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

learn more… | top users | synonyms (1)

1
vote
1answer
526 views

How do I use 'model builder' in QGIS 2.2?

I am trying to learn how to use the 'model builder' in QGIS 2.2. I have used model builder in ArcGIS, but I don't understand how to do it in QGIS 2.2? What I want to do is to make buffers, clip ...
1
vote
2answers
51 views

Where are QGIS application setting file(s) stored?

I have some application settings (Windows/QGIS v2.0) that I would like to pass to other users (such as those settings defined under Settings menu>Options>Rendering tab). In ArcGIS they are stored in ...
1
vote
1answer
224 views

QGIS 2.2 - expression string builder to ignore NULL values

Simply put, I would like to create a rule-based filter whereby you add 2 columns together and you get a certain colour as a result. However, some fields in Column_1 may be NULL and those exact same ...
1
vote
1answer
451 views

How to go with…somewhat complex geological maps in QGIS?

Just a follow-up to this question QGIS: Line to polygon conversion. Not sure do i have to continue there itself... We are currently digitizing a geological map...which has 36 features in total. Some ...
1
vote
1answer
72 views

Run ftools multiparts to singleparts from PYQGIS

Is it possible to run the multiparts to singleparts function from the console with the processing_runalg function? Or is there another way?
1
vote
1answer
332 views

How to add the attributes of selected features to my new layer in pyqgis

I am trying to create a layer from the selected points coordinates. I am drawing a circle to the coordinate of selected points. I also need to add initial attributes of my selected features to my new ...
1
vote
1answer
91 views

How to calculate the area of an ellipse on the earth's surface using Python?

I have a dataset consisting of GPS coordinates. I use a clustering algorithm to generate a two dimensional Gaussian for me. The Gaussian takes the shape of an ellipse if visualized on the map. ...
1
vote
2answers
293 views

How to increase label size of OpenLayers plugin basemap layers?

For QGIS 2.2.0-Valmiera, how does one increase the label size of OpenStreetMap layer or any other basemap layer? Presently the labels are way too small to read. For example, I find that for the same ...
1
vote
2answers
105 views

QGIS 2. Bad layers won't resolve

This is getting worse... I created a project with about 6 vector layers (which I digitised) with some raster tiles. It is stored locally on my Windows 7 PC, running QGIS 2.0 The project was fine ...
1
vote
1answer
70 views

Create and immediately update field using Field Calculator

You can create fields and once created, populate them with data using the Field Calculator. But can you do both at the same time using an expression? Or must you do it in 2 steps?
1
vote
1answer
782 views

How to create a dock widget correctly in QGIS plugin?

I am building a QGIS plugin and would like to use a dock widget. I have used QT creator to design the UI, with the object type being a QDockWidget. When the plugin is enabled in QGIS the dockwidget ...
1
vote
2answers
44 views

Creating Many Uneven Buffers

Qgis 2.2, Windows 7 I am looking to create buffers around city lights (the raster). Currently, I have simple polygon buffers around the point layer (oecdminusa), but this is not accurately capturing ...
1
vote
1answer
140 views

Processing Script: now gives error in QGIS 2.2

I recently updated to QGIS version 2.2, and am now getting an error when running Processing scripts that worked previously (in version 2.0.1). Uncaught error while executing algorithm Traceback (most ...
1
vote
1answer
308 views

Adding attribute list to combobox in a python plugin

I am developing a simple plugin at the moment which contains 3 combo boxes: comboBox_1 comboBox_2 comboBox_3 Combobox 1 & 2 lists the vector layers available, however I would like the 3rd ...
1
vote
1answer
163 views

Is it possible to link a QGis project with an excel file?

I have an Excel file with coordinates and I have used this file to plot the coordinates in QGis. I was wondering if it was possible to permanently link the excel file to the QGis project, so that when ...
1
vote
1answer
75 views

Why do the raster band values have different values than the raster statistics?

I am working on a raster file (1 Band). According to the raster metadata, my minimum value is 0 and maximum is 7458. This seems to be confirmed by the Style options that return some category values ...
1
vote
1answer
33 views

Changing georef backgound colour

Working with a greycale scanned image: when I georef that image it rotates (expected) the blank corners are then filled with black. When the new image overlays I need to make those corners ...
1
vote
2answers
260 views

Missing Dependency in SAGA. Orfeo Toolbox does not work

Hej guys, I am trying to perforem segmentation from Orfeo Toolbox (QGIS last version 2.2), whenever I try to use the toolbox, I get the following message: Oooops! The following output layers could ...
1
vote
1answer
173 views

What do “count”, “mean”, and “sum” in QgsZonalStatistics mean?

