Archive for the ‘Project’ Category

Donnerstag, Juni 12th, 2014

On the SOTM-EU 2014 conference in Karlsruhe, Germany I presented the pgmapcss library, which I developed during the last year. Here are the slides:

pgmapcss – adv cartography for mapnik

MapCSS – ein neuer Standard für Kartographie

Freitag, Mai 9th, 2014

Heute habe ich wieder mal die Ehre einen Vortrag auf den Linuxwochen in Wien zu halten. Dieses mal möchte ich die Kartographie-Sprache „MapCSS“ vorstellen, mit denen man (z.B. aus der OpenStreetMap) Karten erzeugen kann. Der Vorteil von MapCSS ist, dass sie auf verschiedenen Plattformen verfügbar ist, leider mit großen technischen Unterschieden.

Hier können die Folien heruntergeladen werden: MapCSS – ein neuer Standard für Kartographie

Vortrag „OpenStreetMap – Kartographie für alle Zwecke“

Mittwoch, Oktober 9th, 2013

Morgen, den 10.10.2013 werd ich wieder mal einen Vortrag über die OpenStreetMap halten, diesmal auf der „Shareconomy“ Konferenz der Arbeitsgemeinschaft Datenverarbeitung.

Hier mein Abstract:

Am Anfang stand der Wunsch eine lizenzkostenfreie Straßenkarte der Welt zu erstellen und die OpenStreetMap war geboren – quasi die „Wikipedia der Landkarten“. Zuerst wurde sie von den großen kommerziellen Unternehmen belächelt – besonders aufgrund ihres scheinbar unstrukturierten simplifizierten Datenmodells. Schnell hat sich aber eine schier unüberschaubare Datenvielfalt etabliert, die sehr differenzierte thematische Karten ermöglicht – Karten historischer
Sehenswürdigkeiten, Radwegkarten, Karten für Personen mit eingeschränkter Mobilität oder speziell angepasste Karten für humanitäre Katastrophenfälle sind nur ein paar der Möglichkeiten.
Außerdem hat sich rund um die OpenStreetMap ein riesiges Ökosystem an Software entwickelt – das meiste davon natürlich Open Source. Schließlich wollen Daten gesammelt, eingetragen, abgezeichnet und vor allem weiterverarbeitet und schließlich dargestellt werden. Die großen Datenmengen stellen auch besondere Anforderungen an die Datenbanksysteme.
Die OpenStreetMap bildet inzwischen die Basis für einige erfolgreiche Unternehmen. Außerdem kann sie gut mit Open Data Initiativen kombiniert werden. Last but not least gibt es viele wissenschaftliche Projekte die sich mit diesen Daten auseinandersetzen.

Hier finden sich die Folien:



Apache2 AuthExternal and WebDav

Freitag, März 25th, 2011

Now for something technically more challenging, because it cost me several hours of debugging, but was pretty simple actually. In case somebody else on the world tries to restrict read/write-permissions to a WebDav directory with the AuthExternal module, they can find a solution here :)

For my newest project in work I am setting up a project server offering Git repositories, a web page and maybe more. Something similar to GitHub but we want to maintain the repositories ourselves. I’m using Drupal for the web page and the access control and a selfwritten module (called Git Repository) for the interaction with the Git archives (I didn’t really find a matching module for this job, at least for Drupal 7).

Access to the Git Repositories is limited to http(s) via WebDav currently, using the Apache2 AuthExternal module for authentication. In the „Git Repository“-module there are two scripts which handle interaction – they connect to Drupal asking for read/write-permission to the linked node.

For checking read/write-permission I used this howto, but I had the problem it didn’t work, write access was still possible to the directory, though the script returned the correct exit-codes.

This is the .htaccess-file:
AuthType Basic
AuthName "Repository"
AuthBasicProvider external
AuthExternal git_repo
GroupExternal git_repo
Require group may_write
Require group may_read

According to the howto this should be correct … and it is, I tested it without GroupExternal authentication. After several hours of debugging I came up with a really simple solution:

Apparently GroupExternal does a fall-back to the default „Require group“ statement in case the limited „Require group“ statement fails. So my simple solution was to just use negative logic:
AuthType Basic
AuthName "Repository"
AuthBasicProvider external
AuthExternal git_repo
GroupExternal git_repo
Require group may_read
Require group may_write

Voila, problem solved.


Dienstag, Juli 20th, 2010

A couple of years back I developed a script for the backups at the institute where I’m working, it’s called the CGA-Backup. Unfortunately this script is no longer in use there, as my colleagues preferred to change to a more popular solution (BackupPC). Anyway, there are still people using this script and I’m willing to maintain it, as I still use it for private projects and think it’s a nifty piece of code. As I’m lately opening my projects up at Gitorious, I also plucked it from the closed environment of our SVN-server. Here you are.

