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

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4
votes
2answers
1k views

Get a pixel value

How can i do this operation: I want to get a pixel value fro the satellite image (Landat, GeoTIFF, 7 bands) using qgis-python. What operators should i use? (for example in qgis's Python Console) ...
22
votes
2answers
7k views

Does QGIS have the equivalent of ArcGIS's Layer (*.LYR) file?

Using ArcMap, it is possible to add a dataset (eg a shapefile) to the map, and configure the layer's properties (such as the symbology, table joins, switching some attributes off in the Identify ...
12
votes
6answers
5k views

How to identify duplicate attributes in a field?

I have a point shapefile with thousand of points. It has an ID code field that supposed to be unique. Every now and then the data entry clerk wrongly type the id creating duplicates.Right now I'm ...
11
votes
2answers
3k views

How to get FGDB support in GDAL 1.9 without compiling?

I was hoping that I could use the 'master' (nightly-build) version of QGIS to get fgdb support without compiliing (I'm not a developer and frankly have wasted days of productive time trying to get ...
10
votes
1answer
5k views

How to resample GeoTIFF images to the same resolution?

I have two geotiff images that I would like to resample the same resolution. If I use ArcGIS this would be easy to do. But using QGIS I don't know how to do this. Some help will be very appreciate. ...
8
votes
3answers
1k views

Calculating all distances from single points to multiple polygons

I have two layers: a point layer defining properties (95 objects), and a polygon layer defining plots of land associated with the properties (211 objects). Each point relates to one or more polygons. ...
8
votes
2answers
1k views

Are there any tools / plugins to develop mapbooks using QGIS?

Are there any tools / plugins to develop mapbooks using QGIS?
7
votes
3answers
3k views

How to set up a Coverage Layer for Atlas Plugin?

Has anybody utilized the Atlas plugin? I am starting to take a look and setting it up on a project. My question is how do you set up the layer that is utilized for the coverage layer. Is there a way ...
6
votes
2answers
4k views

How to get point attribute from polygon layer?

I have two layer, one (A) has point features and the other (B) has polygons. I need to produce a new table with some (the ID) or all the fields from the A table and some (the area code) or all from ...
5
votes
2answers
1k views

Georeference vector linework

I'm new to GIS and a lot of searching didn't answer my specific question so far, so I hope someone can help me here. What I want to do is creating a small web application to visualize election ...
5
votes
2answers
2k views

How to draw lines from two points in a CSV?

I have a CSV file where one line looks like this: Duration, user, lat-start, long-start, lat-end, long-end 298, Casual,38.9101,-77.0444,38.91554,-77.03818 Each row in the CSV has two points and I ...
5
votes
2answers
1k views

QGIS affine - form of equation

I am at the mercy of a govt authority who have provided utility information in a cad format with a 0,0 origin and a nonsense grid. About a dozen files, the grid and origin are entirely arbitrary. To ...
4
votes
1answer
2k views

Installing LAStools in QGIS 2.4?

Does anyone know where the Processing menu moved in QGIS 2.4? Specifically, I am trying to install the LAStools box for QGIS following these instructions: ...
3
votes
1answer
647 views

How to match a raster NetCDF data with a vector layer in QGIS?

When I load a raster layer with humidity data from NOAA database (for instance rhum.2m.2014.nc at ftp://ftp.cdc.noaa.gov/Datasets/NARR/Dailies/monolevel/) I am not able to match it with a simple map ...
3
votes
2answers
1k views

How to delete column/field in PyQGIS?

How to remove or delete column fields in a shape file using python?
3
votes
1answer
1k views

Joining table to shapefile with pyQGIS

Joining shapefiles is a relatively straightforward proess in QGIS using 'add vector join' in the layer properties menu. I can add a csv file as a vector layer, as well as a shapefile, and join the two ...
13
votes
6answers
5k views

Get Raster Values from a Polygon Overlay in Opensource GIS Solutions

I have two layers. A polygon-shape-layer with many tiles and a raster-layer containing CORINE 2006 land cover with many categories in a colourmap. I want to obtain for each polygon in the shapelayer a ...
9
votes
3answers
10k views

How to access QGIS Plugin Repositories from behind a proxy?

