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

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22 views

QGIS : How to cover a number of points with disks?

I have to cover some points with disks. These disks are not of a fixed size, they have to constraints: - a maximum diameter, and - a maximum number of points covered. I would like to ...
2
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2answers
38 views

How to set Zero values to NULL using QGIS pycalc?

I'm using QGIS 2.4 pyclac and windows 7 OS. I have columns that should show NULL value but instead of that they show Zero (0) value, I need those fields to be NULL. This far I have seen a script that ...
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0answers
8 views

Comparing geographical coordinates of two GML files in a .bat file

I am transforming large files from a projection(pr1) to ETRS89 and back to the projection(pr2). In order to see if the transformation is consequent I am trying to compare the coordinates of pr1 before ...
3
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2answers
2k views

Is there a zonal statistics tool to calculate median and mode raster values for each polygon?

I'd like to calculate zonal statistics for a raster where the zones are defined by polygons in a vector layer within QGIS. Specifically I'm interested in calculating the median and mode raster values ...
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1answer
20 views

How to create spline in QGIS

I want to create spline in QGIS. I have tried to use Cad-tools - Create spline line\poligon but I can only draw it and can't save. What is wrong I am doing? Is there other way to create spline?
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3answers
3k views

How to create polygons with straight lines and right angles in QGIS?

I am running QGIS 1.7.0 on Mac OS X 10.6.8. When creating a polygon, how do I do it so that the lines are straight (90, 0 degrees, etc.) and when I create corners they can be right angles? For ...
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0answers
65 views

Is it possible to get WMS feature info for the WMS layer in the QGIS web client?

When I load a wms layer in qgis, it's possible to get feature information. When I open the web-gis-client on my server, it's possible to get feature information for all layers but not the wms layer. ...
1
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1answer
20 views

How to scale with radius attribute

new user of QGIS. I would like to style vector data based on an attribute (radius). The actual unit is in nautical miles. I don't want to use size-scale field or buffer to style the point rather I ...
3
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1answer
866 views

How does Flow Mapper Plugin work?

I downloaded the Flowmapper plugin for Qgis and I can't seem to find any information on how it is supposed to work... Also the text seems to cut-off and not fully showing for the input fields so I'm ...
1
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1answer
55 views

Why is feature.geometry() None in my user-defined expression function?

I'm trying the user-defined expression functions for QGIS, as listed on Nathans blog: http://nathanw.net/2012/11/10/user-defined-expression-functions-for-qgis/ I always get the feature.geometry() as ...
0
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1answer
19 views

Gdal_sieve not working?

I'm using the Sieve command within QGIS (Raster > Analysis > Sieve), but when I run the command with any variation of parameters, it completely changes the histogram of my raster data from between ...
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0answers
4 views

Tiled raster image to be placed in an OSM/ Leaflet.js map

I have a mapoverlay in a custom projection which I need to add as a layer to an open street map map within a website. Since I was not able to change the projection earlier, I decided to manipulate the ...
3
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2answers
65 views

Unable to zoom beyond scale of 1:2,256 in QGIS?

In QGIS, whatever might be the source, I couldn't zoom beyond the scale of 1:2256. Whether it's a raster or vector, result is the same. Does anyone know how to fix this ? Edit: Thanks to Chris. ...
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0answers
29 views

My map is little bit off

I am pretty new in GIS things and i have been learning how to use QGIS. Most of the maps are fine, but yesterday I went to GIS center at my University and I got the maps of my country that I will be ...
0
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1answer
90 views

Qgis Spatial Join: problem with a column!

I run the function "Join attributes by location" in Qgis 2.2 between a point vector layer and a polygon vector layer. When I open the resulting table of contents of point layer there is a column of ...
6
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3answers
1k views

Can Polygons be generalized to MultiPolygons in GeoDjango?

I set up a model with models.PolygonField in geodjango, using postgres as database. I try to import shp into postgres. The problem is, shp (compiled with QGIS) mixes polygon and multipolygon, hence it ...
3
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0answers
51 views

How to calculate percentages using QGIS field calculator expression?

