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

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How to aggregate data which meet certain conditions using QGIS?

I have a point shapefile with meteorological stations which contains three columns, which are: Date: The date on which the measurement has take place (it covers a range of ten years) Id: The ...
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17 views

Qgis crashes when moving layer with many features [duplicate]

The qgis does not respond and crashes and I can not do what I need. I tried on minimum hardware requirements but have not found. I'm on a core i7 with 4gb memory windows 7, Any tips?
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14 views

Is there a limit to the number of polygon points you can export to CSV in QGIS 2.4?

Using QGIS 2.4 I am currently importing a csv file with ~30,000 polygons (polygons in WKT format). I also have a United States shapefile. I have used the Clip function to get only the polygons that ...
3
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2answers
82 views

LiDAR data density, returns per square meter

How can I compute a raster showing the number of return points per square meter using SAGA GIS or other open source software? My goal is to obtain a mask which would show me the places (cells) ...
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0answers
26 views

Link to pdf file through mouse clicking

I need help in identifying the feature attributes displaying a pdf file when click in that feature. I see many examples but I don't have success. I try this code: command = "firefox"; imagerelpath = ...
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2answers
32 views

How to export a high-res world map image?

I'm trying to get some (very) large world map images (think 10k x 10k pixels etc), but can't seem to do it with QGIS, and would appreciate any help. Manually adding smaller images to a larger one ...
2
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1answer
26 views

How to subtract lines with thickness from polygon

I have a polygon and some lines crossing it. I want to subtract the lines with a certain "thickness" from the polygon, so it splits up into various polygons which do not touch each other anymore. You ...
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48 views

How to create a vector layer from a GeoAlchemy2 query?

I'm currently developing a QGIS plugin where I mapped a PostGIS database via GeoAlchemy2. I wrote a function that returns results from a GeoAlchemy query but have no idea how to create a vector ...
3
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2answers
15 views

QGIS Line End Caps

When styling a road network where all sections of the network between junctions are separate paths, I style the ends of the lines to rounded to remove any gaps that might appear where the joins are at ...
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0answers
62 views

Doubts with Ripley's K function Interpretation

I'm a self-taught person, I'm studying the K Ripley's function and I would need some person who give me some advices. First, I have written a little script of R in QGIS processor: ##Point pattern ...
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1answer
51 views

Issues calculating range with QGIS 2.0 raster calculator

I would like to calculate a simple range using the QGIS 2.0 Raster Calculator, but am getting strange results. I believe I am not using the correct syntax. To get all values between .003-.5, I ...
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2answers
38 views

How to calculate x/y in a different coordinate system in QGIS 2.4?

I'm trying to calculate Northing Easting in QGIS. I can get it to calculate my lat/long using $y and $x in the field calculator. I changed coordinate systems to what I want it displayed at, but it's ...
3
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1answer
38 views

Does QGIS automatically use spatialite spatial indexes?

When you write a query in spatialite you have to manually join your query to the spatial index for that index to be used to speed up the query. When QGIS displays data does it take advantage of any ...
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17 views

How to create correct vector grid in meter

I want to create a vector grid, with squares of 100x100m but have some serious trouble in solving this apparently easy task. I already read all the posts, but didnt find a good solution. Here is what ...
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1answer
29 views

How to split Polygons by line grid?

I want to split a polygon by a intersecting line into different parts, exactly like in this post(Qgis - Is there a way to split a polygon layer with a line layer?). I have a vector grid to cut the ...
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1answer
18 views

Python Error while installing Cartogram

I am quite new to GIS and qGIS especially. I would like to install cfarmers cartogram plugin. From what I understand, this has to be done manually - so I 've followed the instructions from ...
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0answers
19 views

How to write a custom map canvas item by subclassing QObject and QgsMapCanvasItem?

