11.5 VISUALIZATION OF RELATIONS 11.5.1 TREE VISUALIZATION o level 2 O level 3 Figure 11.7 Bubble-tree layout for the same file hierarchy asirFigure 11.5.11.5 VISUALIZATION OF RELATIONS 11.5.1 TREE VISUALIZATION Figure 11.7 Bubble-tree layout for the same file hierarchy as in Figure 11.5