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

learn more… | top users | synonyms

2
votes
3answers
109 views

Making empty parts of aerial imagery transparent

I have a raster file (ECW format) that covers a very large area, however the contents comprise a thin strip of aerial imagery (100m strip centered over the rail line). The bounding box for the image ...
1
vote
1answer
169 views

How do I properly import python sklearn to QGIS PyQt plugin?

A bit of background: I'm somewhat new to python and QGIS plugin development. I've created a plugin structure for QGIS using the Plugin Builder on QGIS and I've added some controls to the gui and ...
2
votes
2answers
299 views

How do you change the scale bar units to feet?

I'm trying to change the default QGIS scale bar from meters to feet. From the API documentation it looks like I should be able to use the QgsComposerScaleBar.applyDefaultSize() function. I thought ...
2
votes
2answers
210 views

How do I count the matching 'many' entries in a one-to-many relationship?

I have a simple SHP line file - where each line has a unique reference. I have a related text csv file using the same reference, in a one-to-many situation. I need a map with the lines (in the 'one' ...
2
votes
1answer
566 views

How to find chainage of points using LRS

I have a Shapefile of road that I have converted from a KML file (created on Google Earth) and a txt file containing lat long (from GPS) of points with some attributes. The points are not exactly on ...
2
votes
2answers
60 views

How to label values every 5th number

I have a string of values(over 10,000) I want to label them but I dont want to label every single one. I need to label every fifth number.
1
vote
1answer
280 views

saga_gui.exe identified as malware by antivirus when downloaded from OSGeo4W [closed]

I downloaded QGIS 2.6.1-2 (Brighton) yesterday from OSGeo4W-setup-x86.exe using the advanced installation option on a machine running on windows 7 professional. The download worked Ok except for saga ...
1
vote
1answer
285 views

Remove white background in Raster in QGIS

I'm sure this is a very simple task, I have a black and white basemap and i would like to remove the white from it in the latest version QGIS. There are setting in layer properties and bands etc, ...
1
vote
0answers
56 views

Detecting geometry change between two line layers in QGIS

Looking to find a method of simply detecting if the geometry between two layers (line) has been altered. I have two layers of the exact same features but I suspect there is a difference in some of ...
5
votes
1answer
765 views

Calculate population within radius

I have population data matched with polygons and a set of points that I have drawn buffers around. Assuming that the population within each geographical area, i.e. the polygons, is evenly distributed, ...
2
votes
0answers
61 views

QGIS one-to-many labels

The one-to-many relations in QGIS is OK with forms, works great. But how to labels or chart data with this one-to-many relations? Martin
2
votes
1answer
292 views

How to enable the snapping options for vector layer using the python programming?

I want to enable the snapping options for the the existing layers using python programming. How can I do this?
0
votes
1answer
663 views

How to position the Qwidget form/QDialogBox in the left corner using python programming

1) I am creating a Qwidget Form or QDialogBox using QT Designer. I am using the following code to move the form: sDialog.move(50,450) But i want to fit the dialogBox to fit in the left corner.How ...
1
vote
1answer
260 views

Topographic correction (for landuse analysis) with ArcMap 10 or QGIS

I've been searching a tutorial to do topographic correction using ArcMap 10.2 or QGIS for days, unfortunately I can't find a good one that can explain the work (like which toolbox should I use). so ...
2
votes
1answer
163 views

How to measure an irregular road line in QGIS?

I'm trying to measure the distance between some coordinate points along a road line from an OpenStreetMap source map, I am using QGIS 2.4.0. My problem is to find a way to measure these distances ...
0
votes
1answer
49 views

How to join two plugins in QGIS?

I have created two different plugins in QGIS using python. I would like to combine both in one plugin. How can I do that?
4
votes
2answers
654 views

Adding a vector layer at QGIS start

I have added a shape file in QGIS using Python plugin. I want to add this shape file when QGIS is loading so i have to add code in the initgui() method. I have used following code in the initgui() ...
2
votes
1answer
296 views

map flood inundation risk QGIS

I am using RADAR data to create a map of biomass estimates. I want to mask out all land susceptible to flooding because water-logged soils affect the backscatter ...and will have an impact on ...
4
votes
1answer
857 views

How can I iterate over several layers and run a process using PyQGIS?

