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

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1answer
291 views

How to create new columns in QGIS by writng Conditional query on other columns of attributes table

First of all, sorry, I couldn't phrase my question better. So I want to be able to add a new column in my attributes table, say B, and it's value should be 1 if Column A's value is 1 and 0 if Column ...
2
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2answers
80 views

How to 'trace' areas from the layer below?

I have some Ordnance Survey vector data for my local area. I want to create a new layer and on it 'trace' some of the areas, fields, verges etc from the layer below with the intention of then ...
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1answer
266 views

How do I add a Corel Draw map as .dxf file to QGIS and how do I georeference it?

I have a vector data map of Poland, which I exported from Corel Draw. I can display the map in QGIS. At first the boundaries and subdivisions are only displayed as lines, after saving the data as ...
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1answer
77 views

I have a .sid image but can't figure out the CRS

There is a .map file: OziExplorer Map Data File Version 2.2 Tiritir_2.sid C:\OziExplorer\Maps\Islands\Tiritir_2.sid 1 ,Map Code, Geodetic Datum 1949,WGS 84, 0.0000, 0.0000,WGS 84 Reserved 1 ...
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0answers
129 views

Qgis ,Area Management of Dealer Network - Analysis of Population versus dealer location and sales performance

I want to analyse a Dealers retail sales performance by location , measuring sales versus population in total and social class etc. I have the shape file for the population of Ireland which includes ...
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3answers
2k views

QGIS Raster Calculater Syntax

I am trying to use the raster calculator in QGIS to combine a number of rasters. I want to calculate a mean, this is easy: (raster_1@1 + raster_2@1 + raster_3@1) / 3 I then want to create a max. ...
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1answer
485 views

Create buffer-lines in QGIS alongside Vector lines

I am currently doing a map of a farm, to see which roads needs to be repaired. Those roads are either one sided fenced, on both sides fenced or not fenced at all. I want to make buffer lines around ...
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1answer
286 views

Error running mapserver export in quantum gis

I have a project in Quantum GIS that I need to export to a .map file using de plugin mapserver export. I fill all the forms but I get this error when running the app. Any ideas of what is ...
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1answer
240 views

Automatic bulk snapping with FOSS

I'm looking for a tool that would be able to automatically snap features closer than a given distance. Is there such a tool/plugin for QGIS/GRASS/OpenJump? Would it be possible to achieve that with ...
3
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3answers
344 views

How do I sort polygons by their latitude?

We have a set of polygons which we would like to sort and number according to their latitude. This will make it easier for local authorities to relate to the numbers of the objects. I have looked ...
2
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1answer
452 views

Output of QGIS raster clipper not as expected?

My goal is to clip a raster with a polygon in QGIS 1.8. Based on an article I read, this should be a pretty straightforward task. However, the output appears to be empty. The raster produced is the ...
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1answer
640 views

How to draw grid cells in QGIS?

I have one ASCII text file with eight columns. The first four provide the x-coordinates (e.g. longitude) of the four corners of a grid cell, while the last four provide the y-coordinates (e.g. ...
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2answers
636 views

How Can I Make QGIS Stop Blinking Every Time I Pan?

The way QGIS draws the canvas when panning is quite annoying. If I pan the map even a little bit everything goes blank for a second or two before the layers are drawn. It looks like this happens only ...
3
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1answer
81 views

Get rid of raster grid cells that are less than 1

I'm using QGIS to work with raster data. I have a raster dataset of a country where each grid cell is assigned a number 1-100. However, the raster is in the format of a rectangle based on the extent ...
2
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1answer
83 views

How to interpret the OSGeo4w software version under Advanced Install option?

When choosing to install QGIS Desktop using the OSGeo4w advanced install option, I noticed that there are what looks like ambiguous software versions to choose. For example, currently QGIS Desktop ...
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1answer
713 views

Wrong coordinates in data when projecting in world map (qgis) [duplicate]

Possible Duplicate: How to find the proper coordinate reference system with two sets of data using different measurements or too convert one system into another I'm fairly new to the GIS ...
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2answers
393 views

Spatial Analysis with Factors/Classifications

When doing analysis on spatial data with associated information that is numeric, it is possible to use techniques such as Kriging or Interpolation or Cluster Analysis to find out interesting ...
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0answers
218 views

How to handle/ avoid intersect errors when clipping the difference between two layers?

