Trade-Off Between Mental Map and Aesthetic Criteria in Simulated Annealing Based Graph Layout Algorithms

Dynamic graph visualization is a key component of interactive graph visualization systems. Whenever a user applies filters or a graph is modified by other reasons, a new visualization of the modified graph should support the user’s Mental Map of the previous visualization to facilitate fast reorientation in the new drawing. There exist specialized graph layout algorithms which adopt the concept of Mental Map preservation to create recognizable layouts for similar graphs. In this work we used Simulated Annealing algorithms to calculate layouts which fulfill aesthetic and Mental Map requirements simultaneously. We investigated criteria of both types and conducted an experiment to examine the competition and trade-off between aesthetics and mental map preservation. Our findings show that even without explicitly optimizing Mental Map criteria, recognition can be supported by simply using the previous layout as a starting point, rather than a new layout with randomly allocated vertices. This results in better aesthetic quality as well as lower algorithm runtime. Another finding is that a simple weighted sum between aesthetic and the Mental Map may not be as effective as one might expect, especially if the weight assigned to the Mental Map is higher than the weight for aesthetics. Finally, we propose approaches for changing other aspects of the Simulated Annealing algorithm to obtain better graph layouts.