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

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3
votes
2answers
192 views

Merging polygons at county level to state level

I have a shapefile that represents counties (admin 2) only, but I need to create a state level (admin 1) polygon file (I'm using QGIS). I will need to sum up (or average) the relevant data at each ...
1
vote
0answers
98 views

Looking for similar tool (like ArcGIS Diagrammer) in open source for QGIS?

Is there any diagrammer tool available (similar to ArcGIS Diagrammer) for QGIS? thanks in advance : )
0
votes
0answers
111 views

Unable to open old qgis files into the new version ( 1.8.0)

I have downloaded QGIS today for my school work also my Qgis version is 1.8.0 and my school's QGIS version is 1.7.0. So My new Version QGIS cannot run the QGIS file they have send me So Please help ...
1
vote
1answer
202 views

Merge 2 layers based on an attribute column in QGIS [duplicate]

I have a vector shapefile map that is divided into polygons. I want to add 2 columns to the attribute table with the eastings/northings coordinates of each polygon centroid. So far what I've tried ...
1
vote
1answer
313 views

How to create routable network by pgrouting with assign_vertex_id?

I'm trying to create the routable network as per http://underdark.wordpress.com/2011/02/07/a-beginners-guide-to-pgrouting/and use assign_vertex_id. Do I still need to create the node table? How would ...
3
votes
1answer
1k views

Qgis OpenStreetMap plugin misbehaviour

I used the plugin successfully. But yesterday, after changing several buildings in JOSM. Import under qgis with the plugin does not work anymore. The buildings are in the layer point! Do you have any ...
2
votes
1answer
188 views

How to reclassify grey scale tiff in qgis

I downloaded a raster image of the sea floor age. The values in band 1 ranges from -32768 to 32767. I need to reclassify it to no. of million of years to make sense of the data. How can I do so? I try ...
5
votes
3answers
153 views

Why does a layer imported from GPS have lat/lng rather than project coordinates?

I am importing tracks from my GPS using the GPS Tool in QGIS. I check the layer CRS and it shows WGS 84 but when I try and view the layer in my project which has a CRS of EPSG:2193 the coordinates are ...
1
vote
1answer
627 views

how to install networkx python in QGIS

How to install and how to compile networkx python on QGIS? I always get an error that no module named networkx in the console of QGIS I copied the file networkx in C:\Program Files\Quantum GIS ...
0
votes
2answers
326 views

QGIS crashes by opening project

Suddenly I got a problem opening the project I was working on since a long time. When I open the project, QGIS crashes. I think the problem might be in one layer, but as I cannot open the project I ...
0
votes
1answer
109 views

QGis different results between $length and measureing in the map

I use QGIS Lisboa and need the lenght of some shapefiles. When I use the field calculator the results are always around 30 % higher than in real, also than a measuring in the map. Does anybody have a ...
0
votes
1answer
505 views

Microsoft visual studio run time library error in Qgis 1.8

When i open Qgis project, I get an error from Microsoft Visual C++ Runtime Library: Runtime Error! For other machine its working fine.Since I have uninstalled and re-installed the Qgis,but still same ...
1
vote
3answers
2k views

How to auto fill or delete sliver polygons without losing precision?

I am developing some boundaries in which precision holds the key value. Using ArcGIS 9.3 I am converting lines to polygons using the "feature to polygon" tool. The lines are accurate but I find ...
2
votes
0answers
86 views

select by location

When performing an overlay or intersect I would like to know if there is a way to ignore selection when intersection or overlay is less than a certain percentage of area or less than a certain number ...
0
votes
1answer
309 views

How to properly add a Python Module to a Plugin?

I've been trying to use a module that is installed in my local version of python, but whenever I open the plugin itself, it does not manage to locate said module. The module in this case is Noise ...
5
votes
3answers
456 views

Adding a GIS feature to existing database entry with QGIS

I've built a database with postgreSQL with tables, which include geometry columns. When I add some data to my non-geometry columns, I can see them in QGIS when I connect to my database using postgis. ...
0
votes
0answers
82 views

What vector file type yields the greatest detail with the Heat Map plugin?

