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

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10
votes
1answer
2k views

How to create desire lines in QGIS?

How can I show the flow coming from an Origin-Destination matrix as desire lines? I need a result like the one in the picture below. I need to scale them proportionally to its value (coming from a ...
4
votes
1answer
419 views

Experiencing transformation anomalies when performing a Save As to convert coordinates between NAD83-Z14 and NAD27-Z13

Good morning all: I have recently discovered QGIS and have been hoping to find a solution for converting bacthes of xy coordinates between two projection systems for our mapping system. I have known ...
1
vote
1answer
271 views

JSON URL won't open in QGIS

When attempting to display the national chargepoint registry from the following URL: http://chargepoints.dft.gov.uk/api/retrieve/registry/format/json The following error returns: ...
1
vote
1answer
218 views

QGIS offset dash line style - dash spacing does not vary with rotation

I'd like to make a USGS-style dirt road marker but with smaller dashes and bigger spacings (i.e. less duty cycle) to indicate lower quality road. First attempt = two simple lines, custom dashes of ...
1
vote
1answer
243 views

Combine shape in folder for on/off

Is it possible to organize some shapes into folders to turn on/off all the shape togheter? Is it useful for the shape that you can punt at the top/bottom of a project.
4
votes
1answer
938 views

How to make the thickness of traffic volume flow symbology proportional to traffic counts?

I can scale the bandwidth proportionally to the traffic volumes; however, I cannot show the directionality of the movements. Volumes for directional moves are stored in two different columns of a ...
3
votes
1answer
226 views

How to represent Typhoon(s) wind speed using Quantum GIS / PostGIS?

I am not completly new to GIS (was taught ArcGIS at Uni) but I would still consider myself (especially compared to all these experts here) a newbie in QGIS or PostGIS. I want to display the ...
-2
votes
1answer
65 views

How to search for text in QGIS?

Does QGIS have any search capability, for example to find text within cadastral polygons? Quantum gis posee algun buscador , por ejemplo para identificar textos en poligonos de catastro ?
2
votes
1answer
280 views

ImportError: No module named qgis.core

I am on Ubuntu 13.04. I get the following error message - Traceback (most recent call last): File "analyse.py", line 1, in <module> from log import shelve File ...
2
votes
2answers
1k views

Setting “R Folder” Path in QGIS Sextante

I have installed R via the R-Project website. I have QGIS installed via OSGEO4W (currently 1.9.0 Master), and have Sextante plugin installed and working with GRASS and SAGA providers. I am now trying ...
2
votes
1answer
404 views

How to perform a cascaded combine from python script in QGIS?

I'm working with a large dataset, and I need to be able to combine up to 400,000 polygons. I have been using the QgsGeometry::combine(QgsGeometry* geometry) function and simply looping over all ...
2
votes
1answer
112 views

How can I confirm the existence of pyramids in QGis?

I have created pyramid layers for my ASTER satellite images (.img) using Gdal Tools "Build Overviews" (Pyramids). The dialog said "Processing completed". I don't have the impression that zooming in or ...
2
votes
1answer
160 views

Lack of Options in Gdal Tool “Build Overviews” QGis

I am using QGis 1.8 and I want to build overviews (pyramids) for satellite imagery using the Gdal Tool. I would like to use the resampling method "cubic convolution", but the option doesn't exist ...
0
votes
2answers
413 views

How to handle an “Input CRS error” when clipping?

I'm trying to clip a soil use shapefile, with a polygon I've created this morning. The clipping function works, but the clipped polygon doesn't have features (the table of contents is empty). QGIS ...
2
votes
2answers
282 views

How to rotate North oriented Map [duplicate]

I want to rotate my North oriented point shapefile to 45%,is there any way to rotate it QGIS or Mapinfo? Thanks, RKM
3
votes
1answer
198 views

How to create a line layer which connects a point layer to a line layer?

In the map shown below, I have manually created the dummy lines (in green). Using python, and without using PostGIS or sextante, I would like to automate the creation of these dummy links between a ...
2
votes
1answer
274 views

Are there Open Source alternatives to ArcGIS Aggregate and Extract Value to Points?

