Matrix Zoom

Matrix Zoom is an extension of my work on hierachical call matrices (see below) and James Abello's work on semi external graphs (i.e. graphs whose edge set does not fit RAM). We used a prototype version to navigate a part of the SEER cancer data set consisting of 7 million edges on a commodity level PC. See paper or video for more details


Integration of Detail and Context in Node Link views

Here we investigate the smooth integration of detail and context in a node link representation by defining a focal area and a distortion function on the hierarchy of the graph. We also incorporated a novel layout method to gain more insight in dense graphs. See paper for more details. A basic Delphi implementation is available here with an older version of the code here, feel free to use as you see fit.


Hierarchical Call Matrices

This work was done in association with Philips Medical Systems. The main problem was the visualization of very large software system (3 Million Lines of Code) to see whether the implementation conformed to the architectural design [more]



Beamtrees are an extension of treemaps that use overlap as a cue for the tree structure. We developed both a two and a three dimensional version. Research also included user studies [more]


Finite State Machine Visualization

Finite State Machines (mathematical process descriptions of programs or protocols) tend to generate very large graphs. Visualization can be used to gain more insight in the structure of the so-called state spaces. [more]