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

learn more… | top users | synonyms (1)

1
vote
3answers
274 views

How to access user credentials in database connection?

I am trying to automate a couple of things when a QGIS plugin is activated: If Layer A is not in the TOC, add it. This requests username and password to access a PostGIS table using the inbuilt ...
1
vote
1answer
151 views

Species atlas (how to automate to create on page for each species with QGIS)

With the use of QGIs, I would like to create an Atlas for a batch of species, with: a background with the country (from a vector layer or from the openlayer plugin). a vector layer (polygon) to show ...
1
vote
3answers
485 views

How to create random point in according polygon for each dataset entry in a list (with R)

I have an area divided into polygons, and a dataset of observations which has a common field with the polygon layer. I now would like to generate a random point for each dataset entry within the ...
1
vote
2answers
131 views

QGIS point sampling tool really slow for polygons?

I have a large field of randomly distributed points (100,000 of them to be precise), and I'd like to get values for a variety of raster and polygon coverages for each point. I've been using the QGIS ...
1
vote
2answers
403 views

What is the equivalent of arcpy “Con” in QGIS and/or R raster-package?

I'm looking for an equivalent of the conditional expression "Con" from arcpy in an open source spatial analysis package. I'd prefer to use QGIS or R. To provide some additional detail, I need to ...
1
vote
2answers
306 views

How to add a dynamic timeline to the QGIS canvas?

I am using the plugin Timemanager which works really great but there is one thing I'd like to improve. Instead of displaying the date and time on each frame, I would like to display a timeline ...
1
vote
3answers
759 views

QGIS 1.8 startup crash - looking for a log file

I have a problem with QGIS 1.8 with OSGEO4W installer (windows 7 - 64 bit). QGIS crash on startup, it shows the splash screen and then nothing. I have updated from an old 1.7.4 QGIS version. I have ...
1
vote
2answers
248 views

How to mask out features outside of the Coverage Layer for Atlas plugin? [duplicate]

Using the Atlas plugin for qGIS how do I set the coverage so that it will only highlight the feature(s) I want but still show the surrounding features as grayed out areas? This would have been easy ...
1
vote
2answers
1k views

Adding .e00 data into QGIS

I wonder if anyone can advise me on how to go about adding .e00 data into my QGIS project. I'd be very grateful for any advice, or a hint on where to find it. Thanks TVZ
1
vote
1answer
409 views

how to open layers with multiple geometry types in qgis?

I recently had some difficulties opening some MapInfo TAB vector layers in QGIS because each MapInfo layer contained two different geometry types: point and line. The MapInfo layers had originally ...
1
vote
2answers
816 views

Interpolation of contours (from one “main-contour-shapefile”)

I calculated, that the best and smalest possible äquidistance (equidistant) for my map is 30m. After I generlized my DHM, I extracted contours of a intervall of 30m and smoothed them. Now I have my ...
1
vote
1answer
783 views

Last edited information missing when used QGIS - Dxf to Shp

I am doing as constructed drawings which require the information to be in a GIS system and more specifically drainage as constructed drawings. I must have a separate file for Pipes and Pits. First I ...
0
votes
1answer
71 views

Blank Shapefile output?

When executing the following command string in the active browser, Qgis projects the triangle polygon and associated attribute table correctly. Upon reopening the shapefile in a new browser, the ...
0
votes
0answers
75 views

Issues creating slope raster layer from a point layer

I'm trying to create a slope raster layer using QGIS 2.0 on Windows XP. I started with a points layer with the Z elevation attribute. I then used the interpolation plugin to create a DEM. But, ...
0
votes
2answers
109 views

Calculate length of line across zones with at least m accuracy

I have created lines between multiple points that are across MGA 54 and 55S (EPSG 28355). I am trying to calculate the distance between points but different methods give different answers (~1km ...
0
votes
2answers
269 views

“Identity” overlay in QGIS?

