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

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3
votes
2answers
209 views

Layer not aligning after georeferencing using BC Albers

I'm currently having trouble with the georeferencer... after what appears to be successful georeferencing, the map image layer does not align to the vector data. I'm trying to use BC Albers ...
3
votes
1answer
898 views

How to convert jpg file to shapefile? [duplicate]

I am developing a GIS application like this: By now my steps are: I have got a jpg file, 5040 x 8179 dimension. In this map, the roads, rivers, towns etc. are marked. I am using .Net to develop ...
3
votes
4answers
925 views

What are the advantages either way between GML and ShapeFiles?

After a good start many months ago of getting into GIS through QGIS, I had to drop what I was doing and did not touch it for quite some time. I am now able to get back into it and have a need to load ...
3
votes
1answer
269 views

How can i merge lines with same name and intersect each other?

I have shp file with 50k lines (roads). Many roads have same name like 'high road' . some of them are the same road (they intersect each other) and some are located in different places of the city. I ...
3
votes
1answer
145 views

Why can't I edit polygons once they have been saved to MySQL?

I have a simple table with an id field and a polygon field in mySql. Using QGIS I can add new polygons and give them an id. Before saving them I can also edit them. But once a polygon has been saved ...
3
votes
2answers
461 views

Why do I get “Failed to transform” when reprojecting from WGS84 to Google Mercator?

I am attempting to re-project a vector shapefile from Natural Earth, following a qgis tutorial. Another user reported this error, but a solution has not yet been reported. Given this post, and the ...
3
votes
0answers
111 views

Why doesn't Polygonizer copy the line ids to my polygonized shapefile?

I am trying to convert a line shapefile into a polygon shapefile using Polygonizer plugin, and when my new polygons are created all the cells in my id field are "Null", although I have clicked "copy ...
3
votes
1answer
2k views

Import GPX file to QGIS and correct apparent CRS problems

I am using Easy Trails software on an iPhone to output a gpx file of a walk. When I import the file (import vector layer) to QGIS, into a project with OSGB information and the correct CRS for OSGB ...
3
votes
1answer
123 views

Points warped when exporting to shape

I have recently purchased a Trimble GeoXH (used) and have done a few surveys. I have done differential correction in Trimble Pathfinder Office and all points seem fine. When exporting to shape and ...
3
votes
1answer
341 views

How to use scale -rule based renderer in QGIS?

I wish to render a shapefile of builindings such that at scales below 1:5000, they have a border, and above 1:5000, they do not have a border. For this, I went into layer properties, selected ...
3
votes
3answers
914 views

Summing attributes intersected by under a radius

Apologies - new user. I am working with QGIS on Mac OS X and with shapefiles downloaded from the US Census Bureau that show population data by state and by county. How do I: select certain points ...
3
votes
1answer
351 views

Why are the features in my memory layer not displayed?

I am trying to create a memory layer, I followed the directions from the page below but no points appeared on my map. First I tried typing each line into the python console and I also create a plugin ...
3
votes
0answers
95 views

How to digitize 90 degree angles? [duplicate]

Possible Duplicate: How to create polygons with straight lines and right angles in QGIS? In QGIS 1.8 is there a way to digitize buildings etc. with perfect 90-degree angles, Or, edit a ...
3
votes
1answer
407 views

Why are the polygons in my GML not rendered?

I tried to view GML files from download services ( http://services.cuzk.cz/gml/inspire/cp/epsg-5514/ ) and I have a problem with viewing of polygons from layer "CP:CadastralParcel". This Layer ...
3
votes
0answers
167 views

How to debug Quantum GIS PlugIn Visual Studio DLL?

I develop a Quantum GIS plugin layer using Microsoft Visual studio and placed it in my plugins folder of my customized quantum gis application. I now intend to debug the DLL using Microsoft Studio. ...
3
votes
3answers
6k views

Editing a KML file or converting KML to Editable format with attributes

I'm using QGIS. I'm trying to either edit a .kml file someone else created in Google Earth or convert it to another editable format (like a .shp file). I've read the following threads without really ...
3
votes
1answer
323 views

Is it possible to programmatically add calculated fields?

