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

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2
votes
1answer
2k views

Using clip tool in qgis - contours to exact map area

I am using QGIS. I am trying to clip contours and water vector layers to the exact size of my map (polygon layer). Sometimes it works; sometimes the program crashes before completion (at the same ...
4
votes
1answer
431 views

How to use scale -rule based renderer in QGIS?

I wish to render a shapefile of builindings such that at scales below 1:5000, they have a border, and above 1:5000, they do not have a border. For this, I went into layer properties, selected ...
7
votes
2answers
129 views

How do you obtain the execution times of processes in qgis?

I am working on QGIS. I need to determine how much time QGIS needed to finish a specific task. I have been unable to get execution times for the processes. What is the proper way to get processing ...
1
vote
0answers
23 views

Retaining original thematic colors in a USA source shapefile [duplicate]

Possible Duplicate: Adding Layerfiles (.lyr) to Qgis New to QGIS and need a lot of help! I am using QGIS with MAC - I have downloaded a USA thematic map but when I open it in my system it ...
3
votes
1answer
290 views

Labels with white (or other color) background

I tried to give my labels somekind of box and a backgroundcolor (or boxcolor) in QGIS, but i couldnt find the right option. My labels are not readable because my layers are too dark. I found offset ...
5
votes
3answers
2k views

How to style points in QGIS based on multiple attributes

While trying to find a useful way having earthquakes displayed, I noticed that it isn't that easy to manage. I'd like to be able to recognize the "Magnitude", "Date", and "Depth" from the style of ...
3
votes
2answers
589 views

How to create a standard deviation map from three rasters in QGIS?

I have 3 normalised (0-100) raster maps. Is it possible to get a map which shows the standard deviation? I'd like to see the areas with smaller and higher std deviation. Thank you!
3
votes
1answer
978 views

How to remove a vector QgsVectorLayer from QGis python plugin

I managed to add QgsVectorLayer in QGIS through a python plugin, for example: vl = self.iface.addVectorLayer(uri.uri(), layerName, self.dbConn.getProviderName()) But how can I remove it?
2
votes
0answers
11 views

updatation query along a point [duplicate]

Possible Duplicate: GIS QUERY on point and buffer All, I have a PostGIS/Postgresql DB that has one table in it. One with point geometries and the other that represents buffer as polygons. ...
2
votes
1answer
808 views

How can I fix QGIS PostGIS Manager error 'shp2pgsql' is not recognized?

I have QGIS 1.8.0 installed via OSGeo Installer and work on win 7. All I need is to upload the shapefile to the database via this plugin. Unfortunately I am receiving an error: Something's wrong: ...
4
votes
3answers
99 views

GIS QUERY on point and buffer

I have a point table and the buffer geometry is created around the point. I have defined the if the point is within the buffer_distance then its value is =1 and if it is outside the buffer its value ...
0
votes
1answer
638 views

How to improve OSM layer resolution in OpenLayers plugin while exporting?

I'm having trouble with the OpenLayers Plugin exporting a map to a png or pdf file: The output resolution of the exported osm-layer is very, very poor. Zooming to 100% in the png file shows big ...
2
votes
1answer
107 views

Error message 'Module qgis.v.kernel.rast.py not found'

How do I repair this error in QGIS: The error message was received whilst trying to run v.kernel from the modules list. I can however run v.kernel from the GRASS shell. A while ago, I installed ...
0
votes
0answers
48 views

Point to Polygon [duplicate]

Possible Duplicate: Create new polygon layers from postcodes latitude & longitude I'm running QGIS 1.8.0 I have a list of points that I need to convert to one polygon. So far I have ...
0
votes
1answer
974 views

Transform Shapefile from WGS84 to NAD83 using QGIS? [duplicate]

Possible Duplicate: How to reproject a vector layer in QGIS? I have some shapefiles whose CRS is WGS 1984 and I have some shapefiles whose CRS is NAD 1983 State Plane Illinois East. I want ...
6
votes
2answers
1k views

How to compile QGIS with GRASS on Ubuntu?

