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

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1answer
44 views

QGIS Symbology changes by number value

I've gotten a state file with count outlines joined to an attribute file that shows numbers of items per county. ArcGIS has the ability to set the symbology to grade the results into pre-determined ...
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0answers
151 views

Why do my Attribute table joins result in all NULL?

I spent hours getting "null" results in joining a downloaded state and county shp file to a self-created file (SCF). What I found was that the SCF had to have "EXACTLY" the same set of names/ID#'s as ...
1
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1answer
1k views

How to transform World data from EPSG 4326 to EPSG 3857

I have tryed different opensource tools to transform a world data shapefile from 4326 to 3857 but I always have an error. Im not sure, but is it because of Antartica? I have tryed with GDAL and QGIS ...
1
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2answers
606 views

Trigger to fill attributes (data, client ip) in table for each new objects, PostGIS

In PostgreSQL/PostGIS database stores shapefiles. Client users software - QGIS. Please help me write PostgreSQL/PostGIS trigger, which for each newly added/updated feature in layer added 'time create' ...
4
votes
1answer
735 views

How to set up Python 2.7 to work in both QGIS and ArcGIS?

I have both ArcGIS 10.1 and QGIS 1.8 installed and both include Python 2.7 in slightly different setups and in different folders (c:\Python27\ArcGIS10.1\ and c:\Program Files (x86)\Quantum GIS ...
4
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2answers
109 views

“GIS” Mapping on Monument - Scaling

I have a Baroque tombstone for which I have to map the damage phenoma. Normally one can use a vector drawing programm but one has always two boundaries between the different polygons. Questions: Is it ...
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0answers
109 views

Problem using grid with a vector layer

I need to establish a model of maritime pollution and I try to use the grid option to work on ocean sectors. I tried to use my grid on a vector file, .shp, with points. Each point is a maritime ...
5
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1answer
4k views

How to select points within a polygon from another layer?

I'm using QGIS 1.8 with a PostGIS database and I have three postgis-layer in qgis a lines layer, a points layer and a polygon layer. What I'm trying to do is to select a polygon in the polygon layer ...
2
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3answers
1k views

How to convert a txt file to shp?

I've got a txt/csv file with the utm coordinates and the hights. Now I want to upload this into qgis. This is not a problem so far. The problem is to create a shapefile out of the data with an ...
1
vote
1answer
246 views

Pseudo Mercator error?

I'm mapping on QGIS, I have a vector layer and his CRS is on EPSG:4326 - WGS 84, but also I wanted to put a satellite image, so when I do it, the image use WGS 84 / Pseudo Mercator. The problem is, ...
1
vote
1answer
241 views

How does QGIS calculate the area of a polygon?

I am working on a project that requires the calculation of the area of a polygon by two different methods. I need to know what algorithm QGIS uses to calculate the area of a polygon. I know ESRI ...
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0answers
125 views

Use QuantumGIS to bulk-import csv files

I have a large set of .csv-files containing geographic information. Every dataset consists out of 2 .csv-files! This is my folder-structure. All files in Tracks are formatted equally and all in Routes ...
2
votes
1answer
95 views

Can I use the globe plugin on a Windows OS and where can I find the plugin for QGIS?

I am trying to add my layers (health facilities and pertinent infrastructure within a region) to a 3D image of the landscape and someone recommended I use the Globe plugin. I can not find the Globe ...
3
votes
1answer
60 views

what is the minimum to install of QGIS for it to work?

This may sound like a daft question, but I'm looking to understand what the minimum parts of the install procedure I need to install to get QGIS to work (i.e. can it be installed without GRASS etc?) ...
2
votes
1answer
164 views

Why are towgs84 definitions missing on Ubuntu 12.04 compared to Windows?

Why for some of my most used CRS the 'towgs84' part of the definition of the layer spatial reference system is missing, compared to the QGIS for Windows? EPSG 3004, 23032, 23033 when used with QGIS ...
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1answer
417 views

CSV with latitude and longitude to a spatial points with QGIS 1.8

i have a csv file with latitude and longitude of several addresses and a shape file of a region. I want to plot this points of the CSV file into the shape file. But I don't know how to transform these ...
3
votes
5answers
2k views

How to convert KML with tracks to Shapefiles?

