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

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Considering “holes” in Voronoi polygon creation in QGIS?

I am trying to create voronoi polygons in QGIS that would consider "holes" in the general domain. An example would be: I actually created the Voronois in this image using QGIS through the GRASS ...
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6 views

QGIS modal value within distance

I have a vector layer with several values associated to each polygon. I then have a point vector layer. I want to get the mode of each value for polygons within 500 km of each point. I'm not sure how ...
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1answer
28 views

QGIS plugin problem, can't reach objects in a Qt-based Stacked Widget

I am creating a plugin for QGIS but am having trouble with the Qt components. I have used Plugin Builder and Qt designer to create all necessary files for the plugin. I want to use a QStackedWidget ...
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2answers
36 views

Points within polygon in QGIS [duplicate]

I have a shapefile with polygons. And I have a csv file with points. Now I want to know for each point in which polygon it is situated. Every polygon has a number, so I want to create a file where you ...
2
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0answers
13 views

Error using grass script v.lidar.edgedetection

I'm in trouble with the grass script v.lidar.edgedetection. When I try to filter an xyz format dsm the script starts but at the end of it an error message appears (see attached image). Somebody ...
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1answer
35 views

How do I create a spatial filter on a layer?

I have a layer that draws points in a PostgreSQL (PostGIS) database. The problem is, all points in the table are being drawn. I want to limit the points drawn to a spatial query. How do I limit the ...
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0answers
22 views

QGIS disappearing coordinate locations [on hold]

I'm having issues with some plotted locations. Some of them do not show up in the map unless I zoom in. How could I fix this in order to have all my locations plotted in the map?
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0answers
15 views

Track administrative changes with QGIS

I use QGIS. I have two shape files with the administrative boundaries in two differnet years. These boundaries have changed: some wards (smallest administrative area) remain the same, some are newly ...
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1answer
37 views

How to load a raster layer using PyQGIS?

I need to load a raster file from the provided file path. I wish to use it further in the Raster Calculator. I wrote a function which converts string (I assume it is a file path) to a raster object. ...
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1answer
34 views

QGIS processing script: Move points by specified distance and add segment

I try to move points (they come as WGS84, but I'm not sure if it works with unprojected CRS) by a specified distance and connect original and new point with a line segment with the below script, but ...
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2answers
51 views

How to overlay a Lat/Long CSV and NAD83 Shapefile in QGIS?

For reference I am new (as in a few hours of messing around) to GIS. I have a shape file/accompany projection files ect: CURRENT.prj CURRENT.shx CURRENT.shp CURRENT.dbf CURRENT.sbx CURRENT.sbn I ...
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0answers
6 views

send attribute from 75,000 object polygon to 20Mil point database

I have sql server 2008 r2. I have two tables: PropertyParameters and REF_GEOID. Property Parameters has four columns: PropertyID, ParcelID, Lat, Long. REF_GEOID has two: GEOID and GEOM. GEOM is a ...
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17 views

Creating KMZ files from QGis using GarminCustomMap plugin

I am new to GIS and QGIS, and really lost with some basic QGIS concepts. I have installed the GarminCustomMaps plugin, and by usign the default plug-in settings I am able to generate a single tile of ...
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1answer
52 views

How to create dissolved buffers in QGIS with PostgreSQL/PostGIS?

Creating a dynamic buffer in QGIS I use the following query: CREATE VIEW buffer40units AS SELECT gid, st_buffer(geom,40)::geometry(polygon, 31492) AS geom FROM point; Now I want to dissolve ...
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0answers
18 views

Action on group of features from layer in QGIS?

I need to implement a rename action on a selected group of features in a certain order. The idea is that I would rename one feature and then select the features that are 'next in line' and execute a ...
1
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1answer
33 views

assigning random points to unique values

I have generated random points in qgis and would like to assign the value of their geometry to a unique column in another table. I would like to do this in qgis or postgres or spatialite. Table A ...
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1answer
39 views

How Does Ogr2Ogr Simplify Work?