I am looking for some kind of Open source GIS library which can perform spatial analytic functions same as ArcGIS. My use case is : I am processing GeoTIFF file provided by USGS and performing ...
2
votes
0answers
90 views

Rounding error in qgis point sampling tool

I'm not sure if this is a bug or of it is due to the implementation. I am using a raster that has values greater than 1,000,000 and Qgis displays these numbers in a scientific notation. For instance, ...
5
votes
1answer
80 views

Permanent Histogram Stretch with QGIS or FWTools

Is there a way to permanently stretch a histogram of a raster within QGIS or gdal? I would like to stretch a satellite image with a Standard Deviation 2.5 stretch. I would prefer to use QGIS or ...
0
votes
2answers
545 views

Why can't I select any of the tools under “edit”?

Why can't I click any of the tools under "Edit?" I want to merge selected shapefile layers together, but all of the tools under "edit" are greyed out.
2
votes
0answers
938 views

QGIS: After performing a table join, all the fields are “NULL”

Within QGIS, I joined .dbf table containing population data to a shapefile of Census tracts. The join field is called GISJOIN in both the target table and the shapefile's table, and this attribute ...
2
votes
1answer
2k views

Instructions for installing Sextante plugin

As a follow-up to the question I recently asked on PyQGIS, can someone please point me to a document, webpage or thread that provides me with step-by-step instructions as to how to install an external ...
4
votes
2answers
524 views

How to average values in a point layer with respect to polygon layer in QGIS?

I am new to GIS and have the following problem: I have 2 layers: a point layer with a column that contains numbers (pollution index from specific measurement point) and a polygon layer with different ...
0
votes
0answers
517 views

How to move/edit labels? [duplicate]

I need to move/edit few labels in a job. How can I work on it? I am using QGIS 1.7.4 and the label option in the toolbar (not the layer options)
1
vote
0answers
240 views

QGIS Points to Path Plugin Date/time error [closed]

I would like to use the Points to Paths plugin to plot the tracks of collared animals, exactly as specified on this page http://spatialgalaxy.net/2011/12/30/qgis-plugin-of-the-week-points-to-paths/ ...
1
vote
2answers
249 views

How to re-calculate area, perim, p2a,width and length in QGIS?

I cut a part out of one feature and added it to another feature in a polygon shapefile. My problem now is that both features has the same values in the area-, perim-, p2a-, width- and length-columns? ...
0
votes
2answers
858 views

Issues with datasets when custom SLD loaded into geoserver

I have created my SLD's in QGIS and want to use them in Geoserver. I have imported and validated them without any problems but when I try to view the data using Layer Preview --> OpenLayers-->Go it ...
3
votes
1answer
437 views

Auto-increment id when adding a feature to a PostGIS layer in QGIS

when I enter edit mode of a PostGIS layer in QGIS 1.8 and add a feature, is it possible to auto-increment the ID? I always have to look what last used ID was and manually enter a new one. I can't ...
2
votes
1answer
420 views

How to keep the same style of a OSM map converted to SHP file

I saved a OSM file as a Shapefile, this is fixing my previous question how to handle bad layers. My question is how to retain the original style from OSM plugin to SHP files, when I copy the style ...
-2
votes
1answer
210 views

What tool(s) in the Sextante toolbox in qgis 1.8 can be used for interpolation? Kriging and spline

I have looked at every single one and can not figure out which on can be used.
0
votes
1answer
282 views

How to calculate the area of the convex hull of a points layer

I have a shapefile in QGIS that I have created by importing a CSV of points, using Points2One to convert to a shapefile and then importing the shape. I am now trying to calculate the are of the shape ...
0
votes
1answer
704 views

How to append a vector layer using Qgis and Python?

I am working on scripting some data processing using Qgis and Python, but I'm running across issues that I need to debug. Since my data is really large, and run-times can be lengthy, I would like to ...
2
votes
1answer
181 views

How can I solve 'Handle bad layers' error when using OpenStreetMap in Qgis?

I can easy download Portion of maps from OpenStreetMap, save them etc. Once I reopen the same map I get a message that says "Handle bad layers" for all the OSM files. What I am doing wrong?
2
votes
2answers
326 views

How can I create a legend with the new data defined symbols functionality?

