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

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3
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0answers
67 views

Where to find comprehensive descriptions of tools in QGIS, SAGA, Orfeo, etc. toolboxes? [closed]

There exists a large number of tools for QGIS (e.g. SAGA, GRASS, ORFEO etc.) - however none of these have sound description of the aim of the tool, the algorithm itself, differences to other similar ...
1
vote
1answer
179 views

QGIS Metatools error

I haven't been able to successfully use the QGIS MetaTools plugin for describing metadata. Has anyone used it before? When I try to create metadata for a shapefile, the plugin creates the xml file but ...
3
votes
1answer
179 views

How to calculate the intersected area from a layer with overlapping buffers in qgis

I need to calculate the area of landusetypes in 50m around various dots (all in one shapfile). My problem is, the buffers around the dots are overlapping each over in some places. I tried to ...
2
votes
2answers
167 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
1answer
149 views

Layer with custom UI not working properly

I have a problem with QGIS 2.4 when introducing layers with a custom UI. More precisely, widgets such as CheckBoxes are not recognised as such (appear as Text Edit in Attributes) and the corresponding ...
1
vote
1answer
70 views

Syntax to add attributes in a line in the Expression String Builder

I have several columns with certain values, here's an example: | Apple | Banana| Orange | Pear | Expected result | 1 | 1 | 1 | 1 | red | 1 | 2 | 2 | 1 ...
3
votes
2answers
103 views

Rotating geometry to specific angle using pyqgis?

I do not know how to rotate a geometry using pyqgis. Is there any sample/example code available to show me how?
4
votes
1answer
131 views

Problem with performance when loading PostGIS layer using pyQGIS

I'm having a question on loading a PostGIS layer into the project from my QGIS plugin. The code is like this: uri1 = qgis.core.QgsDataSourceURI() uri1.setConnection(str(host), str(port), ...
1
vote
2answers
134 views

Export long lat from polyline as csv file in QGIS

I want to draw a line in QGIS and then, export the long-lat of each point into a Comma Separated Value (csv) file. I tried doing this by creating a new shapefile layer and then using the Add Feature ...
2
votes
0answers
116 views

CRS problem: not recognizing the CRS of shapefiles to be the same for all

I'm attempting to aggregate (average) the attributes a point layer to polygon attributes (i.e. block groups and counties) via a spatial join. Both the points and polygons are in the same projection - ...
2
votes
2answers
73 views

How to get for a given pixel the values from different overlapped rasters?

I have a few rasters representing different soil properties, like soil pH and sand content. The rasters overlap perfectly, have the same dimensions and same coordinate reference system. I would like ...
4
votes
1answer
102 views

QGIS equivalent to ArcGIS Aggregate Polygons?

I am looking for a tool in QGIS 2.40 that performs the function ArcGIS refers to as Aggregate Polygons. Basically it takes a group of polygons within a specified distance and creates a concave hull ...
2
votes
1answer
180 views

How set correct options for displaying a grid in QGIS composer?

I am using q. 2.5 4291337 in Windows 7 64 bits. I am working with raster and vector layers in EPSG 26714 (UTM NAD27 14N). In this version of QGIS, you are able to put a grid in a different CRS of the ...
2
votes
1answer
208 views

Possible to set an attribute field to update automatically based on another field?

If I have 2 attribute columns and I wish to change certain values, is it possible for the second attribute column to automatically update its values based on an expression? Example: Age | Status 10 ...
1
vote
1answer
58 views

Import shapefile into GRASS in QGIS

I am using the GRASS interface in QGIS 2.4. I have successfully imported my shapefiles into GRASS using v.in.ogr, but when I try to then use a GRASS tool, like v.net Network maintenance, the select ...
2
votes
0answers
274 views

Remove pseudo nodes in QGIS

I have a shapefile of city streets. I tried to run the Road Graph tool on them but the select box does not populate with the layer. I ran the Topology Checker on the layer and found that there are ...
2
votes
0answers
245 views

Failing to merge rasters in QGIS

I am new to QGIS but have some familiarity with other GIS software (namely ArcGIS). I want to merge a number of LiDAR digital elevation model (DEM) tiles (specifically, 30 individual tiles) to ...
2
votes
0answers
42 views

How I can create a raster and have the same overlay as another raster in QGIS 2.4?

I have made a graphical model in QGIS 2.4. I have to create a raster equation to rasterize a polygon shapefile. I want to rasterize my shapefile and I want to ensure that this new raster will ...
0
votes
1answer
74 views

OpenStreetView or points from CSV but not both showing?

I'm using QGIS on Mac (most recent version) and am trying to map coordinates from a csv file. When I import the file normally without having any base map, the coordinates how up distributed like I ...
2
votes
2answers
101 views

How do you make an unclassed choropleth in QGIS 2.x?

How do you make an unclassed choropleth in QGIS 2.x? I'm using 2.4 and can't find an option in a layer's Style tab like the continuous color option that seems to have existed in QGIS 1.x. I'm curious ...
1
vote
0answers
442 views

Ubuntu 14.04 Another ImportError: No module named qgis.core

Issue I feel like this is covered territory here, but the issue is has appeared on two separate occasions for me--first when upgrading from Ubuntu 12.04 to 14.04 in May. I got it fixed then, but I ...
3
votes
1answer
122 views

What is the status of any ongoing efforts that will allow QGIS to display .las files directly in the main 2D window?

After some research on QGIS's ability to display .las files, I came to the conclusion that it is not possible: currently any attempt at this requires converting .las to .shp as described here and ...
1
vote
1answer
37 views

Point input for polyline not acceptable?

Input QgsPoint(s) are returning an error in a Polyline creation routine. Any clues?! processing.runandload("qgis:polygoncentroids", Base, "memory:CenterNode") ...
4
votes
2answers
88 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 ...
0
votes
1answer
824 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
59 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.
4
votes
2answers
1k 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
230 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. ...
3
votes
1answer
581 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
109 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
317 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
101 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 ...
2
votes
1answer
632 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
40 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
42 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
54 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
123 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 ...
1
vote
0answers
37 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
96 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
97 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 ...
4
votes
5answers
3k 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
127 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
75 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
63 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
110 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
82 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
28 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
874 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 ...
4
votes
1answer
196 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
189 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 ...