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

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1answer
82 views

How can we split a polygon within another polygon in Qgis? [duplicate]

How can I split the green area as a separate polygon fro the grey one in QGIS?
0
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1answer
97 views

Graduated colouring Voronoi polygons? (QGis)

I've got a huge database of depth points for the whole Irish sea which I'd like to be a nice smooth surface, or at least have a depth value associated with the entire area (i.e. include the ...
2
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0answers
29 views

How to save complex expressions in QGIS Field Calculator? [duplicate]

I have been debugging some long case expressions in the field calculator and getting frustrated because I have to remember to copy the expression before I test it otherwise I end up having to reenter ...
3
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1answer
75 views

Do pad functions of QGIS Field Calculator have bug?

I have this expression in the field calculator: regexp_replace('1', '^(\\d+)', rpad('\\1', 3, '0') ) gives 01 rather than 001 as expected. the *pad functions work fine when called outside ...
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2answers
97 views

How can I do more flexible matching in conditional expressions than provided by LIKE?

With LIKE '%' works but I have had no luck with character ranges, i.e. [0-9] to match a digit. Oh for a regular expression ;)
2
votes
1answer
70 views

Can QGIS save layer direct to PostGIS?

I see that there is no option in the layer->save as menu for saving to a postgis database. There are for both SpatiaLite and SQLite. I am guessing that the interface to PostGIS is significantly more ...
3
votes
1answer
145 views

How to map flood areas from a set of points containing surface and height of water?

I am working on the damages made by the typhoon Haiyan. I use QGIS 2.0 with extensions and toolbox, and MapInfo. I have vectors, rasters of the place. I want to map the flood area along the ...
6
votes
5answers
4k views

Open Source equivalent to Collector for ArcGIS to use with QGIS/PostGIS?

From my reading of the Esri web pages the Collector for ArcGIS is tightly tied to that platform. I would be delighted to learn that I am wrong about this. I have a strong interest in generic mobile ...
2
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1answer
170 views

How to programmatically add an algorithm from external plugin to QGIS processing toolbox?

I'm writing a python plugin for QGIS and I'd like to know if it's possible to provide an interface to it from the processing toolbox. I can see how the existing algorithms are loaded into processing ...
4
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1answer
665 views

How to extract pixel value counts from a raster in QGIS?

How does one go about obtaining a summary of the counts of cell values within a raster in QGIS? I know QGIS is doing this, in order to provide the summary statistics and histogram in the properties of ...
1
vote
2answers
625 views

Does QGIS attribute edit form support “relationship” data?

Consider I have a geometry table having one-to-many relationship with a no-geometry table. When I create a feature (geometry), I would like to be able to add the relative no-geometry table data in the ...
3
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4answers
608 views

Esri File GDB multi-user edit through QGIS

I have an Esri File GDB with relationship classes. I would like to import this GDB in PostgreSQL or MSSQL to enable multi-user edit through QGIS (dufour) tool. What are the steps/procedures to ...
1
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1answer
138 views

Is there a bug in Georeferencing in QGIS 2.0?

I recently updated to QGIS 2.0. But now, when I need to georeference some pictures, I have serious problems. When loading the files to be georeferenced, I can see only a part of it in the window, so ...
2
votes
1answer
293 views

How to format labels with leading zeroes?

I'm trying to display a number next to a symbol in QGIS 2.0.1 - The numbers are from an integer-field in a postgresql database. The goal is that single digit numbers get a leading 0. Examples: 12 ...
1
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2answers
171 views

Georeferencer plugin will not load in QGIS

I have downloaded and installed QGIS. I would like to georeference an image using the core georeference plugin. When loading it no toolbar appears and the 'update', 'reinstall' etc boxes in plugin ...
0
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0answers
81 views

Export additional data with ogr2ogr

I am trying to import my ESRI-shapefile with OGR2OGR to an existing mysql table. This works fine but unfortunately only the featureID and the geometry data is exported. How do I add the labels of the ...
0
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1answer
435 views

Need help installing QGIS 2.0 Need GDAL then SQLite3 3.7.16

OSX 10.7.5 I need help installing QGIS 2.0 It says I then need GDAL. When I try to install GDAL it says SQLite3 3.7.16 or newer framework is required. I can't find SQLite3 3.7.16.
3
votes
1answer
381 views

How to set drawing style for QgsRasterLayer in QGIS 2?