I'm using .shp files built from .csv files and having quirky results. Perhaps there is a better way to begin. The heat map appears to be accurately describing the data but calculates a huge area in ...
9
votes
2answers
409 views

How do I generate a large number of maps?

I have to make a large number (hundreds) of distribution maps of species. I have a shapefile that contain the distributions for each species, and for each one, I would like to get a map as an image ...
1
vote
0answers
306 views

Can I create a custom Shapefile for SAS with QGIS?

Okay - I am in the process of configuring GIS within our organisation and am waiting for QGIS to be installed. My aim is to use QGIS to compile a custom shapefile of the business regions used by our ...
2
votes
1answer
2k views

How does Quantum Gis work with Arcgis .xml files?

I'm not familiar to quantum gis, so can anyone explain if it is possible to import/export xml files in quantum gis? If it is possible, how can I do that? I exported some . xml recordset and workspace ...
1
vote
0answers
178 views

QGIS plugin 'sextante' not loading after upgrading to Mac OS X 10.8

Any known issue with sexante and Mac OS X 10.8? After updating from 10.7 and even after reinstalling GDAL sexante is still not working...
5
votes
3answers
879 views

How to drape a simple jpeg image over dem of some area?

How can we drape a simple jpeg image which doesnot have any geo referencing information over the digital elevation model in order to visualize it in 3D in QGIS?
0
votes
2answers
282 views

QGIS 1.8 crashes when exporting from print composer to image on Windows 7

My question is similar to QGIS Crashes when writing to PDF. Today, when I try to export to image, QGIS crashes. I've tried opening a new composer to no avail. This is the problem signature: Problem ...
1
vote
0answers
109 views

'File is too big' error when uploading QGIS Plugin

I have written a simple QGIS plugin which zooms the map canvas to a user specified UK postcode. I would like to share the plugin but the csv file, which contains stripped down OS Code-Point open data ...
2
votes
1answer
529 views

How to interactively get the coordinates of a point in QGIS

I have a shapefile with a single layer of type point. It is in the google CRS (EPSG:900913). When I use the 'Identify Feature' tool it gives me lots of information about the point clicked on, but I ...
2
votes
2answers
976 views

Can't open Spatialite db from openstreetmap in Quantum GIS

I am new to QGIS, OpenStreetmap and Spatialite. I'm trying to get the (OSM) map data into a (SQLite) compact form I can eventually use for realtime reverse geocoding in a vehicle. Quantum is just for ...
3
votes
1answer
912 views

Can the units of the measure tool in QGIS be changed?

All, I'm trying to do some error-checking with some rasters I'm creating, and want to measure line distances on the map in feet, rather than meters - which is what the measure line tool seems to be ...
2
votes
2answers
384 views

Selecting lines occupying identical positions in MapInfo or QGIS

I have two shapefiles from a client, one is their entire network (complete with unique IDs) and another a selection I need. However the selection file does not have unique IDs but the entire one does. ...
1
vote
0answers
92 views

mapCanvas.saveAsImage not functioning as expected in QGIS 1.8

I have a plugin for exporting maps as PNG images. I believe this code was working correctly within 1.6 (but I cannot guarantee I haven't made another change that would have broken it there, too). ...
3
votes
2answers
1k views

How to create a multipart polygon?

I have two polygons that consist of two separate polygons/lines in QGIS). How can I make this into a multipart polygon, which consists of 1 line in QGIS?
1
vote
1answer
893 views

Illustrator to QGIS workflow for vectors

I vectorized a map in Illustrator and would like to import it to QGIS now. I know I must use DXF for that purpose but when I convert the DXF to SHP with the QGIS plugin it is not georeferenced which ...
2
votes
2answers
162 views

How do I stop null values from being assigned extreme color values?

I have a raster surface that I kriged in Surfer and imported to Grass GIS but when I view it in QGIS, the null values outside of the interpolated surface take an extreme value and wash out the ...
1
vote
2answers
152 views

Problems with Combining Layers in QGIS

I am trying to add the political boundaries baselayer from http://www.cec.org/Page.asp?PageID=924&ContentID=2336 and then on top add points where I gathered coordinates from Google Earth (using a ...
3
votes
1answer
644 views

How do I use the GRASS command line tools within QGIS?

