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

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2
votes
0answers
202 views

OziExplorer maps not rendered correctly in QGIS

When I open up some OziExplorer (.ozf2) maps in QGIS they are not rendered correctly in that they appear reversed or in-versed. Text on the map is not legible and looks to be in-versed but this is not ...
4
votes
2answers
2k views

QGIS import polygons in CSV

QGIS 1.8 on Mac: I'm hoping to migrate several dozen local maps from my 30 year old Win3.1 plotting system to QGIS. Polygons are in X,Y (CSV), first point repeated at the end to close it, with ...
3
votes
1answer
257 views

How to upgrade QGIS Capiapo to Lisboa?

I want to upgrade my QGIS version to the newest one, Lisboa, but I'm not sure if I should uninstall Capiapo first. Is there a way to upgrade without uninstalling? Thank you.
0
votes
1answer
51 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 ...
0
votes
1answer
88 views

Reuse same style settings for chloropleth maps based on different datasets

I am new to QGIS. I have been using MapInfo for a couple of years, but I am considering to switch to QGIS. So far I like it, but there are some things that I haven't found out yet. I want to make ...
1
vote
0answers
77 views

What is the main benefit and drawback of: GeoServer, MapServer, Mapnik? [duplicate]

For the purpose of creating a comparison table, please recommend a couple of feature fields that would apply to each FOSS GIS server. And, perhaps answer the question of which desktop GIS System, ...
1
vote
1answer
127 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 ...
4
votes
2answers
792 views

How to automatically reloaded raster layer if source is changed in QGIS?

How to automatically reloaded raster layer if source is changed? (The path is the same but inside source file are changes) I use: qgis.utils.iface.mapCanvas().refresh() but layer not refresh. # ...
4
votes
2answers
599 views

Official source for QGIS icons or banners?

I am going to use maps and analysis results generated by QGIS in a presentation. Besides citing the official reference i want to show a small QGIS icon or Banner on the first slide. I found some nice ...
0
votes
1answer
428 views

min and max values are not correctly calculated for DEM

I'm working with DEM in QGIS and need to know the min and max values of my data. In the Properties window, under the Metadata tab, the statistics section shows such values. However, I usually find ...
1
vote
0answers
860 views

Google Earth export from QGIS

I'm using Quantum GIS. Is there a way to export a shapefile to Google Earth format (*.kmz) using QGIS? Thanks.
0
votes
0answers
104 views

What are the rules for digitizing roads for creating a road network?

I want to create shortest route tool using pgRouting. But I digitised roads in a random manner. Shall I need to give a separate row for each road segment?
1
vote
2answers
214 views

Multiple labels in QGIS QML

I've a GML file from the Ordinance Survey which includes a Cartographic Text layer which I'd like to load and render in QGIS. The layer has attributes which are intended to be use for the font size, ...
2
votes
0answers
333 views

QGIS SPIT errors loading shapefile into PostGIS

With QGIS 1.8 on Windows 7, I just installed PostgreSQL / PostGIS and tried to load my first data into it, a shapefile using SPIT, but failed: ERROR: Geometry type (Polygon) does not match column ...
1
vote
1answer
693 views

QGIS Plugin Windows

I have written a QGIS plugin (RTools) which acts mostly like a independent plugin (minimal interaction with QGIS core functions). On Linux both QGIS and RTools were build using QT 4.8 on Qt creator. ...
0
votes
1answer
173 views

How can i select many rows from a table?

I want to create an action that select many rows from PostGIS table to show many lines in QGIS. How can i select many rows from table with python to add these rows in a layer? Thank you
9
votes
1answer
690 views

Is it possible to show our custom message in QGIS Status bar using python?

Is there any way to show our custom message in Qgis Status bar using python? Just like in arcgis "IApplication.statusbar.message(0) = "Please wait..." like that is there any option to show ...
2
votes
1answer
232 views

How to use WHERE CLAUSE to filter the features by its attribute in PyQgis?

