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

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246 views

How to select two points on a map using QGIS?

I need to select two points on a map in QGIS. I selected the element selection tool in menu view and I want to select two points. How can I accomplish this? Are there other tools or methods to ...
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1answer
184 views

QGIS Python - Convert geometry from Postgres to QgsPoint()

I have made a query in Postgres to get some points to use with python. This points are in geometry data. How can I convert that geometry in decimals to use QgsPoint() in python? Thank you
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0answers
120 views

Adding a WMS - connection timed out?

I am trying to add a WMS service to qgis but am having some problems. After adding the url and name of the service and clicking on connect, I am receiving the following error message:- "Could not ...
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1answer
434 views

Nearest neighbor analysis not showing results

I'm trying to do a nearest neighbour analysis on fish shoals distribution. I go to Vector > Analysis Tools > Nearest neighbour analysis. I choose the appropriate layer and when I hit ok the black ...
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1answer
56 views

How to find the overlap of three polygons?

I have three polygon areas showing different land types and I want to create a new layer based on where the three layers overlap each other. I thought this was a subtraction query but havent been able ...
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0answers
176 views

travel survey multi stop routing problem

I have a travel diary survey dataset that I am attempting to transform into more useful information. Currently, the data comes in the format of: Survey# , PlaceVisited#, TravelMode, TripPurpose, ...
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0answers
263 views

Handling “bad layers” in QGIS version 1.9

I'm having a problem every time I try and open any project in qgis 1.9. It will load part of a few layers and then a yellow bar comes up across the top of the map area that says "Handle Bad layers: 23 ...
2
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1answer
194 views

Why are layers imported into a DB with Spatialite-Gui locked from editing?

I have a Spatialite DB which I have imported some shp files too using Spatialite-Gui. I have full read-write access to these layers via the Spatialite-Gui, however when I open these layers from QGIS I ...
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1answer
458 views

How to create a Winkel-Tripel map of countries with different colors?

I need a good quality rasterized world map, Winkel-Tripel projection, in which all countries have different (random?) colors. No borders, text, grid or anything else on the map. Is GIS the right way ...
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1answer
63 views

How to write an Advanced Query which gets the same results as the simple query option

Working with my data set on Late Woodland Village reanalysis in QGIS, the previous question was somewhat answered by defining the issue as a many to one. As a work-around, I summarized the info into ...
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1answer
207 views

Can I open a form in layer action?

I want to open a form (made in QTDesign) in the layer action. It is possible?
2
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3answers
650 views

How to preserve text when converting from .dxf to .shp?

I have tried using dxf2shp converter in QGIS but the text in dxf file is being lost during the conversion process, despite selecting export text labels. I would be grateful if someone can help me ...
2
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1answer
165 views

Having trouble with Webserver configuration on Windows

im currently working on a WMS with QGIS 1.8.0 Desktop with apache from xampp. What I want to do is to have my .qgs file displayed on my webpage as a OpenLayer. So I followed this tutorial: ...
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0answers
18 views

QGis non blocking notifications with pyqgis [duplicate]

I'm searching for the way to use the new QGis non blocking notification system with the QGis python wrapper. I found informations on this fonctionnality but nothing on how to use this especially with ...
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0answers
53 views

plugins available via WMS?

I have QGIS server up and running and all is well, and I want to create a plugin in PyQGIS. But I need the plugin to be available to the users of the web maps in which my server serves. So is it ...
7
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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
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1answer
707 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
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1answer
103 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 ...
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0answers
402 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 ...
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0answers
211 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
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1answer
267 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
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1answer
179 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 ...
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0answers
223 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
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1answer
112 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 ...
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1answer
259 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) ...
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0answers
114 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 ...
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1answer
760 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
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3answers
933 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 ...
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1answer
380 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
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1answer
380 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
223 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
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3answers
489 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 ...
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1answer
180 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
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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
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2answers
147 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
206 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
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3answers
914 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
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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 ...
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0answers
419 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
141 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 ...
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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, ...
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0answers
105 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 ...
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0answers
224 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 ...
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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 ...
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1answer
741 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
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1answer
194 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 ...
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1answer
369 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 = ...