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

learn more… | top users | synonyms

1
vote
1answer
297 views

Why new feature disappears when editing polygon?

I try to create internal polygon within existing polygon. After I created a ring, I add a new feature inside the ring. Suddenly, this new feature disappears. I confirmed that this feature went to the ...
1
vote
2answers
91 views

Error reported when trying to import prj for data points in New Brunswick Canada into QGIS

I have data points recorded with a Trimble GIS. The projection is New Brunswick Sterographic Double Projection, which as near as I can find via a Google search is EPSG:2953. However, when I try to ...
1
vote
1answer
3k 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
vote
1answer
420 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 ...
1
vote
1answer
855 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 ...
1
vote
1answer
326 views

Problem executing Mean Shift Segmentation: could not open the output layers

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 ...
1
vote
1answer
372 views

Can I open a form in layer action?

I want to open a form (made in QTDesign) in the layer action. It is possible?
1
vote
1answer
3k views

'Couldn't load PyQGIS' after upgrade to Raring Ringtail?

I upgraded my Ubuntu to Raring Ringtail. After that, when starting QGIS I receive a message: Couldn't load PyQGIS. Python support will be disabled. Traceback (most recent call last): File "", ...
1
vote
1answer
112 views

Deleting QGIS CRS

I've created a new CRS on QGIS but I assigned a wrong name mistakenly to CRS's name. Now I have the CRS defined but the name of the CRS is wrong, or not easily identifiable. I was wondering if ...
1
vote
1answer
194 views

Does each road segment need to be digitized into a separate entry for a road network?

I am trying to understand this code in pgRouting for creating topology: CREATE OR REPLACE VIEW road_ext AS SELECT *, startpoint(the_geom), endpoint(the_geom) FROM road; CREATE TABLE node AS ...
1
vote
1answer
173 views

Polygon Nodes do not have separate coordinates [duplicate]

I'm attempting to measure the distance of a series of points from a smaller number of polygons. As a first step, I've changed the polygons into points along their border, via the Vector> Geometry ...
1
vote
1answer
323 views

pgRouting:how to use reverse_cost?

I add a new column, naming it "reverse_cost", and give it the same data in the shape_leng column. But as I run the shortest path algorithm in pgadmin, I got an error message. here's my sql code ...
1
vote
1answer
619 views

Aggregate points with same values to polygons

I have a shapefile with 2M measurement points (each measurement point has a resolution of a 1/10). How can I aggregate points around each other if and create polygons out of it? They do not have to ...
1
vote
2answers
320 views

Qgis 1.8 is not recognizing sdw file

I'm running qgis 1.8, and trying to load a sid file into my map. It imports fine, but seems to ignore the sdw file that comes with it, as the raster shows up without any apparent georeferencing. Is ...
1
vote
1answer
66 views

QGIS - Importing USGS DRGs

I have asked about this before. If I import a USGS DRG raster for Anchorage, Alaska using EPSG:26706 - NAD27 / UTM zone 6N all the UTM coordinates are correct. Now if I want to look at the ...
1
vote
1answer
422 views

How to add MS SQL table using python console?

I have MS SQL Server 2008 R2 database. How to add MS SQL Table using python console in QGIS?
1
vote
1answer
230 views

How to set the path to shapely?

I am using QGIS 1.8.0 on Mac OS 10.8.3 with python 2.7. Thanks to other threads in the forum, I have successfully installed shapely here: ...
1
vote
1answer
77 views

How to identify to which polygon a point belongs to?

I have 3-4 polygons containing lots of lon/lat points. I want to identify to which polygon a specific point belongs. Any help in this matter is appreciated.
1
vote
1answer
323 views

How to fix “Error processing specified tolerance!” in Polygon Centroids tool?

I am using QGIS 1.8.0 to find the centroids of 92 features (i.e. smaller polygons) in a polygon layer. However, while using (Vector -> Geometry Tools -> Polygon centroids), I encountered the ...
1
vote
2answers
370 views

How to handle adding a PostGIS layer in pyQgis without saving password?

I'm writing python plugin and trying to find the right way to add PostGIS layer on the map without storing user password. After adding layer on the map, I strip out the password from uri like this: ...
1
vote
1answer
204 views

plot path of points

I have a sample of the address histories of households. ID ZIP1 ZIP2 ZIP3 01 XXXXX XXXXX XXXXX 02 XXXXX XXXXX XXXXX 03 XXXXX XXXXX XXXXX 04 XXXXX XXXXX XXXXX ... It's easy enough ...
1
vote
1answer
647 views

How to get vector feature by mouse location?

I'm writing a photo grouping plugin. My current problem can be broken up into "end goal" and "baby steps", because I think that's what I want. But if there's a way to get to the end by a different ...
1
vote
2answers
1k views

Problem with WMS layer from SAGIS: Invalid format/can't parse XML

Can you help me the following problem: I try to load WMS layer from SAGIS (Salzburg GIS) into Qgis: http://www.salzburg.gv.at/themen/se/sagis/download.htm for example: Geoland WMS ...
1
vote
1answer
208 views

How to add another layer origin in my installed OpenLayers plugin?

Can I modify my installed Openlayers plugin files to add a new layers origin? If yes, what files?
1
vote
1answer
1k views

QGIS can't find osgeo after GDAL upgrade

Mac OS 10.6.8: I installed QGIS 1.8.0 with GDAL 1.8; then another app requires GDAL 1.9 and installed it; now QGIS can't find osgeo [python-gdal]. (I can't find any trace of GDAL 1.8 left in my ...
1
vote
1answer
951 views

Is it possible to change the Mouse Wheel zoom direction in QGIS?

