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

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5
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1k views

How to calculate the size of a particular area below a buffer in QGIS

I have a point shapefile of villages where data was collected in Northern Kenya. I created a buffer around those villages. The second vector layer contains polygons defining areas according to ...
5
votes
3answers
1k views

How to find line length in QGIS while editing?

I am using QGIS (before, I used ArcView). I would like to know if there is any way during the editing phase of a vector (line or polygon) to know the length of the line (total and partial) that is ...
3
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1answer
369 views

How do I get the x- and y-coordinate values of points in UTM using QGIS?

To get to know the size of the study area and how far objects are separated, I need to know x- and y-coordinate values. Although the $x and $y of Field Calculator returned latitudes and longitudes, ...
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vote
1answer
480 views

How to use buffers to estimate the attribute data for a given polygon?

I have two layers: point and a polygon. The point layer has lat/long and I have created buffers of a 1/4 mile. The polygon layer has data such as age and income. Is there a plug-in that can ...
4
votes
1answer
227 views

Migrating Feature Datasets from ArcSDE to postgis

I am currently planning the migration of a database from ArcSDE/ Arcmap to postgis / Qgis. The data is stored in raster catalogues and feature datasets. Is there an equivalent to feature datasets ...
2
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1answer
629 views

QGIS 1.7.1 and PyQT4 conflict: what am I doing wrong?

I've just started playing with QGIS with a view to eventually developing a few simple plugins in Python. I downloaded QGIS 1.7.1 for Windows and started working through these workshop notes. If I've ...
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vote
1answer
614 views

How to change the the style of a vector layer programmatically?

I want to change the style of the polygon contained in the vector layer. Is there any API available? (I can click the properties of the shapefile, then select the style and change the symbol ...
6
votes
1answer
924 views

Is there a way to automatically snap loose points of lines to close by vertices with Quantum GIS?

I have a vector layer of lines that were drawn with the snapping option off. I need to have them snapped but, there are hundreds of lines. Is there any solution to do this automatically or ...
3
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2answers
489 views

How can I do this geometric-operation in QGIS?

My problem: I have 3 polygons (a, b, c) on layer 1 and two other polygons (1 and 2) on layer 2. Now I want to "crop and melt" (forgive me I don't know the terminus technicus) my three polygons ...
4
votes
3answers
2k views

Conflicting measurement units with buffer ftools

I am new to qgis and I would like to create a buffer around point features. My goal is to create a quarter mile buffer (402.336m) around each point feature, using Geoprocessing Tools -> Buffer(s), ...
1
vote
1answer
2k views

“Add Delimited Text Layer” plugin is enabled, but does not show up in the plugin menu

I'm using QGIS 1.7.1 on Windows 7. I want to import a delimited text layer, but that option does not appear in the "plugins" menu. This problem persists, despite the following steps I've taken to ...
5
votes
2answers
305 views

How can I create a “setback” buffer in QGIS?

I've been going a bit crazy in trying to create a "setback" buffer on QGIS for coastal lines in a map projecting this buffer outwards towards the sea. I've managed to create a normal Bidirectional ...
3
votes
2answers
257 views

strange behaviour of piechart function of QGIS

I am using QGIS to visual health status of elderly in an elderly home, whether they have medical devices or not is one attribute that I am trying to visualize. I have create the map using mapwindows, ...
6
votes
3answers
854 views

How to place multiple symbols on one polygon centroid?

I am using QGIS for visualizing the health conditions of elderly living in an old age home, some of the elderly have multiple medical device with them and I want to show them on the map. Suppose I ...
12
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2answers
2k views

How to select features with NULL attributes in QGIS?

I need to identify which features have null attributes in the attribute table of a shapefile. When i try [field]= 'NULL' it selects the features with value=0 (see picture) Suggestions?
6
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2answers
737 views

Can I change the GDAL/OGR library that QGIS uses?

