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

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1answer
474 views

Delete duplicate geometry in postgis tables

After - I dont know what happend - all my entry's in my postgis tables are doubled! I tryed that to delete them but it does not delete any/all duplicates: DELETE FROM planet_osm_point WHERE ...
2
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0answers
122 views

QGIS Topology checker wrong results?

I am trying to understand topology checker results and frankly i dont get it - probably i am doing something wrong. Source - Point layer Target - Polygon layer Must be inside - that is working as ...
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0answers
23 views

How to delete lines that do not overlap a polygon? [duplicate]

I'am new to QGIS and I run into a problem. I have two shapefiles, one with line data and one with polygon data. I would like to remove all the lines that do not overlap the polygon. So remove all ...
3
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2answers
115 views

How to combine two string replace functions in one expression?

I would like to change some of my street labels like "Musterstraße" into "Musterstr." or "Muster Straße" into "Muster Str." I already did that for the first case: replace("name", 'straße', 'str.') ...
2
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0answers
139 views

How to split a polygon into quadrants in R/Qgis?

I am solving the same problem as How to split a polygon into quadrants?, except that I am looking for a solution in R or QGis. So I have a polygon layer shapefile, which is unfortunatelly not exactly ...
2
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1answer
719 views

How to develop c++ standalone QGIS C++ Application

I want to integrate QGIS in QT\C++ application. I try to write basic C++ apllication to render map and build it using MSVC 2010. class PostGisViewer: public QMainWindow { public: PostGisViewer(): ...
2
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1answer
40 views

Is there a python version of qTuio? [closed]

Is there a python version of qTuio? qTuio is implemented in C++. However, I am currently trying to use pyqgis due to problems with C++ environment (I cannot even create a raster layer). Any help is ...
2
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1answer
219 views

QGIS Calculate distance between polygon vertices / find vertices that are within distance

I have polygon layer and i need to find (select, so i can export selected to new layer) all the vertices that are in provided distance to each other (like 2 meters). I already tried: 1. Export ...
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1answer
241 views

QGIS how to align existing polygon borders

I'm looking for a method to align the borders of two overlapping and already existing polygon layers. I'm aware of the node tool and its tolerance snapping option, but the area I'm working with is too ...
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0answers
60 views

Importing Data Dictionary (DDF) into QGIS (Fields)

Are there any tips/tricks on getting all the Attributes from a data dictionary for a GPS unit to sync with the Fields in a QGIS style? Right now, in order to update the drop-down options in QGIS, I ...
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0answers
26 views

Interpolation plugin from PyGIS? [duplicate]

How to run this plugin from PyQGIS?? http://docs.qgis.org/2.2/en/docs/user_manual/plugins/plugins_interpolation.html
2
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0answers
107 views

Label size changes when exporting or printing WMTS layers

I am using QGIS2.4.0 on a Windows computer. When I export a map containing OSM landscape, the labels in the output map are smaller then in the view in the composer. (even if the view in the composer ...
2
votes
1answer
112 views

How to use a csv file to add values to a value map?

I'm trying to populate a value map in the edit widget with some values from a csv file. Could anyone let me know what format the csv file has to be in? At the moment I have just a list of ...
3
votes
2answers
127 views

Points in Polygon Query but having CRS issues (QGIS)

I have two files: A csv file that has lat longs listed for points. A shapefile that contains England NHS CCG boundaries (which usually uses the British National Grid). When I 'add a delimited ...
10
votes
3answers
414 views

From polygon to continuous measure of diversity?

First of all; I have tried to find a similar question, without success. Maybe it's because I'm quite new to GIS and I don't really know what exactly I'm looking for. If someone points me to a similar ...
2
votes
1answer
164 views

How to print 2 maps in the same PDF page using PyQGIS?

I am trying to generate a one-page PDF document containing the following items: 1) On the left half, a full state map (say, New York State). 2) On the top right quadrant, a map that zooms in to one ...
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2answers
59 views

How to specify a map units line wider than 100000 units

Sorry if this is a very beginner question, but I can't seem to find an answer online by searching. Is there a way to increase the size of the "map units"? I'm trying to draw lines attached to my ...
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2answers
142 views

Getting attribute data from one dataset to another

In the image below you can see two shapefiles: NYC building footprints (outlined), and underneath a PLUTO shapefile rendered with a categorized blue gradient using the "Floor Number" column. The ...
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1answer
176 views

How to deactivate zoom on the mouse wheel?