How do I use the GRASS command line tools within QGIS? I use the QRASS plugin to open the mapset, and then I open the GRASS tools window. I click on 'GRASS shell' under modules and it brings up a ...
2
votes
1answer
107 views

What is No Data Value?

I'm looking at the transparency window of the layer properties of my "Heat map". How does the No Data Value effect a raster layer. I'm assuming an initial setting of -9999 sets it out of the way, so ...
2
votes
0answers
274 views

Can Nearest Neighbor Analysis help determine values for a Heat Map?

Given the below parameters (from Nearest Neighbor Analysis): A) Is there a definite range my Radius value should be within? B) Are there definite values my cell size should be near? C) Is there a ...
1
vote
1answer
144 views

How to use QgsVertexMarker in a python plugin?

I am trying to display a vertex marker for a QGIS python plugin I am writing. I am getting a the following error... 'NameError: global name 'QgsVertexMarker' is not defined' canv = ...
13
votes
1answer
738 views

How to setup QGIS Master and Stable in parallel on one Linux system?

I mainly use the QGis Master (nightly build) for my Debian Linux and I'm quite happy with it. But for educational and demonstration purposes, I now have to work with the Stable(1.8) version. How can ...
2
votes
2answers
2k views

Importing Lat/Long coordinates as CSV file & only displaying single point in QGIS

I am using QGIS and trying to import Lat/Long coordinates as delimited text layer. All points show up in my attribute table, however, only one point is displayed on the map? Any ideas?
1
vote
2answers
140 views

Why does my 113th Congress Shapefile match up with the wrong districts across the country?

I downloaded a Shapefile from the Census on the 113th congress broken down by district nationally: http://www2.census.gov/geo/tiger/TIGERrd13_st/nation/tl_rd13_us_cd113.zip Within the .dbf file, ...
6
votes
1answer
3k views

Best Way to Handle Many Raster Files in QGIS?

I have a project with a large number of raster files, but it is becoming very slow. I wonder which is the best way to handle all this. I'm simply georeferencing these files creating .wld file (geoTiff ...
1
vote
2answers
107 views

Missing GPS Tools button

Following the guidance at, http://docs.qgis.org/html/en/docs/user_manual/working_with_gps/plugins_gps.html I checked my Plugins Manager and verified that GPS Tools is enabled. However, unlike what ...
2
votes
1answer
960 views

how to connect points to create a polygon boundary in QGIS

I have 31 points in a shapefile, which delimit a field (it's an irregular shape). I want to connect those points so they create the boundary of a polygon. Does anybody know a kind of "connect the ...
3
votes
2answers
968 views

How to calculate the area of rasters in QGIS?

I have been working with some rasters and would like to know how to calculate the area occupied by one element of a raster in Qgis.
2
votes
2answers
2k 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 ...
2
votes
1answer
446 views

Creating routable network table in PostGIS

I am trying to create the routable network table, as per http://underdark.wordpress.com/2011/02/07/a-beginners-guide-to-pgrouting/. Everytime I do it in PostGIS extension, QGIS crashes. The area is no ...
1
vote
1answer
94 views

Scaling location points proportionately

I'm trying to get QGIS (1.8) to scale the point markers for each town in a district proportionately to the size of their population (i.e. bigger population = bigger circle). I can get them to vary by ...
5
votes
1answer
138 views

What suit of components do I need to get installed to start with QGIS?

I have a requirement for a GIS product and following advice from firends and colleagues have decided that Quantum GIS seems suitable for what I need. I have input a request to our IT section to ...
2
votes
2answers
784 views

Are there any work-arounds for WMS width and height limit when printing?

I get the following error when trying to export in QGIS to PDF: "Some WMS servers (e.g. UMN mapserver) have a limit for the WIDTH and HEIGHT parameter. Printing layers from such servers may exceed ...
1
vote
2answers
719 views

Error adding a delimited text layer in QGIS [closed]

I'm a GIS beginner here. I'm trying to add a delimited text layer in QGIS. The plug-in is okay. I have created a table in Excel, saved as CSV file, imported the file with QGIS, selected the delimiters ...