I downloaded a KML track from Google Latitude. The service allows to download the tracked route from the user's profile providing a link such as: ...
1
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1answer
406 views

How to export a .sid image as high DPI .tiff or .bmp from QGIS?

I have 2 50 cm resolution areal photographs in .sid format. How can I export these layers as a regular image format (like tiff or bmp) which I can then open in any simple picture viewer program? I've ...
4
votes
1answer
145 views

Can QGIS perform graphic clipping?

In ArcGIS for Desktop there is an option to graphic clip inside the data frame - this clips the feature you're viewing without actually clipping the feature into a new feature. Does Quantum GIS have ...
3
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2answers
1k views

Colouring areas between (vector) contours?

Is it possible to colour areas between (vector) contours without making it a DEM first? Joshdoe seems to have done so in Create filled contour map with GRASS but does not say how.
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0answers
34 views

Change text format and visibility

I need better visible names of towns, because at the big scale is bad reading --> i want to setting visibility and format. For example name "Ústí nad Labem" is good visible but another big city in my ...
1
vote
1answer
141 views

How to symbolize more than one attribute simultaneously in QGIS?

Each symbol can show different properties such as temperature and pressure, etc. I want to change the symbol color according to one property and size with another one. How can I do it in QGIS? Thanks! ...
0
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1answer
152 views

Problem executing Mean Shift Segmentation

I have a problem executing the Mean Shift Segmentation in QGIS with Orfeo Toolbox. I put all the parameter to execute and then, nearly 5s after appear the message that SEXTANTE could not open the ...
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2answers
546 views

How to calculate Image boundary / footprint of satellite images using open source tools?

I'm referring to this question&discussion: How do I create a shapefile showing footprints of Rasters? I need to create the polygon outlines of several single layer raster images, not the ...
1
vote
1answer
591 views

How do you scan/quantify vegetation using satellite images?

I am relatively new to GIS (about 4-5 months in) I did not receive any formal education about this so I am completely clueless about how to go about measuring/quantifying vegetation using satellite ...
1
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4answers
3k views

Get pixel value from a raster in a xy table

I'm trying to find a way to convert a raster (in my case it's a Landsat satellite image) into a table with 3 columns which would represent: 1) x coordinates (the so called "xllcorners" in ASCII ...
2
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1answer
153 views

Can QGIS get the GPS Coordinates via the 'Windows Location Provider'?

Can Quantum GIS get the GPS Coordinates via the 'Windows Location Provider' in Windows 7/8 instead of reading a virtual com port? If not, could this be developed as a Windows-specific plugin? (Is ...
4
votes
3answers
341 views

How to create scattered points in polygon

I have few polygons and I want to create few scattered well distributed point within the polygon. I am used to with ArcGIS and QGIS platform. How can I make it?
2
votes
2answers
577 views

How do I import UK Environment Agency Lidar data (.asc) into Quantum GIS

I have downloaded Lidar data from the UK Environment Agency as ESRI ASCII files but being a complete novice as far as GIS is concerned I do not know how to view them. Quantum GIS was recommended to me ...
3
votes
3answers
2k views

Obtain all elevations points from a raster DEM

I need to obtain all elevation grid points from a raster DEM. I see the steps required as: Read in raster DEM (Arc Info Binary Grid format). Create subset area using Points2One (see triangle area ...
2
votes
1answer
362 views

Combining polygon geometries with python and QGIS segfaults

I am trying to combine polygons, using Qgis 1.8, and every time I run this script in the python console, I get a segmentation fault. Here is the script: from PyQt4.QtCore import * iface = ...
0
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0answers
36 views

How to change value of an Line edit dynamically

I create a form in QT4 and compile with pyuic4. it create an form.py I want to modify the value of the line edit dynamiclly with code. I put this code in the form.py but never happen: ...
0
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1answer
91 views

Make many lines in one layer (Python)

