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

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7
votes
2answers
1k views

Can the new Mapbox Vector Tiles be used as a QGIS basemap?

With the implementation of the mapbox vector tiles begs the question of how these could be used as a basemap in a QGIS printed map (assuming anyone cares about printed maps anymore!). To use OSM data ...
6
votes
1answer
679 views

Splitting polylines according to coincident (or touching) points with other polylines?

The question is unfortunately not answered yet. I'm looking for a method or python script to split polylines according to coincident points with other polylines, but avoid splitting the ones which ...
2
votes
1answer
100 views

How to convert QGIS Field Calculation to ArcGIS?

I have a field calculator expression I use in QGIS to generate unique IDs that are sequential, but start with a text string. I now need to perform the same thing in ArcGIS, but I am unsure of how to ...
1
vote
0answers
391 views

QGis Grid statistics for polygons error - Module caused access violation!

I'm trying to calculate statistics for a raster layer using an overlaying polygon layer, I'm using SAGA "Grid Statistics for polygons" function, but it returns an error, sadly.. So in the sextante log ...
0
votes
0answers
206 views

Spatialite, to speed performance, when should I create Views, Indexes or additional spatial tables?

I’ve got a large Spatialite database with a table of lines (roads, rail and water). I created a spatial index of the geometry to speed things up. This works amazingly well when I’m zoomed in ...
4
votes
1answer
262 views

Raster to vector with gaps in Landsat ETM

I need to find size of water area from a raster (jpg) using QGIS 1.8.0-Lisboa. The raster is a Landsat image with gaps of data in it. I used Polygonize, but the output file shows wrong polygon size ...
3
votes
1answer
168 views

Is there an address gazetteer for QGIS?

I have a SQL database that has our local address database on it - it has no geometry within it, just a list of addresses and X and Y co-ordinates. I want to use this data to enable people to search ...
1
vote
0answers
215 views

Convex Hull issue in QGIS 1.8

When creating convex hulls based on input field in qgis 1.8, there seems to be always one less convex hull created for the unique values in the input field. For example; I have a point vector file, ...
3
votes
1answer
104 views

How to delete points from CSV point layer?

I have a point layer produced from importing a Delimited Text Layer and I would like to delete some points. It seems that it is not possible to toggle editing in a point layer. How can I delete the ...
1
vote
1answer
249 views

Extraction of contour lines starting from 0 elevation

I need your help regarding extraction of contour lines in QGIS. I am new to QGIS (in GIS actually). I followed the tutorials on extracting contour lines from DEM (which I downloaded from cgiar.srtm) ...
1
vote
0answers
112 views

Heatmap plugin with relatively small area

I'm trying to make a heatmap using points in a relatively small area (about 50km by 50km) and I just get a single red block every time (even after switching the color map to 'pseudocolor'). I've read ...
1
vote
1answer
723 views

QGIS - “Bad Allocation” Exception - on identify

I have QGIS (v1.8) set up to identify in Top down mode. When I use the identify tool on the map, I frequently get a Bad Allocation exception message and I was wondering what gives rise to this error. ...
3
votes
3answers
883 views

Is it possible to batch clip rasters in Quantum GIS?

I have been able to batch clip rasters in one directory using python in ArcGIS. However, I am not sure how to do the same in Quantum using the python console. Is this possible? If there are different ...
1
vote
1answer
374 views

spatialite.dll with Python and QGIS - the specified module could not be found

I'm having a bit of a nightmare getting to the bottom of this DLL loading problem. The stand alone script works absolutely fine but the exact same code does not work within QGIS. import sys from ...
2
votes
1answer
364 views

importing coordinates via a csv file does not work

I tried to manually add point data via a CSV file to an empty project in QGIS 1.8.0. The points do show up all right with the correct coordinates, but already the scale is not correct (using the ...
2
votes
3answers
219 views

Which data format can be used with both QGIS Desktop and Android?