How to Get features by their attributes (similar to Iqueryfilter in arcobjects) in Qgis using python? Instead of getting all features and filter it manually, is there any option to use whereclause to ...
3
votes
1answer
170 views

How to determine the longest side of a polygon in QGIS?

Is there a possibility to determine the longest side of a polygon with QGIS? As I need to do that for hundreds of polygons I would prefer an automized method (like a plugin). So far my idea was: ...
2
votes
1answer
177 views

How to get a message when the map is moved in QGIS?

I want to get a message when every time I move the map. I had: def info(self): QMessageBox.information( self, self.tr( "Info" ), self.tr("info") ) I suppose that used to be something like ...
1
vote
1answer
136 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
2answers
129 views

How to make digitization more detailed afterwards with QGIS?

I digitized already two areas, bordering each other on one side. Than I realized, more detail was needed! What do you suggest as a fast way to do so? Adding each time new dots/verteces takes so ...
0
votes
2answers
507 views

I can't export in QGIS a Shape file to PostGis

When I try export a pipe network shape to postgis i get this error: Problema inserindo feições do arquivo: C:/PP/gvSIG_Projects/Shapes/Abastecimento/QGIS_VATROCOADUTOR.shp Ocorreu um erro no banco ...
3
votes
1answer
1k views

How to import QGIS Raster into PostGIS

I have created a IDW heatmap using QGIS 1.8.0 and need to import the raster into PostGIS 2.0.1. QGIS saves the raster layer as a .asc file. How do you import the raster into PostGIS as a Raster? What ...
7
votes
4answers
2k views

How to get features based on their attributes using Python?

How to Get features by their attributes (similar to Iqueryfilter in arcobjects) in Qgis using python? Instead of getting all features and filter it manually, is there any option to use whereclause to ...
2
votes
0answers
143 views

qgis missing menu bar ver 1.8.0-lisboa on ubuntu linux

QGIS emits the following warnings when starting, and fails to display the main menu bar. $ qgis --nocustomization Warning: loading of qgis translation failed [/usr/share/qgis/i18n//qgis_en_US] ...
2
votes
0answers
133 views

Why do most Area Calculation result in 0?

I would like to autocalculate area (acres) for a shape file that is in UTM zone 16 CRS. I have tried the "Vector|Geometry Tools|Add/export geometry columns" and also the field calculator. The first ...
2
votes
1answer
634 views

How to fix erros loading result layers from SAGA functions in Sextante?

Using QGIS 1.8.0 and SAGA When trying to use the IDW function from Sextante SAGA 2.1.0 64bit, I get the following error: Could not load layer: C:/test.tif. This error seems mysterious to me, any ...
1
vote
0answers
132 views

Creating polygons for a choropleth map using PostGIS

I have a grid of points, each with a value to it as shown in the image below. The data was retrieved from PostGIS and rendered in Quantum GIS. The final result should be a polygons of a choropleth map ...
1
vote
0answers
132 views

How to programmatically change an SVG symbol in the Vector Layer?

I'm trying to change the symbol used in a layer via Python. I've been able to tunnel through a vector layer to the symbol layer, but I don't know how to change the symbol it's using. I'd like to ...
2
votes
2answers
640 views

How to create a printable map of labelled markers with OSM background?

I want to create an image of an OpenStreetMap map suitable for printing on A4 at 300dpi. The map needs to have half a dozen markers/points, and each should be labeled with the name of the point. I ...
2
votes
1answer
108 views

How to permanently rearrange the order of features in a Shapfile with QGIS?

I have created a trimmed/clipped map of Europe, the Middle East and North Africa in QGIS 1.7.3 by deleting all the other countries from a world map shapefile. I would like to permanently rearrange the ...
5
votes
3answers
244 views

What is the easiest one click install method for PostGIS and it's entire dependencies?