I have been trying to teach myself QGIS by using this forum and others to help. Most of my questions can be answered by downloading plugins that are available through 3rd party repositories but for ...
7
votes
2answers
4k views

Standalone applications using QGIS and environment variables

I've tried going through IRC to see if people can help me out with this, but the medium seems a little clumsy for making any answers clear, so I'm going to try this instead. I would like to program a ...
6
votes
1answer
2k views

How to create a style file for QGIS from a plain text file?

Using QGIS 1.7. I have a plain text file, which lists 115 rgb values against a map code for a geological map. Viz.: $ head gsv1Msymbology.txt MAPCODE RED GREEN BLUE Oc 143 255 255 WAT 255 255 255 ...
6
votes
4answers
3k views

Quantum GIS and ECW images?

How might I enable Quantum GIS to read ECW imagery? At the moment I'm mostly concerned about this on Ubuntu 10.4 amd64, but I also use WinXP & Win7.
5
votes
2answers
2k views

QGIS relations widget in custom form

I've just begun exploring QGIS relations option, now in version QGIS 2.2, details here: http://blog.vitu.ch/10112013-1201/qgis-relations This is a great implementation of something I've been ...
5
votes
2answers
3k views

How to link to external files with relative path in QGIS actions?

Objective: I have point layers with attributes contain paths to external files (visio, autocad dwg...). I want to put them all in one folder together with the project file, compress the folder into a ...
4
votes
2answers
952 views

Google Maps not Showing in QGIS 2.12

The Google Maps in my OpenLayers plugin in QGIS 2.12 does not show anymore. The other maps do show, that is: OSM Bing MapQuest Stamen Apple Maps I tried in QGIS 2.8 and Google Maps does not show ...
4
votes
1answer
379 views

Debugging errors of SAGA interpolation algorithms in QGIS 2.0 Processing

I encounter recurrent problems with the geoalgorithms that perform interpolations. No matter technique I use I end with the following errors. As state in OGR tab QGIS is unable to open a file in C ...
4
votes
2answers
2k views

How do I split polygons into line segments?

How can I split my polygon file into "segements"? The lines should be broken up like this picture shows:
4
votes
4answers
12k views

Calculating the minimum distance between points and polygons in QGIS

I have two vector layers: one point and one polygon and I want to calculate the minimum distance of each point from the polygons (ie the distance from the closest point of the closest polygon). Is ...
3
votes
2answers
2k views

How to set up QGIS print composer options from the python console?

If I have a print composer called "ABC", I would like to "tell" its composer that I would like to update "Map 0" to simulate the "set to map canvas extent" button activation update certain text ...
2
votes
1answer
455 views

Error: Algorithm not found

I wrote the following code to start using QGIS APIs. in a very short script seen below, the "Error: Algorithm not found" is thrown and "print processing.alglist()" is showing none. Any idea why this ...
2
votes
2answers
6k views

How to add csv file in QGIS 2.0 using Delimited Text Layer Plugin?

I used to import csv files in previous versions of QGIS using the format below, but when I upgraded to QGIS 2.0 the delimited text layer plugin was changed and I can't import the file anymore. The ...
2
votes
1answer
2k views

QGIS Python version

I have brewed python 2.7.3 onto my Mac (Lion), and installed shapely via pip install shapely. The Polygonizer plugin, however, does not find the shapely library. I see when QGIS loads a Python ...
0
votes
1answer
4k views

Create a hyperlink to a pdf file in the attribute table [duplicate]

I want to add a hyperlink to a pdf file into the attribute table of a vector layer. I already read the documentation about evis and the answered questions about this here. It didn't seem difficult, ...
7
votes
2answers
7k views

How to move labels in QGIS?

I'm trying to manually move labels but having some trouble. I'm trying to move the labels while in edit mode. I've added fields for x coordinate (all null), y coordinate (all null), rotation (all =0), ...
7
votes
1answer
9k views

Loading *.adf files into QGIS?

