SRTM Plugin for OpenStreetMap

One of the features of our TrafficMining Project at the LMU was to use additional attributes in routing queries. Standart routing queries usually just use time and distance for calculating the fastest/shortest routes. In order to have an additional attribute we decided to use evelation data as this might be an issue if you also want to take fuel cost into account or if you’re planning a bike tour (instead of crossing a hill, you might want to consider a longer tour that avoids crossing the hill).

The problem just was that data nodes from OpenStreetMap are defined mostly by id, latitude and longitude, which is totally enough for painting 2D maps and standard routing queries. As the elevation is not added to OpenStreetMap data directly (and it is also not intended to be added to the OSM data base), a component was needed that parses both Nasa SRTM data as well as OSM data files in order to combine the data.

In the first version, we parsed the SRTM data directly and addied it to the nodes of the OSM-Graph directly. During one refactoring, we decided to integtrate Osmosis into the project in order to be able to read PBF files (another OpenStreetMap file format). During this integration we decided to separate the SRTM parsing into a separate module so that other people can make use of it as well. The plugin was open sourced some time ago at google code as the “osmosis-srtm-plugin” under an LGPL licence.

Relevant Links:

Drupal shows warnings after migrating to new server

Recently we migrated a Drupal managed website to  a new server. РEverything was fine, just on some pages, some php-warnings showed up that did not show up on the original site.
After some investigation I checked php’s error_reporting setting and realized that the settings of the new new server were more sensitive than the old one.

The solution was pretty simple. As I definately didn’t want to start hacking around in Drupal, I just turned off showing the errors to the user:

Administer > Site configuration > Error reporting
(or in german:) Verwalten > Einstellungen > Error reporting
Error Reporting: Write errors to the log (instead: Write errors to the log and to the screen).

Pretty easy.

Finished my Posters for ICIP and MICCAI

Finally finished the posters for my publications:

F. Graf, H.-P. Kriegel, M. Schubert, S. Poelsterl, A. Cavallaro
2D Image Registration in CT Images using Radial Image Descriptors
In Medical Image Computing and Computer-Assisted Intervention (MICCAI), Toronto, Canada, 2011.


F. Graf, H.-P. Kriegel, M. Weiler
Robust Segmentation of Relevant Regions in Low Depth of Field Images
In Proceedings of the IEEE International Conference on Image Processing (ICIP), Brussels, Belgium, 2011.

Maximum Gain Round Trips with Cost Constraints

The idea is the following: Finding the shortest/fastes path from A to B is rather exploited. But if you start a hike, knowing that you want to spend 4 hours and then come back to the starting point. Then the problem suddenly starts to become a bit complex (NP-hard to be honest if you do not add any constraints).

We propose a solution to do this kind of search a bit more efficient. but don’t expect linear search time ūüėČ And – in contrast to quite some other research – we are operating on REAL data obtained from OpenStreetMap.


Searching for optimal ways in a network is an important task in multiple application areas such as social networks, co-citation graphs or road networks. In the majority of applications, each edge in a network is associated with a certain cost and an optimal way minimizes the cost while fulfilling a certain property, e.g connecting a start and a destination node. In this paper, we want to extend pure cost networks to so-called cost-gain networks. In this type of network, each edge is additionally associated with a certain gain. Thus, a way having a certain cost additionally provides a certain gain. In the following, we will discuss the problem of finding ways providing maximal gain while costing less than a certain budget. An application for this type of problem is the round trip problem of a traveler: Given a certain amount of time, which is the best round trip traversing the most scenic landscape or visiting the most important sights? In the following, we distinguish two cases of the problem. The first does not control any redundant edges and the second allows a more sophisticated handling of edges occurring more than once. To answer the maximum round trip queries on a given graph data set, we propose unidirectional and bidirectional search algorithms. Both types of algorithms are tested for the use case named above on real world spatial networks.


At our project site you can find:


  AUTHOR      = {F. Graf and H.-P. Kriegel and M. Schubert},
  TITLE       = {Maximum Gain Round Trips with Cost Constraints},
  INSTITUTION = {Institute for Informatics, Ludwig-Maximilians-University, Munich, Germany},
  YEAR        = {2011},
  LINK        = {}

Robust Segmentation of Relevant Regions in Low Depth of Field Images

Great, we got accepted (as a poster) on the ICIP 2011 with the paper “Robust Segmentation of Relevant Regions in Low Depth of Field Images”:

Low depth of field (DOF) is an important technique to emphasize the object of interest (OOI) within an image. When viewing a low depth of field image, the viewer implicitly segments the image into region of interest and non regions of interest which has major impact on the perception of the image. Thus, robust algorithms for the detection of the OOI in low DOF images provide valuable information for subsequent image processing and image retrieval. In this paper we propose a robust and parameterless algorithm for the fully automatic segmentation of low depth of field images. We compare our method with three similar methods and show the superior robustness even though our algorithm does not require any parameters to be set by hand. The experiments are conducted on a real world data set with high and low depth of field images. (Abstract from the paper)

The work is a result of a collaboration with Michael Weiler. We extended his Diploma thesis and produced an improved segmentation algorithm for Low Depth Of Field images. Compared to the other 3 competing algorithms, ours is a bit slower but at least it works. The other algorithms turned out to be extremely unstable and/or sensitive to parameters.

