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

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17
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3answers
3k views

How can I switch line direction in QGIS?

Something that is hopefully pretty easy. I would like to be able to swap the direction of a polyline/line in QGIS. I made a custom tool to do this in MapInfo a couple of years ago, however I can't ...
8
votes
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 ...
10
votes
2answers
3k views

How to check Topology in QGIS?

I have two Shapefiles with Polygons ( City and Forerst) Is there a Plugin who is able check the topology (QGIS)? Like "Knots do not overlap" or something like that? I dont want that they overlap. ...
18
votes
2answers
15k views

How to access file geodatabase in Qgis? [duplicate]

How does one access data from an Esri file geodatabase in Quantum GIS? I've seen snippets of conversation that indicate it's possible with qgis 1.7+ and gdal 1.9+ but no clear recipe. I recognize ...
15
votes
4answers
7k views

Join non-spatial CSV to spatial data in QGIS

I have a csv which has postcode data in a field, but it is non-spatial e.g. no Easting and Northing. I have a shapefile with postcode in a field and some additional data. I want to join the csv with ...
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 ...
6
votes
5answers
2k views

How to create points in a specified distance along the line in QGIS?

I want to use QGIS creating points along the line, but in specified distance. I found two GRASS tools in SEXTANTE Toolbox: v.to.points v.segment I tried v.to.points, setting the maximum distance ...
14
votes
1answer
1k views

Voronoi polygons that run out to infinity

I have been working on implementing the voronoi.py script (Bill Simon's translation of Steve Fortune's code). According to the QGIS link it is basically the same code that I am working with, but the ...
11
votes
2answers
2k views

Is it possible to export GeoPDF from QGIS?

Is their any plugin for QGIS which would help me in exporting the map document as a GeoPDF ?
10
votes
1answer
860 views

Is there a way to access QGIS plugins in Python?

Is there a way to access QGIS plugins in Python? I'd like to write a script to do some geoprocessing, and I'd like to use the clip, regular points and convex hull tools in fTools, as well as the Road ...
7
votes
1answer
2k views

Using PostgreSQL with QGIS and ArcGIS?

Is it possible to use PostgreSQL with QGIS and ArcGIS? i.e. one database for different clients. Is it anything that I have worry or any problems to use the DBMS from two different software? I know ...
9
votes
3answers
2k views

How to programatically check for a mouse click in QGIS

I want to know how to check for a mouse click in QGIS. I am trying to write a python plugin and want to provide functionality similar to the "Select Single Feature" tool that already exists in QGIS. ...
6
votes
3answers
3k views

Why don't my Shapefiles and OSM data overlap in Quantum GIS?

So I'm pretty new to GIS, and I'm working on a mapping project using data for Vancouver, Canada. I want to combine Open Street Map data along with data provided by the City of Vancouver. But the City ...
5
votes
1answer
975 views

Shortest distance from point to line (big dataset)

What is the best method to calculate the distance from the nearest road for a series of address points in QGIS, having a very big dataset? (QGIS 2.0.1, Win XP) I read the answers to previous similar ...
4
votes
2answers
2k views

How to generate a DEM from a contour Shapefile?

I want to create a DEM from depth contours (shapefile) in QGIS. I've been trying to work out how to do this based on this previous question, notably from this link from that page, however I'm stuck, ...
4
votes
1answer
1k views

OpenLayers Plugin Error: latitude or longitude exceeded limits

I'm aware the 'traceback' OpenLayers plugin error has been dealt with before, so apologies for raising the issue once again. Unfortunately for me, the solutions posted were way over my head, e.g. ...
3
votes
1answer
3k views

Elseif Conditional Statement in QGIS Field Calculator

I am trying to write an ELSEIF conditional statement in QGIS Field Calculator (version 1.8.0). I have used an example I found online: CASE WHEN val < 0 THEN 'negative' WHEN val = 0 THEN ...
5
votes
1answer
583 views
5
votes
2answers
6k views

How to calculate polygon areas and perimeters?

If I load a polygon layer and make a new column, how do I fill that column with the 1) area of each polygon and another column with 2) the length of the perimeter of each polygon?
5
votes
3answers
11k views

How to get the coordinates in Lat/long from a point layer?

Sorry for asking this basic question, but I couldn't get the solution from the previous answers. I need to extract the Lat/long coordinates of the centroids of districts. My QGIS project SCR and the ...
3
votes
2answers
877 views

Is it possible to colour areas between (vector) contours?

...without making it a DEM first? Joshdoe seems to have done so ("Styled in QGis") here but doesn't say how. Thanks!
3
votes
2answers
6k views

Create polygon layer from polyline layer

Our systems expect polygon shapefiles, representing a collection of non-intersecting and geometrically valid (multi)polygons. Specifically, farm fields. We often receive our representations of farms ...
5
votes
1answer
616 views

Identify Polygons on raster image

I have OS street view mapping as raster images. Is it possible (without the obvious of tracing each dwelling) to identify all polygons on each tile. To clarify, My ultimate aim is to produce a ...
4
votes
2answers
2k views

How to display both scalebar in kilometers and grid in lat/long degrees in Quantum GIS 1.8 Composer?

Also, how to display both scalebar in kilometers and both lat/long degrees and northings/eastings in QGIS 1.8 Composer? Layer is projected to UTM. Thank you.
4
votes
2answers
3k views

Which hardware configuration is necessary for QGIS?

