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

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36 views

QGIS script doesn't commit attribute changes

I have a script to generate random points within a polygon, and to give the points the attributes of their host polygon. It generates points, but for some reason it won't commit the changes to the ...
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0answers
345 views

Does QGIS 2.10 work with Windows 10?

Has anyone tried using QGIS with Windows 10 yet? Does it work?
1
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1answer
32 views

ST_MakeValid is not working?

I have a polyline spatialite database, tried to perform repair geometry in QGIS using python with the following code: from pyspatialite import dbapi2 as db conn = db.connect(r'D:\db.sqlite') cur = ...
3
votes
2answers
54 views

Is the PostGIS st_intersection function viable for very large data-sets?

I am running an area intersection query on two large multipolygon tables (a few million rows). SELECT r.geom FROM public.my_table r WHERE EXISTS ( SELECT gid FROM public.my_table_intersection ...
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0answers
11 views

clustering categorized data

I don't know so much GIS specific terminology, so I am sorry for using the wrong words. I'll try to make my point clear by first describing what I want to achieve and then what I tried. [goal] I am ...
0
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1answer
19 views

Add event listener on QGraphicsEllipseItem

I'm creating a QGis Plugin in python which has a QGraphicsView in which I draw and ellipse on which I want to detect if the user clicks. I know the ellipse inherits QGraphicsItem which has a ...
0
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1answer
36 views

Import shapfile to Postgis using Python and ogr?

Iam not able to import a shapfile to PostGIS using the same library(ogr). I am using below link but it give me error. Import shp to Postgis using Python and ogr Error : Traceback (most recent call ...
2
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1answer
58 views

pyQGIS changing Paletted Raster Layers to Grayscale

I've written a plugin which essentially imports a number of colour geoTifs (map tiles) which works correctly but it would be great to display these as Grayscale after loading in. The geoTifs load as ...
3
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2answers
72 views

What percentage of polygon x is in raster pixel y, efficiently

I feel this is a competition worthy problem, due to its size. I would like to weight a set of raster pixels to the attributes of a set of polygons. To do this I need to know the proportion of each ...
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0answers
16 views

Need help on how to move a symbol over a map

I'm working in c++/qt and the c++ api qgis 2.8.2 In my application i load a map with a s57 file, this part works perfectly, now i need to make some plot representing different object like boat, plane, ...
5
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2answers
128 views

QGIS expression builder include relation attributes

I have a set of symbols based on a table in postgis such as this id|type|action_1|action_2|geom In QGIS I have this table symbolised using a rule expression which works effectively. However this ...
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2answers
50 views

How to make QGIS label only the shapes that are showing up?

I have a layer where shapes are defined by rules (country) and secondly by categories (a type). I then select (check box) the country to show the shapes only for that country. This works very well, ...
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1answer
12 views

In QGIS, add to existing dem tiles and expand corresponding contour coverage within a project

In my first QGIS project I have dozens of digitized layers that have spread beyond the contour and dem tile area that I started with. Please recommend how to safely expand or replace the dem and ...
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0answers
12 views

is the “configuration dialog” = “Processing” > “Options”

Is the the "configuration dialog" referenced to in help "Processing" > "Options" Note: The 'help' I am referring to is the online Documentation QGIS 2.2 » QGIS User Guide » QGIS processing framework ...
1
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1answer
31 views

osgeo4w not installing processing tools in QGIS toobox. [duplicate]

I have uninstalled and reinstalled QGIS several times from the OSGeo4W application. I have done this with no problem on several other times, but now I cannot get the tools to load. Most of the help ...
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0answers
18 views

Defining and exporting a path from discrete points in QGIS

I'm working with elevation data (NED, SRTM, etc.) in QGIS and I'm wondering how I might be able to pick a set of points from my map and export the coordinates to something like CSV. For example, I'd ...
1
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2answers
48 views

How to prompt for layer selection from python console in QGIS?