I am new to QGIS. I am wanting to calculate a field using other fields and some operators. Here is my expression: case When "RVM_CAT" = 'B' OR "RVM_CAT" = 'C' Then ("PC1" /100) * "RE_ha" When ...
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0answers
29 views

3D visualization of terrain data and orthophoto using GRASS NVIZ via QGIS

How can I make 3D visualization of terrain data and orthophoto using GRASS NVIZ via QGIS? I am quite new with GRASS. I have only managed to get a 3D view of the terrain so far.
0
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0answers
12 views

Holes in Rasterized DEM from QGIS [duplicate]

I converted vector contours to a raster DEM using the rasterize command in QGIS. Generally the DEM looks correct, but the are a large number of holes in the DEM. The holes have a value of zero when ...
1
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0answers
28 views

Scaling features based on an attribute

I would like to scale polygon features by a specific factor I have calculated for each feature in a feature class. I know of the Scale tool, however it only allows for manual entry of a scale factor ...
0
votes
1answer
59 views

Get Index for a group QGIS Python

I am trying to add new layers into a specific group which I can get to work if I know the index but how can I get python to fid the index of a group so it can load the new layer into the group ...
2
votes
1answer
58 views

Python console not working at all

My python console won't work at all. I can't open it. My QGIS version is 2.4. OS is win7 64. I've reinstalled QGIS a few times but I always get the same result. Strange. Something went wrong with the ...
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0answers
21 views

How to set image size with Image Map Plugin on QGIS 2.4?

I use QGIS 2.4, but I have noticed that the "Set Map/Image Size" feature on the HTML Image Map Plugin no longer seems to work. No matter what you set the "Set Map/Image Size" for, your image will ...
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0answers
14 views

How to access the map in QGIS Web Client WEB interface

Once you have done all the instructions in this link below, I can access the WMS in QGIS smoothly http://anitagraser.com/2012/04/06/qgis-server-on-windows7-step-by-step/ Now how do I get access to ...
2
votes
1answer
18 views

QGIS Processing - Additional Creation Parameter for GdalWarp

I am having a hard time getting the "Additional Creation Parameters" to work when using GdalWarp through the processing toolbox. I am trying to set the nodata value to 0 for the output raster. ...
1
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1answer
23 views

gdaltools in qgis v2.4?

Where's the GDALTools plugin for QGIS 2.4? It's not listed in list of available plugins, and it's seemingly not installed out of the box. Is it just that it's not yet compatible?
3
votes
1answer
34 views

Why is the OSM map itself is not visible in my qgis window?

I'm new in working with QGIS. I have tried to download an OSM map of Rome and its surroundings into my QGIS. As far as I am concerned, I have followed each step which I could find on various ...
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0answers
11 views

How to install the QGIS Raster Lang plugin?

I´m trying to install the rasterlang plugin for QGIS. I tried several things on this website but it seems to be quite complicated because I need to install binary files and other files. The idea ...
2
votes
1answer
47 views

How to manipulate lidar map using sun azimuth

Hi I am VERY new to QGIS and am struggling. I have a Lidar map and want to change the view so that the ground shadow is manipulated (looking for archaeological anomalies). I think it is the sun angle ...
0
votes
0answers
11 views

QGIS plugins - how to use a custom behaviour on right click and actionPan on left click?

I have been struggling with this problem for quite a long time. Here we go : I implemented a maptool that draws a red cross on the point that is being right-clicked on. There are good how-tos, such ...
5
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1answer
942 views

QGIS Data Management: How to calculate Standard Deviation?

does anyone know of a way to find the standard deviation of an attribute lying within any given polygon? The plugin dialog "Join Attributes by Location" gives only the options Mean, Min, Max, and Sum. ...
2
votes
1answer
31 views

Rasterizing Contours - How to remove 0 values

I want to convert vector contours to a DEM. From other posts, I wanted to utilise the Grass r.surf.contours tool. Initially I converted the vector contour layer to a rasterized contours using the ...
2
votes
2answers
41 views

Date-format conversion

I'm using Time Manager and QGIS 1.8.0 and I am stuck at date-format conversion. Time Manager needs Gregorian format YYYY-MM-DD HH:MM:SS.ssssss in text field and I have thousands of records in ...
1
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1answer
17 views

Performing transformation from GHANA GRID to WGS 84 using QGIS?