I am on Ubuntu building qgis with grass plugin. I have build grass code separately and used --prefix to provide the path GRASS_PREFIX is /usr/local/grass-6.4.2 and GRASS_INCLUDE_DIR is ...
4
votes
1answer
140 views

Problem opening a shp in another application

I helped a colleague converting waypoints from a gpx file to a shape file. My colleague has only arcMap. I gave him the shp and when he opened it in ArcMap, it did not show anything in the attribute ...
5
votes
1answer
72 views

Geographic locators within Polygons

I have a list of geographic locators and a boundary file. In QGIS, is there any way merging them together to create a lookup saying this boundary contains these locators? Not the number the actual ...
7
votes
1answer
244 views

Why is QGIS 1.8 crashing when exporting to PDF?

I want to export for example this: but qgis crashes. Sometimes with an error message std::bad_alloc. But: My Mac has 8 GByte RAM and "just" 5,... something (of 8) GByte are used, moreover there is ...
6
votes
3answers
2k views

Delete multiple features easily in QGIS?

I have a vector layer being rendered in QGis. I want to delete various features in the layer. I'm currently deleting each node by selecting the node through node tool and then pressing the delete ...
8
votes
5answers
313 views

How to ensure uniform colour for DEMs?

This is a silly question, but one I've been trying to figure out for a while. I have two Aster DEM tiles, one next to the other. How do I ensure uniform colour for both?
2
votes
1answer
466 views

What is the easiest way to let a user upload overlayers to openlayers (Geoserver/Mapserver)?

I need to let a user upload vector layers he created with QGIS or MapInfo professional to my website (using OpenLayers as client and either Geoserver or Mapserver as WMS). What will be the easiest ...
2
votes
1answer
202 views

Road graph tool crashes, but works with sample shapefile [closed]

When I try to calculate the distance between two points using the "Road graph" plugin in QGIS (1.8.0-2, on OSX 10.8.2 ML), QGIS just crashes. It does work with the sample shape file from ...
6
votes
4answers
2k views

Why do OpenLayers layers appear shifted in map composer?

I'm having trouble with the OpenLayers Plugin of Qgis and the map composer: If I create an OSM-background layer and if I want to export this, the OSM-Layer looks perfectly all right in the normal ...
3
votes
0answers
155 views

Are there any known problems using GPS connection in Android version of QGIS? [closed]

I install QGIS both my netbook (windows win7 starter) and My tablet (android 4.0). I can used GPS option in windows version and I can save location points from GPS. However, I could not manage same ...
3
votes
1answer
612 views

Problem with generating contour lines and filled contours

I am trying to create contour lines and filled contours from a shape file of height points using the contour plug in (have tried other tools but with no success). The data is sourced from the UK ...
2
votes
1answer
818 views

How to correctly merge layers with overlapping polygons in QGIS/GRASS?

I have 4 vector shapefile that I would like to join/merge, without worrying about attributes. Here are the shapefiles. I would like to do an union and a spatial dissolve, but everytime I do a dissolve ...
1
vote
1answer
836 views

“Please ensure that the GDAL_DATA environment variable is set and try again” on Kubuntu 12.10

I'm having a problem loading the 'convert os gml to ogr' plugin in QGIS 1.8 running on (k)ubuntu 12.10. Basically, clicking the plugin prompts the error: "Please ensure that the GDAL_DATA ...
1
vote
0answers
303 views

Start-up error message QGIS 1.8 Couldn't load PyQt4

After successfully building QGIS 1.8 "Lisboa" on Windows 7 in 32 bit mode by following the instructions mentioned here I am able to start QGIS, however I get the following startup error message: ...
7
votes
3answers
2k views

How to extract slope from topographic raster map?

I am working on a project for a machine learning class wherein I extract features from a topographic raster map and then classify the traversability of the terrain. One of the features I need to ...
8
votes
1answer
2k views

Sort layers in QGIS table of contents?

When I load a bunch of layers into QGIS from PostGIS, they seem to load in reverse alphabetical order. Is there any tools or plugins that allow you to quickly sort the QGIS TOC in a different order? ...
10
votes
3answers
9k views

How to import coordinate data from excel into QGIS?

I have an excel file containing data collected over many years as latitude and longitude coordinates for archaeological sites - how can I import it into QGIS as a new layer?
3
votes
2answers
632 views

How to debug 'Layer is not valid error' from Python plugin?

