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

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Creating polygons representing specific range of values within raster using QGIS?

Using QGIS, I started with LIDAR points (every 5 m) on a 90’000 ha area and then converted it in a raster of elevation (interpolating to fill some holes in LIDAR data). Now, I want to get a polygon ...
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74 views

Clipping polygon using QGIS?

I want to clip a polygon using Qgis "clip" tool. The problem is that the resulting polygon presents areas that where not clipped off. The first screenshot shows the layer I want to clip using the ...
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67 views

reading raster without making QGIS apply the scale factor to the raster

Since QGIS multiplies the image with the scale factor when reading, it messes up the image if the scale factor is not properly defined to the data as QGIS expected. For example, I am reading MODIS ...
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25 views

How to merge shapefile data and pick out what has changed in QGIS?

I work for a conservation charity just starting to use QGIS. I am starting to think about how to consolidate GIS shapefiles returning from different and separate project areas across the UK to be ...
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26 views

The 'mosaic' of my maps on Qgis won't show up in the work space but individual maps do

I have made a 'mosaic' of my maps on QGIS (version 2.10.1-Pisa) yet when I select and un-select each individual map it appears and disappears. I won't 'zoom to layer' and even when 'shown in overview' ...
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42 views

How to label Highways with Canadian Data

QGIS - I've been working with 1:50,000 topo. data from a couple of provinces in Canada. There is attribute data for the highway numbers but how do label them with a circle around the highway number in ...
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1answer
88 views

Importing CSV data with Coordinates in one column

I'm trying to import the Lat/Long coordinates from the "Location" field of a CSV from here :https://data.colorado.gov/Water/DWR-Water-Right-Net-Amounts/acsg-f33s Unfortunately the coordinates are in ...
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1answer
115 views

QuickFinder QGIS plugin generates python errors

I have had no success setting up the QuickFinder plugin in QGIS to search project layers. Once I select the checkbox "Search in project layers" in the settings and create a new QuickFinder file, it ...
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385 views

Is there a best practice for the length of fields?

At my work have inherited several shapefiles that originate from MapInfo that I am bringing into a new project in QGIS. I have the opportunity to change the column names, add and subtract columns and ...
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15 views

How to center the QGIS map on the maximum value of a raster?

I have a very large QGis raster layer showing the differences between two nearly identical rasters. Because of this, it is very difficult to find where in this layer the few pixels that are different ...
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43 views

Cannot access WMS with QGIS Cloud

I have a map uploaded to QGIS Cloud, and I am trying to get access for my partner to use it as a WMS. This is what I see: It would appear that WMS is on, but those checkboxes are unclickable. The ...
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26 views

How to avoid field duplication when joining two vector layers?

I have 2 point vector layers wich differ in 2 fields while both of them have the same number of fields (10). What I want to do is produce a new point vector layer with 12 fields. When I join the two ...
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1answer
56 views

Create common vertex where line was snapped to another using “snap to segment”

I have a schematic diagram within QGIS consisting of a single layer of line segments. Lines have been snapped to others using "snap to segment". When using the snap to segment option the two lines ...
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1answer
76 views

Can't see my geometry tables from postgres in QGIS

When I link my postgres/gis table to my QGIS I expect to be able to add the shape into QGIS. But for some reason QGIS does not recognize my tables as geometry tables. The datasets are originally ...
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1answer
84 views

Building QGIS Master on OSX

My goal is to install the latest build version of QGIS in order to test and identify bugs. I'm on OS X (10.10.4) and am attempting to build from the QGIS nightly source. I'm following the official ...
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1answer
35 views

lasmerge with more than nine input files

Is there a possibility to feed more than 9 LAS files to lasmerge? The user interface only allows 9 LAS files, but at liblas.org it’s described as there can also be a text file holding the file names ...
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1answer
71 views