I'm just starting to learn QGIS. I'm starting with the basic simple things. Coming from an ArcGIS background, I am used to the mouse wheel action zooming in and out the default ArcGIS way. QGIS ...
1
vote
1answer
1k views

How to write a CSV from Python console in QGIS?

I am trying to write out a CSV file from a vector layer made up of points using the python console in QGIS. I've tried the following command: QgsVectorFileWriter.writeAsVectorFormat(layer_Map, Folder ...
1
vote
1answer
90 views

Shapefile CRS damaged. How to bring it back?

I have two shapefiles with same location and extends (EPSG 4326). But one of the shapefiles CRS seems to be damaged after doing a lot wrong with reprojection... its not shown on the same position as ...
1
vote
1answer
476 views

Using Easy Custom Labeling: Where's my missing label?

I’m using the Easy Custom Labeling plugin (with QGIS 1.8). I have one feature label which refused to show itself. It’s just not visible. When I look at the attributes table, the feature name appears ...
1
vote
2answers
2k views

Convert KMZ image to UTM projection jpg file

I have some KMZ files that are basically aerial imagery that has been referenced to Lat/Long. I would like to convert them to a projected UTM coordinates such as NAD 83 in a geo-jpg format. I was ...
1
vote
2answers
464 views

How to create Concentric Circles in QGIS?

I'm trying to build a planning tool for center pivot irrigation system. It involves selecting a field (polygon), a center point, and then an outer circle to set the outer limits of the system. From ...
1
vote
1answer
136 views

Split polygons and extract points

I have a polygon file with 90 adjacent polygons. I also have a lat/long point file that overlaps the entire surface of the polygon file (170,000 points). My problem is that working with all of the ...
1
vote
1answer
168 views

Projection WGS 84 is slightly displaced referring to a hillshade in QGIS

I have a hillshade and a vector layer. The vector layer is slightly displaced referring the hillshade. About lat=100m and long=175m The CRS of the project is EPSG:3397 - PD/83 / Gauss-Kruger zone 4. ...
1
vote
1answer
157 views

segment lines according to point using pgRouting?

I'm working on postgresql and I am trying to create table to generate graphs. I have a table that contains all the objects of a city (points) and another contains the city street. My goal now is to ...
1
vote
2answers
2k views

Can QGIS (1.8.0 Mac) rotate the entire view of a project?

Can QGIS (1.8.0 Mac) rotate the entire view of a project? that is, have north pointing in a direction other than up on the screen and on output? of course, while still allowing adding new layers etc.
1
vote
2answers
1k views

styles for QGIS

Could someone point me to a source of line and point styles for QGIS (*.qml) - railways and transmission lines are the first two I've run up against, but I know there will be more.
1
vote
1answer
190 views

Is the QGIS plugin repository broken?

I'm connected to the QGIS plugins repository, using QGIS 1.8.0 on Windows 8.... and although I can see a total of 119 available plugins, I can't see Sextante anywhere in the browser. I tried ...
1
vote
1answer
41 views

How to report issues with QGIS documentation?

I stumbled across a gotach while installing mod_fastcgi on MacOs 10.8 (mountain Lion) -- there is a bug in 10.8 in the apache build env which breaks the install instructions here: ...
1
vote
1answer
164 views

Get feature while editing

I have created my custom form for features editing, using layer.setEditForm("form.ui") and layer.setEditFormInit("init") properties. init method receives dialog, layerId and featId as arguments. ...
1
vote
1answer
533 views

Merge 2 layers based on an attribute column in QGIS [duplicate]

I have a vector shapefile map that is divided into polygons. I want to add 2 columns to the attribute table with the eastings/northings coordinates of each polygon centroid. So far what I've tried ...
1
vote
1answer
421 views

How to create routable network by pgrouting with assign_vertex_id?

I'm trying to create the routable network as per http://underdark.wordpress.com/2011/02/07/a-beginners-guide-to-pgrouting/and use assign_vertex_id. Do I still need to create the node table? How would ...
1
vote
2answers
235 views

Problems with Combining Layers in QGIS

I am trying to add the political boundaries baselayer from http://www.cec.org/Page.asp?PageID=924&ContentID=2336 and then on top add points where I gathered coordinates from Google Earth (using a ...
1
vote
1answer
263 views

How to use QgsVertexMarker in a python plugin?

I am trying to display a vertex marker for a QGIS python plugin I am writing. I am getting a the following error... 'NameError: global name 'QgsVertexMarker' is not defined' canv = ...
1
vote
1answer
181 views

Scaling location points proportionately

I'm trying to get QGIS (1.8) to scale the point markers for each town in a district proportionately to the size of their population (i.e. bigger population = bigger circle). I can get them to vary by ...
1
vote
2answers
939 views

Error adding a delimited text layer in QGIS [closed]

I'm a GIS beginner here. I'm trying to add a delimited text layer in QGIS. The plug-in is okay. I have created a table in Excel, saved as CSV file, imported the file with QGIS, selected the delimiters ...
1
vote
3answers
1k views

Is there a way to get correctly aligned print export with openlayers plugin? [duplicate]

I am a beginner using QGIS (1.8.0 Lisboa) on a Mac (OS X 10.6.8 Snow Leopard). I work on a file with two layers in the following sequence (top to bottom): a vector polygon layer with a few outlines ...
1
vote
1answer
458 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.
1
vote
3answers
836 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 ...
1
vote
1answer
1k 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 ...
1
vote
3answers
5k views

QGIS Raster Calculater Syntax

I am trying to use the raster calculator in QGIS to combine a number of rasters. I want to calculate a mean, this is easy: (raster_1@1 + raster_2@1 + raster_3@1) / 3 I then want to create a max. ...