THE MULTIPLE VISUAL ATTRIBUTES OF SHAPE - Information Visualisation: Techniques, Usability and Evaluation - page 55

that some of these experiments could be implemented more effectively
using well studied attributes such as size or colour. At this point, the
criteria for understanding which combinations may or may not work well
together are uncertain; and it would be challenging to test all the various
permutations of combinations.
What are the attributes of shape?
It is debatable which shape attributes to include in the working list of
shape attributes (Fig 3.19). For example, early on, concavity seemed to be
a potential attribute. Creating a matrix of possible attributes, using
concavity as one attribute seemed promising.
Fig. 3.19. Sample matrix exploring attributes of shape. In this example three
attributes are considered: open/closed, dominant orientation (angle/square/curve),
and concavity.
To evaluate concavities, an experimental visualization using real data
was created. An “Email Visualization” used basic shapes and then concave
variations of those shapes were used to indicate a second data dimension
(Fig. 3.20).
However, within a visual field of many of these shapes, the more
complex shapes (i.e. concave shapes) did not seem to pop-out visually.
This led to a reconsideration of concavity: perhaps simple notches were
sufficient; or perhaps the design of this particular visualization with
partially overlapping glyphs interfered with the perception of concavities
and thus impacted the ability to identify visually concavity.