I'm writing a QGIS python plugin where I place some QgsVertexMarkers on the canvas like this: marker = QgsVertexMarker(self.canvas) marker.setCenter(QgsPoint(point[0],point[1])) Now i would like ...
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27 views

How to select duplicate polygons? [duplicate]

Although it may seem this has been answered before, there doesn't seem to be a solution. I am trying to simply select duplicate polygons. I don't want to delete them or anything like that. I need ...
2
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1answer
45 views

Is the csv handling in QGIS bugged?

I am using QGIS 2.4.0 and sadly it seems that QGIS imported csv files are somewhat bugged. I cannot use imported csv files the same way as shapefiles. It seems that sometimes it is easier to import ...
3
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1answer
53 views

Is it possible to use comments in QGIS Query Builder?

I am trying different queries in the Query Builder. Is there a way to comment the query? I tried with /* */ # -- without success : An error occurred when executing the query. The data ...
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0answers
18 views

Exporting ArcSDE feature class to shapefile using OGR?

I'd like to export data from ArcSDE for SQL Server to SHP. I've tried first to run this python script in QGIS: http://trac.osgeo.org/gdal/browser/trunk/autotest/ogr/ogr_sde.py But finally I've got ...
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2answers
51 views

Tool for rendering/drawing maps from coordinates

What tools can be used to convert a set of coordinates into polygons? For example: this code represents a room by providing information about it's four corners. <node id='-202' lat='41.015146' ...
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1answer
31 views

Merging vector layers using QGIS? [duplicate]

I have dozens of vector layers that I want to join together in QGIS. They have identical fields. How do I do this?
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17 views

QGIS startup error (symbol lookup error, undefined symbol) after system update

I'm using QGIS 2.4.0 on Linux Mint 16 MATE 64-bit. This afternoon I did a normal system update via apt-get update && apt-get upgrade followed by apt-get autoclean && autoremove. But ...
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12 views

Why is there greyed dupplicated table in Add PostGIS Layers dialog in QGIS 2.X

Does somebody knows why PostGIS 2.X tables are duplicated and greyed in the "Add PostGIS Layers" dialog in QGIS 2.X.? One is coloured with geometry type recognised the other is greyed with unknown ...
3
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1answer
36 views

How to replicate the QGIS vector smoothing effect in ArcGIS?

You can see from the screenshots that QGIS has, in my opinion, much more pleasant on-screen rendering of vector features. I assume there is some sort of smoothing algorithm used in QGIS. Is there a ...
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1answer
25 views

How to install a Reporter plugin for QGIS?

I can not get the plugin Reporter or SimpleReport to run in 2.4 or 2.2. The plugin manager in qgis says there is no metadata.txt. This is obviously not true and is in there. I have changed the ...
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1answer
46 views

Layers not displaying in the correct order

I have a shapefile that is in my Layer tree above an aerial imagery layer. Yet, the map covers the shapefile with the aerial imagery. Any ideas how to fix this?
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28 views

QGIS Rasterization of points

I have a point vector layer and want to make it a raster. Trouble is that many points are very close to each other, so unless I specify a very small resolution of the raster cells, likely several ...
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26 views

How to choose which band is used to calculate DN when converting a raster to vector?

I currently have a raster layer of flood water levels (elevation) which I need to convert to a shapefile for future use. My raster is 4 bands: RGB + one band with values from 0 to 10, representing 10 ...
2
votes
1answer
42 views

Not able to save edits to vector layer in QGIS

I have a vector layer with about 200 features. So far I have been able to add polygons to this layer just fine, now it is giving me trouble. When I draw the polygon and try to save edits, the polygon ...
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23 views

How to set QGIS action to open and search for features on Google Maps?

At the moment, I have an action that takes each term in an address field and conducts a search on EACH term in Google (ie. multiple tabs are opened for each term). The action code I have is the ...
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1answer
54 views

QGIS: Multiply Raster Value with Pixel size

i'm working on a map with population densities. My raster data contains values as [People/square meter] for each cell. I have per capita values of energy demand etc. which I want to multiply with the ...
3
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1answer
40 views

Can QGIS table editor achieve similar results to Pivot tables in Excel?

