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

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5answers
300 views

How to ensure uniform colour for DEMs?

This is a silly question, but one I've been trying to figure out for a while. I have two Aster DEM tiles, one next to the other. How do I ensure uniform colour for both?
8
votes
4answers
2k views

How to use Z-Coordinate in QGIS?

I was mapping an area in Namibia and also tracked a lot of paths on my way with my Garmin device... so I thought it would be nice to see height differences in my area (esp. interesting in the ...
8
votes
3answers
3k views

How to create polygons with straight lines and right angles in QGIS?

I am running QGIS 1.7.0 on Mac OS X 10.6.8. When creating a polygon, how do I do it so that the lines are straight (90, 0 degrees, etc.) and when I create corners they can be right angles? For ...
8
votes
2answers
448 views

How to link dataframes in ArcGIS or QGIS?

The below image shows a layout in ArcGIS 10.1 with four dataframes. Each dataframe is of the same geographic area, although they are different images. For example, the top left image is a 1989 DOQ, ...
8
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1answer
3k views

How to rename attributes/fields in a shapefile attribute table?

I would like to rename some fields in my attribute table: Like rename XRF_N3in something else. It seems quite a easy issue but I don't find any information about how can I do that... I've QGIS 1.8 ...
8
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3answers
785 views

Howto setup and use a remote GIS workstation (QGIS,GRASS,PostGIS)?

I'm using QGIS (and sometimes GRASS and PostGIS) on my 2009 MacBookPro for my thesis project. I was wondering (during an endless batch generalizing in QGIS) if I can set up a server so I can work from ...
8
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1answer
1k views

How to draw perpendicular lines in QGIS?

I have a situation like this: What I need to do is to connect each point to every line that is at most, let's say 200 m, away from the point. In other words, I need to draw a perpendicular line ...
8
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3answers
2k views

Is there a way to concatenate fields in field calculator of QGIS?

Is there a way to concatenate fields in field calculator of QGIS? (e.g. hectares + ' ha')
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2answers
3k views

Is it possible to create Thiessen polygons around nodes in QGIS?

Is it possible to create Thiessen polygons around nodes in QGIS? e.g. http://en.wikipedia.org/wiki/Voronoi_diagram
8
votes
1answer
296 views

Automatically aggregate German ZIP codes by the first two digits in a shapefile

I have a shapefile which contains all German Zip-Codes in a a five-digit format (e.g. 80637). For what I intend to do, this is way to much detail. I would like to aggregate all Zip-Code areas by the ...
8
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1answer
2k views

Will there be an iOS version of QGIS?

I saw that QGIS now works on Android, any chance there will be an iOS version?
8
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2answers
1k views

How can I create random points along a polyline in QGIS?

I am trying to create random points along a polyline shapefile in QGIS. Basically, like the 'random points' tool in 'research tools' but for polylines instead of polygons. I have tried converting ...
8
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2answers
896 views

Are there any tools / plugins to develop mapbooks using QGIS?

Are there any tools / plugins to develop mapbooks using QGIS?
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5answers
308 views

Print out the properties of the attribute table in qgis?

I have to merge a lot of shapefiles into one great shapefile. So I want to compare the properties of the attribute tables to see if there are differences between the tableproperties of each shape ...
8
votes
2answers
432 views

QGIS Categorized Style: Rearranging values so that it doesn't go 57,58,59,6,60,61

I have a a column of data that I'm trying to display in the Categorized Style but when QGIS orders the values it ranks them, for example, 57, 58, 59, 6, 60, 61, 62.... Is there a way to rank them in ...
8
votes
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 ...
8
votes
1answer
383 views

How to address the new “Task-Completed” QgsMessageBar in Python?

I am really amazed what huge steps the QGIS development has taken in the last months. The new iconset, the improved Print composer and many more changes to be seen in QGIS 2.0 are really awesome! ...
8
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1answer
4k views

Create a csv with geometry as WKT in QGIS (and choosing the field delimiter)

Is there a way to choose the field delimiter when exporting to CSV with geometry as wkt in QGIS? I have a shapefile with donut holes and I'd like to export it as a CSV. It's for a partner whose DB ...
8
votes
1answer
842 views

How to add a toolbar via python?

