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

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7
votes
1answer
2k views

Using PostgreSQL with QGIS and ArcGIS?

Is it possible to use PostgreSQL with QGIS and ArcGIS? i.e. one database for different clients. Is it anything that I have worry or any problems to use the DBMS from two different software? I know ...
2
votes
1answer
1k views

How to export vectors from QGIS to MapInfo?

I am trying to save some vector lines that I made in QGIS (1.8 Lisboa) to a format that can be added to MapInfo Professional 6.0 (ancient version I know..). When I save the vector to a Mapinfo ...
5
votes
4answers
3k views

Advanced colour palette for raster data

I'm working with satellite date namely chlorophyll and sst. Each geophysical parameter generally has standard colours to represent them. I'm importing geotiffs into Qgis and I'm having difficulty ...
2
votes
1answer
379 views

polygonize and raster tools [closed]

ok simplest question i have asked i think. but im a running QGIS 1.7.4 and there are no other tools in the dropdown menu other than raster calculator. I have seen in a lot of online demos tools below ...
2
votes
1answer
174 views

QGIS Console error Libgrass

Just installed QGIS 1.8. on Mac OSX Installed GSL Install GDAL 1.9 Complete Installed QGIS keep getting this console error message in QGIS. Failed to load ...
1
vote
0answers
211 views

Problem using addVectorLayer() in Qgis

I am confused a bit, using addVectorLayer() in QGIS plugin. I want to add and display a vector layer, directly when QGIS opens. Hence I am using addVectorLayer() in _init_() function of my plugin. ...
0
votes
2answers
468 views

how to create gis like Uster?

I downloaded qgis, geoserver, openlayers, ext, geoext, qgis-web-client and osgeo. And i have map shape files. i would like create website like this site. i need help. can you send tutorial links thank ...
3
votes
2answers
3k views

How to create a lat/lon grid in QGIS?

I'm using QGIS. How can I create a shapefile consisting of a grid 0.5° latitude and 1° longitude in size?
0
votes
1answer
392 views

How to dissolve based on the overlap of polygons in the input file?

I am using ArcGIS 9.3/10 to dissolve few hundreds of overlapping polygon features. Now, I am seeing that Arcgis is not able to do dissolve for 5000 polygons. Generally, I used to dissolve ...
3
votes
1answer
1k views

Where are decoration (scale bar, etc) plug-ins in QGIS 1.8?

For QGIS 1.8 what happened to the "Decorations" (North Arrow, Scale Bar, etc) plug-in (for the canvas, not composer)? Thanks.
0
votes
0answers
140 views

How to build QGIS with Python on Redhat?

I'm attempting to run QGIS on Redhat 5 64 bit architecture. Version of Python is 2.4.3. Version of QGIS is 1.7.4 (wroclaw). When I run qgis, the splash screen appears, followed by a QMessageBox that ...
5
votes
1answer
585 views

Identify Polygons on raster image

I have OS street view mapping as raster images. Is it possible (without the obvious of tracing each dwelling) to identify all polygons on each tile. To clarify, My ultimate aim is to produce a ...
11
votes
2answers
3k views

How to create a new empty vector layer programmatically?

I am new to python and QGIS. I have looked at a few tutorials of python scripts for QGIS. All of them create new vector and raster layers with some existing data source. eg. shapefile or geotiff or ...
2
votes
0answers
788 views

legend groups and layer position/order qgis 1.8

I'm tring to programmatically create layer sequence also using groups. Simple python code: layer = QgsVectorLayer("004cp000.shp", "004cp000", "ogr") QgsMapLayerRegistry.instance().addMapLayer(layer) ...
0
votes
0answers
80 views

why are split-lines saved in the attribute table? (qgis 1.7.4)

A few months ago I splitted some lines in a shapefile with official roads because they are not accessible anymore. Now I loaded that file again into my project and the splitlines appears. Because I ...
7
votes
1answer
508 views

How to adjust the granularity of a heat map in QGIS?

Not sure I am using the correct terminology here, so I have tried to describe my problem in detail. Please edit as needed. I have a layer of points, a layer of roads and a heat map in a raster layer. ...
7
votes
1answer
2k views

How to fill gaps in SLC-Off Landsat 7 ETM+ Images with QGIS?