I have been adding a new format to OGR, all seems well and OGRInfo works. Now I would like to test my code out using QGIS. Is there an easy way to switch which GDAL lib QGIS uses on a windows box? ...
21
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3answers
4k 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 ...
7
votes
3answers
1k views

Does anyone know how to install the Orfeo Toolbox in QGIS?

I already tried this http://hg.orfeo-toolbox.org/OTB-Qgis-plugins/ repository and couldn't get it... This guy seems to have it: http://www.elance.com/samples/orfeo-toolbox-qgis/24111664/ Help, ...
3
votes
2answers
2k views

Workflow for creating line features between two coordinate pairs in QGIS

I have a table of stream reaches with xy coordinates for their respective tops and bottoms. I'd like to convert the table to a feature, using the xy coordinates as the endpoints of the line. Any ...
11
votes
1answer
577 views

Nearest Neighbor Grouped Selection in QGIS

OK - so I have an interesting problem I am trying to solve. I have a list containing over 100,000 points in lat/long format which I have imported into qgis. Now, what I am trying to do here is group ...
3
votes
2answers
4k views

Why does QGIS scalebar show a wrong scale?

I'm using QGIS 1.7.1 and have added a scalebar. The scalebar usually displays in degrees, unless I switch the map's projection to meters, in which case the units are display in cm. This is not ...
7
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2answers
2k views

How can I export a linestring to a GPX file in QGIS?

I have a linestring in a vector layer in QGIS. How can I expot/save this linestring as a GPX file? I tried to select the linestring, then right click on the vector layer and choose "Save selection ...
5
votes
2answers
2k views

Statistics or simple pie chart in Quantum Gis

Does anyone know how to perform pie charts based on table values within QuantumGis and include them in the print outs? thanks a lot
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?
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0answers
235 views

GIS “hack”: ways arbitarily assigning coordinate in order to match the raster and vector layer in QGIS

Before I raise my question, I have to admit that I am a total newer on GIS, I don't have much background on GIS. But suddenly I need to take over the GIS job from a GIS specialist who just left the ...
0
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1answer
1k views

Import Error while Importing osgeo package [duplicate]

Possible Duplicate: How to install GDAL with Python on windows? I have downloaded Fwtools for python2.5 from http://fwtools.maptools.org(windows installer) after installing it, it was ...
6
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2answers
2k views

Join attributes of point and line layer by location (closest distance) in QGIS

My problem is the following: i have a line shp (target layer) and a point shp (join layer). the second one (point layer) holds an attribute which i want to join with a line layer based on closest ...
6
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3answers
2k views

Create Shapefile with auto increment primary key in QGIS

Is there a way to create an auto increment primary key column when creating a new Shapefile in QGIS?
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2answers
2k views

How to set cell size for vector to raster conversion in QGIS GRASS plugin?

I'm converting a vector (loaded in GRASS plugin in QGIS (1.7.0.-wroclaw) and would like to convert this to a raster with a defined cell size. At the same time I need a value from the attribute tabel ...
6
votes
3answers
502 views

Is there a way to syncronize the current view extent in QGIS with Google Earth?

I already have the openlayers plugin but it's not working has I need it and I wanted to have the same view on both QGIS and Google Earth. Any ideas? Update: I'm using the openlayers plugin which ...
3
votes
3answers
517 views

How can I import only a subset of the polygons in a Shapefile using QGIS?

I have a shapefile that is covering a huge area, with lots of polygons. The area I'm insteresting in is small and limited. Is there any way to only import (using "add vector layer") the polygons from ...
6
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5answers
5k views

How to load Shapefiles into a remote PostGIS db using command line?