I have two polygon layers I'd like to overlay using QGIS or another open source tool. What I want as output is a polygon layer with the extent of one polygon, but with each polygon in that layer ...
0
votes
1answer
969 views

Can not make qgis.db private copy

I've just installed Qgis 2.0.1 and the above error message appears. Does anyone know how to resolve this problem? I think I need to change the permissions of the relevant folder, but I'm not ...
0
votes
2answers
99 views

How can I delete dangling paths after merging features

In my previous question I've asked how to can I merge different polygons while converting to GeoJSON and TopoJSON. After a day of researching I've realized that, rather trying to do it command line, ...
0
votes
1answer
580 views

How to read the attribute values using pyQgis?

What is the way to get the information contained in the attribute table, say in column 2, row 2 using pyQgis?
0
votes
1answer
2k views

How to convert a regular point grid to raster? [duplicate]

Possible Duplicate: How to convert a point grid to a raster? I´d like to convert a regular grid (25 meter) of points (XYZ) to a raster. I have tried the GRASS-tool r.in.xyz but I always get ...
-1
votes
1answer
4k views

Opening TIFF DEMs in QGIS

I have files, in Tiff format, downloaded from ASTER-GDEM. Can I open this file with QGIS? If yes, how? Thanks in advance
12
votes
0answers
236 views

Qgis 2.0: Disable log messages? [closed]

Is it possible to disable log messages in QGIS Dufour? When I work in QGIS 2.0, log messages increase to more than 2000 and it makes QGIS very slow. Then I save project and open it again, then QGIS ...
12
votes
2answers
1k views

Is it possible to manually correct a raster DEM (OpenSource)?

Is it possible, to correct a raster DEM by changeing the raster-cell-values manually, like by "painting"? My DEM (ASTER) have one small error where the elevation is about 300m below the actual ...
11
votes
3answers
580 views

Contours: Interrupt contour lines beneath a elevation number

Is there a way to interrupt a contour line beneath a elevation number? Thanks!
10
votes
1answer
365 views

PyQGIS file lock release

I was wondering what triggers the release of file locks in pyQGIS? I am trying to delete a few data sources (used temporarily) by calling QgsVectorFileWriter.deleteShapeFile, but I have to quit QGIS ...
10
votes
4answers
2k views

How to buffer in pyQGIS?

I'm looking for some examples to do simple python scripts in QGIS. How would I do a buffer analysis on a dataset? I can't seem to find much in the manual and QGIS python that quite matches the Esri ...
9
votes
1answer
345 views

Why are some columns not recognized as numeric even though I have a CSVT?

I have problems importing a .csv file. Some Values of the file are not supposed to be formated in text style, but in number style, thus i created an additional .csvt file like explained here. Both ...
9
votes
2answers
1k views

What is the standard Mercator projection?

I'm using QGIS in order to re-project a shapefile I have into "Mercator" so that something like protoviz understands my co-ordinates. Protoviz tells me "Mercator" ...
8
votes
2answers
434 views

Finding polygons without right angles

Now we are digitizing some buildings in specified area. The obligatory rule for this work - in most cases buildings should have right angles. We are using QGIS with CAD tools for this work. But ...
8
votes
3answers
791 views

Best way to manage large number of geoTiff rasters

I have around 2-3000 1-bit geoTiffs of size 11000x9400. Color 0 should be transparent, and QGis gets it wrong in the first place, so I used a .vrt file to set all the parameters in one single place. ...
8
votes
4answers
3k views

Is there a way to concatenate fields in field calculator of QGIS?

Is there a way to concatenate fields in field calculator of QGIS? (e.g. hectares + ' ha')
7
votes
4answers
2k views

How do I open personal geodatabase in QGIS 2.0?

Good afternoon. I am trying to use an ArcGIS (10.2) personal database MDB as a container for data to pass to a QGIS user. I formerly used QGIS 1.8 for Mac OSX, and after some fiddling around, I was ...
7
votes
2answers
192 views

How can I force text to appear underneath other layers in QGIS?

To emphasise one particular polygon area, I have used rule-based styles (QGIS) to apply a 50% transparency white fill to every polygon but the one I am interested in. This polygon layer is above all ...
7
votes
2answers
2k views

How to split an irregular polygon into equal areas?