Explanation of the problem: On 31 May 2003 the Landsat 7 Enhanced Thematic Mapper (ETM+) sensor had a failure of the Scan Line Corrector (SLC). Since that time all Landsat ETM+ images have had ...
3
votes
2answers
2k views

How to calculate LS Factor of Watershed for RUSLE Calculation?

I managed to get subbasins for my catchment (7 km^2) with their areas but I haven't figured out how to get the LS factor (see Revised Universal Soil Loss Equation) from it. I have the vector file ...
2
votes
3answers
3k views

How to convert from EPSG:4326 to WGS84/UTM 32U?

I am unable to convert from the project's coordinate system to a different one using QGis 1.8.0. I have a .shp file with a certain coordinate system information (WGS84 EPSG:4326 according to qgis). I ...
1
vote
1answer
127 views

Is there something like SQLselect from MapInfo in QGIS?

I am a user of MapInfo that will need to adapt increasingly to QGIS. Is there something like "SQL select" in MapInfo which allows me to easily query between two tables or spatial queries? MapInfo ...
1
vote
0answers
506 views

How to change feature's geometry?

Hy, I'm creating my layer like this: crs = core.QgsCoordinateReferenceSystem(4326, core.QgsCoordinateReferenceSystem.EpsgCrsId) uri = "Polygon" uri += '?crs=' + crs.authid() uri += ...
0
votes
1answer
650 views

Is getting wrong attribute values from a feature in qgis

I make two polylines features(in my example both consists of two points) with the add feature tool. Then I (with code) add some attribute values on the first feature, then changes the geometry of the ...
1
vote
3answers
581 views

Deleting columns from joined attribute table in QGIS

After joining the attribute tables from two layers, I have a lot of duplicate columns on my table, making it hard to read. However, even when in "edit" mode I am unable to select and delete columns. ...
2
votes
1answer
70 views

Which class should I use to work with vector layers?

I'm doing different operations on vector layers. Kindly suggest which class should I use for vector layer i.e QgsVectorLayer or QgsVectorLayerDataProvider.
7
votes
5answers
14k views

How to install Openlayers plugin on Qgis 1.8?

After having installed Qgis 1.8 i am not able to find the Openlayer Plugin. In "the old days" I know I was supposed to check "add 3rd party repositories", but that button has disappeared? I tried ...
0
votes
1answer
540 views

Qgis install can't find Gdal framework (Mac OS X 10.7)

After having installed Mac OS X 10.7 I can't install Quantum Gis as it maintains that I have not installe the GDAL Framework, which I have done (several times). Have anyone experienced the same ...
1
vote
0answers
293 views

NVIZ runs from GRASS but not via QGIS

When I try to run NVIZ from QGIS I get an error which states 'Can't find usable init.tcl in the following directories" and then goes on to list a number of directories. (I did have a screenshot here ...
5
votes
1answer
850 views

Why do TIF loaded into PostGIS lose their colormap?

I have successfully loaded a TIF image (using raster2pgsql) into my PostGIS 2.0.1 database. I can load the raster image into QGIS and it displays in the correct space. However, it has lost all colour ...
0
votes
0answers
29 views

Multiline labeling [duplicate]

Possible Duplicate: How to create multiline labels in QGIS? I got it by following the second method mentioned by you.But my doubt is that how we can use multiline label property? You said ...
0
votes
1answer
140 views

Can QGIS wrap labels on second space?

The answer to this question tells us how to wrap labels on spaces. Is it possible to wrap labels on defined spaces? For example, wrap on just the first space or on just the second space. Secondly, is ...
3
votes
1answer
1k views

How to create multiline labels in QGIS?