What kind of hardware is necessary to run QGIS on Win XP? Closely related: Specifications for GIS desktop hardware
3
votes
1answer
145 views

QGIS display does not reflect projection

I have slight experience with ArcGIS, but am new to QGIS. I'm trying to set the projection of my map, and I understand that this is done by altering the CRS (coordinate reference system) of each ...
3
votes
1answer
619 views

How to style a layer from console?

I am new to the QGIS python console. I am trying to load a raster layer from the console, set the crs and a specific style from a qml file. layerPath = os.path.join(raster_dir,raster_name) fileInfo = ...
1
vote
1answer
779 views

How to evaluate raster calculator expressions from the console?

How can I execute from the console an expression that should be used with the raster calculator? I'm searching for something like this: qgis.someRasterCalcClass.evaluate("boh@1 + boh@2", ...
11
votes
1answer
5k views

How do I calculate the latitude and longitude of points using QGIS?

I'm trying to figure out how to calculate the lat/long of points using the QGIS field calculator. Is there an easy way to do this? I saw a previous related question, but it deals with a more advanced ...
20
votes
3answers
4k views

How can I calculate the average width of a polygon?

I'm interested in examining the average width of a polygon that represents the road surface. I also have the road centerline as a vector (which is sometimes not exactly in the center). In this example ...
24
votes
3answers
6k views

Visualising WKT geometry string in QGIS

A very simple question: Is there a simple tool in QGIS to graphically visualise geometry formatted as text? Example geometry: "POLYGON((571178 6337246,571178 6402217,598061 6402217,598061 ...
20
votes
4answers
3k views

Is there any model builder in QGIS or other open source GIS?

Like the ModelBuilder of ArcGIS for Desktop to run simultaneous geoprocessing tools, is there any model builder available in QGIS or any other open source GIS software?
15
votes
9answers
21k views

How to install QGIS on Ubuntu 12.04?

Has anyone had any luck with getting QGIS working on Ubuntu 12.04? I have tried the stable and unstable versions and with not luck. I also get the following: "Some packages could not be installed. ...
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 ...
6
votes
2answers
2k views

What are valid values for “data defined” labeling settings?

I'm using QGIS 1.8. I'd like to customize label features on an existing shapefile using the new label engine and it's "data defined settings" option. I'd like to know what the attribute table field ...
7
votes
1answer
4k views

Is there are QGIS plugin to allow the 3d visualisation of geological borehole data similar to the functionality of Target for ArcGIS?

I'm very new to QGIS, I have started using it as my new company is not willing to pay for ArcGIS and Target at this stage so I'm hoping QGIS can substitute not just in the interim but for good. What ...
7
votes
1answer
2k views

How to fill gaps in SLC-Off Landsat 7 ETM+ Images with QGIS?

Explanation of the problem: On 31 May 2003 the Landsat 7 Enhanced Thematic Mapper (ETM+) sensor had a failure of the Scan Line Corrector (SLC). Since that time all Landsat ETM+ images have had ...
5
votes
2answers
2k views

How to install QGIS on Centos 6?

I'm new on this; I really tried a lot before ask.. but nothing works. I did all that the qgis page says. Install ELGIS. after that i investigate and tried diferents comands.. but nothing works..the ...
4
votes
4answers
3k views

Is there a Rotate Tool in QGIS?

I can see the move tool. But coming across versions, i did not see any Rotate tool in Quantum GIS. As a hardcore feature editor myself, i have found it rather difficult. Am i missing something ...
15
votes
8answers
12k views

Can QGIS open KMZ files?

I know I can add KML files once I have unzipped the KMZ files, but is there a way to open KMZ files directly? When I try to open a kmz file on QGIS 1.8.0 on Windows XP, through the all files filter, ...
10
votes
4answers
8k 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 ...
10
votes
2answers
2k views

How to get FGDB support in GDAL 1.9 without compiling?

I was hoping that I could use the 'master' (nightly-build) version of QGIS to get fgdb support without compiliing (I'm not a developer and frankly have wasted days of productive time trying to get ...
8
votes
2answers
890 views

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

Are there any tools / plugins to develop mapbooks using QGIS?
7
votes
1answer
576 views

Is there a QGIS equivalent of the erase tool in ArcGIS?

Is there a QGIS equivalent of the Erase tool in ArcGIS for Desktop?
3
votes
2answers
1k views

Batch Dissolve Polygons based on Attributes in QGIS or FWTools

I was wondering if anyone can help with batching a dissolve. I have a few hundred polygon shapefiles that I want to dissolve based on an attribute. I would like to do this in QGIS or FWTools. Any ...
12
votes
6answers
6k views

How do I create a shapefile showing footprints of Rasters?

I have around 1,000 satellite images in tiff format, and I want to create a shapefile which will serve as an index to the rasters. This is something similar to a raster catalog, but I do not want to ...
8
votes
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
6
votes
4answers
4k views

Qgis - Is there a way to split a polygon layer with a line layer?

I am drawing administrative regions that have boundaries follow streets in another layer. As these streets are pretty long with many vertices, I don't want to re-trace them. I am looking for a way to ...
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 ...
5
votes
1answer
2k views

Calculating distance to points in QGIS

Is there a way of calculating the distance to the nearest points in QGIS? In ArcGIS there is a function called Euclidean Distance, which can take an input vector or raster, and generate a raster of ...