Clipping raster-image increases file size

Working with QGIS 2.4.0 Chugiak I have a question regarding the clipping of raster images. I have an aerial picture that I want to clip using the extents of a shape file. So far so good, I used the ...
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62 views

QGIS Redirecting WMS Request to localhost

Whenever I add a WMS layer, from a server on the local intranet, the WMS request gets sent to localhost instead of the actual server I am referencing. I am enclosing screenshots to make sure my ...
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1answer
71 views

Error in “Fill Nodata in QGIS”

I am dealing with landsat ETM+ images after 2003. While filling the line drop outs usiung QGIS Fill Nodata, I keep getting this error, ERROR 1: TIFFOpen:7948_0fill_y_work.tif: Permission denied ...
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1answer
69 views

Natural Earth doesn't render well in Robinson World projection

QGIS Pisa 2.10.1 Mac Pro, Mac OS I don't seem to be able to create a simple World Map using the Natural Earth Dataset and the Robinson World projection, unless I zoom in. What could be the problem? ...
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1answer
49 views

Strategies for grouping polygons

I'm looking for strategies to replicate the functionality available via ArcGIS' "Aggregate Polygons" tool. This is different from a straight dissolve on the polygons - the operation has to fill in ...
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25 views

SLD for dot density

I am trying to find, or get help creating, an SLD to render dot density symbolization for a polygon shapefile for an online GIS display - in this case WorldMap. The dataset is county level US Census ...
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1answer
85 views

QGIS:joinattributesbylocation gives empty shapefiles and QGIS:joinbylocation does not give summary of all fields

I am trying to make a spatial join to calculate the mean value of many variables (100+ columns) of census tracts by city. In order to do that, I would, in QGIS Desktop, run a spatial join (join ...
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1answer
42 views

How to return elevation for point data in QGIS?

I have a dataset for the Western USA and want to get elevations for the point data added to the point attribute table. What is the best way to batch process this so the whole operation is done at one ...
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44 views

Some layers won't load when running application out of QGIS. “Item has already been added to this scene”?

I'm developing a basic application out of QGIS and am having trouble getting my code to generate all the layers I have set. Currently it only generates two of the four layers: "self.basemap_layer", ...
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2answers
156 views

QGIS 2.10.1 Clipping Algorithm Results In Empty Layer

I apologize for the redundancy of this issue, but I have explored all the information I could find over the past couple days and have yet to find a solution to what seems to be a very simple task. I ...
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1answer
46 views

Can qgis cooperate with phpmyadmin?

Can this two cooperate together? I am asking this, because I have database in myadmin with column for long. and lat. informations. Is there a way to connect qgis with myadmin? Or what type of ...
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36 views

How to check if a point is snapped to a line in QGIS

I have two vector classes, sg_point and sg_line. Any sg_point HAS to be snapped to a sg_line. I should not find errors if I use snapping correctly, but in case there are errors how do I check in QGIS? ...
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0answers
20 views

qgis toolbars revert to default positions on re-opening application

On my PC and most of my users, we can move the toolbars into their optimal positions for our purposes, save and close the application, and they are still there on re-opening, as you would wish. ...
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27 views

Plug-in Install troubles

I tried to install following plug-ins into QGIS2.8.(My PC is Win8, 64bit.) *Table Manager *Group Stat But error message says "The Plug-is is broken. Python said: GroupStats instance has no ...
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1answer
35 views

QGIS: How to scale attributes when clipping / intersecting

I'm working on a project involving a ratio of frequent travellers / population divided in Forward Sortation Areas from Canada Post (FSAs are the first three characters of a postal code: A1A). I ...
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2answers
131 views

How to fill holes in polygons automatically?

Is there an option in QGIS to fill holes in polygons automatically by setting parameters e.g. maximum area, distance between borderlines? I want to delete/fill holes that a very "thin"/small.
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17 views

Is it possible that QGIS is truncating my distance matrix?