My data is in MS Access geodatabase(creating with ArcGIS). I want use Qgis desktop and Qgis android (and dropbox) Is it required to convert my mdb file to another format? (Qgis on Android can't ...
3
votes
3answers
472 views

What Is The Ideal Workflow To Map (British) Postcode Territories

I'm looking for the best workflow for mapping postcodes and calculated territories, but being relatively new to mapping I'm struggling on a few details and also the best practices for displaying these ...
0
votes
1answer
174 views

How to access the button on the form?

I have a form that appears when you start the plugin.How do I properly apply to the button on the form, so that when you click on the button performed "function". import sys,os import win32api from ...
6
votes
4answers
1k views

Examples of Animated maps

I am currently looking examples of animated maps. Creating animated maps with the help of this post and similar post checking Animaps site also I am presenting this map in local school so those ...
3
votes
2answers
145 views

How can I visualize a route in QGIS?

I have a route in QGIS that visits every road/edge at least once. By using a marker line I can see the direction of the route, but it doesn't show the order of the segments (see the screenshot below). ...
6
votes
1answer
2k views

How can I programatically create and add features to a memory layer in QGIS 1.9?

I had a working plugin in QGIS 1.8 which read data from an MSAccess database and added it to a series of memory layers. There is some processing involved in the interim so I don't think simply using ...
2
votes
1answer
195 views

QGIS join data not transferring

I'm reanalyzing data from a VA Late Woodland Palisaded Village. The site is mapped in CAD and exported as a shapefile. QGIS brings up the 1059 features as polygons. I am using a CSV file for the ...
2
votes
3answers
850 views

Data-defined Styles in QGIS

I have downloaded a shapefile of bedrock geology. I need it to be displayed as it should be with the style applied. The supplier will no give me a qml. but i have noticed in the .dbf file the Cyan ...
2
votes
3answers
4k views

Which CRS to use for Google Maps?

I am trying to map a Shapefile (download) onto a Google Map using the Javascript API. The Shapefile describes the boundaries of NYC School Districts. The file's projection was Lambert Conformal ...
2
votes
1answer
55 views

How to symbolize different information that's joined to a single plot in a shapefile

I am a student doing an industrial survey in Windhoek, Namibia. We mapped different businesses and later did spatial analysis. Questionnaires were handed to different businesses and then that ...
1
vote
0answers
402 views

Arrow flow lines from a contour map

using QGIS (or even GRASS) is it possible to label a contour lines shape with arrows that indicate the flow direction? Briefly: I have a point shape with elevation values. I make an interpolation map ...
3
votes
1answer
139 views

Are there plans for improving performance of vector files in QGIS? [closed]

Does anybody know if there are any improvements planned pertaining to the performance of vector files in QGIS? Right now, a 1 GB file with contour lines needs several minutes to open. In addition to ...
3
votes
4answers
2k views

Cannot fix QGIS after upgrade to Ubuntu 13.04 Raring

I have following problem. After upgrade to 13.04 I had problem with PyQGIS mentioned here. I followed almost all advices described there, finally removed QGIS (had 1.8 Lisboa) and added the Ubuntugis ...
1
vote
2answers
88 views

Is it possible to have another CRS in the status bar than used for the map?

I am new to QGIS. When I use OSM or Google Maps as a basemap via Open Layer Plugin, the map should be projected as EPSG: 900913. However, the Coordinates shown in the status bar are useless for me, ...
1
vote
0answers
103 views

How to compute a point trend line?

I have a track of GPS position dots that are roughly going in a straight line, I would like to simplify the line to only have the central point from a group as in the bottom image creating a trend ...
0
votes
0answers
218 views

Display colour coded road traffic data in QGIS

I would like to colour code a shape file containing road polylines to represent the heaviest flows of traffic. The shape file contains attribute data linked to each section of road where road traffic ...
1
vote
0answers
84 views

Base station coverage analysis in QGIS

I want to find base station coverage for a instant location. I have building data. And i determine optimum coverage as 500m far away from a base station (buffer). So how can i find optimum base ...
0
votes
1answer
709 views

How can I create a line with three points with Python in QGIS?