Through tutorials I learned how to add a toolbutton to the plugins-toolbar via python. Now I wonder how to add a complete toolbar with toolbarbuttons via python. Can anybody give some example-code? ...
8
votes
2answers
363 views

Where did the polygons go after projecting a map in QGIS?

I'm fairly new at GIS know-how, but I've run into a problem with a projection of a world map. I have a shapefile of all countries I downloaded from Natural Earth. After projecting it into a ...
8
votes
1answer
2k views

How to reproject a raster file in QGIS with datum transformation?

I want to reproject a tiff raster file from projection A (ETRS89/UTM Zone 32) to projection B (DHDN/Gauss-Kruger zone 2). The two projections have a different datum so I have to use a datum ...
8
votes
1answer
395 views

How to render a table with mixed geometry types in QGIS?

I created a table with geometry type "GEOMETRY" AND inserted data of point, line and polygon type. My question is how to show this spatial data Qgis not supporting for geometry type "GEOMETRY".
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2answers
2k views

Converting ms-access database into easy to use spatial database

I've recently come into ownership of an MS-Access database (2007 accdb), which I want to be able to use in a GIS. I know a little bit about GIS (I've used QGIS and ArcGIS quite a bit) but very little ...
8
votes
1answer
2k views

How to add labels outside of features?

I'm trying to achieve this kind of labeling using QGIS. Apparently, it doesn't seem to be easily supported. Would you have an idea for a workaround ? I managed to have circled text using ...
8
votes
4answers
1k views

How to run sextante algorithms outside of qgis python console?

I'm kind of stuck trying to figure out the way to run sextante from a standalone python from OSGeo4W distribution. The reason I want to do this is that I got tired entering parameters in the dialog ...
8
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2answers
3k views

How can I iterate over map layers in QGIS python

I'm having trouble figuring out how to iterate over map layers. I can access the currently highlighted layer in the table of contents via iface.activeLayer() but I want my code to operate on all ...
8
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2answers
649 views

Can QGIS Read Spatialite Views?

I have a spatialite database I created that spans several years of crime data. To facilitate a real-world scenario where I may simplify the interaction for a user by introducing a View that simply ...
8
votes
2answers
2k views

How to correctly install QGIS with plugins and GRASS-integration from source?

I'm running a Sabayon GNU/Linux (based on Gentoo) at my home desktop system and I want to install Quantum-GIS. I'm currently using the qgis-1.7.0-package from the repositories. But this is somehow ...
8
votes
3answers
767 views

Best way to manage large number of geoTiff rasters

I have around 2-3000 1-bit geoTiffs of size 11000x9400. Color 0 should be transparent, and QGis gets it wrong in the first place, so I used a .vrt file to set all the parameters in one single place. ...
8
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5answers
625 views

What cartographic line symbol could make a coastline represent water like this old map?

I live in a coastal area with lots of islands. Sometimes with a black and white map it's hard to distinguish land from sea. So I'm trying to replicate this old map's style. I'm trying to do this in ...
8
votes
1answer
200 views

How to automatically populate fields instantly?

I am looking to create an attribute table where the first field is a drop-down menu (I have achieved this by using the 'value map' edit widget), but I'm struggling to find a method for the next part; ...
8
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2answers
1k views

Trouble with graduated symbols after joining shapefile with csv file

I have successfully joined data from a csv file to a shapefile in QGIS but for some reason I am having trouble symbolizing my data. I want to use a graduated symbology however this option is not ...
8
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2answers
395 views

Finding polygons without right angles

Now we are digitizing some buildings in specified area. The obligatory rule for this work - in most cases buildings should have right angles. We are using QGIS with CAD tools for this work. But ...
8
votes
1answer
259 views

How to automatically reduce polygon size?

I am working with two polygon layers (counties & states) which I will 'intersect' to find which counties are within which states. Due to data inaccuracies I have to change all county polygons and ...
8
votes
1answer
412 views

What version of SVG should I be saving my images with for QGIS? Any particular options I should use/avoid?

