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

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342 views

Unable to load PostGIS vector layer into QGIS using python cookbook recipe

I'm having trouble loading a PostGIS layer using Dufour (from osgeo4w), using the guide at http://www.qgis.org/en/docs/pyqgis_developer_cookbook/loadlayer.html. I just get the 'invalid layer' message. ...
2
votes
1answer
94 views

Is there no editmode for CSV files? [duplicate]

I load a delimited text layer and it get's visuialized. Unfortunatly I don't know why I can't switch to edit mode. I already worked with similar .CSV files in edit mode before, under the same setup :( ...
1
vote
2answers
45 views

Linking data to road colour scheme

I'm getting started with a qgis map showing the quality of roads in my town. I have various data which create an index of 1-5. How do I link this index data to road data in a map, showing the bad ...
1
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0answers
86 views

How can I change the NoData value in QGIS 2.x using the python console

I'm trying to add a NoData value to a single band raster image in QGIS 2.0 using the python console but can't find the right bit of code to do it. Here's what I see on the console: >>> ...
2
votes
1answer
423 views

How to label vector features programmatically?

I am using python for QGIS 2.0.1 and I have a vector layer of points representing the positions of state labels. I want to display the 'state abbreviation' attribute on the corresponding point for ...
2
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1answer
187 views

How to use SAGA ShapesToGrid via Processing in a Python plugin?

I run these lines in my code: vectorlayer_vector = ftools_utils.getVectorLayerByName(inputLayer) Elevation = self.lineAttrib.currentText() cellSize = int(self.linePix.value()) outPath = ...
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2answers
96 views

Problem loading view from postgres

My problem is loading view table from Postgres. Here is my view table: SELECT h1.gid, h1.st_buffer FROM vmo_buffer_2m h1 LEFT JOIN vodomjeri h2 ON st_intersects(h1.st_buffer, h2.geom) WHERE ...
3
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1answer
274 views

How to define a line's width graduated by its attributes?

I have a line shapefile with lots of lines that have different attribute values. I want to present these lines in different widths according to their attribute values without classes but a graduated ...
2
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0answers
143 views

Accessing existing instance of qgis from stand-alone python script

For my own data analysis pipeline, I am running a split screen setup with iPython notebooks on one side, generating variables from source data, pushing them to a csv file which qgis then reads/joins ...
4
votes
1answer
126 views

Data defined label alignment option greyed out on new Quantum GIS Dufour

I am trying to customise the positioning of labels in relation to points in a vector file layer in the new QGIS 2.0. In QGIS 1.8 I was able to enter two customised X/Y columns in the attribute ...
0
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1answer
77 views

Interpolation without a point layer in QGIS

I have a vector layer with incidence data (i.e. frequencies) and I made a graded color map from this using the above frequencies. Now I am looking forward to creating an interpolated (kriging) map ...
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0answers
198 views

Select Expression and Field Calculator in ONE STEP with QGIS

I have an Open Street Map Shapefile and i want to use Field Calculator to add information to a field called a800900 according to the field TYPE of street, by different area (field called ID_2). The ...
3
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1answer
545 views

Does QGIS feature a tool like ArcGIS Data Driven Pages?

Has QGIS progressed to the point of having a Data Driven Pages type tool set yet? Or perhaps something similar to the old DS MapBook pre arcgis 10?
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0answers
171 views

How to Export/Print/Save CMYK colored map to SVG, PDF, or PRN/EPS file

I am a beginner using QGIS 2.0.1 on Windows. Following Data-defined Styles in QGIS I fill CMYK values on my map layers, but I cannot Export/Print/Save CMYK to SVG, PDF, or PRN/EPS file. I see only ...
1
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1answer
105 views

How to calculate weighted mean coordinates with negative weights in QGIS?

