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

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18
votes
1answer
1k views

Gravity/Huff model tools

I am looking for a way to simulate a gravity model using a point-based layer. All my points are assigned a z-value and the higher this value, the larger is their "sphere of influence". This influence ...
5
votes
1answer
2k views

Is QGIS Supported on Windows 8?

Can QGIS be installed on Windows 8? I'm going to buy a laptop with Windows 8, but I have no idea if Windows 8 can run QGIS.
6
votes
2answers
1k views

What's the Workflow for buffering in meters/km using WGS84 layers?

I'm a little bit new to GIS, so bear with me a minute.... I'm using QGIS 1.7.4-Wroclaw and working with an SHP layer in WGS84. I want to buffer out to a certain number of kilometers from this layer ...
1
vote
1answer
120 views

Raster menu does not have any tools in QGIS

in raster menu in QGIS, only raster calculator is available, how to get other tools, like wrap (reproject) please see the image for help. help me to get this.
6
votes
1answer
292 views

QGis Making Column Value of Attribute table unique

For a shapefile, I have a field named id with the following contents in it: 1 1 2 2 I want to make these values unique such as: 1 2 3 4 Is there any way to achieve this in Quantum GIS (using any ...
2
votes
1answer
151 views

How to best execute the same query on many different vector layers?

I have some vector layers in my project and I need to separate the polygones by area (I need a copy of all shapes > 2ha). I know how to do this for each separate layer (query) but is the a tool to do ...
3
votes
1answer
1k views

Export to new projection in QGIS 1.8

I would like to use QGIS to convert a CSV file from UTM to lat/long. I imported the CSV file with the "Add Delimited Text Layer" plugin. This works fine, the data looks like it is projected properly ...
5
votes
2answers
1k views

How do I use QGIS python console to iterate through simple layer queries and png outputs?

I'm really new to QGIS coding and I'm having a hard time finding (especially) the api classes/functions to carry out actions of the Query Builder window. I'm basically trying to do this: Iterate ...
5
votes
1answer
268 views

What tool do I need to have satellite background images to draw features of a postgis database?

What tool do I need to have satellite background images to draw features of a postgis database? I looked about Geomajas but seems very complex for what I'm trying to do. I have osm data imported in ...
3
votes
1answer
242 views

How to filter layer of osm data?

I have a table osm_roads that has a column named geometry geometry geometry(LineString,900913). If I want to filter a city to draw districts, I cannot do it by geographic coordinates? What if in ...
1
vote
1answer
657 views

How do I copy all feature attributes to a feature in a new layer?

I'm trying to create a new layer in QGIS based on an existing layer. The new features should have all the attributes of the corresponding features in the original layer. I've been trying to use ...
2
votes
1answer
195 views

How to fix the “The inserted Ring is not contained in a feature”?

I am trying to add a ring in a feature in a shapefile. This feature is a single part feature but has already a few rings. When I try to add the new ring, I have the error message : "The inserted Ring ...
3
votes
2answers
585 views

Can python read the value of a cell in a spreadsheet? [closed]

Can python read the value of a cell in a spreadsheet? The simplest example would be a script that ran a buffer tool on a given shapefile. For the distance parameter, instead of just using a number ...
2
votes
2answers
529 views

shapefiles in QGIS and ArcGis

Hi I'm working with a set of shapefiles and have some problems with the "align" of them in QGis when I load Openlayeres to reference some points. OLs has an straight horizontal baseline but the ...
2
votes
1answer
147 views

Can QGIS be installed on a Server

My question is whether QGIS can be downloaded and installed on a server for multi-user access. Rather than installing the software locally, can QGIS be stored on a server and accessed by many?
3
votes
2answers
485 views

Creating seperate layers out of one big polygon shape by using attributes

I try to explain may problem. I have a big polygon shape (> 200 fields). I have the owners of these fields in a column. I need the seperated shapes for each owner. Is there a tool to do that? Is it ...
1
vote
2answers
171 views

Making Multipart Features to Unique features

I have a layer with two lines crossing over each other. I create intersection point over them and then create a buffer for a specified distance and then using difference tool, I delete the buffer ...
1
vote
1answer
144 views

estimated population around a point qgis

I have a shapefile with points distributed in a polygon. The points are post office locations within a census district. How can I estimate if the post office is a representation of the concentration ...
3
votes
1answer
430 views

Calculate number of people within 50 km of a point

I have two data sets: World population (raster) in EPSG:4326, from http://sedac.ciesin.columbia.edu/data/set/gpw-v3-population-density-future-estimates/data-download A shp file with points ...
1
vote
1answer
294 views

Where is the default QGIS Point layer style .qml file installed in Win 32?