I need to fixed scale in canvas in QGIS but I didn't find this function. If I fix scale it is impossible to make zoom in or zoom out into canvas. Only one move which layers loaded can be do are ...
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0answers
25 views

Columns decimalLatitude and decimalLongitud not recognized while creating a layer from a csv file in QGIS

I'm using QGIS 2.0.1 Dufour to create a layer from a csv file. When I try to define the geometry and assign the x y coordinates sources, I'd expect QGIS to recognize the decimalLongitud and ...
0
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0answers
26 views

Raster import problem

I have raster images (orthos) and feature layers in a GIS program (Global Mapper). When I import these files with the same CRS into QGIS they are literally 9000 miles apart and I cannot figure out ...
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0answers
52 views

How to update the items of qCombox in custom form?

For my project I use a custom form with multiple value relation comboboxes. This works quite fine and I can access the widgets via my script. Init the two comboboxes which are correctly filled ...
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1answer
145 views

Displaying WMS Attribute Data in Lizmap

I have successfully built a Web server using ubuntu 14.04, Qgis 2.6, with the plug-in lizmap as a local server. I have several polygons being displayed and some WMS raster's from NOAA's WMS. I know ...
3
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1answer
169 views

Reprojecting between NAD27 and WGS 84 part III

I am trying to perform a reprojection for data with datum Nad27 to WGS84 datum. According to AndreJ in some previous questions in Stackexchange (CRS reprojection for instance) QGIS uses internally by ...
4
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1answer
823 views

How to use QGIS field calculator in python?

I would like to use QGIS Field Calculator in Python to update the existing column based on certain conditions? How can I do this?
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1answer
168 views

OTB Pansharpening Error: Adapter for adaptPansharpening-bayes not found

When I try to use the OTB pansharpening tool inside the processing tool box I always get this message: "Adapter for adaptPansharpening-bayes not found". I guess it's an issue withe the configuration. ...
2
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1answer
163 views

QGIS: How to merge single polygons to multi part polygons by maximum distances?

I have a polygon layer with a land-use class and ID for every polygon. How can I merge polygons (into multi part polygon) which do not adjoin, but are not further than x meters apart from each other. ...
2
votes
1answer
204 views

QGIS: raster import “nan”

I've been importing raster files in ZMAP format using QGIS 2.4 and 2.6. Some of the files work fine but other files for some reason import a black image with nan as a default black and white value. ...
2
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0answers
54 views

Creating QGIS multi-layer Topo Map of Lorraine Region of France?

I have a project I'm working on where I need a QGIS multi-layer Topo Map go the Lorraine Region of France between Metz and Nancy as a starting point, but I don't know where to start. What I need is a ...
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1answer
152 views

Automatically select small polygons contained within currently selected large polygons - QGIS

I am using QGIS (2.4.0) and I am trying to identify regions in Australia that are close to working mines. For this purpose I have 2 layers: Layer 1 - 535 polygons defining the various regions across ...
2
votes
1answer
123 views

Problem or ERROR in converting from raster to vector!

I wonder if anyone could help me out, i am kind of a beginner at QGIS. I´ve built a DEM for a project that i am developing than i´ve made the slope raster with the terrain analysis,it seemed that ...
0
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2answers
94 views

way/tool to automatically generate polygons on map knowing polygon width and height and spacing

I need to create a large number of polygons (say 1000) on a georeferenced mosaic (from aerial photographies). I know polygons' height and width, and I know the spacing between them. I can also provide ...
2
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0answers
104 views

Finding the slope of a polyline in QGIS 2.2 Valmiera

I am trying to find the average slope of a water course. I've drawn in the water course as a polyline over a large number of contour lines (the water course is long with a very large catchment area). ...
2
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3answers
94 views

Need to extract OSM data for my area from 2 neighbor countries

I need to prepare offline background data for my area of interest which is located around border between Czech Republic and Germany. I need to convert the OSM data to spatialite and then to use in ...
3
votes
2answers
136 views