I am working with Qgis and making some analytics of lightdata. I've used these commands: rasterfile = qgis.utils.iface.mapCanvas().currentLayer().source() vectorlayer = ...
1
vote
1answer
190 views

problem reading netcdf

I am using qgis 2.2 (I have also tried this in qgis 2.0 and arcgis 10 with the same result) (I have some basic understanding of netcdf, but I am probably missing a lot of details...) I have manged to ...
1
vote
2answers
85 views

How to use eVis to launch AutoCAD with a relative path?

I found this post, which leads me towards what I need: How to link to external files with relative path in QGIS actions? Now, I'm trying to use the eVis plugin to open .DWG and .DXF by launching ...
1
vote
1answer
344 views

QGIS loads PostGIS layers but DBManager can't connect

DB Manager can't connect to PostgreSQL, but "Add PostGIS Layer" can. My eventual goal is to save created layers to PostGIS. I assume I can do this using the DBManager Tool. I can alternatively use ...
1
vote
1answer
75 views

naturalearth sqlite db not loading into qgis 2.2 [duplicate]

I downloaded the naturalearthdatabase in sqlite-format (http://www.naturalearthdata.com/downloads/, the downloadlink goes to http://kelso.it/x/nesqlite), but qgis 2.2 (running under win 7 64bit) does ...
1
vote
1answer
460 views

Code works on python console in QGIS but same doesn't work in stand alone script

I'm trying map rendering with stand alone script, so I have small script which works fine in python console provided QGIS, however when I run same code in stand-alone script it executes without error, ...
1
vote
4answers
344 views

How to change a CSV layer attribute value from text to number - once again?

i have read most of the related postings and answers allready ... (e.g. http://anitagraser.com/2011/03/07/how-to-specify-data-types-of-csv-columns-for-use-in-qgis/ and How to change a CSV layer ...
1
vote
1answer
117 views

Can one batch-automate the creation of QGIS heatmaps?

I have 4k point shapefiles, from which I would like to generate heatmap TIFFs using the QGIS heatmap plugin (or a functional equivalent featuring triweigth, radius and cell size selection). Is there ...
1
vote
1answer
180 views

pgrouting unexpected output

Thats my ways.shp file. I loaded this to PostgreSQL DB using PostGIS shape file loader. I ran pgr_anlayzeGraph() on it and found it had a lot of isolated segments. Next I ran pgr_nodeNetwork() to ...
1
vote
1answer
2k views

Add file GDB in quantumGIS 2.2

In QGIS 2.2.0, while adding vector layer, 'ESRI FileGDB' option was missing under Source-Type, refer the attached screenshot.In this case, how can I attach a file GDB in QGIS 2.2.0?
1
vote
3answers
147 views

Invalid geometry message when using Difference tool

I am using the Vector \ Geoprocessing \ Difference tool to get the resulting area when taking a) current ground disturbance away from b) historic total ground disturbance to give c) what has been ...
1
vote
2answers
326 views

QGIS: drawing order of lines and polygons (line between polygon)

I have 2 layers. One with forests and lakes (polygon) and one with rivers (line). Now I want the features to draw in that order: The river have to be UNDER the LAKES and the forest have to be UNDER ...
1
vote
1answer
2k views

Clip raster layer with *raster* mask layer in QGIS

Given two input layers 1. The clip layer - an arbitrary layer (though in my case it's a float 1 band geotiff) 2. The mask layer - a paletted raster in which every pixel is either NO DATA or a single ...
1
vote
1answer
64 views

Using QGIS, features are suddenly placed 7.5 thousand kms off correct location

I've been counting an muskrat dens on lakes with aerial photos by creating a feature in a separate shapefile. I checked my progress after doing about 80 small lakes and suddenly, half of the lakes ...
1
vote
1answer
736 views

how do I install QGIS for Android?

I am new to Android (just brought a Nexus 7) and I am trying to get QGIS onto it but I can not find any installation instructions. I have found http://android.qgis.org/download/qgis-installer.apk and ...
1
vote
1answer
48 views

How to randomly select from existing points within each polygon?

