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

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How to add Direction and Distance to attribute table?

anyone who can help. i just want to add direction (Bearing: i.e N 25 35 E) and Distance (Length: 125 meters) as my new field in polyline/line data. is there a plug-in to generate these fields? i tried ...
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2answers
6k views

Converting point sets to polygon boundaries

I'm trying to convert sets of points to their respective polygon boundaries. I think this is something like a Voronoi diagram or Convex Hull, but not quite. I'm sure there's a technical term for it, ...
9
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4answers
6k views

Tutorial on how to model flooding using data from gauging stations along rivers in QGIS?

Can someone please direct me to a tutorial where I can learn more about how to model flooding using data from gauging stations along rivers using QGIS?
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4answers
8k views

How to calculate raster statistics for polygons?

how can I calculate sums, averages etc of raster-points (multi-band) per polygon of a vector-layer. I was told that this is called "zonal statistics". I tried that with QGIS first. There is a way to ...
9
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6answers
7k views

Rasterfile clipping error: Cannot compute bounding box of cutline

I have a raster file and want to clip it, a vector file is supposed to be the mask layer. I use the most obvious method (Raster->Extraction->Clipper). No matter what I do, I get this error (see pic): ...
9
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1answer
1k views

Is it possible to show our custom message in QGIS Status bar using python?

Is there any way to show our custom message in Qgis Status bar using python? Just like in arcgis "IApplication.statusbar.message(0) = "Please wait..." like that is there any option to show ...
9
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2answers
9k views

Is there a way to manually place labels in QGIS?

Is there a way to manually place labels in QGIS? I have a map which has almost-duplicate labels in some places (e.g. E 1st St and 1st St) and I'd like to remove some of them. Also, I'd like to move ...
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7answers
10k views

How to copy attributes from one polygon layer to another?

I have a problem that I can't seem to get my head around. I have two polygon layers: Polygon A - is a subset of polygon B with the same fields and has identical polygons to Polygon B Polygon B - has ...
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3answers
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What are common methods for converting raster digital elevation data to vector contours?

In researching this I have found many references to the opposite, creating elevation data from contours, but nothing regarding contour creation. Preferably, I am looking for open source solutions like ...
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6answers
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QGIS users - What plugins do you consider to be essential?

The title says it all - vector, raster, geoprocessing plugins?
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2answers
1k views

How to only show labels for an arbitrary selection of items?

I'm curious how others go about solving this problem: You've created a map for something with a large number of features that are labeled. The customer/client asks that you only show labels for X, Y ...
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1answer
471 views

How to auto-generate map images with different styles in QGIS?

I have got a simple map in QGIS, containing only 1 layer which consists of 10+ features. Now I need to (programmatically) generate about 200 different JPEG map images of the same area. Each map should ...
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1answer
2k 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?
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427 views

How do you protect your PostGIS credentials when using QGIS 1.7?

I'm fairly certain this should be a community wiki, but I don't know how to make it one. So if an admin sees this please change if appropriate. So.....How do you protect your PostGIS database data ...
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5answers
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Developing GIS Application on Android

Is there any Open Source GIS Software for Android in which we can perform Various Geoprocessing Operations (like Buffering,union and intersection) and that should be customizable eg: what we do in ...
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2answers
4k views

Derive WGS84 Longitude & Latitude from British Northings & Eastings

I'm looking for a fairly simple way to append columns with WGS84 longitude and latitude to a table containing northings and eastings. The source data is Ordnance Survey's CodePoint Open, which I is ...
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2answers
2k views

How to split non-contiguous feature in QGIS?

I have a shapefile with a feature that is non-contiguous. I want to split the areas on the left from the area on the right. However, QGIS's Split Features tool requires you to draw a line over the ...
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2answers
14k views

How to enable projection transformation in QGIS

My QGIS project has two layers, one layer is retrieved by Google layer plugin which fetches the static Google map image whose CRS is +proj=merc +lon_0=0 +lat_ts=0 +x_0=0 +y_0=0 +a=6378137 +b=6378137 ...
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2answers
2k views

QGIS 2.4.0 How to display only selected features on map?

Not sure if this option ever existed, but the new QGIS version hides a lot of things somewhere else and this seems so simple that I'm kind of convinced it was possible to do this before. I have quite ...
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3answers
4k views

QGIS, Postgis: Geometry type does not match column type

I'm trying to import some polygon shapefiles to Postgis in QGIS via SPIT. One of them can't be imported and returns this error: ERROR: Geometry type (Polygon) does not match column type ...
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3answers
6k views

How to control Image Output Settings in QGIS?

I am exporting a QGIS map to an image format. I would like to have control over the output settings of the image (dpi), as currently it is only exporting the images at 96 dpi. Does anyone know if this ...
9
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1answer
324 views

HERE background maps in QGIS possible?

The OpenLayers plugin for QGIS allows one to add background maps from various sources to the data frame. These sources include OSM, Google, Bing, MapQuest, and Apple. However, Nokia's HERE Maps, is ...
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1answer
900 views

Import GRASS and SAGA modules to python script

I'm new at this. I am "building" a python plugin for qgis and I want to import modules from GRASS and SAGA but I don't understand how to do it. The plugin I want to import is Kriging interpolation ...
9
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1answer
171 views

How to save python session in QGIS?

