ANGULAR TREEMAPS - Information Visualisation: Techniques, Usability and Evaluation - page 87

consume significant computational time. Our approach has competitive
running time, compared with other standard rectangular treemaps.
Compared to the rectangular approach, our Angular Treemaps can
achieve flexibility for layouts with orientation angles that differ from 90
degrees. Empirical results prove that a difference in orientation does not
impede a subject's graphical perception of area size, when the aspect ratio
of the area is not in a wide range [21]. Hence, this new technique will be
used effectively to emphasize a particular data section of the user's interest
and a general data structure with differentiation of orientation.
The new technique proposed here emphasizes sub-hierarchical data in
a hierarchy. The first objective is to enhance the interpretability of the
visualization by providing flexibility of effective layouts through
relaxation of the vertical-horizontal partitioning constraint. The second
objective is that, with relative simplicity of algorithm and reasonably low
computational time, the proposed technique could be suitable for in-depth
visual analysis of hierarchical structures encoded in large data sets.
Angular Treemaps
Fig. 5.1. An example of a visualization using an angular polygonal algorithm on
sub-structures with various partitioning angles.
This section explains the methodology of the approach and presents results
in both rectangle and arbitrary enclosed display areas. The algorithm is
implemented within a file system organization application to demonstrate
the concept of Angular Treemaps in a real example. To prove attainment
of the first objective defined above, this section will extend visual