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

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2
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2answers
8k views

How to clip a line layer based on polygons with QGIS?

I have a line layer and a polygon layer. Both files have the same SRS. I want in a new shape file only the lines covered by the polygons. I tried in QGIS the Vector -> Geoprocessing -> Clip ...
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
3answers
4k views

How to change null values raster values to 0 in QGIS?

I need help... I'm having problems with QGIS. I have some rasters that appear to have null values, even though I reclassified them to obtain a boolean raster :( How can I change the NULL values to 0?
7
votes
2answers
6k 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), ...
6
votes
1answer
5k 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
713 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 ...
5
votes
3answers
597 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
726 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 ...
5
votes
2answers
3k views

Total of attribute field of point layer per polygon layer

I have a polygon shapefile of many lakes, I also have a point shapefile of locations on those lakes where fish were caught. The point shapefile contains the attributes: Fisherman_iD, Fish_Caught, ...
5
votes
1answer
8k views

Loading *.adf files into QGIS?

Is there a possibility to load .adf files to Quantum GIS?
5
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.
4
votes
2answers
692 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
5answers
6k 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 ...
3
votes
1answer
71 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
2answers
136 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 ...
3
votes
3answers
220 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
304 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
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 ...
3
votes
4answers
2k views

QGIS 2 Python error on Mac OSX

Have just installed newly released QGIS 2.0. I installed the gdal package available at the official kyngchaos site. It seems to run ok, but when the program loads up I get a lengthy error message ...
3
votes
1answer
1k views

QGIS 2.0.1 Runtime error and crash at Add Delimited Text Layer plugin

I just installed Dufour on my Windows 7 Lenovo ThinkCentre desktop. When I open 2.0.1 I get this error window: And when I try to add the 'Add Delimited Text Layer' plugin I get this message: ...
3
votes
4answers
2k views

Can I use QGIS with Qt5?

I want to use QGIS with Qt 5.But i don't know the exact relationship between Qt and QGIS.Will there some problems if i use qgis with qt5 or it will not depand on it...
3
votes
2answers
4k views

How to install the Python module shapely for QGIS use?

I'm using QGIS 1.8.0 on a Mac with OSX 10.6.8 (Snow Leopard). I've installed QGIS including GDAL, GSL, UNIXImageIO, Freetype, and Matplotlib all from www.kyngchaos.com. When installing the plugin ...
3
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
3answers
6k views

How to install Python libs for XYtools to read Excel files

I need to use the XYtools plugin to read an Excel file. After choosing the XYtools incon and indicating an Excel file to read in, a message appears "there is a problem with loading a python module ...
3
votes
1answer
3k views

How to install SDA4PP plugin for Kriging in QGIS?

I am trying to do kriging in QGIS. I have loaded the SDA4PP plug in. Almost all of the items in the SDA4PP dropdown menu are not highlighted and are unresponsive when clicked on - including the ...
3
votes
2answers
5k views

Why does QGIS scalebar show a wrong scale?

I'm using QGIS 1.7.1 and have added a scalebar. The scalebar usually displays in degrees, unless I switch the map's projection to meters, in which case the units are display in cm. This is not ...
2
votes
5answers
3k 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 ...
2
votes
2answers
234 views

Creating sub sections (groups) of layers in QGIS?

I am working on a project regarding Fish species and fishing methods with many layers. This creates confusion. I would like to create layer sub sections (groups) like the following: Fish Species ...
2
votes
2answers
263 views

Is there any way to 'clean' up ASTER v2 DEM data?

I downloaded all the tiles I needed, then plotted them to find that they don't all seem to have the same quality. Basically, you can see all the edges of a lot of the tiles. Is there any way to clean ...
2
votes
2answers
848 views

How to determine which polygons, if any, points fall within?

I am a amateur at GIS and need some help. I have a group of shapefiles of various areas and an Excel spreadsheet of addresses I have geocoded to points. I want to determine whether each point falls ...
2
votes
1answer
340 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
1answer
3k views

How to export QGIS contour attributes in a DXF file?