Can we import a Shapefile from a system which doesn't have PostgreSQL installed (client machine) into a system having PostGIS installed? I am getting problem with 'shp2pgsql' and 'psql' since both ...
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0answers
513 views

QGIS Layer Properties Field Tab

When I setup my layer properties I selected some of the attributes to be hidden on the Fields tab. I would like to change the EDIT WIDGET from hidden to a different function however some of them are ...
2
votes
4answers
930 views

relationship between sp package in R; mapwindow; ArcGIS/Quantum GIS

I am using ArcGIS at office for some visualization work, but I feel it kinda dump to performing the same tasks several times for visualizing some data on different maps. I am think of automating it ...
5
votes
1answer
509 views

Is there an open source tool to planarize graphs?

I read about the planarize function in ArcGIS, which seem to do exactly what I want. Is there a similar feature in QGIS or another free tool? I have a shapefile with various shapes intersecting each ...
4
votes
5answers
1k views

Is there a Log or Ln function in QGIS Field Calculator?

I can't seem to find any way to take the logarithm (natural or base 10) of a field in QGIS. I have gotten to the field calculator but there is not a button for log and I can't seem find any formula ...
3
votes
3answers
1k views

Georeference to x y coordinates with one lat long origin?

We are running parallel transect lines for a survey, which will roughly cover a rectangular area. When making the transects, we will periodically capture spatial locations of features and events we ...
4
votes
1answer
2k views

How to select and copy a group of polygons in QGIS?

I'm new to QGIS. I opened a few shapefiles that cover Europe. Now I want to select a smaller area and if possible copy the polygons in this area so I can work with a smaller set. How should I do this ...
4
votes
3answers
1k views

How to create a map of only one state in QGIS?

This is a very simple question but a Google search did not provide an answer. Basically suppose you have a map of the U.S. with states and county layers, as well as other layers like roads, etc. ...
6
votes
1answer
1k views

How to create a style file for QGIS from a plain text file?

Using QGIS 1.7. I have a plain text file, which lists 115 rgb values against a map code for a geological map. Viz.: $ head gsv1Msymbology.txt MAPCODE RED GREEN BLUE Oc 143 255 255 WAT 255 255 255 ...
2
votes
3answers
447 views

How to align TIF and GPX layers in QGIS?

My initial layer is an OS tif file, with its associated tfw. I can zoom into the area I want, no problem. The CRS is OS 1936 (and that's the project CRS as well). I download a 'track' layer from an ...
6
votes
2answers
1k views

Is it possible to show Pie charts in QGIS Legends?

I would like to display some pie charts on my map. They show in the map frame perfectly but in legend on the print composer I am unable to show the legend for the pie charts. QGIS just shows the style ...
3
votes
2answers
257 views

Hand fit curve and then apply to time series of rasters, make a map. How?

Maybe a data management problem, not too sure, but likely a challenge which someone has dealt with before. I have a time series of rasters. I can summarise the information by taking averages of each ...
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 ...
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vote
1answer
120 views

Qgis or ArcMap ,find later added data from two layers?

i have two layer which consist of 2010 and 2011 years poi. and in qgis i want to find which poi have been added new in 2011 data .. or can we get result from arcgis or any tool ... thnks
9
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3answers
2k views

How to connect QGIS to SDE?

I read your amazing solution in this topic Is it possible to connect to ArcSDE using QuantumGIS?. Unfortunately I'm not so expert in open-source products (we use only Esri suite) and I need to ask you ...
5
votes
3answers
1k views

Developing Web Application For Map [duplicate]

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. ...
2
votes
1answer
267 views

How to modify area polygon in postgres? [duplicate]

Possible Duplicate: Automated correction of parcel geometry based on area measure I need a function to modify area polygon in postgres the major probleme is automated correction of parcel ...
4
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0answers
153 views

What open source solution would work best for auto extracting features from satellite images? [duplicate]

Possible Duplicate: Feature Extraction - Land cover I have been looking for an open source solution which would allow me to define a region (or collection of images) and extract features ...
5
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2answers
3k views

Where to store (premade) styles?

I have downloaded a set of premade styles (*.qml). Where do I have to store this files for usage?. I am using QGIS 1.7 for windows. thank you! Updates @Underdark, thanks for answering, if found ...