I am a surveyor and use QGIS for maintaining soil test records on civil projects and am constantly provided with test lot area or number of lots required. These are more often than not irregular in ...
7
votes
1answer
528 views

QGIS: subtypes and domains like in ArcGIS?

s there a opportunity to use subtypes and domains in QGIS (Desktop 1.8.0) like the way you use in ArcGIS? I´m specially interested in the possibility of dependencies between subtypes and domains: not ...
7
votes
0answers
67 views

How can I automatically split a spatial layer to a grid [duplicate]

Possible Duplicate: Divide vector in equal smaller parts in QGIS or similar I am a software engineer and the company I work for has a project that needs some spatial data manipulation in ...
7
votes
1answer
212 views

Why is there a black hole in the Heatmap?

After running the Heatmap tool in QGIS I like to color the geoTiff according to my wishes. Using Psuedo color works fine, but it leaves me with no options, as type of color scheme or transparancy on ...
7
votes
3answers
4k views

How to delete multiple selected polygons at once?

I'm new at this, a novice at best. I'm using QGIS 1.7.3. I simply want to select a large number of polygons on screen and hit the delete key to delete them and resave the shapefile. Can this be done?
6
votes
3answers
241 views

How to find out if OpenStreetMaps contains low emission zones?

Since I never really digged into the data contained in OpenStreetMap I ask myself what would be the recommended way to identify layers or tags within the overall data. In my current use case I want to ...
6
votes
1answer
606 views

How do I convert a .dxf to a .shp containing a field with height information in QGIS?

I received two .dxf for my project that represent my area of interest. One of them contains buildings, the other one terrain elevation. They both are 3D. I can convert them to shapefiles successfully ...
6
votes
2answers
995 views

Why do my Shapefiles not align correctly?

First: I'll summarize what I understand so far so please confirm or correct me. When On-the-Fly is selected a layer is re-projected from that of the layer's CRS to that of the project CRS, IF ...
6
votes
3answers
2k views

What is XYZ format in QGIS?

Basic question, but I have been asked to export data to an XYZ format. Is this the same as CSV files. I am using QGIS 1.8.0. So i am presuming i select the data I want to export, right click its ...
6
votes
1answer
210 views

How to consecutively number polygons from north to south following a polyline?

I have a shapefile (polygon) with a large number of polygons (roughly 10,000) that form a narrow but very long belt that windes through half a country and another shapefile (polyline) that represents ...
6
votes
1answer
125 views

How to change all values in a field in one operation?

I am setting up a couple of shapefiles with text x, text y, text rotation and text size fields in order to utilize the labeling toolbar where I can move and rotate labels. I would like the values for ...
6
votes
2answers
283 views

How do I compute v.kernel maps in less than 16 hours?

I am using the GRASS GIS 6.4.2 bundled with QGIS 1.8.0, using a PostGIS dataset exported via v.in.org.qgis from QGIS, to create kernel density maps. The layer has 738,288 points. My problem is the ...
6
votes
2answers
4k views

Create a polygon layer from point data

I'm currently using QGIS 1.8.0 I would like to create a polygon layer from a point dataset, where the size of the polygons relates to the resolution of the grid reference. The ultimate aim would be ...
6
votes
3answers
2k views

Is there a way to count the number of vertices of polygons and lines?

In QGIS, is there a way to count the number of vertices of polygons and lines in a given layer, and create a separate field containing these values? I suspect it's a function somewhere in the field ...
6
votes
1answer
2k views

Features to 3D from 2D in QGIS

Is there a way to convert 2D features to "3D" features in QGIS? I know there is a way to do this in ArcMap by using an attribute value in the attribute table, but I am looking to do this with ...
6
votes
2answers
6k views

How to change the language setting/interface of Quantum GIS (to English) using Windows XP in French?

I want QGIS interface in English in order to share the information with the GIS community. Using other language than English when chating with the GIS community is very difficulte. When I installed ...
6
votes
1answer
784 views

Is it possible to setup fiddler to capture requests from QGIS

I want to know if it is possible setup fiddler to capture WMS/WFS requests from QGIS and how to do it. Fiddler is capturing the requests from MapInfo and I don't remember making any setup in fiddler ...