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

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0
votes
2answers
177 views

Interpolation using GRASS plugin in QGIS

I have been using the IDW interpolation tool through GRASS plugin in QGIS and the interpolation output I am getting is for the entire mapset region. My question is: Is there a possibiltity that we ...
0
votes
1answer
278 views

Merging Raster: ImportError: No module named _gdal_array

When I try to merge rasters I got following error message: _gdal_array = swig_import_helper() File "C:\PROGRA~1\QGISDU~1\apps\Python27\lib\site-packages\osgeo\gdal_array.py", line 18, in ...
8
votes
5answers
369 views

Print out the properties of the attribute table in qgis?

I have to merge a lot of shapefiles into one great shapefile. So I want to compare the properties of the attribute tables to see if there are differences between the tableproperties of each shape ...
0
votes
1answer
199 views

Using GRASS plugin tools from OSGEO4W command line

I am trying to do the interpolation of GRASS vector shapefiles using GRASS plugin tools. My objective is to run interpolation tool in GRASS plugin from OSGEO4W command line, which will help me ...
1
vote
1answer
431 views

Floating point calculations in QGIS

How do I manage floating point calculations in QGIS? I have carried out 3 consecutive calculations on landsat bands. I end up with 32 bit floating point rasters on which I can't carry out a 4th ...
0
votes
0answers
173 views

How to create a new table with point geometry column using QGIS DB Manager?

I have been trying to use QGIS DB Manager to create an empty table (QGIS 2.0 on Win7). My hope is that I can make an empty point file and use it to add data to, via heads-up digitizing (like you ...
1
vote
1answer
181 views

Maximum scale dependent visibility changes from 1:0 to -2147483648:1

QGIS 2.0.1 Dufour. When i open the layer properties and the scale dependent visibility is unchecked and when i check it, the maximum (inclusive) shows 1:0. I click Apply, OK, reopen layer properties ...
3
votes
0answers
129 views

How to fetch openlayers layers from pyqgis? [duplicate]

My objective is to fetch maps provided by openLayers, as in openLayers_plugin, from a stand alone python script. I would like to get it superposed to my shp file. As can be read on ...
0
votes
1answer
110 views

Can QGIS report/calculate areas/perimeters of individual polygon components within multipart shapefile?

Can QGIS report/calculate the areas/perimeters of individual polygon components within a multipart shapefile without using the "explode" vector tool to generate a new file? using QGIS 2.2.0 on ...
1
vote
2answers
394 views

Breaklines in QGIS interpolation plugin

How can I prepare data to generate a DTM using points and breaklines, but where every breakline has nodes at different heights. For example, a river valley, which regularly falls, or a dorsal line, ...
2
votes
2answers
1k views

How do I open images georeferenced in ArcMap in QGIS? (.aux.xml)

We have several ArcMap georeferenced images (raster datasets) that we are attempting to open in QGIS without any luck. These are not inside of a geodatabase and are not Arcinfo Binary Grid format or ...
0
votes
0answers
25 views

QGIS - unable to change projections [duplicate]

I am relatively new to QGIS (version! 2.0.1) and having trouble changing projections. No matter what I choose the view is the same. For example, in the attached screen shot I have chosen Alaska Albers ...
3
votes
1answer
138 views

Re-registering a GEOTIFF in qgis

I'm working on some images taken from a UAV over the course of a year. They are OSGB 1936 projection as is the whole project. Annoyingly they don't quite line up so I am trying to a few of the images ...
3
votes
1answer
260 views

Where is qgis getting the NO DATA value from?

I have a project that contains an 8-bit paletted layer (call it the mask layer) and a float 32 single band layer (call this the clip layer). I create a new raster by using the raster calculator, ...
1
vote
0answers
54 views

Error running SEXTANTE in QGIS on Scientific Linux

I've installed SEXTANTE into qgis on my Scientific Linux machine and I am getting the following when attempting to run Warp; INFO|Mon Feb 24 2014 15:56:20|GDAL execution console output|/bin/sh: ...
1
vote
0answers
62 views

How to get the signal when the color changes in pyQGIS?

