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

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4
votes
2answers
103 views

QGIS renders outlines where none should be

QGIS always renders the borders of a feature polygon. How can I disable this? Even if I set Border style to "No Pen" and the colour is exactly the same for different categories there is a small grey ...
1
vote
1answer
2k views

QGIS Processing error with SAGA, “output layer could not be open”

QGIS 2.4.0 SAGA GIS 2.0.8 DESCRIPTION ERROR when processing with SAGA. I used the "Shapes to Grid" function. The error given: "Oooops! The following output layers could not be open". This error ...
1
vote
1answer
73 views

Where is the log for advanced Python calculator errors?

There is a specific log file for Advanced Python calculator in QGIS 2.4.0? I got the tab message below point to a log file there I wasn't able to find by myself.
6
votes
3answers
4k views

How to create contour lines from point data using QGIS?

I'm using QGIS 2.4.0 and I have a shapefile of points with elevation data and X and Y coordinates. I'm using windows 7 OS. The idea is to create a contour line SHP using my point data. My question ...
6
votes
2answers
503 views

Wrong $area from field calculator (QGIS)

The area of the polygons in a layer, calculated by the field calculator with "$area" is wrong (much too big) for some polygons. If I draw the concerned polygon again, the area is calculated correctly. ...
4
votes
1answer
2k views

How to create a catchment from a point using a DTM raster in QGIS?

I need to find a better way to delineate a catchment from a given point on a watercourse using a DTM - currently I am either using FEH, or if the catchment is too small using contours to draw ...
3
votes
1answer
232 views

Automatically create Text/HTML annotations in QGIS on a Point Layer

How would one proceed to generate an HTML annotation or a Text annotation for all points in a shapefile? They are all points. What I want to do is load up a shapefile containing coordinates and values ...
2
votes
1answer
2k views

Cannot toggle ''edit'' of shapefile in QuantumGIS 1.8

My problem is as follows: I imported a number of shapefiles from a .gpx-file from a gps-device. Each shapefile contains a number of waypoints. For the study I am doing, I need to give all of them ...
2
votes
1answer
213 views

Clusters of points: Determining the centroid (QGIS)

I've basically got the same issue as this post, but can't find a way to transplant the ArcGIS solution to QGIS. I have household-level geo data for 10 villages spread out across the country. I need ...
3
votes
1answer
1k views

Looking for QGIS 2.4 C++ Hello World example?

In the project I'm working on (C/C++/Qt application), we are trying to integrate QGIS (latest version desirable, 2.4 for the moment). But there is very little information in the web on how to use QGIS ...
2
votes
0answers
44 views

QGIS how to make unedited data?

I have a table in QGIS (using QGIS 2.4). I have created a form for adding attributes. When I add new objects on the layer, I also create it's attributes. Can I make attributes that I have added ...
1
vote
0answers
50 views

Distorted exported georeferenced tif from far north

I'm trying to export a tif file for R, to plot my data on top of. I have geo-referenced this tiff file: "background_changed" from "Background". But when i export it, the file is very compressed in ...
1
vote
0answers
81 views

How to load style from postgresql?

Is there any way to load a postgresql style for a vector layer using python? There is a function: loadNamedStyleFromDb (const QString &db, const QString &theURI, QString &qml).Does it ...
3
votes
2answers
195 views

Why are there no line breaks in my labels even though I added \n?

I'm having an issue with creating multi-line labels in QGIS. I believe I have the syntax right in the label expression because the output preview looks correct. However, on the map, everything ...
2
votes
0answers
45 views

How to do LOS Analysis in QGIS?

I am not able to do LOS analysis in QGIS. I have point Features and Raster SRTM Data. I have installed the LOS Plugin in QGIS but not getting any results. Kindly suggest?
2
votes
1answer
182 views

Using TIN - interpolation plugin - to calculate volume

I am having trouble calculating the volume of my TIN. I have attempted to create a TIN using the interpolation plugin in QGIS. Here are the steps that I followed. I added a Zvariable row in the ...
2
votes
1answer
153 views

How to change parameters of certain algorithms in QGIS process modeler during run time?