I have a shapefile which was referenced using Ghana's grid system. I imported it to QGIS and specified WGS 84 but the coordinate bar still displays the Ghana grid values in the coordinate bar. Is ...
3
votes
1answer
125 views

Using Engineering symbols (*.svg) in QGIS?

QGIS looks straight forward except for the symbols or icons. I have created SVG symbols and when I place my pointer to the obvious blank areas in the symbol library a pop-up says that my symbol is ...
1
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1answer
120 views

QGIS Python Labelling

i want to label a point layer with those values exceeding a set of variables attribute table as follows 'loc field'(text),'a'(float),'b'(float),'c'(float) variables as follows vara = 5, varb = 3, ...
3
votes
1answer
33 views

How to install Apache Web Server from OSGeo4W?

Good morning, I'm trying to create a QGIS web client on my Windows 8 But with OSGEO4W not appear the option to make Apache installs Web Server, as of this writing in several tutorials and ...
10
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4answers
8k views

Is there a SVG symbol library for qgis?

Im currently using default simple symbol capabilities or dingbat fonts for point objects. Is there maybe a SVG symbol library for qgis that is a bit more extensive than that which is included? I've ...
6
votes
2answers
2k views

How do I layer stack rasters in QGIS?

I have some multi-spectral data, where the individual bands are separate Raster files. How do I layer stack these rasters so that I get one raster with 3 bands instead of 3 different rasters? This ...
1
vote
1answer
133 views

How to get a the minimum value of a raster layer in qgis with python? [on hold]

I'm very new user of QGis and I work with landsat 5 images. In this framework, I would like to make an atmospheric correction subtracting the minimum value present in each band (1 to 4). My ...
2
votes
0answers
37 views

Setting up qgis web client

I have a problem with setting up a qgis web client on remote server. I set it up on localhost and it runs smoothly, but when I done exactly the same on remote server it is just not working, even a ...
4
votes
4answers
2k views

Where can I download the exercise data for The Free Quantum GIS Training Manual?

Where can I download the exercise data for The Free Quantum GIS Training Manual? The pdf of the manual just mentions the sources of the data, but doesn't give any links.
3
votes
2answers
202 views

Per-pixel (statistical) calculations on a raster stack using GDAL

In R, it's relatively trivial to perform per pixel calculations based on a raster stack (e.g., get std.dev for each pixel on a 12 layer GeoTIFF). Unfortunately, the speed is less than desirable when ...
0
votes
1answer
98 views

Problems running model in QGIS

I am trying to make a batch model to convert band 2 and band 1 MODIS 8 day composites into NDVI. The input files are in tif format, but I want the output to be saved in Idrisi .rst format. I am ...
2
votes
2answers
1k views

Is it possible to use WMTS in QGIS?

Is it possible to use WMTS e.g. by http://data.wien.gv.at in QGIS? ich möchte gerne daten der stadt wien als WMTS-Layer in qgis hinzuladen. ist das überhaupt möglich? ich bin kein profi und bitte ...
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0answers
33 views

Where can I find “QGIS Training Manual” data? [duplicate]

I can't find data for this lesson in Quantum GIS: 9.4 Lesson: Supplementary Exercise. Can anybody help me?
3
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1answer
77 views

Reverting QGIS to version 2.2 from 2.4

I have QGIS 2.4 installed on a machine running Windows 7 64-bit "by accident". I was using 2.2 and when I added some package(s) it also installed the 2.4 version. Can anyone provide some advice with ...
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0answers
30 views

Best Landsat band for forest classification?

Using Qgis and the Semi-Automatic Plugin for Classification, which are the best Landsat bands to use to classify trees species (in central Argentina)? In Landsat 5, 7 and 8?
4
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1answer
65 views

How do you set the position of a plugin window when you start the plugin?

I'd like to set the position of a plugin's window or dialog relative to the map canvas frame. For example, if I start a plugin, I want it to appear somewhere in the left upper corner of the map ...
2
votes
1answer
36 views

PyQGIS - Start/Stop Editing with data Provider - Commiting changes

I want to edit a specific field for a QgsVectorLayer, within a QGIS application. I am facing inconsistent results from my code, ie: changes are not alway commited. Please could someone point me to ...