I am using PyQGIS. In QGIS1, I can use: rlayer.setDrawingStyle ( QgsRasterLayer.PalettedColor ) but In QGIS2, I got some errors. I follow pyqgis developer cookbook, put some demo scripts in ...
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2answers
389 views

GRASS algorithm r.los does not produce raster

After running the r.los algorithm through QGIS 2.0, I'm getting a 'Problem loading output layers' box which gives the following message: Oooops! The following output layers could not be open Output ...
3
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0answers
519 views

How to use the linear referencing plugin?

I need a guide how to use this plugin properly, I'm a newbie on PostGIS and I'm trying to use the linear referencing plugin of QGIS. I've created a database on postgreSQL with the postGIS extension ...
1
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0answers
1k views

Issue installing QGIS on Mac OS X 10.7.5 (Lion)

I am having difficulty installing QGIS on my Mac OS X 10.7.5 (Lion). I understand that QGIS requires GDAL Complete 1.10 framework package and Matplotlib Python module. I installed GDAL (which includes ...
4
votes
1answer
108 views

How do I calculate the distance among all points in set in QGIS?

I am a very new user of any GIS. In QGIS I have input my UTM data as a CSV file. Under Vector -> Analysis Tools -> Distance Matrix, I have been able to create a distance matrix but it just takes one ...
2
votes
1answer
750 views

Read and Export OSM Road Data as a Network of Road Segments [Adjacency Matrices]

I wish to extract from an OSM file a road network, and export it as an array (adjacency matrix) where the nodes are the road intersections and the edges represent the road segments. I don't want to ...
1
vote
1answer
36 views

Simple pixel analysis [duplicate]

I am very new to QGIS and I simply have two tif images which I need to do pixel analysis on so I can compare the change in vegetation over time. I have no idea how to go about this and if anyone has ...
1
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0answers
36 views

Creating contours from partial data set

Is it possible to create contour lines based on part of the points and not the entire dataset?
1
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1answer
42 views

QGIS 1.8 Project in 2.0.1 Bad Layers

I have a confusing problem with a project generated in QGIS 1.8 when trying to open this on a new windows pc with Darfour (same OS, Win7) The hard drive including the project has been moved from old ...
1
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0answers
128 views

updating the extent automatically in the print composer

Just started using QGIS (after trying what I need to in GRASS). Using the Print Composer, I've put down a map which is based on the map in my map canvas, which is what I'll want to print. Then put ...
2
votes
2answers
200 views

Can I use the LEFT (string) operator in ExecuteSQL()?

In QGIS I can use the LEFT operator on a dataset like this: LEFT( "Name2",3) ='031' What is the syntax for using this expression with ogr in python? Isn't this the right syntax? ...
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0answers
79 views

Custome QGIS application with WPS and GDAL/OGR

I have basic question on how to start a project with QGIS. There are two kinds of users, and they are supposed to sign in (Login in) before they start using so that depending on the user type the QGIS ...
1
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1answer
112 views

Can't open Spatialite plugin in QGIS

After installation, I got the error messages below when I click the Spatialite (V.7) Plugins: -------------------------------------------------------------------------------------- An error has ...
3
votes
1answer
117 views

Add more info in the attribute table after executing “Line intersection” in QGIS

I have executed the "Line intersection" tool on a road shapefile. This is under Vector > Analysis Tools > Line intersections. I get an output with attribute table having just two columns: type_1 ...
2
votes
1answer
914 views

How to use PyQGIS ( Python QGIS API ) to open/close Update Drawing Order checkbox in QGIS2's Layers (Legend Interface)

Thanks qgis 2, the Legend Interface (layers dockwidget) now has Update Drawing Order check box on right-click mouse context menu. I think this feature can let user temporally closes rendering, then ...
0
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1answer
81 views

How to view attribute information in shapefile using QGIS? [closed]

I have a polygon shapefile (*.shp) and want to view its attribute data. How can I do this using QGIS?
1
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0answers
208 views

Qgis web client search

I install Qgis web client on windows 7 and it's working fine! Now I wont to setup search feature! First I added line in Apache config file: -LoadModule wsgi_module modules/mod_wsgi.so In ...
1
vote
1answer
145 views

How to use overview map with atlas plugin in QGIS 2

I'm using atlas plugin to batch generate maps. I insert an overview map but it doesn't get updated over iteration and generation of maps.Is it possible? If it's not, is there any alternative?
3
votes
1answer
119 views

Is it possible to save frequently used expressions in QGIS?

