represents rates like 10%, etc. (this was also pretty clear from 2 years ago) -- been trying to do this for 2 yrs... the points dont represent numbers of events since they are rates ...
6
votes
4answers
1k views

How to sum up pixel values in QGIS?

I need to know the value of the sum of all pixels in a raster. However, in the Statistics section of the Metadata tab in Properties, under Sum of All Cells it always indicates 0.00. I have tried with ...
6
votes
2answers
3k views

How to change DEM's gradient colour?

I'm a newbie about GIS. I'm from Italy and I've got a *.tif file of my region. I've loaded it has raster but I have a question: The dem has a gradient colour magenta. How change this colour to ...
6
votes
4answers
4k views

How do I convert a polygon into a point?

I want to convert polygons into points. I know how it's done in ArcGis and I think this may sound trivial but it's a serious issue :/. I'll appreciate any hints :)
5
votes
2answers
454 views

How can I make segmented roads appear as one line?

I am footling around with Quantum GIS and the British OS Strategi dataset. If I render the roads with a simple line style they look fine: However, if I apply something slightly fancier, it looks ...
5
votes
2answers
370 views

How to accomplish conditional labeling based on map scale and attribute in QGIS 1.7

How can I label with qgis 1.7, based on attribute and scale of map? For example scale>1:1000 then label all those features whose area>100000 at font size 12 and those features whose area<99999 at ...
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
786 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
2k views

How can I transform a polygon to a linestring in QGIS?

I have a polygon, imported from a shapefile in QGIS. I would like transform it to a linestring instead so I can save it as a GPX file later. How can I transform a polygon to a linestring in QGIS?
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 ...