Hi, I'm pretty new to prof. GIS, but have OSM experience. So if I just miss something obvious, please don't punish me :) I have a .CSV file with measurements of wifis along a track. I like to guess ...
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0answers
26 views

Style Manager Symbols and Ramps Missing in QGIS 2.0 [duplicate]

This is very frustrating. I already posted a question about the missing color ramps in QGIS 2.0. I´ve even installed the development version without success. No color ramps available, and I have to ...
5
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2answers
2k 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 ...
0
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1answer
238 views

How to define correctly the Grass region in Qgis

I know that my question could be pretty basic for some of you. I am trying to learn GRASS. I have some raster layers and a vector file in EPSG 32614. Using the grass plugin I defined a new map set, ...
2
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1answer
299 views

How to reclassify a raster (tiff) with multiple bands?

i have a raster file containing information about the windspeed average for the year. My purpose is to reclassify the 15 classes based on their rgb-composite. The color is the only information given. ...
6
votes
2answers
678 views

How to extract mountain peak points from a given digital elevation model?

For past couple of days, i m trying to determine how many mountain peaks are visible (line of sight) from a given location using POSTGIS. The data i have is DEM for Swiss and address locations from ...
2
votes
1answer
179 views

How to join USDA SSURGO soil table data to features in QGIS?

I am trying to make a soil map using QGIS. The only problem is that I cannot join table data to features in QGIS. In ArcGIS for Desktop you just open the folder and then join the tabular table ...
3
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2answers
412 views

QGIS DB manager Import layer/file tool won't allow me to choose “Append data to table”

I want to append some data to a layer in my PostGIS DB using a shapefile, but when I use the Import layer/file tool in QGIS, it doesn't allow me to choose the append option. Why is this and how do I ...
1
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1answer
139 views

Why does georeferencing reduce the image resultion?

I'm trying to use a raster as a base image in my QGIS project. It is a building schematic which is fairly high resolution. Importing this into QGIS, it seems that the only way to re-position an ...
4
votes
1answer
628 views

How to use the Intersects function in the Field Calculator of QGIS?

I would like to have an example on how to use the Intersects function in the Field Calculator of QGIS. Basically, I want to know which feature from a polylines layer intersects a polygons layer and ...
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0answers
131 views

Why are the colors of my WMS layer messed up in QGIS?

I have a raster image on my computer, and I used it to test some geoserver features. (I'll upload images to show you what the problem looks like) I have the same raster, but transferred by wms. And ...
9
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1answer
647 views

Import GRASS and SAGA modules to python script

I'm new at this. I am "building" a python plugin for qgis and I want to import modules from GRASS and SAGA but I don't understand how to do it. The plugin I want to import is Kriging interpolation ...
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2answers
113 views

SUDS (SOAP) from the Python console in QGIS

I´m trying to install a SOAP API called SUDS, on a Windows 7 OS, to be able to run SOAP from the QGIS Python console and pyQGIS/Python scripts. The only Python I have installed is the one comming ...
2
votes
1answer
1k views

Configure Orfeo Toolbox to work with QGIS v2 Windows 7 from standalone installer

I have asked this question on the QGIS mailing list, but have not yet had a satisfactory result. The QGIS manual at http://www.qgis.org/en/docs/user_manual/processing/3rdParty.html is confusing about ...
6
votes
1answer
1k views

Atmospheric Corrections for Landsat 8 OLI Using Orfeo Toolbox

I am trying to correct some Landsat 8 OLI imagery using the Orfeo Toolbox Optical Calibration tool via QGIS. I've retrieved data from Aeronet as well as relative spectral response data for the OLI ...
4
votes
2answers
285 views

How do I generate a random raster (or probabilistic cellular automaton) in QGIS?

I'm trying to create something like a cellular automaton land cover change model using QGIS, in which cells randomly change land cover based on probabilities determined from various input rasters. ...
5
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3answers
387 views

Cleaning up data in Excel for use in QGIS

I am trying to clean up a large .txt dataset in Excel. I think that a macro or another application may be able to clean up the data they way I want but I have limited programming skills. I need to ...
4
votes
2answers
469 views

How do I set layer transparency in QGIS 2.0 with Python?

I have a raster layer loaded in QGIS and I'd like to be able to set its transparency via the Python console. I'm new to the API and have not been able to find out how to do this. Any help would be ...
18
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3answers
325 views

Python literature relevant to QGIS

Python for ArcGIS is a book that I have been looking at. Does anyone know if this would be applicable in QGIS? I am not looking to write application/plugins, simply get better at understanding ...
11
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3answers
337 views

How to update file locations in QGIS projects?

