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

learn more… | top users | synonyms (1)

1
vote
1answer
269 views

Polygonize function doesn't overlay the shape file over the raster file

To convert the raster into a shapefile I use raster->conversion->polygonize but QGIS doesn't open the new layer overlayed the first (the raster) but reflected above it. I read this question ...
3
votes
1answer
339 views

color gradient (or color ramp) in Arcgis and Qgis

I am currently working on my thesis and I would like to ask you: does anybody know the mathematical formula that calculates the color gradient in Arcgis and Qgis? In other words, which mathematical ...
1
vote
1answer
242 views

Displaying only points within a polygon I created in QGIS?

Thank you in advance for any advice you might give me. I am new to qgis and believe what I'm asking is probably fairly basic. I am trying to map policing activity in NYC for two areas: one area in the ...
0
votes
1answer
91 views

Should a GDAL Plugin be the same version as GDAL aready built into QGIS

Should a GDAL Plugin be the same version as the GDAL that's aready built into the QGIS version installed? Or,can another different version of GDAL be built and it installed as a Plugin for QGIS, ...
3
votes
0answers
162 views

How to achieve better Dissolve results?

I applied the Vector>Geoverarbeitungswerkzeuge>Auflösen (Dissolve) on a zoning plan (see picture zoning plan). I used the attribute village name as the dissolving criteria. The resulting geometry for ...
3
votes
1answer
214 views

Can I color different layers with the same pseudocolor color map?

I have multiple DEM layers in my map (downloaded from atlas.louisiana.gov/lidar), but I cannot seem to get the colors to line up. You can see in the attached image that the colors are not continuous ...
2
votes
2answers
119 views

What specifically is an 'attribute' and how does it work with the related chart?

I'm a new QGIS user (and GIS technology in general) and I'm trying to learn its fundamental features. I have a big dilemma about vector shapefiles, and points in particular: basically, I don't ...
4
votes
1answer
674 views

How to break (both) lines at their point(s) of intersection in QGIS?

I'm working with a road network where some of the road segments cross each other but no point is inserted at their intersection. Is there a way to break these line to shorter lines at their points of ...
3
votes
5answers
1k views

Batch processing DEM rasters in QGIS/GDAL

I am attempting to add relief shading to map using .asc raster files, following this tutorial. It works well, but I have only tried it on single tile of raster data which is 20x20km. I want to ...
0
votes
0answers
105 views

How to access the rules of QgsRuleBasedRendererV2 using python?

I can't get access to the rules of rule-based renderer, python says there's no attribute "rootRule", though documentation says it should be (http://www.qgis.org/api/classQgsRuleBasedRendererV2.html) ...
3
votes
0answers
59 views

Programatically reorder layers in qgis? [duplicate]

Possible Duplicate: Sort layers in QGIS table of contents? I write a qgis python plugin ,and i try to connect keybord keys to reoder layers in qgis . Are there a method in qgis allows me to ...
9
votes
1answer
190 views

Advanced labeling formatting (centered and different sizes)

I would like to place the elevation-number of a point in a different front size and centred under its name: Is that possible? (That is my actual labeling: label || '\n' || elevation) Thanks!
4
votes
1answer
79 views

Reduce number of vector field arrows in qgis

OK, now that I have figured out how to get my vector fields in qgis, I can't figure out how to reduce the number of vector arrows on the map. Is there a setting for how many vectors are sampled? ...
2
votes
2answers
628 views

Couldn't load plugin fTools due an error when calling its classFactory() method

When I start qgis I get a python exception: Couldn't load plugin fTools due an error when calling its classFactory() method ... 309, in _import mod = _builtin_import(name, globals, locals, ...
1
vote
1answer
213 views

How do I create rendered vector field in qgis

Perhaps I am misunderstanding the "vector field renderer" and "VectFieldCalc" plugins, but I have no idea how to make a vector field of arrows, with directions and magnitude. I have the data loaded ...
4
votes
2answers
589 views

Can I download the current version of QGIS if I am running Mac 10.8.2?

