I’m very pleased to announce that Packt Publishing is organizing a giveaway contest for Learning QGIS 2.0. All you need to do is comment below the post and win a free copy of Learning QGIS 2.0. Read on for more details.
Amongst other topics, Learning QGIS 2.0 covers:
- Loading and visualizing vector and raster data
- Creating and editing spatial data and performing spatial analysis
- Designing great maps and printing them
How to Enter?
Simply post your expectations for this book in comments section below and you could be one of the lucky participants to win a copy.
DeadLine: The contest will close in 7 days on December, 12th 2013. Winners will be contacted by email, so be sure to use your real email address when you comment!
Please note: Winners residing in the USA and Europe will receive print copies. Others will be provided with eBook copies.
Processing has received a series of updates since the release of QGIS 2.0. (I’m currently running 2.0-20131120) One great addition I want to highlight today is the improved script editor and the help file editor.
The improved script editor features a toolbar with commonly used tools such as undo and redo, cut, copy and paste, save and save as …, as well as very useful run algorithm and edit script help buttons. It also shows the script line numbers which makes it easier to work with while debugging code.
The model editor has a similar toolbar now which allows to export the model representation as an image, run the model or edit the model help.
When you press the edit script help button, you get access to the new help editor. It’s easy to use: On the top, it displays the current content of the help file. On the bottom-left, it lists the different sections of the help file which can be filled with information. In the input parameters and outputs section, the help editor automatically lists the all parameters specified in the script code. Finally, in the bottom-right, you can enter the description. The resulting help file is saved in the same location as the original script under the name
It has been a real pleasure to chat with Caitlin Dempsey at GIS Lounge about open source GIS and how I got hooked on QGIS.
In related news: It’s great to see the many great and creative contributions to the QGIS Map Showcase on Flickr! If you have some maps you are proud of, please share them with the community. If you would like to see your image reused on the QGIS website or in other QGIS marketing material, please choose an appropriate license for your image.
I’ve also started to work on a new Processing script that identifies similar line features. It currently uses a length comparison and the Hausdorff distance between two line features to calculate the similarity value, but more on that in a future post!
Did you know that there is a network analysis library in QGIS core? It’s well hidden so far, but at least it’s documented in the PyQGIS Cookbook. The code samples from the cookbook can be used in the QGIS Python console and you can play around to get a grip of what the different steps are doing.
As a first exercise, I’ve decided to write a Processing script which will use the network analysis library to create a network-based route layer from a point layer input. You can find the result on Github.
You can get a Spatialite file with testdata from Github as well. It contains a network and a routepoints1 layer:
The interface of the points_to_route tool is very simple. All it needs as an input is information about which layer should be used as a network and which layer contains the route points:
The input points are considered to be ordered. The tool always routes between consecutive points.
The result is a line layer with one line feature for each point pair:
The network analysis library is a really great new feature and I hope we will see a lot of tools built on top of it.
Today, I want to take the opportunity to thank everyone who made my first book “Learning QGIS 2.0″ possible.
A big thanks goes to Werner Macho and Nathan Woodrow who took it on them to review the text and provided valuable feedback. I would also like to thank my publisher who had to be as patient as the rest of us while waiting for the 2.0 release. I’m also very thankful for all the encouragement from my friends and family who kept me going.
And of course I also want to thank everyone for making quite a buzz on the different social media channels and for the great feedback I’ve received so far! I hope you find it useful.
Joining polygon attributes to points is a pretty common geoprocessing step. There are multiple ways to solve the problem in QGIS, so I thought I’d have a look at how they perform. There is Join attributes by location in the Vector menu and Add polygon attributes to points in the Processing toolbox.
My test data: Two shapefiles with 18,713 points and 17,397 irregular polygons.
(Some system specs: 1.3GHz dualcore with 4GB RAM)
And here are the results:
|SAGA Add polygon attributes to points:
|Vector | Data management tools | Join attributes by location:
||killed after 16 hours
This point clearly goes to Processing and the SAGA algorithm it provides access to. Join attributes by location offers some nice options for aggregating data but it just can’t cope with the number of features in this test.
To measure execution time (in a very unscientific way), I just ran the tool from the python console using:
Some notes of caution:
SAGA comes readily installed in OSGeo4W. As far as I know, the stand-alone installer for Windows currently does not include SAGA but it can be installed manually. On Ubuntu, the standard repos only contain SAGA 2.0.8 but 2.1 is required.
Great shot! – photo by Kenneth Field
FOSS4G 2013 in Nottingham is history. It was my first FOSS4G and a great event. Meeting so many people for the first time in person is really exciting. I had the great chance to present some of the work I did at AIT on comparing street networks. If you couldn’t make it to the conference or missed my talk, here’s the chance to hear it again:
(Tip: You’ll find many more FOSS4G presentations on Youtube.)
Slides and the paper are listed on my publications page. If you are interested in the code, you can find it on Github.
So far, I couldn’t find Tim Sutton’s QGIS keynote video on Youtube. Maybe it will be uploaded later. In the meantime, you can enjoy his slides.
Of course, you already know that the release of QGIS 2.0 was also announced at FOSS4G. In case you haven’t seen the great list of new features yet, have a look at the visual changelog.
Map Gallery – photo by Kenneth Field
The results of the FOSS4G 2013 map contest have also been published now. Thanks to everyone who voted for my entry “FLEET Taxi Tracking” which made it to Runner-up: Best Anti-map Map!