I'm new to Python and I'm having some dificulties. I want to create a simple layer with a line in the console of QGIS with Python. How can I do that?
2
votes
1answer
179 views

Creating a systematic rectangular grid

How can I produce a point shapefile (or simply point coordinates) that represent a systematic rectangular grid? At least three input variables would be required: distance between points, distance ...
0
votes
1answer
358 views

Check if layer is a QGSVectorLayer from Python Plugin within QGIS

I am trying to extend some concepts in the QGIS Workshop tutorial. Basically, I would like to check if the layer is of type "QGSVectorLayer". In the QGIS Python console, I am able to type canvas = ...
2
votes
2answers
371 views

How do I set the working directory in QGIS?

I'm learning QGIS and lovin' it. But one thing that annooys me a little is is that each time I want to save data, the default directory is the QGIS folder under Program Files. How can I set this, ...
4
votes
2answers
353 views

Does QGIS support internationalization?

Does QGIS support multiple languages? I have some shapefile with Arabic names in its attributes, and they appear as: ???? If I want to see the names in Arabic, do I need to purchase multi-language ...
0
votes
1answer
1k views

Producing NDVI maps in qGIS

I'm trying to produce a simple NDVI map in qGIS using a Macbook pro (2011) from landsat raster images. I've tried using the 'Measuring Vegetation' plugin, but for some reason that goes absolutely ...
4
votes
2answers
3k views

How to generate a DEM from a contour Shapefile?

I want to create a DEM from depth contours (shapefile) in QGIS. I've been trying to work out how to do this based on this previous question, notably from this link from that page, however I'm stuck, ...
1
vote
0answers
121 views

GRASS v.overlay.or Error when trying to split a polygon with a line

I am using the Grass plugin in QGIS for Windows (1.8.0). I am trying to split a polygon with a line feature. I am using the v.overlay.or function within the QGIS Grass plugin. I have the line layer ...
1
vote
0answers
50 views

Generating “weighted convex hull”

sadly I don't have any keyword that reflects what I'm looking for: I have a vector layer consisting of points, which have an integer attribute ("signal quality" here), that I want to plot as a convex ...
2
votes
0answers
55 views

“Map 1” vs “Map 0”

When I compose a map to print, and get everything all set; then close it for some reason; then reopen it--the scale bar appears messed up. I then go to the Scale Bar settings, and find that under ...
0
votes
0answers
167 views

catchment delineation

I am trying to use qgis to delineate between three sub-sub-catchments. I have contour shape file of 20 meter height. Sub-catchment is about 12 square kilometers area but consist of three ...
0
votes
1answer
292 views

Running a script with QgsFeature from within the console

I am trying to run a script from the QGis Python console (similar to: http://spatialgalaxy.net/2012/01/27/qgis-running-scripts-in-the-python-console/) The line feat=QgsFeature() operates fine from ...
0
votes
2answers
192 views

How to rotate (svg) symbols in QGIS map composer to match map rotation?

Because of my thesis layout requirements, I have to rotate 270° some of my maps in composer. There are (many) svg smbols (icons), and they are rotated as well. I would like to (non-)rotate them in ...
1
vote
0answers
129 views

Is it possible to integrate the mapping capabilities of QGIS with Stata?

I was wondering of the possibility of integrating the mapping capabilities of Q-GIS with Stata, by using the programming aspect of Stata as opposed to using R or python. Is this possible?
0
votes
2answers
2k views

Multi-Band (RGBA) into single band raster

I have the raster which contains 4 bands (RGBA), which ilustrates the pupulation (traffic) density. I want to convert it to the simple gridded ascii, however I'm getting in the trouble when I try the ...
0
votes
1answer
258 views

CSV and GDAL 1.10 in QGIS

It seems the GDAL upgrade from 1.9 to 1.10 changed the way CSV files are handled so that I now have a non-functioning QGIS. App hangs trying to import csv data file when previously had no problems ...
2
votes
2answers
1k views

saga & grass configuration in sextante (ubuntu)

I have some trouble in running saga and grass algorithms in sextante. When I double click it appears a pop-up saying: Missing dependency.This algorithm cannot be run :-( This algorithm requires SAGA ...
1
vote
2answers
1k views

Find and list all polygons that overlap with another polygon

I am working with two polygon layers which overlap but are unrelated (one is congressional district boundaries, the other is MPO area boundaries). I would like to generate a list of all the ...