Can someone explain how the ogr2ogr simplify works? I am trying to use raster data which has a spectral resolution of 30m. The vector file that I am trying to import into Google Fusion is large in ...
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0answers
19 views

Transform GeoTiff to WMT

I'm not a gis specialist at all so this question may seem dummy to you. I have a GeoTiff base of images (hundreds) I'd like to transform to a WMTS repository to put behind a web server. Web pages are ...
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1answer
36 views

Calculate area intersected areas, problem

(I'm working in QuantamGIS) I intersected two layers creating a new layer. Within the attibute table of this new intersect layer i would like to calculate the new areas. However, it just doesn't ...
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0answers
31 views

Strange circles have appeared on QGIS map?

Why are circles appearing on my map? It started after using QGIS dev build 2.9 and now appears even on 2.8.1. Also I've noticed that the usual list of CRS does not appear while using the dev build. ...
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0answers
18 views

Is there a way to export entire projects or groups to KMZ?

There is a lot of questions about exporting single files, Im trying to see if there is a way to export an entire group in QGIS to a .kmz file that can be opened in google earth. I know there is a way ...
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0answers
18 views

Display tabs don't appear when files and folders are selected in QGIS?

My setup: QGIS 2.8.1 Wien on OS X 10.10.2 I'm a complete beginner at GIS and I'm having trouble on getting the Param/Metadata/Preview/Attributes tabs to appear in the Display Window. When I select a ...
2
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0answers
22 views

ST_Buffer with segment AND endcap parameters

Making a QGis plugin that buffers a line and I want to declare a high number of segments and a flat endcap. ST_Buffer(geom, 40, 25, 'endcap=flat') This doesn't work with both parameters entered, ...
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0answers
14 views

QGIS topology overlap check

I have checked topology rule must not overlap with and i get error The problem is that i have check this many times, and made hole vertex after vertex so it is not possible that these objects ...
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1answer
24 views

Clip layer with selected object from another layer in QGIS

In ArcMap, I can clip a layer with selected objects from another layer by using the editor toolbar. I want to do the same operation in QGIS. I want to create holes in the landuse layer by selecting ...
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1answer
20 views

Change name of category heading in legend

In QGIS 2.8.1, I have a SHP layer. In the display it is categorized by one of the fields, "Sannsynlig". In the table of layers and in the legend, it is also identified as "Sannsynlig", as the name ...
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0answers
20 views

Black map after attempt to style by column in QGIS [on hold]

I'm very new to QGIS and I'd really appreciate some guidance. I have a shapefile of NYC census tracts and 2 csv info files with tract info joined with it. I'm trying to style the individual tracts to ...
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0answers
17 views

How to control QGIS from within Anaconda's Spyder (Continuum Analytics Python distribution) in Windows

I would like to control QGIS from within Anaconda's Spyder, in particular use the QGIS core modules. My config: Windows 7 Anaconda 64x for Python 2.7 Spyder 2.3 Postgresql 9.4 PostGIS 2.1 QGIS 2.8 ...
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1answer
13 views

Where can I find Open feature form under options menu?

Going through the tutorials in the documentation for QGIS and I am stuck looking for a check box in the Options menu. The check box is labeled "Open feature form" and seems to have been moved in QGIS ...
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0answers
10 views

How do you snap polygons as you draw in QGIS? [duplicate]

I need to draw a long row of patient rooms for a hospital. I have the following plugins installed in QGIS 2.6: Rectangle Ovals Digitizing CAD Digitize I want to drag a set of polygons that aligns ...
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1answer
23 views

Is there a solution to glitches when deleting features from Shapefiles on network drives?

We are a small GIS department of 4 folks working with a shape file composed of points. We have local installs (C:) of QGIS 2.8.1 on our workstations, which run Windows 7 x64. The shape file in ...
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10 views

Easy to Install QGIS Server Web Client for Windows

I am looking for an easy to install (.exe file for example) web client for QGIS Server. I found a hard to install software: QGIS Web Client in Windows does not load map But maybe in the last months ...
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0answers
16 views

ECW support on ubuntu 14.04 - QGIS 2.8.1

I've followed instructions for lubuntu 14.04 - QGIS 2.2 ( Answer in Unable to install ECW support on lubuntu 14.04 ), adapting to QGIS 2.8.1. No problem to install packets, but result of gdalinfo ...
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0answers
16 views

How to reset query format in QGIS?