I am using Process modeler to automate a bunch of things like Create Graticule -> Extract points at the graticule centeroids -> Add coordinates to the points -> update certain fields of the point file ...
9
votes
6answers
7k views

How to fix quickly a lot of geometry validity errors in QGIS?

I am working on ownership data at a US county level. I have one shapefile per county that contains thousands of tax parcels. I need to dissolve the polygons representing parcels owned by the same ...
4
votes
3answers
166 views

USA County level, detailed OpenStreetMap basemap in tiff?

Is there any way to get detailed (close zoom) OSM tiffs at the county level in the USA? I would like to use them as basemaps for a class I am teaching in GIS, using QGIS. I know about (and love) the ...
1
vote
0answers
104 views

Word cloud labels in QGIS from database

I would like to do some word clouding as labels in QGIS from a series of tables in a database. Examples of word clouds can be found here: Word Cloud - Google Search I have two tables in a database: ...
-1
votes
1answer
108 views

How to clip a raster with a mask in QGIS? [duplicate]

I am trying to clip a raster using a virtual raster as mask layer in QGIS. It doesn't create a file. Could anyone explain how I should proceed to do that?
3
votes
2answers
183 views

Show categories in QGIS

I have a .csv file pointing at coordinates. It is a large file that is edited often. In it, I have three groups of data (say A, B, and C). Within each group there are a number of Names, and each ...
1
vote
1answer
139 views

How can I fix a broken gdal-tools plugin in QGIS?

I have QGIS installed on my 2011 macbook pro and I recently upgraded my OS to 10.9. After the upgrade, I noticed that QGIS gives me this error (see attachment 1) saying that the plugin is not ...
1
vote
0answers
31 views

Problem Loading Plug-Ins in QGIS 2.2 on Mac

I'm trying to load the 'processing' module in QGIS (2.2.0-Valmiera on Mac OSX 10.8). However, this module and others (e.g. GarminaCustomMap) re failing to load with a message: ImportError: No ...
1
vote
1answer
2k views

qgis polygonize error 4 “file does not exist in the file system”

When I try to convert a raster DEM (in asc or geotif format) to polygons I get the error below. ERROR 4: `Y:/GIS/oversvmmelser/tmp/out.tif' does not exist in the file system, and is not recognised ...
6
votes
2answers
419 views

Simplified flood “model” / estimation from elevation data

The goal is to present an estimation of potential flooded area. But still keeping it simple. I know this will not be accurate. The question is: will it be good enough for at gestimate / rough ...
1
vote
0answers
347 views

How to enable Map Tip display text in qgis and qgiscloud?

I'm using the free version of qgiscloud and qgis 2.4. I noticed that if I'll use the HTML option in "Map Tip display text", the map in qgiscloud will only show the title of the layer when I ...
3
votes
0answers
211 views

Create vector grid from canvas using script

I've modified "Hex grid from layer bounds" script to my need. Just added cellsizex and cellsizey. Changed the hexagonal - 3 to "1" to make it as a square grid. Is it possible to include an option to ...
3
votes
0answers
329 views

ISOdata classifier in QGIS?

Is there a function that produces an ISODATA unsupervised classification in QGIS? The only unsupervised classification function I can find is a KMeans.
2
votes
0answers
38 views

QGIS is locking the clipboard from other application? (SitesPlus)

We are starting to use QGIS along with Sales Forecasting software Sites Plus by Gravitec. An ugly problem just popped up: Whenever QGIS is open, any attempts to calculate a data table in SitesPlus ...
6
votes
1answer
549 views

Interactively determining upslope and downslope areas on DEM?

I know SAGA GIS can be used to interactively generate maps of upslope and downslope areas for a cell within a DEM, but the output is pretty ugly. An upslope area is defined as all cells (for a ...
2
votes
1answer
356 views

QGIS show gdal_polygonized file in EPSG:54004 instead of EPSG:3857

I am polygonizing a TIFF with the gdal_polygonize.py and the resulting Shape is shown in QGIS in the wrong projection - EPSG:54004 instead of EPSG:3857. I have a TIFF in EPSG:3857 and polygonize it ...
3
votes
1answer
136 views

Calculating distances from points to the centre of cells

I am using QGIS 1.8.0 (using older version because I need the Qmarxan plugin which is not available for 2.4.0). I have a study area that has a vector laying of "planning units", or cells over the top ...
2
votes
1answer
128 views

How to use inbuilt tools in QGIS Modeler?