Is there a possibility to load .adf files to Quantum GIS?
6
votes
1answer
7k views

Cut polygon shapefile by line shapefile

I have two shapefiles, a polygon shapefile (lake) and a line shapefile (boudary) I want to create a new shapefile "polygon to the north of the boundary" What tool can I use in QGIS or other free ...
6
votes
1answer
1k views

How to calculate te area between contour lines on a DEM with QGIS 1.8?

Does anyone know how to calculate the area in km² for each altitudinal band (between 100 and 200, 200 and 300...) based on a DEM? I added the contour lines with a distance of 100 metres but could not ...
6
votes
1answer
773 views

Where are the Expression-based Labeling options in QGIS?

I have imported a layer into my map to show the location of towns/cities. However I had to set graduated styling so that only cities over a certain population show. I now want to label the ones that ...
6
votes
6answers
8k views

How to redefine the nodata value into zero in QGIS?

I have an image which i cliped with an AOI polygon. The contour area was set to pixel value = 0 and I have a nodata value of -32768. I want to redefine the nodata value into zero. I used to do this ...
5
votes
3answers
755 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) ...
5
votes
3answers
924 views

How to visually sort the order of Points with QGIS, GDAL, …?

The following Points layer is the basis of a rendering in a Android application. Android allows to draw a shape from the provided points. I cannot use LineStrings. However, the order of points ...
4
votes
1answer
2k views

Why are the Google basemaps no longer appearing in QGIS?

I had done a few projects using Google Physical/Streets as basemaps but now when I re-open those projects all layers appear except for the google basemap (other layers include .kml). I had ...
4
votes
2answers
153 views

CRS reprojection

I am trying to change the CRS of one shapefile that is originally in NAD27 to WGS84 in Qgis 2.6. When I proceed to make the change, I still continue to see the file in UTM coordinates... I've tried to ...
4
votes
2answers
783 views

Setting rendering order of line layers in QGIS

I have a dataset where different road types are in separate layers, i.e. motorways, primary roads and secondary roads. In turn, each layer is subdivided by embedded codes into different sub-types - 4 ...
4
votes
2answers
2k views

How to install shapely for python 2.6 (Mac) NOT 2.7?

I'm trying to use Polygonizer plugin inside QGIS, but it needs Shapely to work. I've installed Shapely (pip install Shapely) but that's for python 2.7. QGIS works with python 2.6 (on Snow Leopard) and ...
3
votes
1answer
77 views

Exploding features based on numerical field in QGIS?

I have a set of data as polygons, each with a Number field with value X. Is there then a way to copy this into X number of polys at the same location? (ideally points distributed across the poly but ...
3
votes
5answers
4k views

Getting No module name exifread error from QGIS Photo2Shape plugin?

I had Photo2Shape plugin installed on QGIS 2.4 (Windows 64 bit), following installation of 2.6.1 and an upgrade of the plugin itself Photo2Shape is now broken. Error message on install is "No module ...
3
votes
3answers
246 views

Spatial join without operation on the variable of interest

I have a simple problem: I've got to spatially join records of an epidemic in forests to some plot coordinates I have gathered. Problem is, I cannot obtain the records for each year on each plot, I ...
3
votes
2answers
375 views

How to Make an Outside Buffer in QGIS?

I have a layer of street segments that are within a given distance of a fire station. Now I want to make a border around these street segments. If I use Buffer, it puts a buffer around each segment. ...
3
votes
3answers
3k views

Qgis server on Ubuntu Server 14.04: Permission denied

I'm trying to install and configure Qgis Server (2.0.1) on a virtual server with ubuntu 14.04, Apache 2.4.7. After trying to install normally, the server gave me 404 error, so I tried to add ...
3
votes
1answer
1k views

QGIS says “osgeo [python-gdal]” isn't installed on Mac

I know similar questions have been asked (like this one) -- but I'm encountering a unique problem. I installed GDAL complete 1.11 from KyngChaos, but when I open QGIS, I get the following error ...