During script development it's useful to use the QGIS python console to test the same script on different layers. Currently I've been hardcoding layer strings and just swapping out but it isn't ...
1
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1answer
22 views

QGIS Treat null as zero in raster calculator

In QGIS - I have an irregularly shaped raster - I wish to clip an irregular area out of it (call it raster A) with that area set to null. I masked the area (vector polygon) I want to remove and used ...
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0answers
5 views

SegFault on create an EmptyDataSource From a typedef

I had to create a specific type of point, in order to do that I create a function that create a layer from shp file and data extract of the Code : typedef bool ( *createEmptyDataSourceProc ) ...
2
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2answers
52 views

Install QGIS on ubuntu using the compressed format qgis-2.8.3.tar.bz2

I just cant use apt install becuase slower internet connection and size of QGIS can you show me how to do insall using qgis-2.8.3.tar.bz2 file. I have tried decompressing and use the command ...
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0answers
24 views

How to remove temporary layer source files in QGIS

I am new to QGIS and python. Titles says it all. I'm modifying a plugin that creates some temporary files (layers) during it's run and I need to loop it a couple times. The algorithm works fine for ...
2
votes
2answers
40 views

Avoid intersection is missing QGIS 2.10, 2.8.2

I need to digitize a lot of polygons and I want to ease my work with the 'avoid intersection' button so that the new polygons do not overlap. In the manual I found (for version 2.6) that the button is ...
2
votes
1answer
34 views

pass custom command line arguments?

Is there a way to start QGIS with custom command line arguments and to access those arguments at runtime in a plugin? Background: I'm trying to start QGIS using a third party application(click on a ...
0
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1answer
48 views

Is it possible to remove small transparent outline effects between polygons?

after using the vectorizing tool I get the following result (picture). Around the cells you can see a small "boundary". This thin line is transparent and annoying. Is it possible to remove these small ...
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0answers
42 views

Coordinate transformation fails in QGIS

I am new to qgis, so this maybe a simple problem, but I don't know how to handle it. I have two layers: One layer is based on WGS84, the other on Gauss-Krueger zone 3 (GK). How can I successful ...
1
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1answer
32 views

Explanations for attributes QGIS

I have one column in my attribute table with attributes "1", "2" or "3". 1 = normal route 2 = special route because of the event (every year) 3 = special route because of the event and construction ...
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0answers
11 views

Error using gdal IDW in processing script for postgis layer

I am running QGIS 2.10.1 and I am trying to use the processing toolbox to interpolate a point layer. If I use a shape file with all the default settings it works well but if I use a point layer coming ...
2
votes
2answers
44 views

QGIS legend without print composer

I'm trying to export a series of images using the TimeManager plugin. I'd like to have a legend on each, to demonstrate why my datapoints are sized the way that they are (i.e. this circle size ...
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0answers
22 views

new shape file addition problem

I am using QGIS 2.8.2 version, me unable to add new shape file layer. After drawing the line when I right click the mouse the line was disappearing (fig2). The new layer being shown in layer window ...
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votes
1answer
79 views

Why there is no EPSG code in ArcMap? [closed]

In Arcmap, when you right click on the layer >> go to properties >> select source tab there you see the properties of projection. I cannot understand why ESRI did not managed to add SRID EPSG in ...
-2
votes
0answers
29 views

How to calculate Areas of NDVI with Qgis? [duplicate]

How to calculate the area occupied by each pixel of a raster NDVI in QGIS? Excuse me, I do not speak English. Ya calcule el NDVI de una imagen Landsat con Qgis, como calcular el área ocupada por ...
1
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2answers
36 views

Query ShapeFile to get informations from coordinates

I have a shapefile that represents all the Hydrological Basins in the world. You can download the file from here: ...
2
votes
1answer
78 views

Google Maps Openlayer plugin not aligned with the OpenStreetMap building layer in QGIS

I am working on an OpenStreeetMap (OSM) building layer (I download the imposm geojson in city Dar Es Salaam, Tanzania from https://mapzen.com/data/metro-extracts and used the building layer) and the ...
2
votes
1answer
36 views

External Standalone QGIS Application with Default Toolbars

I want to develop a standalone application and add the default digitizing and advanced digitizing tools in QGIS as-is on my application through PyQGIS. Is it similar the way you add the navigation ...
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0answers
19 views