I have a illustration in Adobe Illustrator that I'm trying to export as an SVG file and add to my map layout using the Print Composer of QGIS 1.7.3. When I add the image, I get strange artifacts that ...
8
votes
2answers
1k views

How best to share QGIS data with an ArcGIS user?

I mainly use QGIS and have a large project to complete. Once I am done I'll need submit my data to an ArcGIS user. The data will consist of mostly point and polygon shape files. Is there a best ...
8
votes
3answers
853 views

calculate area of vegetations in a raster file

How do I calculate area of several vegetation types in a raster (.img file type) image. They are color coded. Am using QGIS (1.8.0) and ERDAS 9.2.
8
votes
1answer
399 views

How to split two interscting polygons by the average linestring of the shared area (QGIS / python shapely)

I have two polygons, POLYGON((-5 -5,-5 5,5 5,5 -5,-5 -5)) POLYGON((1 1, 1 7, 7 7, 7 1, 1 1)) and wish to split them evenly. The result should be a split along the red marked line. I'm using ...
8
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1answer
1k views

Open software tool or QGIS plug-in to make land cover classification

Is there any tool or plugin for QGIS/GRASS to make an automatic land cover classification from satellite imagery --- based on CLC nomenclature for example? Of course, it will not be 100% sure but it ...
8
votes
1answer
660 views

QGIS- “On the fly” projection ON by default?

In QGIS 1.6, can users set "on the fly projection" to be checked ON by default (at application launch)? I know how to turn it on, but some users find they use it more often than not, and would like ...
8
votes
4answers
2k views

How to modify single Pixel values in QGIS?

I would like to modify a raster (pixel values) in QGIS. The plugins "value tools" can easily provided me with the value of the pixel of my raster. However I know know how to modify it. I have found ...
8
votes
3answers
948 views

How to fix “Unable to initialize ODBC connection to DSN for ALC_AV_CO”?

So I am new to the QGIS community, and I have been trying to bring in some rather large access databases with little to no success. I have windows 7, so I've gone in through administrative tools/Data ...
8
votes
2answers
585 views

Building FGDB support for GDAL 1.10 on Ubuntu

Because data.gc.ca is now distributing some of its data in FGDB format (example: Plant Hardiness Zones), I would like to be able to use it with gdal/QGIS. The compile/install is not going as planned, ...
8
votes
1answer
492 views

How to create a Human Trafficking Heatmap in QGIS?

I'm trying to create a heatmap with about 325 points distributed around the city of Houston. (FYI Houston is a major human trafficking in the US: a title shared with LA and Atlanta depending upon ...
8
votes
1answer
1k views

Tiled Map Services from Geowebcache in QGIS?

Can QGIS consume Tile Map Services from GeoWebCache? I know there is a article on the QGIS website which states that it does support tiled map services but it lists Tile Cache from Meta Carta labs ...
8
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1answer
266 views

Where is this raster offset being introduced in the QGIS processing toolbox?

I'm using the (awesome!) processing toolbox in QGIS 2.0 to reclassify some NoData values in a raster from -9999 to 0, but at some point in the process there's an offset of about 0.2 degrees being ...
8
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1answer
2k views

Issues Accessing ESRI File Geodatabase within Quantum GIS Desktop

I am trying to access ESRI file gdb from Quantum GIS. I am on Windows 7, 64-bit. I have found many useful threads on how to set up this functionality within Quantum GIS. The method I went for is ...
8
votes
2answers
876 views

How to create svg symbols that have modifiable fill color, stroke color and stroke width?

I want to create some svg symbols for Qgis using Inkscape, those symbols must have attributes as described in the question. For the last two days, I have been experimenting as instructed by Sourcepole ...
8
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0answers
257 views

Solutions for fast operations on large GIS datasets [duplicate]

Possible Duplicate: Acquiring ArcGIS-like speed in Postgis I have been using PostGIS 2.0 for all of my GIS operations. PostGIS is an excellent GIS database, but no matter how I format my ...
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0answers
558 views

How to define Winkel Tripel in proj 4.8.0?

I have QGIS with proj 4.8.0 installed. I'd like to add Winkel Tripel projection which seems to be defined as +proj=wintri But that definition string does not work. Is this a bug in my proj version, ...