I would like to have the signal when the color of a vector layer is changed by the user. In the doc, there is a signal that seems to fit ...
1
vote
0answers
51 views

“System not initialized. Programmer forgot to call G_gisinit().” message when loading table into GRASS via QGis

I am trying to load a CSV table into Grass with v.in.asciifrom the interface of Qgis 2.0.1 on Windows XP. As the progress bar indicated 74% of the data already loaded, I got the message "System not ...
3
votes
1answer
301 views

Qgis 2.2 how to fix bad epsg.wkt load

I installed Qgis 2.2 this morning from the ubuntugis repository for ubuntu precise. Qgis works great, except that all the common projections have been deleted. So, I am a Little bit having a heart ...
7
votes
2answers
1k views

How to configure QGIS and SAGA on Ubuntu (12.04 and others)?

During the past weeks, I have tried QGIS to recognize SAGA via the processing toolbox, both being installed from the ubuntugis-unstable repository. I have tried this on several virtual ubuntu ...
2
votes
1answer
37 views

Wrong sorting of elevation classes QGIS

I'm a totally beginner with QGIS and maybe I have a very easy problem, but I can't help myself. I got an elevation shapefile with classes of elevations like that: 1-100m, 101-200m, ... When I try to ...
3
votes
2answers
2k views

QGIS GISBASE specify location

I am just a beginner at this QGIS and GRASS and I am using this QGIS 2.0.1 Dufour which throws a error at the startup that "QGIS couldn't find your GRASS installation. Would you like to ...
2
votes
0answers
103 views

How to Simulate Venn Diagram of Buffers using QGIS?

For the sake of simplicity, suppose I have only 2 points on one layer. Point A have population of 100, and point B have population of 150. I do find buffer of these 2 points and it is intersect. I ...
1
vote
0answers
207 views

how to add polylines(routes from public transport) on postgresql(pgrouting) with GUI

After searching a several long time... i decide to ask here for help, im currently using ubuntu 12.04(because of compatibility) with postgresql 9.1, postgis2, pgrouting2 and qgis2.2 i need ...
2
votes
0answers
684 views

Move Scale Rotate raster in Qgis

I have some archaeological scanned raster that they have a north arrow and a scale bar. There is no grid, no coordinate system.I would like to put those files in a general map. I don't care about the ...
2
votes
2answers
400 views

How to write a new layer to PostgreSQL from QGIS plugin

The PyQGIS cookbook states that QgsVectorFileWriter can write vector layers to any format supported by OGR: https://www.qgis.org/en/docs/pyqgis_developer_cookbook/vector.html#writing-vector-layers ...
1
vote
1answer
173 views

Can I automatically save datetime for every entry in my spatialite tabel? [duplicate]

I'm using QGis and SaptiaLite. Is it pssible to store date and time in a field "datetime" for every entry automatically - maybe with some python code? Already existing datetime should not be updated. ...
1
vote
2answers
268 views

How can I centralize QGIS connections for multiple QGIS installations

I have multiple computers with QGIS installed on them. I regularly use the same WMS / WFS services. Now I have to connect to these services for each QGIS installation separately. It would be great ...
0
votes
1answer
134 views

v.edit break: how to loop through XY coordinates on using GRASS on Windows 7

Trying to follow the suggestions on this thread: splitting a lines layer using points However, how to do so in a windows environment using the GRASS command console is beyond me, so I'm attempting ...
2
votes
4answers
512 views

How to turn all lines into one direction?

How can I turn all features of my polyline (postgis and/or shapefile) into one direction - it doesn't matter what direction. I know how to switch the direction of lines but I have no idea how to ...
2
votes
2answers
254 views

Open Arabic Shapefile in Qgis

I have a shape-file all it's fields are in Arabic. When I opens it in qgis 2.0 all the data is replaced by "?". I changed the encoding to Arabic or UTF-8 but with the same result. How can I Open an ...
1
vote
1answer
125 views

Why do features in QGIS drawn on same datum as Google imagery from OpenLayers move? [duplicate]

I have just started using QGIS. I've loaded the "openlayers" plugin and added a google hybrid layer, which is based off the WGS84 datum to my understanding. Now I create a shapefile and add a new line ...
2
votes
1answer
235 views

Is there a limit to the amount of data in a spatial join in QGIS?