I am taking an introductory course in GIS at my university and my teacher recommended QGIS for Mac users. Unfortunately, I haven't been able to download the software. I just upgraded to Mac OS 10.8.2 ...
1
vote
2answers
595 views

Import Civil 3D DEM to ArcMap or QGIS

I have some survey data exported from Civil 3D in both dtm and dem formats. I thought the I would be able to use the dem more easily, but I think the format is different from a USGS DEM. Is it ...
2
votes
0answers
149 views

QGIS 1.8.0 suddenly sluggish/unusable on Gentoo

QGIS 1.8.0 has been working fine for a number of months. Then I upgraded my system generally, which possibly included upgrades to xorg-server and QT, and now QGIS is sluggish/unresponsive to the point ...
4
votes
2answers
121 views

Creating space at intersection of two links

I have a shapefile consisting of two links which are crossing over each other. I want to create an empty space at the point of intersection of the two links. As of now, I have been manually doing ...
4
votes
1answer
61 views

How to deliver an additional Python Library with own Plugin?

For my own plugin I need a special library (pyexiv2) to write a comment into a jpg file (PIL does not do that). When I want to share my plugin in one of the repositories in the future, what would be a ...
2
votes
1answer
581 views

How to save WMS getFeatureInfo points to a layer?

This may be a poorly worded question, because I am not sure of the exact terminology, but I'll give it a shot. I have imported a vector layer from a WMS server into QGIS. I am able to query the ...
2
votes
1answer
1k views

How do I get and install the latest version of QGIS in Ubuntu?

I'd like to get the latest 64-bit dev build of QGIS on my Ubuntu setup. How exactly do I go about it? I assume it's some kind of arcane terminal command...
1
vote
3answers
204 views

Is it possible to create a PostGIS sequence to populate Area column of a polygon

I've created Postgres/PostGIS sequences before to assign unique gid values when a feature is created in QGIS but is it possible to create a sequence that will automatically populate an area column? ...
6
votes
4answers
1k views

How to find dead-ends in a road network

I'm trying to remove all the dead-end roads in a road dataset (lines) that are less than 100m long. How do I identify roads that are dead-ends (no exit)? The 100m part is easy. I know how to use Arc ...
0
votes
1answer
131 views

There is no menu bar on Mac OS 10.7.3

I installed the latest version of QGIS on Mac OS 10.7.3 with 2 additional frameworks (GDAL Complete and GSL) but there is no main menu bar (not at the top of screen, not at the window of QGIS). Where ...
6
votes
5answers
834 views

What is the Typical Workflow from QGIS to Publishing Programs?

I have been playing with using Inkscape to combine my CAD title block and the map project created in QGIS. I was curious to understand what a typical workflow might be to Inkscape or another post ...
5
votes
3answers
360 views

Polygonize vegetation area from Landsat7 RGB using QGis / Bilko?

I'm trying to extract the areas with vegetation as a polygon-shape from a landsat7-image, 30m resolution, RGB, using QGis 1.8 or Bilko or (hopefully in the near future) ArcGIS. The area is in Northern ...
4
votes
1answer
173 views

How to install QGIS on a 2006 iMac?

I would like to know if there is QGIS version for a 32bit Mac (Intel Duo core processor). The newer versions require a 64bit processor.
1
vote
1answer
184 views

QGis compile with Qt Creator error

I followed the steps in this article http://linfiniti.com/2011/06/using-qtcreator-with-qgis/ to compile QGis on Ubuntu 12.04 64bit with Qt Creator. I got the latest source for master with git. I get ...
7
votes
2answers
168 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 ...
1
vote
1answer
109 views

QGIS CSV file sorts low numbers as high

So I have numbers that range from 5 to above 50, and when I sort these from least to greatest, the numbers less than 10 are treated as higher than anything else. It also does the same when I try to ...
0
votes
0answers
100 views

trying to make a point to polygon attribute join with a many to many match

I am trying to match US charter schools to noncharter schools in QGIS. I have constructed a buffer of 10 miles around each charter schools and then tried a join attributes by location match with non ...
1
vote
1answer
485 views

How to fix the “Snap tolerance” error message in QGis?

I am trying to use the "Delete part" tool on a shapefile. While I am starting to use it, an error message shows up : "Could not snap segment. Have you set the tolerance in Settings > Project ...
1
vote
1answer
146 views

How to Add New Freehand Shapes and Data in QGIS?