In the Memory provider described in PyQGIS Cookbook or in question How to create a new empty vector layer programmatically? I can see how to create a vector layer programmatically using standard ...
3
votes
1answer
1k views

Is it possible to increase/reduce features proportionally?

Is it possible with QGIS to increase or reduce features (polygons or lines already drawn) proportionally? Preventing me to redraw several times new polygons :) See picture above: Making it possible ...
3
votes
1answer
535 views

QGIS custom CRS for map of manufacturing shop floor

I'm working on a web app that shows a map of a manufacturing plant's shop floor. I've built it in Inkscape and QGIS, but when I try to load it into Tilemill, I get a CRS error. Specifically, it ...
3
votes
2answers
284 views

Looking for qml specification

Where I can find qml specification which is used for store symbology information in QGIS? Try to googe it - no result.
3
votes
1answer
1k views

Qgis - How to change GDAL version

im working on Ubuntu 12.04 server; i noticed this when i installed additional support for ECW format into the GDAL 1.9.1 which worked ok. Then i tried to add ECW files to Qgis but it said they still ...
3
votes
1answer
973 views

Using Qgis server with Ubuntu 12.04

I realise there had been many posts on this subject but unfortunately I need to post again. I've been banging my head against this all day. I'm trying to get qgis server working with Ubuntu 12.04 ...
3
votes
1answer
2k views

How to create a polygon (fixed width buffer) around a polygon in QGIS?

I have created a polygon in QGIS (in this case it describes a country's maritime baseline). I need to create a second polygon whose boundary is a fixed distance from the original polygon. (in this ...
3
votes
2answers
3k views

How to fix “The entry point for the procedure sqlite3_open_v2 cannot be found in the dynamic link library sqlite3.dll”

Translation: Hello, I have a problem installing version 1.0.8. The following error message appears: The entry point for the procedure sqlite3_open_v2 cannot be found in the dynamic link library ...
3
votes
1answer
1k views

Why can't I download the georeferencing plugin for QGIS 1.7.4?

I used the georeferencing plugin with QGIS 1.6 and now that I've upgraded to 1.7.4 I'd like to do it again. But when I search for the georeferencer plugin, it's not available! Am I doing something ...
3
votes
2answers
669 views

Normalize raster values to 0-255

I need to normalize the values attained from a band ratio to 0-255. I'm using QGIS. How do I do this? Any ideas?
3
votes
3answers
262 views

How to visualize the vertices of a graph in QGIS?

I tried to visualize the graph generated by osm2po and rendered that graph in qgis. Now what I am trying to do is plot the vertices in the graph. So that I can visually see where the nodes/vertices ...
3
votes
1answer
201 views

Create new polygon layer based on areas of varying numbers of stacked polygons

I have several species range maps (as polygons) that overlap/stack. From this, I am trying to identify areas of highest biodiversity. Ideally, I'd like to create a new polygon layer, where 1 part is ...
3
votes
1answer
2k views

How do I clip/mask a satellite photo to a polygon?

Given a shapefile composed of contiguous polygons, I'd like to clip (or mask) regions of satellite photo to the polygon outlines, and export each resulting raster in medium resolution for further ...
3
votes
1answer
170 views

Is it possible to change the year range of time manager in QGIS?

I have a shapefile with a start and end time field, properly formatted. However my dates range from 1864-1995. When I try to use the shape file with the QGIS time manager plugin I keep getting this ...
3
votes
0answers
358 views

Map is missing when I “export as image” via print composer [closed]

I have point data on a vector layer that prints accurately via print composer (when I "export as image"), however my map below either does not show up or shows up at an incorrect scale. I used ...
3
votes
1answer
2k views

How to filter features in a layer?

I am trying to display certain features in a shapefile-based layer using QGIS. I have found the subset function in the properties panel, which does exactly what i want, but is too tedious given that I ...
3
votes
0answers
2k views

How to load and view .gri and .grd files in QGIS [closed]

An online GIS Repository called DIVA-GIS (http://www.diva-gis.org/gdata) offers data in three formats - ERSI files, "DIVA gridfiles", and DBF files The DIVA gridfiles have extensions .gri and .grd ...
3
votes
1answer
992 views

How to create a Hillshade model with multicolor “alà IMHOF”?