I am using Quantum GIS and trying to spatially join a point grid with polygons that are overlapping. If I get the sum of intersecting features, then I can get a good raster value. Well, every time I ...
0
votes
0answers
69 views

Zonal statistics won't work after re-projecting vector layer

I have qgis 2.0. I want to analyze raster information within a buffer of 30 miles around a vector layer of cities across the world. However, both the raster and the vector are in WGS84. I have no ...
1
vote
2answers
324 views

QGIS Installation - Oracle Link

Trying to connect an oracle 10g database to QGIS. I'm getting the error below: ORA - 12154: TNS:Could not resolve the connect identifier specified Anybody ever seen this error, or could provide some ...
2
votes
1answer
293 views

Calculate distances between polygon centres in QGIS

Is there a practical way to calculate distances between polygon centroids in QGIS? I have a UK city region map divided into administrative units (1 ward = 1 polygon). I want to represent their ...
3
votes
2answers
622 views

How to produce a CSV file from .tif file with elevation data? [duplicate]

just want to ask, I have a .tif file that contains all the elevation of a country. How can I convert that to a CSV file that contains x,y,z values where x and y are the latitude longitude respectively ...
1
vote
2answers
59 views

QGIS 2.0 How can i get a precisely Rendering time?

I work with QGIS 2.0.1. I have a large number of raster data files and i selected different methods to represent them. Method: Import all raster data as individual files Method: Generate a single ...
3
votes
1answer
439 views

Plugin Tutorial issue: trying to work around changes in QGIS API

I'm currently following the tutorial to create my first python plugin for QGIS: http://www.qgisworkshop.org/html/workshop/plugins_tutorial.html and have similar issues to this thread: QGIS 2.0 Plugin: ...
4
votes
4answers
863 views

How to georeference Tiffs after manipulation in Photoshop?

I am exporting very high-res (7000x7000px) hillshades from ArcMap as tiff files. I am then doing some work in photoshop to the images. How can I easily georeference these tiffs after working on them ...
2
votes
1answer
104 views

Why am I losing part of my raster when I reproject?

QGIS 2.0 Working with tiff raster file. Reprojections are in WGS84 Mercator. Here is my problem: I am trying to use buffers or urban areas to analyze light intensity on a raster layer. I want 30 ...
3
votes
3answers
1k views

How to reproject WGS84 to a metric coordinate system with own reference point in QGIS?

I have GIS data in EPSG:4326 consisting of 2D points, linestrings and polygons that are all close (i.e. less then a couple of hundred of meters) to a certain WGS84 coordinate point. I would like to ...
1
vote
1answer
341 views

How do I get the vector output segmentation algorithms to work properly in QGIS 2.0?

I'm trying to run the Watershed Segmentation algorithm, specifically, but I have been receiving the same error message using any of the available segmentation algorithms. I'm new to QGIS and have been ...
2
votes
1answer
96 views

QGis draw over simple jpeg image

I'm pretty new to GIS, and since 2 months ago QGIS is a great tool to achieve very simple tasks, such open some shapefiles I find in the web and load that data on my website geoJSON formatted. Now ...
1
vote
0answers
147 views

How to apply categorized symbols to polygon layer with PyQgis?

I'm fetching a polygon layer from postgres like this: uri = QgsDataSourceURI() uri.setConnection("localhost", "5432", "mydb", "postgres", "xxx") uri.setDataSource("public", "my_table", "geom") lyr = ...
0
votes
1answer
82 views

Why is the map content not displayed when I reopen Print Composer?

I just updated from QGIS 1.7 to 2.0 on Mac. When I now open a project and create a map in the print composer the content of the map is lost when I open the project again later. The settings of the ...
0
votes
2answers
263 views

Unable to implement pgrouting(plugin) pgr_astar routing algorithm (shortest path) [duplicate]

I have been working on a project for indoor navigation. I made the floorplan of the building and road-map for routing purposes as shp files (using JOSM, making GeoJSON and then converting to shp file ...
1
vote
1answer
267 views

Problem connecting local POSTGIS in QGIS

I'm trying to connect to local POSTGIS database using QGIS. I'm using the POSTGIS Tutorial form Buondless (rif. http://workshops.boundlessgeo.com/postgis-intro/index.html). The context is the ...
0
votes
1answer
62 views

Fail to get heatmap from MULTIPOINT column of Spatialite layer in QGIS?

I got a heatmap from a POINT column of spatialite layer. But, when I made another heatmap from MULTIPOINT column, it was blank. What is the possible reason of this problem?
1
vote
0answers
157 views

Install PyQGIS in virtualenv

Is it possible to install PyQGIS in virtual environment? I want to use rendering capabilities in my own application which runs using virtualenv.
1
vote
1answer
57 views

Can't see map after renaming fields using Table Manager plugin

I'm quite the beginner at using QGIS and I'm not sure what I did. I tried renaming two of my columns/fields using the plugin Table Manager, and after changing the names, my map no longer appears. I ...