I'm new to this. I have a .tiff data file that generates contours in QGIS. I save it as .dxf. The contours don't have any attributes or data. That's bad, because I want to make a 3D landscape in Revit ...
2
votes
1answer
5k views

Import MySQL Spatial vector layer in QGIS

I have a spatial table called 'places' in MySQL, with a spatial column 'pt' (point). I tried to import it in QGIS and no points appear. I created a view 'places_as_text' which reproduces the table but ...
1
vote
2answers
255 views

Problems with plugin/installer manager in QGIS 2.6.1 Debian

An error has occured while executing Python code: Traceback (most recent call last): File "/usr/share/qgis/python/pyplugin_installer/installer_data.py", line 460, in xmlDownloaded if ...
1
vote
2answers
2k views

Make a polygon from intersecting lines in QGIS, using Polygonize or similar?

In QGIS, I want to make polygons from a set of intersecting lines. Looking at the screenshot here, I want chop the purple line (it's a closed line, not a polygon) where it crosses the green and blue ...
1
vote
1answer
1k views

Delineate polygonal catchment areas from a raster using open-source GIS

I'm 90% sure this basic question has been asked before but looking through the other posts I simply do not see a useful answer. I need to calculate polygonal(vector) catchment areas from a raster ...
38
votes
8answers
17k views

QGIS and gvSIG comparison

Many debutant GIS users are asking me which one is better QGIS or gvSIG. Since I use Qgis and I don't have any experience in gvSIG, I aways say that both are very nice softwares and the chose is a ...
27
votes
2answers
11k views

How to style beautiful road maps with QGIS?

I am trying to design a beautiful map using Qgis. As I'm a software developer not a designer, I was hoping that this will be easy, but it isn't! There is a similar question here Qgis tutorials and ...
21
votes
5answers
6k views

Obtaining print quality PDF or PNG output from QGIS?

I work with people who use ArcGIS Desktop and they have found the best resolution output images are made by creating PDFs. They tell me that *.png and the rest out of ArcGIS Desktop are not ...
14
votes
5answers
2k views

Find pseudo nodes in free GIS software

Software gvSIG OA Digital Edition 2010 have tools topology for finding pseudo nodes in linear geometry. I set cluster tolerance 0.00002 and maximum number of errors -10000 for 20000 link count linear ...
6
votes
2answers
8k views

How to connect to Postgres with QGIS?

Oddly, it should be simple, but I can't connect to a local PostGIS database. My installation is with Mac OS X (10.8), Postgres.app (in doc it's said to have PostGIS included) and Quantum GIS 1.8. ...
18
votes
5answers
7k views

A SQL console in QGIS

I know QGIS comes with its field calculator, which is not bad. It also comes with ftools which permits several operations on geometry and attributes. But we often need more control and I haven't seen ...
16
votes
2answers
2k views

How can I merge/collapse nearby and parallel road lines (eg. a dual-carriageway) into one single line?

I have a shapefile from OSM which contains all the roads within a city. Larger roads (like dual-carriageways) seem to have 2 parallel lines. I'd like to collapse / combine those into 1 line so I can ...
15
votes
4answers
16k views

Feature comparison between QGIS and ArcGIS for Desktop [closed]

I am learning to use QGIS and ArcGIS for Desktop but I cannot find the differences between them. What are the differences between the capabilities of QGIS and ArcGIS for Desktop?
10
votes
2answers
2k views

How do you display related records in QGIS?

Coming from an esri background I have always used relationship classes in a gdb to display records related to a feature. Eg. Relate 1 survey point to many documents, photos etc. Does any one know how ...
9
votes
3answers
19k views

How to export Polygons to CSV with coordinates?

I am very new to QGIS, so please bear with me. I have a ".shp" file, which is contains a set of boundaries for suburbs of Australia. I opened it to QGIS and I would like to export it into a CSV file ...
7
votes
1answer
1k views

Is there a python option to “join attributes by location”?

I am trying to perform the function join attributes by location as found on the QGIS menu Vector>Data Management Tools. I am seeking an open source python option for this. I know arcpy has a spatial ...