CRS reprojection

I am trying to change the CRS of one shapefile that is originally in NAD27 to WGS84 in Qgis 2.6. When I proceed to make the change, I still continue to see the file in UTM coordinates... I've tried to ...
0
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1answer
31 views

problem changing CRS of a shapefile [duplicate]

I am trying to change the CRS of one shapefile that is originally in NAD27 to WGS84. When I proceed to make the change, I still continue to see the file in UTM coordinates... I've tried to save the ...
0
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2answers
242 views

Displaying polylines in different color / Color gradient

Though i am using QGIS, yet I am not confined by tool (can use an entirely different tool or a plugin for QGIS) usage.. Only aim is to get the following: I am reading various shapefiles in QGIS and I ...
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5answers
971 views

Selectively removing whitespace from a string with SQL

I have two columns of adresses that I need to join. Column 1 has the adresses formatted as "Some Street 12 A" while column 2 has them formatted as "Some Street 12A." Ie. the last whitespace between ...
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1answer
78 views

QGIS GPS Information Menu Automatically Add Points

We are using a Surface Pro 3 with Windows 8.1 64bit, Bluetooth GPS, and QGIS (2.4 standalone download). We have opened a new QGIS project and are able to connect to the GPS unit within the GPS ...
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2answers
230 views

QGIS project with PostGIS layers freezes irregularly for minutes

I'm using about 30 more or less complex PostGIS layer in my QGIS project. Some of them are PlanetOSM layer generated with osm2pgsql. The Project loads fast (ca 5 sec). The canvas update by moving or ...
3
votes
1answer
112 views

Is it possible to subdivide scale bar segments in QGIS?

How can I subdivide the scale bar segments in smaller subsegments? I want to style my scale bar like this To make the question clear I edited the posting.
2
votes
1answer
917 views

shapefile for mumbai area or section wise

I am working on a project in which i need to plot data on Mumbai city map section wise or area wise but i am not able to get Shapefile for the same. Can anyone please provide me the link where i can ...
1
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0answers
129 views

QGIS 2.4.0 seems to have issues with “Select By Location” for complex polygons. Are there alternatives?

I am attempting to use the "select by location" tool to select polygons from one layer that overlap with certain polygons in a different layer. Unfortunately this is causing QGIS to freeze. Doing a ...
2
votes
2answers
280 views

Highlighting features in qgis2leaf export

I have exported a QGIS map to Leaflet using the qgis2leaf plugin. I am looking for some assistance as to how to highlight features (polylines) when the mouse hovers over it. I just want the polyline ...
2
votes
1answer
42 views

Spatial join by categories in QGIS

I am using QGIS 2.4.0 and I have a vector layer which contains a remoteness indicator which is broken up into 5 categories. I would like to turn this into a layer that has these 5 categories collapsed ...
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1answer
248 views

PyQGIS export to JSON: writeAsVectorFormat and precision

In my QGIS plugin qgis2leaf I am exporting all layers as JSON into a JSON directory. Therefore I would like to enable the user to define the precision in the GUI. The normal "save as" dialogue in QGIS ...
2
votes
1answer
68 views

How to switch rule-based styles in loop?

I'm a working on a QGIS script that could activate/deactivate rule-based styles of the vector layer in a loop (one active layer per iteration). On the every iteration this scenario should: Activate ...
2
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0answers
171 views

How to open a second window in QGIS plugin from a button inside the main window

If I already created a qgis plugin, and i need to create a button inside that plugin that opens a new window, how is that possible? Qt creator won't add a slot unless there are a header file. I looked ...
2
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0answers
41 views

What does the Join button in the categorized style tab do?

I'm just studing gis, and I use QGIS. I have found in the layer properties some JOIN and don't understand how can I use It? Maybe someone can help me to undersan it, thank's!
1
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1answer
173 views

Why is the QGIS map composer grid showing unreasonable lat/lon?

I need to print a map with coordinates in the format of Degree, Minute and second. CRS is set to WGS 84 (EPSG 3857) for both layers and on the project properties it is set to enable transformation on ...