After running a lot of scripts in QGIS' python console, I have more than 10 dictionaries and lists, and I need these for further analysis. Is there a way to save python session, with all these ...
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5answers
11k views

How to join multiple records to single feature?

apologies for what I'm guessing is a really easy problem to solve. GIS user, not programmer here. I'm trying to create a join/relate in QGIS where I have a shapefile of buildings and to that I would ...
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2answers
685 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 ...
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1answer
2k 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 ...
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2answers
1k views

Why are heatmaps on qgis 2.8.1 produced in the wrong CRS?

I noticed that the heatmap calculation on the new upgrade version of qgis is given the raster map without any coordinate system. Have you got the same problem?
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5answers
695 views

GIS analysis to find duplicate geometries

I have a big shapefile that contains all the buildings and houses of the town that I work in (approx. 90,000 features). The data of the buildings/houses are saved by the town's surveying engineers and ...
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2answers
704 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 ...
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3answers
2k views

How to get a list of distinct values from a shapefile field using QGIS?

I have a shapefile whose features I can filter by specifying a where clause in the query dialogue. F.x. I have a field named 'city_name' and by stating 'city_name = "London"' in the where clause only ...
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1answer
7k views

How does snapping in QGIS work?

I have read a number of posts and tutorials, even the QGIS manual on snapping. I set the snapping options under settings>snapping options; selecting the two layers that I would like snapping on, ...
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1answer
472 views

Why are some columns not recognized as numeric even though I have a CSVT?

I have problems importing a .csv file. Some Values of the file are not supposed to be formated in text style, but in number style, thus i created an additional .csvt file like explained here. Both ...
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3answers
1k views

How to sum up values of neighbouring polygons?

I hope that you can help me with the following problem: I have a vector (polygon) layer. I would like to add an attribute to the layer that - for every polygon - sums the values of a specific field of ...
9
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1answer
4k views

Grid and Graticule in QGIS Print Composer

Is there any other option to display DMS grid and graticule in QGIS Print Composer, since there is no plugins available yet?
9
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1answer
1k views

How to add features to a PostGIS layer using Quantum GIS?

I am using Quantum GIS and the PostGIS dbms. I am able to call the PostGIS layer into QGIS but i am unable to add feature to it. I am using the method of adding features to a Shapefile but still it is ...
9
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2answers
163 views

Cleaning blocks pattern from urban LIDAR (blocks uplifted from streets)

We have a 1-meter LIDAR DEM from a city. A small subset can be downloaded from this link: This screenshot shows raw DEM with gray palette (darker belts are streets, and greyish and whitish ...
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2answers
621 views

Are there Desktop GIS alternatives to ArcGIS 10.X for topology and vector conflation?

Is there any options other than ArcGIS for Desktop for topological rules and automatic topology integrity enforcing in a Desktop GIS? I am looking for something that will automatically snap features ...
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1answer
1k views

How can I see the coordinate transformation parameters in QGIS?

How can I see (and edit if possible) the transformation method and parameters used by QGIS for "on-the-fly" transformation, and then for saving data in another CRS? Like in ArcGIS? Here is the ...
9
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2answers
3k views

How to remove the border of a symbol?

I have a point layer in QGIS. I have created a graduated color scheme, but it doesn't look good because the border of all the symbols is showing and are overlapping (so you hardly see the color of the ...
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5answers
2k 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 ...
9
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1answer
3k 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 ...
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2answers
2k 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 ...
9
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3answers
4k views

Divide a complex shape file into a grid

I have a decently detailed shapefile with polygon/multipolygon features (the file is about 500mb). It's actually a shapefile of the entire world, with the features representing coastlines. I need to ...
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3answers
2k views

How to create a Hillshade model with multicolor “alà Imhof”?

I would like to make a Hillshade-Model with multicolor "alà Imhof". That means, I dont want a "usual" gray hillshade, I would like to use grey-blue and grey-violett from different sun directions. ...
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3answers
3k 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 ...
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2answers
2k views

How to smooth large vector polygons from Raster

I have a landuse classification raster file (6 classes) of a large area. But I need it in vector polygons so I vectorised it. No problem so far, but the result is - of course - that every pixel is ...
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1answer
2k views

When iterating over a vector layer with pyqgis, how do I check whether a feature is selected?

While iterating over a vector layer using the following code (summerized from the example in the pyqgis cookbook), is there a way to check whether a feature is selected? provider = ...
9
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2answers
324 views

Options for a historic Web Map?

EDIT: I'm an intern at a small local history museum. We have a budget of $0. Project overview: I've got a bunch of old paper maps. When I say old, I mean 1800s and up. They've been scanned into ...
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4answers
9k views

Splitting shapefile into separate shapefiles for each feature using QGIS/GDAL/SAGA?

I have a polyline shapefile with about 20 kinds of roads. I would like to know how can I create automatically a vector file for each one. I am aware of how to do it using ArcGIS for Desktop - see ...