I don't know if there is an answer to this question, aside from the obvious. I have about 30 different QGIS Project files for 30 different clients. Each is saved onto my computer and all their ...
2
votes
2answers
149 views

Set projection/CRS in map and shapefile to produce buffer

I simply want to create a buffer of a specific size, around a single point. When I create a buffer it uses degrees/ or radians, or whatever, and the buffer is created that covers the whole screen. I ...
2
votes
2answers
74 views

Delete photos with no location in EXIF information

I can extract the locations of my photos in QGIS using Photo2Shape or Geotag and import photos, but I want to be able to delete the photos that do not have location information with them (they are ...
1
vote
2answers
375 views

QGIS - load data by SQL window

I have problem with QGIS (2.0.1), PostGIS (2.0.4) combination. - A can load tables or views by Add PostGIS layer. This is OK. - But a can't load data by DB Manager and SQL Window. Executing query ...
4
votes
3answers
1k views

How to convert raster to point in QGIS

I wanted to convert Raster into Point Vector in QGIS. Is it possible? QGIS have option to convert it into polygon but i didn't found any tool to convert it into point. can anyone help me?
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0answers
40 views

How to perform Visibility Analysis using QGIS? [duplicate]

How can I calculate Visibility using QGIS? I have not found any suitable plugins for QGIS to do this.
2
votes
1answer
66 views

QGIS; Is it possible to show layer name in attribute table in print composer?

When adding attribute tables in the print composers it is not possible to distinguish between various tables from various layers; each table is generic and does not indicate which layer the table is ...
0
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1answer
60 views

Setting up Raster Calculater for QGIS Python Console: ImportError?

I'm trying to follow the instructions here How to evaluate raster calculator expressions from the console? to set up the python console to to use the raster calculator. I tried: from qgis.analysis ...
0
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1answer
109 views

QGIS raster calculator “not equal”?

Is there a syntax for "not equal" in the QGIS Raster Calculator? If so, what is it?
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2answers
213 views

Editing vector data over the net: WFS or PostGIS?

I'm using QGis to update the attributes of a large vector dataset (~20,000 polygons) stored in PostGIS. I'm going to have to do that to other large datasets so the idea is to bring in more people, ...
3
votes
2answers
129 views

Why can't I open a .xls with QGIS in OSX?

I'm trying to open an .xlswith QGIS 1.8 in a Mac, I'm loading the vector layer from Add new vector layeretc. etc. the procedure works in Windows but not in Mac where I have an error Invalid source ...
0
votes
1answer
454 views

installing older version of QGIS on Ubuntu

I recently installed the latest version of QGIS (2.0) on my UBUNTU 12.04. But am not very satisfied with it. I would like to uninstall it and reinstall QGIS 1.8 v on Ubuntu. Am unable to do so. It ...
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0answers
29 views

Map algebra from QGIS python console? [duplicate]

What command do I use to do map algebra on rasters from the QGIS python console?
1
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1answer
55 views

Problem about exporting the project

I'm working on a project using QGIS. I have 3 layers in the project, city boarder, the location of the natural monuments, and a layer as background card. I am going to have these three layers in my ...
0
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1answer
130 views

Problems installing the Astun Technology Loader in Windows 7

I previously asked a question Using OS Mastermap SLDs in QGIS I got several answers suggesting that I use the Astun Technology Loader. There are details on how to do this ...
10
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1answer
393 views

PyQGIS file lock release

I was wondering what triggers the release of file locks in pyQGIS? I am trying to delete a few data sources (used temporarily) by calling QgsVectorFileWriter.deleteShapeFile, but I have to quit QGIS ...
0
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1answer
253 views

How to check if REST plugin is installed for GeoServer

Hi I am having trouble uploading vector files onto GeoServer 2.4 using 'Import Vector' in the QGIS Processing toolbox. After reading around about the 'REST' plus in I went to: http:// Also when I run ...