Is it possible to achieve similar results to Pivot Tables in QGIS table editor so as to use just QGIS instead of several software solutions? Or are there maybe some plugins capable of achieving those ...
2
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1answer
34 views

Problems with the Clip and Intersect tool

I am having a problem with the clip and the intersect tool on QGIS Valmiera. I have a large vector map of sublocations of a country and am trying to clip them to a district level since I do not need ...
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35 views

Retrieving all towns/cities/villages within 2km of river path?

I need to find all the cities/towns/villages that are within a 2km range along a river path. So the solution I have now is to create a google custom map, and draw a polygon which will be 2km from ...
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15 views

QGIS 2.4: adding feature with setLineEdit() data not saving to database

A while ago, I struggled to get a combo box working correctly for QGIS 2.0. This involved transforming a combo box into a line edit if the item named "other" was chosen, enabling the user to add a ...
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0answers
22 views

Euclidean Distance Function performed on unprojected data

I am looking to perform a simple multi-criteria analysis on a data set comprised of two criterion: occurence of wildfires and road accessibility. First, the project CRS was enabled with "on the fly" ...
2
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0answers
43 views

Need help selecting strange line-like objects

I'm having a difficult time trying to select what seems to be a dead polygon. Does anybody know how do I get rid of those? select and delete operations. I'm attaching an image to help me explain ...
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1answer
47 views

Save As in QGIS 2.4

I am trying to save edits to a raster file in QGIS, but; When you edit a raster file and select "Save As"; no output file is generated. My version is in Spanish; however "Save as raster layer" is ...
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1answer
23 views

Process to georeference corners of vector file?

I am new to QGIS and trying to wrap my arms around it so please bear with me. I have vector files (DXF) that I need to add back in the georeferencing. They were edited with Illustrator so I loose ...
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0answers
12 views

Python error with OpenLayers [duplicate]

I have recently downloaded QGIS 2.2.0. I am trying to use OperLayers, but I constantly get this message: Errore durante l'esecuzione di codice Python: Traceback (most recent call last): File ...
2
votes
1answer
69 views

Calculate population coverage

I am relatively new to QGIS and hope I explain this right. I am looking at the percentage of an population that has geographical access to healthcare. Therefore I have one shapefile with village ...
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1answer
44 views

How to join two tables and convert joined table to a vector layer containing points in QGIS? [duplicate]

I have one table that contains 450 locations and a table that has 10'000 rows containing data and no spatial information. I have a column that allows me to join them. The issue is that I want to have ...
2
votes
1answer
42 views

Calculate distance between point and linestring and how to represent that on QGIS?

I have loaded my data with osm2pgrouting and I have my network with ways (Linestring) and nodes (Point). The problem is : I have a database of doctors addresses (point) and I should calculate the ...
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1answer
58 views

how to permanently add raster to satellite image in qgis

As mentioned in the title i need to integrate a raster to a satellite image but have no idea as to how to do this. I tried the add grid function and it works nice but is not permanent. I insert it ...
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1answer
33 views

System variable PATH overwritten in Qgis

The system env variable 'PATH' seems to be overwritten in Qgis, replacing it with their own values. Not sure if it was intended or not. Anyway in version 2.2, I could solve it by go into settings and ...
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1answer
25 views

QGIS - fix raster layer projection

I have a 2048x1024 PNG representing a WGS 84 projection of global data, where pixel 0,0 is lat 90 lon -180 and pixel 2047,1023 is (just shy of) lat -90 lon 180. When I add it as a raster layer in QGIS ...
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26 views

GDAL Installation help in windows

I'm trying to build a GIS application in Django Framework. I completed the GeoDjango installtion (postresql, spatial libraries). I installed OSgeo4W in my C drive. I also setup environment ...
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1answer
42 views

Converting a JOSM indoor map to QGIS

I have created an OpenStreeMap layer of the indoor of a bulding by following this tutorial: https://wiki.openstreetmap.org/wiki/IndoorOSM, since that is only a proposed tagging schema for indoor ...