I am trying to find road intersections within each of my memory Polyline layers (which are named road_layer_i for i in (0-99)) so this is what I tried: import processing self=qgis.utils layers = ...
1
vote
1answer
177 views

QGIS Composer Big Red X

I am working with QGIS version 2.01. I created a print composer to export the map with legend, scale bar and title to an image or pdf. When I opened my QGIS project again and went to my print ...
4
votes
1answer
449 views

MapInfo “Boundary Select”, “Sum Attributes”, and “Update Column by Spatial Query” in QGIS? [closed]

I´m a MapInfo user, I´ve gone over to QGIS and it´s got a lot going for it, except for some "missing" simple features from MapInfo I just can´t do without.... MapInfo Boundary Select - spatial query ...
1
vote
1answer
192 views

Updating QGIS version through OSGEO4W - Unable to get setup.ini

I want to update the QGIS versions that I am using through OSGEO4W. I am currently running QGIS 2.0.1-Dufour (and also have an QGIS 191a229 version) on Windows 7. However, when I go through the ...
3
votes
1answer
463 views

WindowsError: [Error 32] The process cannot access the file because it is being used by another process

I am reading images (through Python) and do something. These images are placed in a temporary file, through: tf = tempfile.mkdtemp(filename) I use gdal to read the images (short part of code): ... ...
3
votes
1answer
97 views

I hid the QGIS Menu bar, how can I bring it back? [duplicate]

I was trying to save customization templates in QGIS 2.4 and have managed to hide the MENU bar. Now I cannot access Settings->Customization to switch it on again. I even un-installed and deleted ...
1
vote
1answer
139 views

Create polygons from point dataset, where each polygon contains 3 points from the dataset

I'm using qgis Brighton I have a dataset of 1500 points. I want to create polygons, where each polygon contains n=3 points from the dataset. The aim of this is to have clusters of 3 points, which ...
1
vote
1answer
172 views

How to sum 10 raster bands instead of 9 from code?

I want to sum 10 raster bands but the problem is that the following code will only work for summing 9 bands, which means the output image consists of 9 bands. from qgis.core import * from qgis.gui ...
1
vote
2answers
168 views

The use of QGIS with a Magic Mouse

I have been using QGIS with an Apple Magic Mouse. Despite disabling all the point and click features and gestures in the systems preferences, the maps constantly zoom in and out extremely and ...
2
votes
1answer
127 views

How to re-project shapefile to be compatible with Openlayers satellite imagery

The goal: Visualize a map using google's satellite (and projection) using my collected points. Right now I have a shapefile of my collected points from surveying. I created it by adding my csv file. ...
1
vote
1answer
58 views

How to add neighborhood names from shp to csv data points QGIS

I'd like to add the neighborhoods listed in a shp file to the data points in a csv Link to shp Link to csv Here are the data points overlaid on the shapefile map of the neighborhoods. I'd like ...
0
votes
1answer
108 views

Converting osm_id to OSGB coordinates

I've downloaded from http://extract.bbbike.org/ a map of the waterways and waterbodies within Greater London, Uk. I've loaded the shapefile into QGIS and opened its attribute table. I see that the ...
2
votes
1answer
182 views

SLD based on two attribute values

The map below is produced in ArcGIS software using the multiple attribute visualization tool (a map based on two attributes the color represents different zones based on the zone attribute value and ...
1
vote
1answer
42 views

QGIS 2.6.1: “no enhancement” option not working on DEMs

When I import DEM raster layers and try to change the contrast to "no enhancement" I get a blank white image in the map window. Changing "black to white" to "white to black", the map remains a blank ...
0
votes
1answer
118 views

How to avoid 'join features by location' for polygon to polygon creating extra areas

I am trying to work out which large polygons contain smaller ones within them in QGIS. I have a set of smaller features already defined (dark green below). However, for those smaller areas which sit ...
3
votes
2answers
858 views

Join table field with shapefile programatically (via PyQgis)?

