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

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597 views

Can PostGIS and QGIS provide dependable multi-user editing?

After considering a few options, I'm trying to give my 15-20 QGIS 2.2 users the ability to concurrently view/edit one or two basic point PostGIS layers, largest one has just 16,000 records. I've ...
10
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1answer
496 views

What is the best way to represent bridges using a point vector layer in QGIS?

I'm working on a hiking/biking maps of trails in the woods which sometimes have bridges that need to be shown on the map. I'm trying to figure out the best way to capture and represent them using QGIS ...
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2answers
2k views

How do you display related records in QGIS?

Coming from an esri background I have always used relationship classes in a gdb to display records related to a feature. Eg. Relate 1 survey point to many documents, photos etc. Does any one know how ...
10
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1answer
188 views

Automated detection of tracks

Given an area with depressions in open area from; say all terrain vehicles driving on soft surface. The vehicles will cause parallel depressions (paths) of about 10-20 centimeters in depth and around ...
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2answers
626 views

How to build a minimum convex hull crossing the 180 degrees line?

I've been building convex hulls for species that inhabit the Indo-Pacific (~ from 20 to -65 degrees of longitude). The problem I've encountered is that for the species that can be found on both sides ...
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3answers
2k views

How to prevent text labels from overlapping other markers?

Is their a way within QGIS to prevent text labels from overlapping icons used to label a point layer? In the example map shown below, there are two layers: Roads layer which is labeled using the ...
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1answer
423 views

Is it possible to edit layers from a FGDB - File Geodatabse in QGIS?

I think I've found the answer (you can't edit FGDB's) but there seem to be few reports around that it is possible to edit FGDB files in QGIS. Can anyone advise if it's possible to setup QGIS ...
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1answer
350 views

Is there a simple way to sort layers alphabetically in QGIS?

I am working on a big GIS project and not being able to sort the items in the Layers panel is giving me hard time. I can have up to 250 layers in the Layers panel. I have a special naming scheme for ...
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1answer
555 views

PyQGIS file lock release

I was wondering what triggers the release of file locks in pyQGIS? I am trying to delete a few data sources (used temporarily) by calling QgsVectorFileWriter.deleteShapeFile, but I have to quit QGIS ...
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2answers
1k views

How can I improve my Georeferencing results?

Background This is my second question related to georeferencing naked raster maps in order to re-visualize them on different coordinate systems and in conjunction with other data layers. The previous ...
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1answer
372 views

How to do Manhattan Voronoi on QGIS?

I've spending last two weeks trying to discover how to do a Manhattan Voronoi on QGIS. For the difference between Manhattan Voronoi and "normal" Euclidean Voronoi, please check this link Can someone ...
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2answers
9k views

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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5answers
7k views

How to change the order of features in a shapefile?

I have a shapefile and I want to change the order of the features. Is that possible?
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2answers
7k 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, ...
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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 ...
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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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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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3answers
1k views

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
2k views

QGIS users - What plugins do you consider to be essential?

The title says it all - vector, raster, geoprocessing plugins?
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2answers
2k 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
499 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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5answers
2k views

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
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
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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5answers
5k views

Why do OpenLayers layers appear shifted in map composer?

I'm having trouble with the OpenLayers Plugin of Qgis and the map composer: If I create an OSM-background layer and if I want to export this, the OSM-Layer looks perfectly all right in the normal ...
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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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1answer
394 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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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
5k 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
946 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 ...
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1answer
718 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! ...
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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
702 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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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
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
790 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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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
487 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 ...
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2answers
168 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
643 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 ...
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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
972 views

How to read/write from/to QGIS project file using Python?

I'd like to save the project-dependent configuration of my Python plugin inside the QGIS project file. Is this possible and what are best practices to do so?