I have a raster layer (wms) that I can query for some info (1). The query window offers different formats for this (2). However when I select "Object", the query result vanishes (3). I looked ...
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2answers
25 views

QGIS modeler - how to extract polygons by multiple arguments?

I'm using QGIS modeler to extract lines by not one, but multiple attributes. For example, I have a road network, and I want to extract only road with character values in field TYPE: value_one and ...
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1answer
33 views

How to read landsat images from Amazon S3 using python?

I would like to read and process landsat images from Amazon using pyton thanks,
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1answer
17 views

Using pyQGIS transform a layer of polygons into a layer of holes inside a bbox

I'm using python in QGIS. I have a layer of polygons (its a result of some earlier dissolving and has no overlapping polygons but some holes and islands in holes etc). I want to build a new layer ...
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1answer
35 views

Resolution problem in QGIS raster

I have a raster file I need to clip. I created a virtual raster which I used to "copy" the extent from in QGIS raster calculator. As a result, I get the raster with the extent I need, but pixel size ...
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1answer
20 views

Cleaning shape file with multiple boundaries defined more than once

I have a shape file which contains a lot of polygons which define airspace. These polygons overlap and this is fine (e.g. different airspace configurations for the same airport). My problem is that ...
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0answers
21 views

QGIS Map Export in PDF / PNG format - overlapping layers - not printing

I am using map composer in QGIS 2.8 (Wien) where the legend layer overlaps the Map layer without any transparency. While I export the map to PDF or a PNG, the legend layer is not printed. What ...
0
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1answer
21 views

QGIS bar chart with labels

I am trying to get a simple bar chart on my QGIS 2.6 map. I have done that with diagrams. It seems to me it is not possible to add simple values to each bar (say there are three bars at a point). I ...
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0answers
23 views

Selecting polygons using another polygon? [duplicate]

Hi, How is the best way or fastest(if there is) of selecting polygons of a different shapefile using a polygon of another shapefile. exercise example: i want select all the light brown polygons ...
5
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1answer
71 views

Why are all tiles white when using the OpenLayers plugin?

I installed the OpenLayers-Plugin and set the CRS to EPSG:3857. When I go to Web / OpenLayers plugin I get the menu with the various maps, but whatever map I choose, all the tiles are white. The ...
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1answer
24 views

How can a QGIS user plugin reflect the events of UI?

I am developing a plugin for QGIS 2.8 which uses the data of the active layer. It has a dockable window. When the user changes the active layer, the contents of the plugin window's widgets must ...
2
votes
1answer
60 views

Conditional Value Map widget in QGIS

I am looking for a way to implement conditional value mapping in QGIS. This means that the values available in attribute number 2 depend on the value provided in attribute 1. Example: If the user ...
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1answer
33 views

Merging small area units [duplicate]

I am working with population data organised in parish units for the whole of Denmark. Many parishes are very small (ie <500 inhabitants compared to a median of around 1500) so I plan to merge these ...
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0answers
16 views

QGIS/GeoJSON: Dissolve featurecollection consisting of polygons and multipolygons into a large multipolygon

I've read this question. I would like to know how to do this in QGIS. I have a Geojson file with a featurecollection, starting with: ...
2
votes
1answer
43 views

How to change no data value from -32768 to -3.40282e+38 in raster in QGIS?

I am trying to change the null values of a raster from -32768 to -3.40282e+38 in QGIS. I tried using warp tool setting the no data values to my desired number but it did not change it. Then I used ...
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2answers
61 views

Is there any library can perform polygons buffering/ inflating/ merge/ overlap at server side?

I have a set of polygon data express in lat long. I would like to perform some tasks (polygon buffering, inflating etc etc ..) in server side and output the result to client side (client is a web ...
0
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1answer
20 views

QGIS GPS not editing offline database

I have a set of layers from PostGIS that I have converted to offline. I am attempting to edit them via GPS. If the layer is point data, then I can add in that data without issue. However when I go to ...