Using QGIS + Grass, I've added a shapefile of coastline and islands to my map. I then buffer this shapefile to create a coastal zone of a known width. At this stage the buffer consists of the ...
2
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1answer
812 views

How to apply a graduated renderer in pyQGIS?

Just trying to run the following code already given in the pyqgis cookbook to create graduated colors symbology (as in example with 2 classes) I define the source info for the shapefile but when I ...
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1answer
386 views

Why do I get 'KeyError: 0' when using Line Intersection tool?

I'm using Quantum GIS version 1.8.0-Lisboa and trying to create intersection point using Intersection tool. (Vector -> Analysis tools -> Line Intersections ) But when I do that for my shapefile, It ...
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1answer
347 views

How to convert a finished project in QGIS to PDF

I have finished my project and need to convert it into a PDF file. How can I do it?
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1answer
321 views

matching georeferenced jpg with GPS data in WGS84 [closed]

I have imported my georeferenced jpg which I believe (on the basis of metadata in xmml file) to be in the NZGD2000 TM coordinate system. metadata: Origin: 1.76759e+06,5.94938e+06 Pixel Size: ...
6
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1answer
457 views

How to label a lot of nearby points?

I am currently working with a lot of points of which every point has to be labeled. I am already using the "Easy Custom Labeling" tool to move the labels and create lines to connect points with ...
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0answers
717 views

How to resample a raster in QGIS?

I've got a boundary file that I would like to resample the raster file from a 30m grid to a 10m grid inside the boundary file. When I try and do it in Qgis or Grass all I get is one big raster cube ...
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0answers
292 views

How to change shape file's extent in QGIS

I have created a network from 3 shapefiles using GRASS. While haveing problem to perform a network analysis with it, I've been told that the extent of the network shouldn't exceed that of the original ...
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2answers
610 views

Python module “shapely.wkb” missing

I am trying to follow a tutorial from here http://qgistips.spatialthoughts.com/2012/12/find-neighbor-polygons-in-layer-in-qgis.html#more I have downloaded the relevant python script and edited it as ...
6
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1answer
413 views

QGIS line style

I found the latest QGIS has a great tool to create complex styles, however looks like one small but very useful thing is missing, or I can't find it. I'm trying to create a line style something like ...
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1answer
271 views

Polygonize function doesn't overlay the shape file over the raster file

To convert the raster into a shapefile I use raster->conversion->polygonize but QGIS doesn't open the new layer overlayed the first (the raster) but reflected above it. I read this question ...
3
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1answer
341 views

color gradient (or color ramp) in Arcgis and Qgis

I am currently working on my thesis and I would like to ask you: does anybody know the mathematical formula that calculates the color gradient in Arcgis and Qgis? In other words, which mathematical ...
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1answer
242 views

Displaying only points within a polygon I created in QGIS?

Thank you in advance for any advice you might give me. I am new to qgis and believe what I'm asking is probably fairly basic. I am trying to map policing activity in NYC for two areas: one area in the ...
0
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1answer
91 views

Should a GDAL Plugin be the same version as GDAL aready built into QGIS

Should a GDAL Plugin be the same version as the GDAL that's aready built into the QGIS version installed? Or,can another different version of GDAL be built and it installed as a Plugin for QGIS, ...
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0answers
162 views

How to achieve better Dissolve results?

I applied the Vector>Geoverarbeitungswerkzeuge>Auflösen (Dissolve) on a zoning plan (see picture zoning plan). I used the attribute village name as the dissolving criteria. The resulting geometry for ...
3
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1answer
214 views

Can I color different layers with the same pseudocolor color map?

I have multiple DEM layers in my map (downloaded from atlas.louisiana.gov/lidar), but I cannot seem to get the colors to line up. You can see in the attached image that the colors are not continuous ...
2
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2answers
119 views

What specifically is an 'attribute' and how does it work with the related chart?