For someone new to database servers and their dependencies, what is the easiest assured way of installing PostGIS on a machine with no other software beyond what comes with its operating system? I'd ...
2
votes
3answers
1k views

Connnect to PostGIS db using QGIS - when not on localhost

I"m just getting started with PostgreSQL/PostGIS db (v9.2) and I'm wanting to connect to db while not on the localhost using QGIS. I've been able to connect successfully on localhost, however I'm not ...
3
votes
1answer
501 views

Watershed extraction using different DEM tiles

I would like to extract the watersheds for a particular area using QGIS. However, I only have Aster 30m DEMs to work with, each tile covering one degree square. The problem is that I need to use ...
2
votes
1answer
208 views

Writing python plugin: How terminate plugin from script without closing QGIS?

I'm writing a QGIS conversion plugin in python to be able to create Obstacle-files for a model from shapefiles. What I want to do now is just to close the plugin cleanly. This means, to close the ...
3
votes
0answers
300 views

Problems printing OpenLayers Pluggin Maps To Scale

It the print composer I can print all maps to scale and satisfactory. However, when I add the OpenLayer, usually Bing Aerial, to the project I cannot print it out to scale. I click the scale box, ...
1
vote
1answer
73 views

Problem with labels on export/print a map (qgis master) [closed]

As you can see on the images below, the labels on the exported map (right) are much bigger then in the original map (left). Same by pdf, image, and vector - export. Whats the problem? Can I fall ...
3
votes
1answer
624 views

Joining table to shapefile with pyQGIS

Joining shapefiles is a relatively straightforward proess in QGIS using 'add vector join' in the layer properties menu. I can add a csv file as a vector layer, as well as a shapefile, and join the two ...
3
votes
1answer
172 views

How to see print commands through Python Script while programming plugin for QGIS?

This might sound like a silly question. Is there a way that from running a custom plugin made for QGIS that a Python Shell can appear along when the plugin is run, like a debug screen. I'm asking ...
0
votes
1answer
727 views

How to calculate polygon areas in acres or square miles instead of feet?

I have a layer in State Plane NAD83. When I use "Vector|Geometry Tools|Add/export geometry columns" or Field Calculator they both create the area in feet. What if I want acres or square miles? Thanks ...
2
votes
1answer
84 views

Adding a delimited text layer in QGIS 1.8 only imports a fraction of the total rows

I am trying to add a delimited text layer, and I think I've formatted it correctly as a CSV file. There are no errors when I import the data. But even though there are 1300 rows total, only 189 appear ...
0
votes
1answer
71 views

pgRouting:routing problems using reverse_cost

I saw this post:Routing issues with pgrouting, and try the ability of reverse_cost. As the result of this post, if there is only one way to go from one node to another, even though the reverse_cost ...
5
votes
1answer
230 views

Can I edit shapefile while using a definition query in QGIS? [duplicate]

Is it possible to edit shapes while using a "definition query" or "query builder" in QGIS? I'm trying to do this in the same way I used to in ArcGIS. Thanks!
0
votes
1answer
107 views

Can pgRouting work more efficiently?

I use a river network on which has a lot of nodes to test pgRouting, and I run the SQL, searching for the shortest path between nodes. SELECT * FROM shortest_path(' SELECT gid as id, ...
0
votes
1answer
171 views

Is it possible to update layer source in qgis

I've loaded a few shape files as layers in qgis, and I'd like to make a duplicate of the project and all associated shape files into a single directory. However, all of the layer sources are still ...
1
vote
3answers
758 views

QGIS 1.8 startup crash - looking for a log file

I have a problem with QGIS 1.8 with OSGEO4W installer (windows 7 - 64 bit). QGIS crash on startup, it shows the splash screen and then nothing. I have updated from an old 1.7.4 QGIS version. I have ...
5
votes
1answer
882 views

Speed of editing attributes in QGIS from a Python plugin

I'm trying to edit the value of an attribute for each feature in a layer using a QGIS Python plugin. I've found that doing this outside of editing mode is much slower than while editing (even ...
1
vote
1answer
196 views

How can I map data points to OpenStreetMap (OSM) line data?

my goal is to filter measuring points of vehicles by mapping them to streets. So I could filter out all the false data located in fields and rivers and so on. I imported my data into a PostGIS ...
1
vote
1answer
164 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 ...