I'm trying to understand what goes wrong with a QGIS python plugin. Basically I'm trying to render a series of POINT. The query works fine, at least giving it by hand from inside PostGIS DB: "SELECT ...
3
votes
3answers
1k views

Summing attributes intersected by under a radius

Apologies - new user. I am working with QGIS on Mac OS X and with shapefiles downloaded from the US Census Bureau that show population data by state and by county. How do I: select certain points ...
2
votes
1answer
117 views

How to close and fill Gulfs and inlets in QGIS or Grass?

I have a raster layer from which I extracted only zones with a certain color, then polygonized it with QGis. I just generalized the new vector layer in GRASS to smooth things a bit. There are many ...
4
votes
3answers
2k views

How to extract POINT from a [LINE|MULTILINE]STRING

I'd like to create a vectorLayer in QGIS to display all the points that form a LINESTRING or a MULTILINESTRING stored in a PostGIS DB. I think that I need to transform all points of LINESTRING (or ...
1
vote
0answers
61 views

calibrating vector line in qgis

I have loaded GPS points into a QGIS vector layer. I also imported a vector line from a dxf file which doesn't have georeferencing. I would like to fit in line geometry between the GPS points - how ...
4
votes
1answer
137 views

Measurement not correct in QGIS 1.8

I have a SHP file of sub-areas of U.S. counties (roughly about the size of a Census tract) that I've reprojected into a 'true distance' projection (World Equidistant Cylindrical) in QGIS 1.8. However, ...
1
vote
1answer
1k views

QGIS, how do you break segments of a polygon, ie break 1 polygon into 2 or more?

I have a polygon but would like it to be in broken up to put into different layers. I can't work out how to do this.
7
votes
1answer
272 views

How to debug a QGis python plugin

I'm trying to write a python plugin for QGis. I'd like to debug some DB queries and I need a way to display the result. I thought about using a popup to display it, but I don't know how to show a ...
10
votes
2answers
471 views

How to build a minimum convex hull crossing the 180 degrees line?

I've been building convex hulls for species that inhabit the Indo-Pacific (~ from 20 to -65 degrees of longitude). The problem I've encountered is that for the species that can be found on both sides ...
4
votes
1answer
572 views

Vector tools missing in QGIS 1.8 (Ubuntu)

I installed QGIS 1.8 on an Ubuntu 12.04 Precise Pangolin virtual machine. everything seems to work fine, but I don't get any of the vector or raster tools that (I assume) are part of the standard ...
2
votes
2answers
611 views

Why is Spatialite delivering “Invalid SRID” error message

Qspatialite in QGIS 1.8 (and also Spatialite-gui) delivers an "Invalid SRID" error message when I try to load shapefiles with a SRID value of 3814 (Mississippi Transverse Mercatur). The SRID is ...
5
votes
0answers
133 views

How to add shapefile name as attribute during merge? [duplicate]

Possible Duplicate: How to add field with filename when merging shapefiles with ogr2ogr? I have more 200 shapefiles with a unique name. I would like to merge all of these together and save ...
3
votes
2answers
760 views

set geotiff 0 values to nodata

Is there a way to set all the 0 value pixels on a raster to nodata using gdal or qgis?I world like to use fillnodata to fill some holes, but holes are set to 0,so I need to delete them first
7
votes
1answer
5k views

Is there are QGIS plugin to allow the 3d visualisation of geological borehole data similar to the functionality of Target for ArcGIS?

I'm very new to QGIS, I have started using it as my new company is not willing to pay for ArcGIS and Target at this stage so I'm hoping QGIS can substitute not just in the interim but for good. What ...
3
votes
1answer
276 views

How to create a line with start and end points which are in another layer in QGIS?

In my map, there are lots of points in layer A. I want to make a line layer B and I want to make start & end points of lines snapping to points in layer A manually. Can I use points of layer A as ...
4
votes
3answers
95 views

Left click then right click is treated as double click in Mac QGIS Layers

I am having an issue with QGIS 1.8.0 on my Mac where I left click then right click which gets treated as a double click if the timing is too close together and brings up the Layer Properties box. ...
4
votes
2answers
677 views

How do I set mmqgis create grid options?

I am having a puzzle about using mmqgis create vector layer option. I want to use UTM CSR this are my options. I want a grid of 20,000 meters in the east and north axis. Nevertheless i have an error ...
5
votes
1answer
421 views

Stats on individual grid points nearest neighbours

First, thank you for this extremely useful and easy-to-access forum! I have shp of points where each point is the centroid of the individual cells of a 1*1km grid (~ 500 000 points). For each of ...