I'm a new QGIS user (and GIS technology in general) and I'm trying to learn its fundamental features. I have a big dilemma about vector shapefiles, and points in particular: basically, I don't ...
4
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1answer
680 views

How to break (both) lines at their point(s) of intersection in QGIS?

I'm working with a road network where some of the road segments cross each other but no point is inserted at their intersection. Is there a way to break these line to shorter lines at their points of ...
3
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5answers
1k views

Batch processing DEM rasters in QGIS/GDAL

I am attempting to add relief shading to map using .asc raster files, following this tutorial. It works well, but I have only tried it on single tile of raster data which is 20x20km. I want to ...
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0answers
106 views

How to access the rules of QgsRuleBasedRendererV2 using python?

I can't get access to the rules of rule-based renderer, python says there's no attribute "rootRule", though documentation says it should be (http://www.qgis.org/api/classQgsRuleBasedRendererV2.html) ...
3
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0answers
59 views

Programatically reorder layers in qgis? [duplicate]

Possible Duplicate: Sort layers in QGIS table of contents? I write a qgis python plugin ,and i try to connect keybord keys to reoder layers in qgis . Are there a method in qgis allows me to ...
9
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1answer
191 views

Advanced labeling formatting (centered and different sizes)

I would like to place the elevation-number of a point in a different front size and centred under its name: Is that possible? (That is my actual labeling: label || '\n' || elevation) Thanks!
4
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1answer
79 views

Reduce number of vector field arrows in qgis

OK, now that I have figured out how to get my vector fields in qgis, I can't figure out how to reduce the number of vector arrows on the map. Is there a setting for how many vectors are sampled? ...
2
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2answers
630 views

Couldn't load plugin fTools due an error when calling its classFactory() method

When I start qgis I get a python exception: Couldn't load plugin fTools due an error when calling its classFactory() method ... 309, in _import mod = _builtin_import(name, globals, locals, ...
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1answer
214 views

How do I create rendered vector field in qgis

Perhaps I am misunderstanding the "vector field renderer" and "VectFieldCalc" plugins, but I have no idea how to make a vector field of arrows, with directions and magnitude. I have the data loaded ...
4
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2answers
589 views

Can I download the current version of QGIS if I am running Mac 10.8.2?

I am taking an introductory course in GIS at my university and my teacher recommended QGIS for Mac users. Unfortunately, I haven't been able to download the software. I just upgraded to Mac OS 10.8.2 ...
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2answers
599 views

Import Civil 3D DEM to ArcMap or QGIS

I have some survey data exported from Civil 3D in both dtm and dem formats. I thought the I would be able to use the dem more easily, but I think the format is different from a USGS DEM. Is it ...
2
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0answers
149 views

QGIS 1.8.0 suddenly sluggish/unusable on Gentoo

QGIS 1.8.0 has been working fine for a number of months. Then I upgraded my system generally, which possibly included upgrades to xorg-server and QT, and now QGIS is sluggish/unresponsive to the point ...
4
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2answers
122 views

Creating space at intersection of two links

I have a shapefile consisting of two links which are crossing over each other. I want to create an empty space at the point of intersection of the two links. As of now, I have been manually doing ...
4
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1answer
61 views

How to deliver an additional Python Library with own Plugin?

For my own plugin I need a special library (pyexiv2) to write a comment into a jpg file (PIL does not do that). When I want to share my plugin in one of the repositories in the future, what would be a ...
2
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1answer
584 views

How to save WMS getFeatureInfo points to a layer?

This may be a poorly worded question, because I am not sure of the exact terminology, but I'll give it a shot. I have imported a vector layer from a WMS server into QGIS. I am able to query the ...
2
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1answer
1k views

How do I get and install the latest version of QGIS in Ubuntu?

I'd like to get the latest 64-bit dev build of QGIS on my Ubuntu setup. How exactly do I go about it? I assume it's some kind of arcane terminal command...
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3answers
205 views

Is it possible to create a PostGIS sequence to populate Area column of a polygon

I've created Postgres/PostGIS sequences before to assign unique gid values when a feature is created in QGIS but is it possible to create a sequence that will automatically populate an area column? ...