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

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2
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3answers
858 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
403 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
89 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
713 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
180 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
361 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
373 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
354 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
51 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
294 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
130 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 ...
3
votes
1answer
490 views

How calculate areas between certain contour lines in qgis?

Sorry for asking a question which I found in similar ways already here, but I am trying this for days and just got no result: How do I calculate the area between certain contour lines (e.g. 0-800, ...
1
vote
1answer
104 views

how do i assign values to shapes to be displayed in my map

I apologize for the simplistic nature of this question, I'm VERY new to QGIS. I'm trying to use QGIS to display political information. I have a map of my state, with each town as it's own shape. I ...
-1
votes
1answer
332 views

QGIS and Python - create line with multiple points in postgis [closed]

How can I create a line, with Python functions, with many points that are records in Postgis? Thank you
1
vote
0answers
138 views

Looking for best practice to connect multiple road vector line layers for routing (pgRouting) purposes

The Data I have: Bridges (line layer) Municipal_roads (line layer and does not include information in Bridges) State_roads (line layer that doesn't include Municipal_roads or Bridges) Question: ...
15
votes
2answers
6k views

What's the relation between QGIS and GRASS?

I have been working with GIS and remote sensing in an university and professional environment some ten years ago (ArcInfo etc), so I have some experience even though somewhat outdated Right now I am ...
1
vote
1answer
3k views

'Couldn't load PyQGIS' after upgrade to Raring Ringtail?

I upgraded my Ubuntu to Raring Ringtail. After that, when starting QGIS I receive a message: Couldn't load PyQGIS. Python support will be disabled. Traceback (most recent call last): File "", ...
0
votes
2answers
240 views

Emergency Services: How to optimize routing by measured travel time?

I would like to optimize the service areas / catchment areas for an emergency service. Therefore, I have several measurement points on the streetmap, where people have stopped the travel time from ...
-2
votes
1answer
676 views

How to digitize a map in QGIS?

I am relatively new to QGIS and using it on windows vista. Problem: I have to digitalise an aerial map and then extract the coordinates. I have absolutely no idea how to start Thanking you in ...
2
votes
1answer
2k views

Watershed Analysis using DEM [duplicate]

I stumbled upon your question regarding the mosaic feature in qgis, the thing is I'm also using Quantum and this is my first encounter with GIS this semester, so if you can please help me with a ...
0
votes
0answers
148 views

QGIS GDAL polygonize - how to set scale

I've got some old contour plots, paper copy only, that I'd like to be able to put into QGIS. I get as far as a successful polygonize into shp and it looks fine, but the scale is wrong. How might I ...
1
vote
2answers
226 views

Hypothetical Cost Saving Question: Proprietary v Open Source

I am writing a paper for my GIS MSc and trying to justify a move for the EPA from proprietary GIS software to open source (QGIS). Can anyone hazard an educated guess as to how much ArcGIS would cost ...
0
votes
1answer
337 views

AttributeError: HelloWorld instance has no attribute 'connect'

Here's the code: import sys,os import win32api from PyQt4.QtCore import * from PyQt4.QtGui import * from qgis.core import * import ctypes from PyQt4 import uic class HelloWorld: def ...
2
votes
0answers
208 views

ArcGIS Raster Calculator VS QGIS Raster Calculator [closed]

Are there any major differences between ArcGIS Raster Calculator and QGIS Raster Calculator?
1
vote
2answers
164 views

How can i mark movement route to the map with QGIS?

I am beginner with QGIS and i am having problem with marking movement route to the map. So i would like to ask how can i mark movement route to the map with QGIS. I have a list of cities and i have to ...
0
votes
1answer
74 views

Give Properties to a shapefile to be used by another person [duplicate]

I have bedrock geoology data. I want to classify the data so it appears with the same propeerties as it does on the suppliers website. Is there a way i can attribute a property to a layer (in this ...
0
votes
2answers
257 views

How to select polygons in polygon and export to CSV?

I have two polygon layrers, each layer a table in PostgreSQL: One layer with polygons areas in a city. Another layer with buildings (polygons) that are within areas. How can I to do to know what ...
2
votes
2answers
265 views

Identify points near roadside in QGIS

How do I create an attribute list from points that run along roads in a shape file containing road data? The points don't intersect the road centre lines and are not consistent in their distance from ...
2
votes
1answer
264 views

Merge attribute data using spatial query in QGIS

I have 2 vector layers that I wish to correlate attributes - a shape file containing boundary polygons and a shape file containing point locations. I'm using the vector>spatial query tool to generate ...
3
votes
1answer
146 views

Filter contour lines in QGIS

I have a shapefile of contour lines, with an ALTITUDE attribute with the height ASL in metres. The source data is in 0.5m intervals, but I'd like to filter it down so I get contour lines at (for eg.) ...
0
votes
1answer
692 views

Cant Instal psycopg2 on mac 10.8.2

I know there Have been a lot of similar questions asked but none address this issue as I far as I can tell. When I am trying to install the sextante plugin, or run PostGIS Manager in QGIS I receive ...
2
votes
0answers
118 views

Installing knn on PostgreSQL for windows

I am trying to install the extension KNN for clustering as an extension on my PostgreSQL database. I have downloaded the file http://www.pgxn.org/tag/analysis I found instructions on how to ...
0
votes
1answer
676 views

How to set Marker Line symbol for QgsVectorLayer by using Python?

QgsVectorLayer Right click->Properties->Style->Single symbol->click on simple line in tree node ->symbol layer type -> Marker line Kindly help me to set marker line symbol programmatically by using ...