I what to create many lines with this code: v_layer = QgsVectorLayer("LineString", "cable", "memory") pr = v_layer.dataProvider() seg = QgsFeature() ...
0
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2answers
981 views

How to Join Attributes by Location in QGIS 1.8.0

I have a points layer with site attributes and a polygon layer with region attributes. I'd like to join the names of the regions to the point site locations using QGIS 1.8.0., on Windows XP. ...
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2answers
85 views

Python to get ids from shp dont return all records

I have some Python code to get the ids and georeference from a shapefile: canvas = qgis.utils.iface.mapCanvas() allLayers = canvas.layers() nos = QgsFeature() for i in allLayers: if ...
8
votes
1answer
292 views

How to automatically reduce polygon size?

I am working with two polygon layers (counties & states) which I will 'intersect' to find which counties are within which states. Due to data inaccuracies I have to change all county polygons and ...
0
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1answer
102 views

How to convert geometry of SHP to decimals

I try to create a line with two points. These points are obtained in a SHP layer. How can i convert that points to decimals? Thank you
2
votes
1answer
184 views

How to clip roads to exclude those within a flood zone?

I have OSM road network data in QGIS along with a shapefile showing the possible extent of a flood. My question is: is it possible to exclude all of the roads that are in the flood zone (so as to ...
5
votes
2answers
708 views

Calculating distance and/or time taken to travel from population centre to nearest hospital in QGIS

I'm trying to find out how long it would take to travel by car from each of the Lower Layer Super Output Areas (LSOA) in Norfolk, England to the nearest Hospital (or just what the distance is and I ...
0
votes
2answers
527 views

How to display data from a feature?

I want to display data based on the feature currently selected/clicked on. I am following a tutorial from http://www.qgisworkshop.org/html/workshop/plugins_tutorial.html. It initially shows you how ...
0
votes
1answer
308 views

How to use expression in QgsVectorlayer label by using python?

how to show the two field values as a label on features. I have done it for a field called "ErrorDescr" with this i need to show another field values. Other field is "MarkerId" ...
0
votes
1answer
89 views

trace a transmission line for a certain distance

I’m looking for a way to easily trace a transmission line for a certain distance. Here is the scenario that I am working with. We have an issue with our transmission line; our OMS tells us that there ...
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votes
1answer
132 views

How to change windows can't find D:\Program [closed]

Today, I setup QGIS. When I run msys, it appear 'windows can't find D:\Program'. Why? Thank you!
1
vote
1answer
71 views

looking for datum to georeference maps of 19th century Maine

I am trying to georeference 3 (1840, 1844, and 1877) northern Maine maps. I really am not able to find which datum to use. Can anyone point me to a list of historic and regional datums? thanks
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2answers
295 views

Easy Custom Labeling plugin does allow to save?

I use the Easy Custom Labeling plugin chose positions of the labels and safe the layer and project for continuing later. When opening again the project, the layer opens but without any objects inside. ...
4
votes
1answer
115 views

How to select behind feature which is overlapped with the same layer on QGIS 1.8.0

My issue: I received data which was created without "Avoid intersection of new polygon". There a few overlapped feature with the same layer. I could fine overlapped feature by the spatial query. But ...
2
votes
1answer
1k views

How to find the watershed area for each point in the river network using DEM?

Update#1: Thanks, Micha, I have followed your instruction and successfully use the modules in GRASS. I use r.watershed to get the basin raster and the drainage line: and I use r.water.outlet to get ...
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1answer
1k views

How to get correct format of coordinates for export to geojson from QGIS?

I've created a custom map in QGIS with a few shapefiles. I'm using leaflet.js to render the map and the shapefile points and everything lines up correctly. The CRS is set to 4326. When I export the ...
4
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0answers
1k views

Loading raster from PostGIS DB into QGIS: succeeded yesterday, fails now [closed]

I have a PostgreSQL(v.9.2)/Postgis(v.2.0.3) database which includes raster layers (added through raster2pgsql). To open them in QGIS (v.1.8.0-Lisboa), the "Add Postgis layer" menu will not work; ...
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2answers
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 ...