Column-based graph layouts

Abstract

We consider orthogonal upward drawings of directed acyclic graphs (DAGs) with nodes of uniform width but node-specific height. One way to draw such graphs is to use a layering technique as provided by the Sugiyama framework [10]. However, to avoid drawbacks of the Sugiyama framework we use the layer-free upward crossing minimization algorithm suggested by Chimani et al. and integrate it into the topology-shape-metric (TSM) framework introduced by Tamassia [11]. This in combination with an algorithm by Biedl and Kant [2] lets us generate column-based layouts, i.e., layouts where the plane is divided into uniform-width columns and every node is assigned to a column. We show that our column-based approach allows to generate visually appealing, compact layouts with few edge crossing and at most four bends per edge. Furthermore, the resulting layouts exhibit a high degree of symmetry and implicitly support edge bundling. We justify our approach by an experimental evaluation based on real-world examples. © 2013 Springer-Verlag.