I have a polygon layer (where each feature has a class attribute), and a point layer, and there are at least 10 points within each feature of the polygon. Is there a way to randomly select only "k" ...
1
vote
2answers
1k views

QGis 2.0.1 mapserver extension missing

I tried to export my Qgis projects to mapserver, using RT mapserver extension, because there is not any other extension in my version of QGis.(QGis 2.0.1 Dufour on ubuntu 12.04 LTS). After installing ...
1
vote
1answer
200 views

Apply r.neighbours or Neighbourhood analysis (LecoS plugin for QGIS) to 3000 rasters

I need to apply r.neighbours or Neighbourhood analysis (QGIS plugin LecoS (or equivalent) to 3000 rasters and define a neighbourhood of 5 x 5 and calculate the mean. I suppose I need to create a ...
1
vote
3answers
192 views

How ensure data put into PostGIS gets proper CRS attached?

I recently had an intractable problem that we finally traced back to the fact that some points in a PostGIS table had a CRS associated with them and others did not. This resulted in some points being ...
1
vote
2answers
271 views

How to change raster cell values within a polygon using QGIS GUI?

I would like to know how to change the values of raster cells which are within a polygon, leaving all cell values outside the polygon unchanged. I would like to subtract 1.5m from each raster cell ...
1
vote
1answer
647 views

QGIS Advanced String Filter Expression returns too many results

"GNR" is a string column and I expect the filter expression "GNR"='.11' to only return the feature with the value '0.11'. Why are the other features with values of '.110'and '.1100' included? Is ...
1
vote
1answer
35 views

Show the changed CRS in the Qgis attribute table

I am a GIS newbie, so bare with me if this is a duplicated question. I could not find the answer anyway. I am using QGis to read a polygon shapefile with a Dutch CRS (EPSG 28992 to be precise). Now I ...
1
vote
1answer
88 views

draw multipart polygon with one surrounding border

As you can see on the image below, the waterbody is divided by the border line because it consists of several polygons. I could merge the polygon, but I dont want to change the shapefile. Is there ...
1
vote
1answer
63 views

How to read the count of the cells with data with non “no-data” values ,in QGis?

How to read the count of the cells with data with non "no-data" values ,in QGis
1
vote
2answers
138 views

Georeferencer plugin will not load in QGIS

I have downloaded and installed QGIS. I would like to georeference an image using the core georeference plugin. When loading it no toolbar appears and the 'update', 'reinstall' etc boxes in plugin ...
1
vote
1answer
104 views

Can't open Spatialite plugin in QGIS

After installation, I got the error messages below when I click the Spatialite (V.7) Plugins: -------------------------------------------------------------------------------------- An error has ...
1
vote
1answer
67 views

Find single line strings in MultiLineStrings

I have a layer of line geometries in QGIS (version 2/Dufour) and want them all to be singlepart linestrings. However, some of them are multipart geometries (MultiLineStrings in a GeoJSON export). The ...
1
vote
1answer
152 views

Delete duplicate spatial point/points in mssql from a perticular location

I am working with a Spatial data which has a street intersection points.... I get the intersection points from spatial query on street/roads datain MMSQL . but in my case some streets/roads are multi ...
1
vote
1answer
336 views

get data from WFS and present in using d3js - correct projection

I'm trying to get data for map of Poland. I found WFS service that provides GML files. It is located under: http://sdi.geoportal.gov.pl/wfs_prg/wfservice.aspx?request=getCapabilities&service=wfs ...
1
vote
2answers
370 views

How to add a new column in attribute table with attribute with indexes of another max-min ordered attribute field?

I've an attribute column named e.g. VALUE with different values I would like to make a column named e.g. ORDERsuch that the greatest value has the attribute 1 the second value 2 etc. etc. so order ...
1
vote
2answers
3k views

How to export and import gps points from Garmin 62S and QGIS

I'm pretty new to using QGIS and I'm curious about how to import and export GPS points created in QGIS. I have QGIS 2.0.1 dufour on windows XP and a Garmin 62s. Any suggested walk throughs would be ...
1
vote
1answer
91 views

python scripts for accessing info from a postgresql database in case of a qgis application?

I am beginner and I need to know if I could access a postgresql database from python script made for a qgis application