How to set QGIS mapCanvas to exact values

My QGIS 2.8.2 standalone app's mapCanvas fills a central widget with a fixed quadratic size x=y=1000 pixels. When I set the mapCanvas extent() to an area defined quadratic as well given by a ...
2
votes
0answers
36 views

Creating new empty vector layer that has same set of atributes as another layer and then copying subset of features into it

I am new to both Python and QGIS. Here's a sample of my code: unique = layer.uniqueValues(index) attributes = layer..dataProvider().fields().toList() assistant_layer = QgsVectorLayer("Point", ...
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0answers
50 views

Merge raster layers error

Is there an issue with the SAGA-tool "Mosaicking rasters"? I tried it with different rasters. In Sage itself it works fine. Algorithmus Mosaick raster layers startet... io_gdal 0 -TRANSFORM ...
2
votes
2answers
130 views

QGIS 2.10.1 on Mac/ Multiple versions on Mac

I have Version 2.8.2 running fine on a recent iMac running Yosemitee. I have tried the install of 2.10.1 from http://www.kyngchaos.com/software/qgis but it doesn't work. I would like to be able to ...
1
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0answers
34 views

Running a custom function on each line of a PostGIS table

I am trying to run a custom function on each parcel in a PostGIS table, (in this case its a function that finds the standard deviation value of the pixels intersecting a raster) Here is the code for ...
1
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2answers
32 views

Map with just City/Country/River/etc names.

I am looking for a plug in or a map, that only has the names of the countries and cities and other urban and/or geographical features. Does anyone have or know of such a map/plugin. I'v e been ...
1
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0answers
47 views

64 Bit Win 8.1 grass 7 missing dependency

I searched for an solution but couldn't find it. Problem is: previous i had an working grass 7 within qgis 2.6/2.8 I know that there were more people with the same issue. When executing a grass 7 ...
0
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0answers
27 views

NDVI Workflow Problems, Red Channel Seems High Causing Low NDVI value?

I did some searching but nothing came up around this. I'm trying to verify a workflow from images to an NDVI to verify I have a basic workflow correct. Process images example dataset through ...
3
votes
1answer
60 views

How to apply a radial fill to a voronoi polygon centred on its original home point in QGIS?

I'm working with a point layer (airports from OpenFlights), and I want to create a map of distance to the nearest airport. I thought I might be able to do this by using radial fill on the voronoi ...
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0answers
17 views

Using Lastile in Qgis

I want to tile one large las tile into few minor. But i just cant get it done. My original LAS file have around 30mil points and i want to get 5 smaller LAS files with 5mil points in it. What is ...
3
votes
2answers
109 views

How do I make equidistant circles covering the whole globe in QGIS?

What's the simplest way to make equidistant circles in PostGIS/QGIS? (my software versions are Postgres 9.3, PostGIS is 2.1, QGIS 2.10) I tried this in PostGIS, but the circles that come near or ...
1
vote
1answer
80 views

Sorting points based on Northing and Easting

I have around 1320 point/centroid features in a shapefile for my research plots. Each point/centroid has X and Y coordinate associated with them which were calculated using Field Calculator > Geometry ...
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0answers
29 views

Displaying heatmap with large number of dense points of interest in QGIS?

I am currently trying to make heatmaps of bird observations in an area. I have had a lot of success making the actual heatmaps for most birds, except the ones that are extremely abundant. I use the ...
2
votes
1answer
26 views

OTF reprojection and reprojecting layer not working in QGIS

more troubles in QGIS. I georeferenced this raster in Corrego Alegre UTM23S and loaded up, so project CRS automatically changed to that. So far so good. I need it to be however in WGS84 UTM 23S. None ...
1
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1answer
100 views

Qgis network analysis why find vertex return always -1

I'm trying to compute the shortest path between points using the QGIS networkanalysis library. But the graph.findVertex always return -1. Basically what I'm trying to do is : 1/ Given a set of ...
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1answer
42 views

Loop to check multiple polygons overlap in r

I have a set of polygons (available here: http://ulozto.cz/x39ELbFt/polygons-zip) created in QGis and processed in R. I would like to know if they are overlapping or not, and if yes, where is the ...