I'm new to QGIS. Can anyone either direct me to a good tutorial or explain? I want to draw freehand new shape layers on to Google Earth to map vegetation types and embedded data for each feature. I am ...
3
votes
1answer
709 views

Hydrologic analysis with sextante-saga in qgis

(rough translation): Hi, I want to do hydrologic analysis of a DEM with sextante-saga in qgis. I found the plugin and the needed algorithms in SAGA, enabled them in the sextante toolbox, but when I ...
4
votes
3answers
280 views

How to subset X number of features from Shape file in QGIS

I'm looking for a means to take a rather large Shape file and split it out into separate, smaller shapefiles based on number of features. So for example, if I have a file with 1 million features, ...
4
votes
2answers
1k views

Spatial distance analysis in QGIS

I'm quite new to QGIS and trying to figure out how to analyze the following problem. I have three layers: settlements point layer with 253 entries waste treatment facilities point layer with 24 ...
1
vote
1answer
148 views

Why won't QGIS let me write to a file?

I am writing a QGIS Python Plugin. I am trying to write data to a file using with open("filename.txt", "w") as f: f.write("file text.") QMessageBox.information(None, "Test", "Written to file.") ...
1
vote
0answers
272 views

DLL problem with PyQGIS

I am having problems with Python Shell importing the module "qgis.core". When I type "import qgis.core" the Shell ("idle.pyw") gives me this error: Traceback (most recent call last): File ...
2
votes
0answers
174 views

How to Create a Vector Field from Separate u and v Data Files?

I am using Quantum GIS and trying to create a vector field using data from two separate netcdfs. One contains the u data, one contains the v data. Can this be done, and if so, how? Thanks. Jason
2
votes
3answers
1k views

Spatial join including attributes - kind of like right join

I've run in to a little problem. I have two sets of polygons with important attributes. I need to join over the attributes from the first set to the other, but I can't seem to figure out how. ...
2
votes
2answers
126 views

Are you able to buffer labels to prevent other labels within the buffer area?

I saw a post that talks about label offsets, but that was in 1.7. I did some internet research with no success. Is there a way to apply a buffer area so that labels from another layer are not placed ...
4
votes
3answers
2k views

How to install QGIS 1.8 plugin Georeferencer?

My question is about qgis 1.8 georeferencer plugin. I installed the new version qgis 1.8 but I don't have the georeferencer plugins, how do I install it? I used the georeferencing plugin with QGIS 1.6 ...
3
votes
1answer
140 views

Help with intersections in QGIS

I have a shapefile which defines for me the area of each oil field in the North Sea (~300 fields). I also have a shapefile which defines the location of every well that has been drilled (~13000) ...
0
votes
1answer
65 views

QSpatiaLite query syntax

Using the QSpatiaLite plugin in QGIS I composed the following query SELECT 'AddressPoint_2'.'buildingNu', 'AddressPoint_2'.'postCode' WHERE 'AddressPoint_2'.'postCode' = 'NR13 3AA' FROM ...
3
votes
2answers
88 views

How can I fix incorrect links in my QGIS install?

Today I installed QGIS 1.8.0 and I have the same error as this one: How can I fix QGIS 1.8 startup issues due to missing qwt5.dll library?. The sollutions how ever don't seem to work. What I have ...
1
vote
1answer
131 views

Error after installing QGIS 1.8

I have a problem with the installation of QGIS 1.8.0. After finishing the installation two icons show on the desktop: Qgis desktop and Qgis browser. When I click on these, it shows the same ...
4
votes
2answers
2k views

How to change length to 2 decimal places?

I'm trying to work out how to calculate the length of a line to only 2 decimal places in QGIS. When I use the field calculator to create a new field, it doesn't matter what changes I make to the field ...
7
votes
1answer
455 views

How to make working with Postgis vector layers in QGIS faster?

I have just imported a Spatialite database into Postgresql/Postgis. The problem is: using QGIS to work with them is much slower in Postgis (spatial indexes created) than doing the same in Spatialite. ...
7
votes
3answers
483 views

How to use ZonalStats plugin?

I am using QGIS 1.8.0 on a Windows Home Premium 7 machine. I have a single band TIFF that is 187 MB in size. My vector polygon shapefile represents a regular grid of a 147x112 36kmx36km grid cells. ...