Is it possible to incorporate inbuilt tools like, for eg: vector grid of Research tools in QGIS model builder ?
2
votes
1answer
639 views

What's wrong with my expression to control label colors?

I am struggling to alter the label colours according to field values (as strings) in the attributes table. In my mind what I want is: If the string in column X = 'Proposed' Then label the point ...
2
votes
0answers
286 views

How to develop a real-time navigation App using QGIS API?

I want to develop a navigation application based on QGIS using C++, for live tracking. I think it is quite normal for GIS to do such things, especially QGIS as it is a very mature GIS platform. But ...
4
votes
1answer
274 views

Is there an issue with Zonal Statistics calculating wrong mean values?

I tried to solve the following issue by myself but without success. On the one hand I have a raster file which is the result of the processing "shapes to grid" tool. On the other hand I have a ...
2
votes
0answers
79 views

Why does my clipped raster seem to be slightly moved?

I'm having some problems with clipping rasters. I started clipping my raster using extents, but I saw that the clipped raster is different from the original raster. I created a virtual raster to use ...
0
votes
3answers
175 views

What Open Source Packages are available to provide routing

I am looking for ways to validate mileage charged by our contractors. They are paid from a central location to a customer, and then from the customer to a drop off location. I use QGIS for a bunch ...
2
votes
1answer
413 views

Cannot load postgis layer from sql string in pyqgis

I'm trying to load a layer using the following code in qgis python console: sql = "(select the_geom, ID from mytable)" uri = QgsDataSourceURI() ...
2
votes
2answers
250 views

How can you create a depth raster from a DTM and a polygon in QGIS?

I have a DTM raster and a flood outline in polygon format - how do I create a depth raster for the flood outline (i.e. flood level minus DTM level)?
3
votes
1answer
117 views

In QGIS, is it possible to save graduated styles to use on different columns? [duplicate]

I'm using QGIS to produce thematic maps of 9 quantities (given in 9 columns in the attribute table) which have values broadly within the same range and I would like to plot them using the same ...
2
votes
2answers
129 views

kml does not overlay correctly in QGIS

In QGIS, when I insert a kml contour that was created in Google Earth, it appears misaligned in respect to all the other layers. Note in this image how the red contour is moved upwards with respect ...
2
votes
0answers
101 views

How to design labels which look like a fraction (with a fraction line)?

I want to create labels like a fraction using data from two columns. I have tried to use: "Field" || '\n' || '――' || '\n' || "Field2" but it doesn't look good. How can I do it using other method? ...
2
votes
0answers
51 views

Creating Form in QGIS

I want to create a form for editing attributes in QGIS. I have a lot of question and hope somebody can suggest how they work or where I can read about the next elements of form: Classification List ...
1
vote
0answers
182 views

How to create a svg item onto Map Canvas in QGIS API?

I'm working on a project with QGIS-2.4.0 API using C++. I need to load some svg files to the application for displaying as symbols. QGIS API has a class named QgsMapCanvasItem, which is an abstract ...
2
votes
1answer
498 views

Setting up QGIS Server at low cost for small user community?

I want to setup QGIS Server at a low cost for a small user community (mainly me). Parameters: Some data is private so something like qgis cloud not an option (not enough money for paid option). ...
1
vote
1answer
140 views

How to use bold text in QGIS font marker symbol?

Is it possible to use bold text with the Font marker symbol in a QGIS (point) layer?
1
vote
2answers
366 views

How to style graduated using size-scale field

Is it possible to style based on size-scale field using graduated symbol but instead of using color ramp, I would like to display its size. I would also like to display this in the legend in the map ...
3
votes
1answer
386 views

Dark Object Subtraction QGIS

I'm trying to do Dark Object Subtraction (DOS) for a Spot2 and 4. I have calculated the TOA reflectance and now want to get the at surface reflectance. Using QGIS I would like to know how I can do ...