I have a large geology data set that I need to display using an industry standard set of symbols and colours. The symbols and colours are attributes of the data. I have been using the data defined ...
1
vote
1answer
314 views

QGis creating shape file of several points out of two Excel sheets

I am about to create a Qgis file on which it should be visible which companies are working together. As source I have got two Excel Tables. Table = Distribution Centers Table = Point of sales I ...
1
vote
0answers
29 views

How to Edit FileGDB attribute using QGIS? [duplicate]

I am able to attach a file GDB in QGIS (version 1.9). But I cann't edit it's content available in attribute table and 'Toggle editing mode' button was also disabled in Attribute table. Does anyone ...
3
votes
0answers
120 views

Why are my raster mean and standard deviation -1?

I have a set of about 25 rasters whose descriptive statistics I have been examining. The data in the rasters were calculated in Python and the rasters were created using Python-GDAL. In all but one ...
2
votes
2answers
246 views

What is causing this distortion in QGIS georeferencer results?

When importing a JPG map using QGIS's georeferencer plugin, the resulting map layer is distorted and does not look anything like the map that I am trying to import. I can't work out what is causing ...
2
votes
2answers
562 views

Why is QGIS Field calculator button greyed out?

I'm using QGIS to attempt to calculate the area enclosed by a set of points that I have capture used a GPS device. I have imported the coordinates from a CSV but when trying to open the field ...
3
votes
2answers
130 views

Is there a means of recording all user actions in QGIS?

Is there a means of recording all user actions in QGIS, in particular date/time of data access? Most of our data is in Postgresql which is fine, I can run logging from there and QGIS is recorded ...
1
vote
1answer
271 views

QGIS Dev install issues

I need to use some of the new functionality in the Dev build and just can not install it on our windows 7, 64 bit machines. It works fine on my personal windows 8 laptop but I can't get it to work at ...
0
votes
2answers
481 views

How to uninstall and re-install a stable version?

I just posted about a DEM problem after installing the latest nightly build...now I am completely screwed. I uninstalled the latest nightly build and associated files, hoping to resort back to the ...
0
votes
1answer
57 views

Qgis nightly build - DEM error

I installed Qgis 1.8 several months ago. It's been working like a charm. Earlier today, I decided to check out the latest nightly build. Installed GDAL 1.10 (already had 1.9 installed) and SQLite ...
7
votes
1answer
407 views

Can QGIS projects be opened in ArcGIS for Desktop?

I am about to start a project with a number of people for a nonprofit organization. I am wanting to create the files in QGIS, but some of the people that I am working with are city officials and might ...
1
vote
1answer
275 views

Looking for PyQGIS Syntax Examples/Guide

I am a long-time user of arcgis with intermediate experience python scripting for automation of geoprocessing workflows. I am moving towards using QGIS on the regular and I would like to dive into ...
7
votes
1answer
130 views

Open source implementation of “feature density” algorithm

I'm working on a dataset of house searches - 1 polygon for each area in which people want to find a house from an online search tool. This produces many overlapping polygons. It would be great to ...
1
vote
0answers
113 views

Unable to open project

I recently got a virus in my computer and, after having that fixed, was unable to open my Quantum GIS project. I received an error message: Microsoft Visual C++ Runtime Library Runtime Error! ...
2
votes
0answers
251 views

QGIS Atlas generation - crash dumped [closed]

In QGIS 1.9.0 there's a new funcionality named Atlas generation. Everything works fine until I start generating more 5000 images. Now, after some time (not always the same) the QGIS crashed with the ...
1
vote
0answers
152 views

Spatial Filter in Qgis Using Python

Is it possible to create buffer and get intersected features in Qgis using Python? I did in ArcObjects.but i need the same in QGIS also. Dim topo As ITopologicalOperator topo = chkPoint Dim sFc As ...
0
votes
0answers
76 views

Confusing offsets in shapefile written by QGIS/OGR

I think I'm stuck here. A shapefile has been updated in QGIS. Records have been deleted and those records have been marked with an asterix in the first byte of the record in the dbf file. I open the ...