I would like to make a Hillshade-Model with multicolor "alà IMHOF". That means, I dont want a "usual" gray hillshade, I would like to use grey-blue and grey-violett from different sun directions. ...
3
votes
1answer
839 views

In QGIS map composer, how do I get the Item Properties dialog back?

Yes, well if there is button there, one is bound to click it.... I closed both the Item Properties dialogs in Map Composer. And I can't get them to give me any joy no more... QGIS Trunk
3
votes
1answer
2k views

Why does the QGIS Server WMS layer not load in QGIS Desktop?

I have created a .QGS file with one PostGIS layer which is the alaska.shp file that comes from the samples. It was loaded via the shp2pgsql utility. When looking at my qgs project referencing the ...
3
votes
4answers
3k views

How to redefine the nodata value into zero in QGIS?

I have an image which i cliped with an AOI polygon. The contour area was set to pixel value = 0 and I have a nodata value of -32768. I want to redefine the nodata value into zero. I used to do this ...
3
votes
0answers
824 views

How to create point labels from midpoints of road polylines in QGIS?

Heres what i want to achieve: i have a roading polyline layer (singlepart ie has several features per road, grouped by an id field), and i want to (after merging the parts) find the mid point of the ...
2
votes
1answer
59 views

Low quality legend symbols in QGIS

The legend symbols in my QGIS map composition render very pixelated, like this: However, they render fine for actual point data. They appear this way within map composer, when printing, and when ...
2
votes
1answer
45 views

Is it possible to create Rule-Based Styling with $geometry intersecting a second layer?

I am trying to create a rule-based style based on geometries from another layer. I have found an example that does exactly what I want, except that it uses a geometry from WKT: intersects( ...
2
votes
1answer
49 views

Method for automatic aggregation of polys with sparse data

I am part of a project on presenting health related data on maps. In order to maximize the analytical usefulness of the data, we wish to divide them into as small areas as possible. However, to ...
2
votes
1answer
58 views

Referencing Qt UIs external to plugin with python

I'm developing a plugin that sets up a working environment for a user: loading layers (from db), applying styles and several custom designed (Qt) UI files etc. Primary user interaction is in the ...
2
votes
1answer
34 views

Valid values of mollweide projection in QGis

i just imported a vectorlayer (without any reference points) to qgis as mollweide projection to save it to longlat. What i am wondering about is a mathematical problem: Not every x,y coordinate on the ...
2
votes
1answer
119 views

How to merge hundreds of vector layers and sum attributes in QGIS?

I'm still at a fairly beginner level with QGIS and I've been banging my head against the wall trying to figure this out, so I would like to turn here for the internetz help. I am trying to construct ...
2
votes
1answer
138 views

Problem installing QGIS Valmeira on Windows 7 Professional 64-bit

I have been having trouble installing QGIS Valmeira on Windows 7 Professional with SP1. When I installed to the default directory C:\Program Files\QGIS Valmiera\, many of the predefined coordinate ...
2
votes
2answers
224 views

Is it possible to export cross sections from QGIS to HEC-RAS

Is it possible to create cross sections along a river in QGIS and then export the data to HEC-RAS? Thanks
2
votes
1answer
57 views

Can you create a CRS of superseded NSW Datum

I want to use a superseded projection (NSW integrated survey datum - referred to as ISG) because my main client utilises it. The projection is based on AGD66. We regularly receive survey files in this ...
2
votes
1answer
86 views

QGIS html annotation relative paths

I find the QGIS html annotation tool is very useful for quickly accessing a combination of key data attributes and photos. I am having trouble using relative paths for images. This doesn't work: ...
2
votes
2answers
127 views

How to produce a CSV file from .tif file with elevation data? [duplicate]

just want to ask, I have a .tif file that contains all the elevation of a country. How can I convert that to a CSV file that contains x,y,z values where x and y are the latitude longitude respectively ...
2
votes
1answer
62 views

How to properly establish a PostgreSQL connection using QgsCredentials

I'm trying to establish a Postgres connection using QgsCredentials as described here: How to access user credentials in database connection? The only problem is that I cannot establish a working ...