The following is currently unsuccessful at fulfilling a table field join to a point shapefile in Qgis. All instances of the join object will print the proper values, and no error is flagged when ...
2
votes
1answer
1k views

How to deal with clipper error “cannot compute bounding box of cutline”?

I have merged about 20 OS tiles in to a single raster and I am trying to clip the merged tiles using a single polygon which itself was created from a small number of ward boundaries, merged using the ...
2
votes
2answers
619 views

How to load a data table as a 'vector layer' using PyQGIS?

This might be a simple problem, but how does one load a simple two column CSV with no associated geometric data? I have given a couple go's via QgsVectorlayer[delimited text, spatialite] types - but ...
2
votes
1answer
317 views

Combine Shapefile with address information

I downloaded a UTM32 shapefile (.cpg, .dbf, .prj, .shp, .shx file, where other available georeferences are GK3 and TM32) that shows the exclusive division of Germany in its municipalities. Above, I ...
3
votes
0answers
165 views

How to change the group icon in legend via Python in QGIS 2.6?

How to change the group icon in legend via Python in QGIS 2.6? At version 1.x I did it this way: self.legendTree = self.iface.mainWindow().findChild(QDockWidget,"Legend").findChild(QTreeWidget) ...
1
vote
2answers
233 views

How to make a contour map from a list of points and values? [duplicate]

I need to create a nice map with contours that represent various thematic data on a scale of a country, for instance, average temperatures in Germany. I have a list of coordinates with the values, ...
1
vote
1answer
62 views

QGIS Web Client Raster not visible

I have loaded rasters from PostGIS and Oracle Spatial 11g with below script.Both layers are visible in QGIS Dekstop.My OWS settings are correct but the Oracle raster layers are not visible in QGIS-Web-...
1
vote
1answer
198 views

Creating many-to-many table from intersection between two polygon layers in QGIS?

I have created a buffer around several points. I want to intersect this layer with a Census Tract layer. My end goal is to create a table that would list all the census tracts that intersect with the ...
2
votes
1answer
336 views

Keeping symbology style in a polygon shapefile when converting to KML

I have a polygon shape with 23 classes and have created patterned symbology styles which I will like to have retained when I open in Google earth pro. Is there any how I can achieve this in either ...
1
vote
1answer
103 views

How to fill column with several conditions using QGIS field calculator?

I know the synthax in order to fill one field with only one condition (field calculator): case When "attribut" = 'value' then value End But how to do populate automatically one field with ...
1
vote
1answer
41 views

What's the easiest way to generate many attribute-based depictions of the same layer?

I'm trying to show (in QGIS) how the distribution of 7 or 8 different attributes of a given shapefile vary across polygons within the layer. For a given attribute, this is simple (well, the basics ...
0
votes
0answers
14 views

Why nodes may link to remote ones?

I've noticed that sometimes when creating or editing lines or polygons some nodes may connect spontaneously with nodes in remote areas of the map, creating geometry problems. Why does it happen? Is ...
2
votes
1answer
301 views

Layer properties dialog in my QGIS plugin

I am developing a plugin which should display some information like geometry of the layer, feature count etc. Now those are currently displayed in QMessageBox.information. I want it to be displayed ...
2
votes
2answers
2k views

Connect to postgres localhost in QGIS

I am firly new to actively work with databases. I wanted to try out some stuff on my home computer where I have installed pgadmin and postgres previously. I can connect to my localhost in pgadmin but ...
4
votes
3answers
503 views

Separate a string value in two integers in QGIS

My problem is the following. I have a huge dataset of forest stands. All the information are separated but in many cases the stands have different age and this is marked in one attribute for example ...
0
votes
1answer
127 views

MySQL primary key column not visible in QGIS 2.6

I've tried adding a vector from Mysql table (Mysql 5.1, MyISAM) to QGIS 2.6. All columns are visible except Primary key column(s). Could anyone confirm this behaviour? Could we consider it a bug?
1
vote
0answers
121 views

Extracting the contents of a Google-KML file

I finally found all the datasets I could possibly need from http://globe.six.nsw.gov.au/ ...but a few hours later I'm not sure if it's possible to access this data into QGIS. I've tried MapWindow (w/...