On the project site you can find

  • an online demo
  • the test images,
  • the masks
  • the NetBeans project including the full Java source code for our algorithm and the reimplementation of the comparison partners (of course we had to re-implement as we didn’t even get binaries – as usual)

So if you plan to do some image segmentation, just go there download the stuff and cite our work ūüėČ

Fully automatic detection of the vertebrae in 2D CT images – the Talk

Yea finally I gave the talk for my Publication “Fully automatic detection of the vertebrae in 2D CT images” Paper 7962-11 at SPIE Medical Imaging 2011, Conference 7962 Image Processing (see index) in front of about 200 people.

Everything went fine. Just some nice questions right after the talk and some hints afterwards. Hey – some guys even remembered the talk 2 days later! ūüôā

Thanks, SPIE Medical Imaging.

Bibliography Extension for MediaWiki

MediaWiki > Skins > Extension … a use case story

In mid 2009 we were asked to redesign our homepage to fit the corporate design of the LMU. During this time, I introduced and established MediaWiki as content management system for our website as it provided the needed flexibility, freedom and usability for our group.

One major issue was the list of publications which is very important for every researcher. In the old system, everyone maintained his own publication list manually. In parallel, all the publications were maintained in a central BibTex-file stored in CVS. Nice example for ‘Redundancy‘ – hey we’re a data base group – there shouldn’t be redundancies. So I wrote an extension in my spare time which parses a bibliography-file into a more convenient format. The result of such an automatically generated list can be seen for example on my publications list. – Well, finally I just put it online. Maybe you are a researcher or just maintinaing the website of some researcher(s) who already have a bib-File of their own publications and want to put your publications list online.

What this Extension can do / Features

The extension in action
The extension in action

This extension allows processing a central bibliography file in BibTeX format in order to create personalized publication pages for authors, projects or keywords. The BibTeX data can be stored in a file in the filesystem or in a special wiki article.

Implemented Features

  • The bibliography can be stored in a filesystem file or in a separate article of the wiki.
  • Multiple authors can share a single BibTeX source and have individual publication lists on their personal pages (=articles)
  • Filtering can be done on all attributes of the bibtex file/article.
  • Filters can be combined: for example, all papers of year=2010 AND author=xy AND keyword=xyz
  • Supports optional bibtex entries (“pages =100–110” may be entered in one bibtex entry but not in another – but if the entry is present, it should be formated as “p. 100-110”. If the attribute is not there, “p. ” should also not appear)
  • Different bibliography-types (article, book, inproceeding, …) use different styles according to the mandatory and optional fields.
  • @unpublished entries will be ignored
  • Supports @String-replacement as it is can be done by BibTeX
  • Automatically adds a separator between entries of different years
  • Provide additional links for each BibTeX entry (like PDFs or links to articles with further informations)
  • Author names can be linked automatically to pre defined wiki articles


Just visit my How-To page, to see what the extension can do.
You can download the extension by using the link in the download section.

Maybe you can just drop me a line if you find the extension useful.

Google Maps auch in Desktop / Non-Browseranwendungen

War die Benutzung der Google Maps API bis vor … einiger Zeit nur auf Browseranwendungen beschr√§nkt, lese ich gerade in den Nutzungsbedingungen:

Kann ich die Google Maps-APIs auch in anderen Anwendungen als Webanwendungen verwenden?

Ja, die Google Maps-APIs k√∂nnen jetzt in Desktop-Anwendungen verwendet werden, vorausgesetzt, diese entsprechen den weiteren Einschr√§nkungen der Nutzungsbedingungen. Eine Desktopanwendung gilt nur dann als “√∂ffentlich zug√§nglich”, wenn sie von einer √∂ffentlich zug√§nglichen Webseite heruntergeladen werden kann. Weitere Informationen finden Sie in Abschnitt 7.1 der Nutzungsbedingungen.


Fully automatic detection of the vertebrae in 2D CT images

FINALLY submitted the paper which we sent to the SPIE Medical Imaging Conference  (and got accepted!)


Knowledge about the vertebrae is a valuable source of information for several annotation tasks. In recent years, the research community spent a considerable effort for detecting, segmenting and analyzing the vertebrae and the spine in various image modalities like CT or MR. Most of these methods rely on prior knowledge like the location of the vertebrae or other initial information like the manual detection of the spine. Furthermore, the majority of these methods require a complete volume scan. With the existence of use cases where only a single slice is available, there arises a demand for methods allowing the detection of the vertebrae in 2D images. In this paper, we propose a fully automatic and parameterless algorithm for detecting the vertebrae in 2D CT images. Our algorithm starts with detecting candidate locations by taking the density of bone-like structures into account. Afterwards, the candidate locations are extended into candidate regions for which certain image features are extracted. The resulting feature vectors are compared to a sample set of previously annotated and processed images in order to determine the best candidate region. In a final step, the result region is readjusted until convergence to a locally optimal position. Our new method is validated on a real world data set of more than 9 329 images of 34 patients being annotated by a clinician in order to provide a realistic ground truth.

More Information and the paper as PDF can be found at my publication site.

Excel 2007: Diagrammflächen schraffieren

Schraffuren f√ľr Diagramme gibt es in Excel 2007 offenbar leider nicht mehr. Abhilfe schafft jedoch ein Add-In.

Am besten, das Add-In nach C:Dokumente und Einstellungen[Benutzername]AnwendungsdatenMicrosoftAddIns kopieren und dann der Installationsanleitung folgen:

  • Excel-Button dr√ľcken (der gro√üe runde button oben links)
  • letzte Zeile: Excel-Optionen
  • Add-Ins
  • fast ganz unten: “Gehe zu”
  • Durchsuchen
  • PatternFills.xlam anklicken und fertig


  • Diagramm anklicken
  • Diagrammtools > Format > ganz rechts gibt es jetzt eine “Patterns” Schaltfl√§che