QGIS 1.7 has landed. After some delays due to a major infrastructure overhaul, a new version of QGIS is available for download. For a list of what’s new in 1.7 check the release announcement.
QGIS 1.7 Released!
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Yearly Archives: 2011
Browsing Spatial Data with QGIS Browser
QGIS trunk now comes with a separate tool called “QGIS Browser”. It enables the user to browse through all spatial data files on the system as well as all WMS configured in QGIS. Both files and WMS layers are listed in a tree widget on the left side while metadata, attributes and a preview can be seen on the right.
WMS preview in QGIS Browser
This is a great way for example to check through all layers of a WMS fast and without having to go through the “Add WMS Layer” dialog in QGIS all the time.
Multi-line Labels in QGIS
Ever wondered how to create multi-line labels in QGIS? The new labeling engine has a “Multiline labels” option but it’s not so obvious how to create a usable labeling attribute. Here is how it works (credits to @nhopton on QGIS forum):
- Create a big enough text field (if the data doesn’t contain any yet).
- In Layer Properties – Fields, chose a “Text edit” edit widget for the label field.
- Enter the multi-line text into the label field. You can do this using Attribute Table or Feature Form.
A feature form with "Text edit" widget
- Activate labeling. You’ll have to tick “Multiline labels” option in Layer Labeling Settings – Advanced – Options. That’s it:
Simple multi-line label example
A common use case is the wish to show multiple attribute values in a feature’s label. Using Field Calculator, you can combine them into multi-line labels. All you need is to combine the fields with the || operator and add ‘\n’ (newline) wherever there should be a line break:
Field1 || '\n' || Field2
Populating a multi-line label field using Field Calculator
And finally, the result:
Multi-line labels displaying city name and population
WMS-T Support in Geoserver and Mapserver
“-T”, this small appendix can be found after many popular GIS-related acronym. But of course, it always means something different. Take for example GIS-T (GIS for Transportation), WFS-T (Transactional WFS) and WMS-T (WMS with time support). The world of acronyms is a fun place!
Let’s see what a WMS-T can do for us. From the WMS standard:
Some geographic information may be available at multiple times (for example, an hourly weather map). A WMS
may announce available times in its service metadata, and the GetMap operation includes a parameter for
requesting a particular time. […] Depending on the context, time
values may appear as a single value, a list of values, or an interval, …
Currently, only Mapserver supports WMS-T but the Geoserver team is working on it.
Mapserver
MapServer 4.4 and above provides support to interpret the TIME parameter and transform the resulting values into appropriate requests.
Time attributes are specified within the metadata section:
METADATA
"wms_title" "Earthquakes"
"wms_timeextent" "2011-06-01/2011-07-01"
"wms_timeitem" "TIME"
"wms_timedefault" "2011-06-10 12:10:00"
END
Mapserver supports temporal queries for single values, multiple values, single range values or even multiple range values:
...&TIME=2011-06-10&...
...&TIME=2011-06-10, 2004-10-13, 2011-06-19&...
...&TIME=2011-06-10/2011-06-13&...
...&TIME=2011-06-10/2011-06-15, 2011-06-20/2011-06-25&...
Geoserver
GeoSolutions has developed support for TIME and ELEVATION dimensions in WMS.
There are plans to backport this feature to the stable 2.1.x series after the 2.1.1 release.
Configuration of time-enabled layers can be done via the normal user interface:
The following video by GeoSolutions demonstrates the use of Geoserver’s WMS-T:
Both server solutions seem to support only one time attribute per layer. An optional second time attribute would be nice to support datasets with start and end time like Time Manager for QGIS does.
Free and Open Source GIS on gis.stackexchange.com
The gis.stackexchange community keeps on growing and it’s questions and answers span a wide spectrum of GIS-related topics. As of today, the page lists 2,700 questions and 6,400 answers.
As was to be expected, ‘arcgis’ (549 times) is the most used tag followed by ‘arcgis-10.0’ ;)
From an open source perspective, PostGIS gets most attention (rank 8), followed closely by OpenLayers (rank 9) and Geoserver (rank 10). QGIS is the highest-ranked desktop GIS (rank 13). Users of other open source desktop GIS like uDig or gvSIG don’t seem to be using this platform yet.