OpenStreetMap – Eine Einführung

Samstag, Mai 8th, 2010

As I told you, I’m giving an introductory talk about the OpenStreetMap on the Linux Wochen in Vienna today. Here are the slides (in German for sure):

Linuxwochen 2010

Dienstag, Mai 4th, 2010

The coming weekend there are the „Linuxwochen“ (Linux weeks) again in Vienna. It’s an exhibition of several free software / open source initiatives, there are also a lot of talks. One of those talks will be about the OpenStreetMap, held by me. The date: Saturday, May 8th, 10:30 in the Festsaal. So if you haven’t heard of the OpenStreetMap yet (which I doubt if you know me), there’s the place and time to go :) You can also meet me at the OpenStreetMap-stand in the exhibition area (Thursday and Friday afternoon, Saturday more or less the whole day).

My daily picture

Mittwoch, Januar 13th, 2010

As my blog is a little bit boring right now (isn’t it?), I got a new idea. I’m gonna post one good picture per day on Flickr. You can find them here: . I hope you’ll like them. Have fun!

Again OpenStreetBrowser

Dienstag, Mai 5th, 2009

As I told I’m gonna present some features of the OpenStreetBrowser from time to time. It’s also a good documentation for the project.

Routes of public transportation

Routes of public transportation are still not being displayed on the main Mapnik and OsmaRender renderings, although they are very important in my opinion. For me this was actually the start of the project, I had planned to make a nice map with public transportation routes. Now they are only an overlay, as they would clutter the main map too much.

There are two noteworthy features: The references of routes sharing the same way get collected and separated by ‚,‘, which looks much better, and stops with the same name get combined and get a box drawn around. Both of these features improve visibility.
Tram and Bus routes around Alser Strasse in Vienna, Austria

Link to Wikipedia

In the OpenStreetMap it’s possible to link to the Wikipedia. The key is „wikipedia:language“, e.g. „wikipedia:en“ or „wikipedia:de“. If such a link exists, the OpenStreetBrowser displays an abstract of the article and an image, when it finds one (it has to be before the first abstract … this is something still to improve).
Showing the Wikipedia-Entry of the “Altes Rathaus” (old town hall) in Potsdam, Germany

Stylesheet for the Overlays

The last feature for this time is the newest feature. The styles of the Overlays „Food & Drink“, „Shops“, „Culture & Tourism“ and „Services“ is generated from a page in the OSM-Wiki. So if you find something missing on these overlays, or you have better icons (many objects don’t have an icon or share icons with other features), feel free to upload them there (the new style sheet will be used after the next database reload, so typically after 1-3 weeks).
Showing the Culture-Layer over Paris, France

If you have suggestions for new feature, complaints or praise, feel free to leave me a comment :)

Some Features of the OpenStreetBrowser

Montag, April 13th, 2009

This time I want to show you some features of the OpenStreetBrowser. One of the goals of my project is to display as many information as possible in a simple and understandable way. Sounds like the quadratur of the circle? Maybe it is :)


The first feature I want to show you are house numbers. Sounds rather boring, isn’t it? The default Mapnik and Osmarenders styles don’t rotate the numbers, so it’s hard to say where they belong to. It’s also a problem of the software (I can only speak for Mapnik, because I’m using it too), there isn’t really a possibility to rotate texts and icons. So you have to use crude workarounds, which are a pain in the ass. But I think I’ve done a pretty good job … although ideas for improvements are always welcome! The house numbers are also being listed in the details of the street in the side pane.

Housenumbers in Vienna

More informations about entering house numbers to OSM.


I don’t know about you, my precious reader, but I like visiting cemeteries. Maybe it’s a Viennese thing, they were always crazy about their afterlife. On cemeteries you can visit all these graves of famous people. Even better if you can see them on the map, isn’t it? The important graves on a cemetery are also listed in the side information pane. Time to visit your local cemetery!

What is still missing is the background of the cemeteries, at the moment there are theses crosses, which is not really appropriate for graves of other religions.

Waldfriedhof Dahlem in Berlin

There is no approved method for tagging graves in OSM yet, the OpenStreetBrowser currently accepts cemetery=grave and historic=grave.


Places (Countries, Regions, Cities, Villages, …) are only entered as Point (Node) to the OSM right now. In many cases you also have borders, but it’s hard to see them and the information which border belongs to which node is missing. The OpenStreetBrowser combines the borders and the nodes and shows both of them if you see the places‘ details.

City border of L’Aquila

The border is a relation of the type boundary or multipolygon, the tag admin_level matches more or less to the place-tag. To help find the correct border add the node to the relation and give it the role ‚label‘ (which is a proposed feature).

These were just three of the features of the OpenStreetBrowser. I will show you more another time.  If you have some ideas or questions, you can post them as comment here or to this page.