Is there any way to save frequently used expressions in the selection or field calculator dialogs? Obviously I can cut and paste them into a file where I might save them, but I mean within the context ...
1
vote
1answer
793 views

Pseudo-Mercator projection with Decimal Degrees?

Hope this isn't a duplicate, did some searching but none seemed quite the same. Projection I want: WGS84/Pseudo-mercator. Selected. Looks Great. Canvas units I want: Decimal Degress. Selected. ...
3
votes
2answers
188 views

Expression to calculate and sort data from several layers into one layer

I am trying to develop an expression whereby one layer can add data from 2 other layers and then rank them, is this possible? I have also tried the problem with using just 1 layer but I cannot work ...
0
votes
1answer
206 views

How do I use wildcards to work around the GDAL character limit?

I am attempting to use the 'Merge' & 'Create VRT' tools in QGIS 2.0 on a folder with 3000+ raster tiles in. However whenever I try to perform this operation the following error appears: 'The ...
-1
votes
1answer
93 views

Automatic capture (Raster to Vector) [closed]

I would like to know the automatic process for Scanned hand drawn line Raster to vector conversion. Please can anyone help me.
1
vote
2answers
100 views

Qgis “Layers menu from project” plugin doesn't open files

Has anyone out there any experience with a plugin to Qgis called Layers menu from project? This plugin gives you fast access to layers that you specify in a Qgis-project file. It won't work on my ...
1
vote
4answers
1k views

How to install TauDEM to work with QGIS?

I'm having trouble setting up TauDEM to work in the processing tools of QGIS 2.0.1. I download TauDEM from here and select "TauDEM 5.2 Command Line Executables for 32 bit Windows PC". I extract them ...
0
votes
1answer
77 views

Creating quintiles in QGIS when the number of observations per row is variable

I have a list of 100s of schools (1 per row), and a variable column with the total students in each school. The number of total students in each school varies widely. I want to split the list of ...
11
votes
4answers
2k views

shp2kml license expired, looking for free solution

So I work for a small African non-profit. I do all the GIS and data work. Most of the layers I create, I convert to kml layers so my boss can then use them quickly and easily in Google Earth. But now ...
0
votes
1answer
187 views

Open multiple hyperlinks in one point directly from QGIS?

I have an enormous shapefile and each point has about twenty different attributes. About five of these twenty are hyperlinks- is there anyway to open these directly from selecting a point in QGIS? ...
1
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1answer
435 views

How to install the GDAL plugin for QGIS 2.0 on Linux Mint?

What do I need to access the GDAL plugin in QGIS 2.0? I've installed QGIS on my Linux Mint 16 64bit system, but can't access the GDAL Contour tool. The problem seems to lie with my package ...
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0answers
79 views

Slow processing with QGIS Raster Calculator- Size issue?

I am first trying to determine what size raster is too large for processing in QGIS. I have 2 raster datasets that are over a GIG a piece (both have ige files) and I need to see how they are ...
1
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0answers
162 views

How to create a spatial view when allowing multiple selection in qgis’s edit widget “value relation”?

I've a point layer in qgis and serveral non spatial tables in a spatialite database. In qgis the fields were filled using the edit widget "value relation" (multiple selection allowed for some fields). ...
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0answers
112 views

Step by step LCP Analysis QGIS 2.0

i'm relativley new to GIS and i want to do the following analyse: I have to points between which i would like to reconstruct an ancient road. It should fit the following criteria: 1. cross rivers ...
0
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1answer
797 views

How to extract geo data out of a polygon shape file into csv kwt [duplicate]

I have a polygon shape file that contains all the neighborhoods in the Netherlands. My aim is to export the neighborhoods and coordinates to csv file (KWT). Without success I tried (with QGIS) these ...