Here’s the full list of open source GIS tags with a count of more than 10:
postgis × 149
openlayers × 137
geoserver × 121
qgis × 97
open-source × 94
grass × 85
gdal × 68
postgresql × 32
pgrouting × 20
geodjango × 14
mapnik × 13
Custom styles for Google Maps in OpenLayers
Recently, @simo has posted an elegant solution for defining custom styles for Google Maps layers in OpenLayers on gis.stackexchange. An example with source can be found at http://www.empreinte-urbaine.eu/mapping/styled_gmap.html. The idea seems to be to use a StyledMapType:
The StyledMapType allows you to customize the presentation of the standard Google base maps, changing the visual display of such elements as roads, parks, and built-up areas to reflect a different style than that used in the default map type.
How great would it be if it was possible to define such styles in QGIS OpenLayers plugin too!
A First Glimpse at the QGIS Processing Framework
The aim of QGIS Processing Framework developed by Polymeris is to provide a generic framework for accessing existing geo-processing functionality of e.g. SAGA, GRASS, Orfeo Toolbox, etc. This should enable users to script their geo-processing work in python console and allow development of a tool to graphically build workflows using VisTrails an “open-source scientific workflow and provenance management system”.
For a first impression, Polymeris has published some screenshots of QGIS with SAGA modules loaded: [1],[2]
This project is big and if it turns out well, QGIS will profit enormously from it. Both scriptable geoprocessing functionality and a graphic workflow builder can improve user experience a lot if they are implemented well. You can follow further development on the project homepage on GitHub.
Converting MXD to QGIS Project File
On Wednesday, Allan Maungu announced MXD2QGS, a converter that exports layers from an Arcmap 10 document into a Quantum GIS project file. The tool is built as an ArcToolbox and can be downloaded from the blog.
I’d be very interested to hear whether this tool works for you.
Fast SQL Layer for QGIS
For everyone working with spatial databases in QGIS there comes a time when “Add PostGIS/SpatiaLite Layer” and “RT Sql Layer” start to be annoying. You always have to retype or copy-paste your SQL queries into the user interface if you need to change the tiniest thing in the layer’s definition.
This is where “Fast SQL Layer” can be a real time saver. Fast SQL Layer is a new plugin for QGIS by Pablo T. Carreira. It basically adds an SQL console for loading layers from PostGIS/SpatiaLite into QGIS. And it even comes with syntax highlighting!
Installation
Fast SQL Layer comes with one dependency: Pygments, which is used for syntax highlighting.
On Ubuntu, all you have to do is install it with apt-get:
sudo apt-get install python-pygments
For Windows with OSGeo4W, @Mike_Toews posted this on gis.stackexchange:
I downloaded and extracted Pygments-1.4.tar.gz, then in an OSGeo4W shell within the Pygments-1.4 directory, type python setup.py build then python setup.py install
Usage
When you activate the plugin in plugin manager, a dock widget will appear which contains the console and some fields for specifying the database connection that should be used. Then, you can simply write your SQL query and load the results with one click.
Fast SQL plugin
In this example, I renamed “gid” to “id”, but you can actually edit the values in the drop down boxes to adjust the column names for id and geometry:
A second layer loaded using Fast SQL plugin
It certainly needs some polishing on the user interface side but I really like it.
WMS & WFS for Vienna Open Data
Please note that this post was written in 2011 and the server addresses have changed. Please refer to data.wien.gv.at for the latest links.
The city of Vienna has started their open data initiative. They’re offering data on a variety of topics, including: infrastructure, population, education, environment and traffic.
For use in GIS, they serve the data through WMS and WFS:
- WMS: http://data.wien.gv.at/daten/wms?service=WMS&request=GetCapabilities&version=1.1.1
- WFS 1.0: http://data.wien.gv.at/daten/wfs?service=WFS&request=GetCapabilities&version=1.0.0
- WFS 1.1: http://data.wien.gv.at/daten/wfs?service=WFS&request=GetCapabilities&version=1.1.0
Both WMS and WFS work well with the developer version of QGIS.
Looking forward to new datasets. Announcements should be published via RSS feed.
Free and Open Source GIS Ramblings 
![[1]](https://github.com/polymeris/qgis/wiki/Panel-Screenshot.png){kind=link}
![[2]](http://www2.udec.cl/~cpolymeris/QGIS_Screenshot_04032011.png){kind=link}