Where is the default QGIS Point layer style .qml file installed in a Windows 32 bit installation? I have done a search on *.qml and can only find four python plugins styles.
8
votes
3answers
942 views

How to get a list of distinct values from a shapefile field using QGIS?

I have a shapefile whose features I can filter by specifying a where clause in the query dialogue. F.x. I have a field named 'city_name' and by stating 'city_name = "London"' in the where clause only ...
3
votes
1answer
133 views

How to set a default raster style?

Most of my layers in Qgis are shapefiles but I have some raster data which is terrain relief shadings that are GeoTIFFs. In order to save a lot of time with the default colour and density that Qgis ...
7
votes
4answers
1k views

How to create different diameter circles round points?

I want to map a tree survey. I am thinking that I will plot positional points of the trees and then add other data like tree type etc. to the attribute table later. Is there a way I can have an ...
11
votes
3answers
251 views

What is the most appropriate journal for publishing a paper about data collection with QGIS and mobile equipment?

I am a QGIS user, and a few months ago, we used QGIS on a PC Tablet to collect data on nesting birds on a cliff directly on the field. The principle is to have QGIS installed on a PC-Tablet with an ...
1
vote
1answer
102 views

What's the purpose of wms_metadata.xml and admin.sld?

I've installed QGIS Server and it works fine. But in /usr/lib/cgi-bin/ folder I've found 2 additional files - wms_metadata.xml and admin.sld. What is the purpose of these file? I've never used them.
10
votes
2answers
447 views

How to perform repetitive tasks in QGIS?

I am trying to do a treatment on many feature files, so I would like to automate it. In fact, I have one shapefile with the spatial distribution of some species, and one with vegetation type. I ...
2
votes
1answer
168 views

Why are some SVGs not displayed properly in print composer?

I am having weird problem with adding .svg to qgis print composer. I have done some smaller symbols before in inkscape and they work - however the latest one displayed itself as huge black square. I ...
4
votes
1answer
318 views

Is it possible to do spatial interpolation using points in a field?

I would like to use Quantum instead of ArcGIS to make field map but before, I need to know if its possible to do spatial interpolation with definited points in a field (ex. pH points). Is there a ...
1
vote
3answers
537 views

How to create one KML per polygon (from one Shapefile)?

I have a shapefile containing hundreds of polygons. I need to create a kml of each of the polygon. Is there any way that I may not have to deal each polygon individually and my polygon file may give ...
5
votes
1answer
251 views

QGis 1.8 fails to rotate point geometries with rule-based style

I have to do some visualizations in QGIS (1.8.0) and up to now I've been very happy with the new Dialog "Layer Properties -> Style", using the rotation-field to rotate Point-Geometries visualized by a ...
4
votes
1answer
112 views

QGIS printing to file, shading?

Hi I am not even sure how to ask this question and I have googled what i think is wrong with no success. When i create a map with different shadings on it, it looks perfect until it is wrote to pdf. ...
0
votes
1answer
155 views

Joining intersected polylines using rules based rendering [duplicate]

Possible Duplicate: Setting rendering order of line layers in QGIS I have trouble getting two intersecting polylines to look like they were joined at rendering. I am using rules based ...
5
votes
1answer
1k views

What is the best way to connect spatial data with attributes in Excel table?

I have many attributes which are stored in an Excel table. They refer to USA counties. I need to somehow connect those attributes to polygons in some format (don't know which is the best) and ...
2
votes
1answer
262 views

Problems with NAD27 projection in QGIS

I have some data that is in NAD27, but I am having a hard time displaying it in QGIS. I think that the problem is with the CRS. I cannot seem to find the correct NAD27 option. The closest one seems ...
4
votes
1answer
249 views

How can I avoid reprojection gaps when merging DEM rasters?

