Bilkent University
Department of Computer Engineering


ChiLAT: An Effective Animation, Debugging and Fine Tuning Tool for Force-Directed Graph Layout Algorithms


İstemi Bahçeci
MSc Student
Computer Engineering Department
Bilkent University

A graph is a way of representing a set of objects (nodes) and relations (edges) between these objects. Graphs are commonly used to model relational information in many areas such as relational databases, software engineering, biological and social networks. In graph visualization, laying out a graph automatically in an aesthetically pleasing way is one of the most essential criteria for efficient utilization of underlying information.

Force-directed graph layout algorithms are a class of graph layout algorithms that are regarded as one of the most flexible and successful algorithms in literature. Also known as “Spring Embedders”, such algorithms model a graph with a physical system. In such a system, every vertex is represented as a charged particle, causing repulsive forces to each other, and every edge is represented as a spring, exerting an attractive force to its end vertices. The graph is laid out iteratively, where repulsive and attractive forces are calculated for each vertex, and vertices are moved accordingly until the simulated system reaches a stable state with its total energy minimized. It is vital to observe the evolution of a force-directed algorithm’s behavior through time, in order to debug the algorithm in detail and fine tune its parameters before it’s put to use.

In this talk, we are going to present a software called ChiLAT (ChiLay Animation Tool). Main goal of ChiLAT is to provide an animated view of a force-directed layout algorithm in ChiLay (Chisio Layout) library, which is developed and maintained by i-Vis Research Group at Bilkent University. With such animation capabilities, ChiLAT offers important fine-tuning and debugging functionality for layout algorithm developers. The tool effectively allows users to visualize details of the underlying force model in each animation state through its rich and easy to use graphical user interface. Underlying methods, algorithms and visualization techniques used in ChiLAT will be detailed in this talk.


DATE: 23 March, 2015, Monday @ 16:15