hcp@cogsci.ed.ac.uk
In the creation of graph drawing algorithms and systems, designers claim that by producing layouts that optimise certain aesthetic qualities, the graphs are easier to understand. Examples of these aesthetics include symmetry (where possible, a symmetrical view of the graph should be displayed), minimize edge crossings (the number of edge crossings in the display should be minimized), and minimize bends (the total number of bends in polyline edges should be minimized).
The aim of this project is to validate these claims by performing empirical studies of human understanding of graphs drawn using various layout aesthetics. This work is important since it helps indicate to algorithm and system designers what are the aesthetic qualities most important to aid understanding, and consequently to build more effective systems.
The seminar reports on experiments which aimed to validate five aesthetics. Subjects used an online experimental system, and were asked three graph theoretic questions about a series of graph drawings which were created such that the aesthetics were varied appropriately. The dependent variables were time and number of errors.
The results indicate that reducing the number of edge crosses is by far the most important aesthetic, while minimising the number of bends and maximising symmetry have a lesser effect. The effects of maximising the minimum angle between edges leaving a node and of fixing edges and nodes to an orthogonal grid are not statistically significant.