I need to calculate the pairwise distances among 330 points that are in one shapefile and also pairwise distances among 948 points that are also in one shapefile. These points are in shapefiles, each ...
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32 views

Data not showing in QGIS when connecting to Oracle

I have an Oracle XE 11g spatial database that is connected to a web map. All the layers of the web map are stored in the database and they work just fine. I sometime need to edit some of the layers in ...
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1answer
121 views

Why does iface.activeLayer() not work in a PyQGis standalone app?

it is my second day on PyQGIS. Not sure why layer doesn't return anything. Anyone can help me on this? Code: #!/usr/bin/python from qgis.core import * from qgis.utils import * from PyQt4.QtCore ...
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1answer
464 views

How exactly is the centroid of polygons calculated?

I would like to know how exactly QGIS Geometry tools -> polygon centroid is calculating the point coordinates. For example does it divide the boarder of the polygon into small points, take two pairs ...
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1answer
43 views

Labels position in Qgis

I'm using QGIS 2.10.1. Is there a way to avoid labels of different layers overlapping each other?
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1answer
59 views

QGIS Web Client cannot select Map Layer or use Layer Order

I have installed the QGIS Web Client from git with the install.sh script and went directly to copy a QIS project in the project directory (with map layers in Postgis). After struggling with CRS (in ...
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1answer
46 views

Delimiting regions of influence for ports

I have datasets containing origin-destin (ports) and volumes for trade data. From these datasets, I can extract points of origins that are related to only a particular port. Interpolating such data, ...
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33 views

How can I see the 'Custom Options' metadata following Save As in QGIS?

In QGIS 2.10 Pisa, I've right-clicked a layer in the TOC and used Saved As ... to save a shapefile with a new name. During this process, I used the Custom Options (Data Source and Layer) to include ...
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1answer
75 views

Calculating percentage using QGIS Field Calculator?

I have a shapefile containing counties and their respective population for a given area. I woould like to use the Field Calculator to create a new field that contained the % of the total population in ...
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18 views

Mapping negative percentage values from *.xls table in QGIS?

Trying to map some negative percentage values in QGIS. Working with a .xls table and importing this as a vector file to QGIS, then joining the file with a shapefile. Have converted negative percent ...
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0answers
30 views

Advice needed to get my layers to html with mouseover for all layers

I'm a casual user of Qgis for my job. This latest project has taken me to unfamiliar waters and I need advice on last remaining steps to get me to my goal. My goal is to have a choropleth map of the ...
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36 views

qgis-processing: possible to specify variable number of output layers?

Qgis-processing advises that output layers are specified with syntax such as ##foo=output vector The manual advises against manually loading output layers (in your script code) as QGIS will do this ...
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1answer
39 views

How to see the 'example provider' in processing toolbox of QGIS?

I would like to create my own provider with the processing toolbox. I see the example provider in my folder C:\QgisWien\bin...\algs\ExampleProvider. It seems to be a good start but unfortunately, I ...
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0answers
38 views

QGIS Georeferencer tool not keeping inserted coordinate values

I'm currently giving a basic training course on QGIS and, on the last class, one of the students stumbled upon a problem I wasn't able to solve - nor can I find a reason for it. We are using QGIS ...
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40 views

QGIS Composer labels with expressions - Custom functions

I'm trying use GetPrint request with qgis server and I find feature that you can assign value of function to label (with id) ex. ...
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29 views

Shortest path routing doesnt work

Let's say we have the following line layer. Why is that when we perform routing, it doesnt go from point A to point B like below: Instead, it goes in the other path. I've sent the oneway ...
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22 views

How to create a raster “grading” several different layers (polygons)

So I have a bunch of different shapefiles loaded into qgis: i.e.: - shape of poor soil quality - shape of cheap land areas - shape of poor weather areas now I would like to create a map which ...
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1answer
68 views

QGIS kml export with symbols

I'm new in qgis and I need some help. I'm trying to export a specific layer with defined some points using different symbols. The exported kml file will discard the symbol type layout. This is the ...