I have two raster DEMs in same resolution I want to bring together. I was using the merge-function in SAGA, GRASS and QGIS but I always get the following result: What do I need? Where could the ...
4
votes
1answer
892 views

Revealing the different layers of a shape file in QGIS

Shapefile I am referring to is 'NUTS_RG_03M_2010' which is together with several other Shapefiles available in a ZIP file on the Eurostat web site. the ZIP file the available map sets at Eurostat I ...
0
votes
0answers
154 views

How do you normalize a field in Qgis symbology?

I'm trying to normalize a field in symbology in Qgis but there is no normalization option like in Arc. I've tried to add a field to the attribute table and use the field calculator to do the ...
3
votes
2answers
160 views

How to modify two polygons which have common point and line at the one time

I would like to modify two polygon at the one time because these two data has same point and line. Is it possible?? In the present circumstance, I have to modify polygon one by one. First, I ...
1
vote
1answer
144 views

How to remove terracing from Civil3D GeoTIFF export?

I've received a GeoTIFF DEM that was exported from Civil3D and at every contour there is a distinct terrace created when I process an aspect or slope in QGIS with the GRASS plugins. I've looked ...
4
votes
1answer
144 views

Problem with custom projection definition in Qgis

I want to define a custom crs valid for Mexico. The context is that older cartography in Mexico is based on the NAD27 datum. I wanted to test the following proj4 string +proj=longlat +ellps=clrk66 ...
3
votes
0answers
749 views

How to join data from a CSV to a shapefile using QGIS

I'm new to GIS and new to StackedExchange. I need help joining a CSV of Accessibility data to a LSOA shapefile in QGIS. The process explained here does not work for me and I don't know why. The ...
3
votes
3answers
897 views

Auto-calculate field (area or formula)

I'm wondering if anyone has any insight into the potential to auto-calculate the value of a field, either area or distance (ideally) or a formula (based on the values of say 2 other fields, or an ...
2
votes
3answers
9k views

How to convert shape files (.shp) to Cad (.dwg ) format using Quantum Gis 1.7.0?

How to convert shape files to .dwg format using Quantum GIS 1.7.0 ? Thank you
2
votes
1answer
102 views

Can you change the location of .qgis from the home directory to another folder on Windows in QGIS1.8?

Is it possible to change the location of the .qgis folder to another location ( for example on a network drive H:\ ) in Windows?
1
vote
0answers
129 views

How do I fix this QGIS sextante error? NameError: name 'sextante' is not defined

A colleague of mine posted this the other day. We haven't got any nibbles yet and I wanted to elaborate on the issue. We are having trouble running the r.mapcalculator function and receive the error ...
1
vote
1answer
365 views

How to create layer from shapefile in QGIS?

I have a road network shapefile that I want to use to create multiple maps from it, each based on some selection of original shapefile. For example, I want to show all highways with some custom ...
0
votes
1answer
243 views

How can I find and fix broken raster metadata using QGIS?

I have a raster (TIFF) hillshade image that I would like to use in a mapping project. However, I'm having a hard time lining it up properly in QGIS. Through a series of investigations, I have ...
1
vote
1answer
408 views

How to create new columns in QGIS by writng Conditional query on other columns of attributes table

First of all, sorry, I couldn't phrase my question better. So I want to be able to add a new column in my attributes table, say B, and it's value should be 1 if Column A's value is 1 and 0 if Column ...
2
votes
2answers
82 views

How to 'trace' areas from the layer below?

I have some Ordnance Survey vector data for my local area. I want to create a new layer and on it 'trace' some of the areas, fields, verges etc from the layer below with the intention of then ...
0
votes
1answer
314 views

How do I add a Corel Draw map as .dxf file to QGIS and how do I georeference it?

I have a vector data map of Poland, which I exported from Corel Draw. I can display the map in QGIS. At first the boundaries and subdivisions are only displayed as lines, after saving the data as ...