How can I apply Multiline label option in the label property.Name field contains a lengthy name. I want to wrap it. How can I do it? please help me. My QGIS version is 1.8
3
votes
1answer
270 views

How to calculate buffer surface that falls within another layer's borders

The image below shows what two selected layers. One contains a series of borders, and the other a series of buffers. I am trying to obtain the buffered surface within each of the borders in the ...
2
votes
1answer
202 views

different labels at various scales

I have a locality layer of neighborhoods and suburbs from a spatialite database. How do I label this single layer with the neighborhood name at a lower scales, but as I zoom out, I would like the town ...
2
votes
1answer
747 views

Importing QGIS core into Python on OSX

I am interested in learning how to write standalone scripts using QGIS. An answer to my previous question directed me to the PyGIS CookBook which has the following instructions for importing the ...
3
votes
2answers
3k views

How to merge many individual KML layers into one?

I'd like to open a USGS KML file of bedrock geology for an entire county, but there are over 2,000 individual polygon layers. Does anyone know if there is a way to merge all of these layers together ...
6
votes
1answer
2k views

How to write standalone Python scripts using QGIS?

I've been learning how to use the Python Console in QGIS using references from qgisworkshop.org. I'm familiar with writing standalone scripts in ArcGIS and want to learn how to do the same with QGIS. ...
0
votes
0answers
27 views

Set buffer radius in metric units in qGIS [duplicate]

Possible Duplicate: What is up with QGIS buffer tool units? A similar question to this one has already been asked QGIS - Change unit of measure from degrees to meters, but none of the steps ...
4
votes
2answers
575 views

Looking for an explanation of QGIS Edit Widgets

I have noticed "Edit Widgets" under the Quantum GIS and would like to know in detail the use case and usage of this widget. For any opened vector file, under the Properties -> Fields Tab, for every ...
2
votes
1answer
128 views

interfacing multiple gps

I am trying to interface NMEA output of multiple GPS units transmitting wirelessly to a single PC, each GPS position can then be shown on georefance map of that area. My question 1.) How to ...
3
votes
1answer
2k views

How to draw a cross section in QGIS

Given my enthusiasm for QGIS, does anyone have a simple workflow for drawing cross sections of earth features? My thing is that QGIS is being used to present the plan view, but we have a little ...
3
votes
1answer
398 views

QGIS Polygon layer table of adjacent polygons

In a polygon layer, how can I generate a table of adjacent polygons?
5
votes
2answers
5k views

How to calculate polygon areas and perimeters?

If I load a polygon layer and make a new column, how do I fill that column with the 1) area of each polygon and another column with 2) the length of the perimeter of each polygon?
3
votes
1answer
1k views

How to import LAS to QGIS? [duplicate]

I need to import LAS files to Qgis. I´ve never worked with Qgis till now. Could anybody explain me this problem to the details? I´ve installed Quantum GIS v. 1.8.0. Thanks
1
vote
1answer
369 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 ...
2
votes
1answer
881 views

SID and/or ECW support on QGIS for Linux

Running QGIS on Ubuntu 11.04 and QGIS for Android on Galaxy Tab 10.1 (which is an awesome project by the way) NEED to figure out a way to get SID and/or ECW files loaded. Saw some posts about ...
2
votes
2answers
109 views

“show only visible features” doesn't seem to work

I'm trying (unsuccesfully) to place the attribute table next to a map containing the same in print composer. Let's say for example my map in the primary window contains 6 districts and my map in the ...
4
votes
1answer
707 views

How does QGIS handle opening files and how can I improve this?

We are using shapefiles with a large attached database to it (162 Mb for 133000 features) Opening this shape file on a remote server takes about 5 minutes whereas DivaGIS takes 7 seconds for the same ...
4
votes
1answer
232 views

Surface covered by buffers in QGIS

In QGIS, I have plotted buffers around points. I would like to calculate the area which falls under buffers without over counting due to buffer overlaps. Is there a quick and easy way to do this?
2
votes
1answer
187 views

Point count within borders, in two different layers, using QGIS

I have a layer of georeferenced points, and a layer of vectorized borders. Is there a way I can use QGIS to calculate how many points fall within each area of the borders layer?
8
votes
3answers
1k views

Creating regularly spaced, defined # of points within polygon in QGIS

I used the research tool "Regular Points" to produce a certain number of points within a polygon, but it forms a rectangular grid of points rather than only within the shape of the polygon. Since I ...