User preference of graph layout aesthetics: a UML study

The merit of automatic graph layout algorithms is typically judged on their computational effciency and the extent to which they conform to aesthetic criteria (for example, minimising the number of crossings, maximising symmetry). Experiments investigating the worth of such algorithms from the point of view of human usability can take a number of different forms, depending on whether the graph has meaning in the real world, the nature of the usability measurement, and the effect being investigated (algorithms or aesthetics). Previous studies have investigated performance on abstract graphs with respect to both aesthetics and algorithms, finding support for reducing the number of crossings and bends, and increasing the display of symmetry. This paper reports on preference experiments assessing the effect of individual aesthetics in the application domain of UML diagrams, resulting in a priority listing of aesthetics for this domain. The results reveal a dif- ference in aesthetic priority from those of previous domain-independent experiments.