THE MULTIPLE VISUAL ATTRIBUTES OF SHAPE - Information Visualisation: Techniques, Usability and Evaluation - page 54

Fig 3.18. Upper images: Aircraft fuselage silhouettes (U.S. War Department's
Newsmap, Monday, July 20, 1942) [USA09]). Lower images: LEGO blocks of
similar size, colour and orientation, differentiated only by shape (from lugnet.com
[LEG09]).

Background summary

This background provides a basis for different shape attributes as used
in different fields, and potentially applicable to information visualization.
Many of the attributes can be applied to both categorical and quantitative
visual tasks. As outlined at the IV09 keynote [Bra09], a working list of
shape attributes may be considered as follows (Table 3.2):
Shape Attribute Example Categorical Examples Quantitative Examples

Global Form circle, square, kite, star, etc -

Closure closed/open -

Curvature curved a bit/a lot/not amplitude, skew, bulge

Corner Angle obtuse/right/acute degree of angle

Edge Type straight/spiky/etc amplitude, frequency

Corner Type sharp/round/serif/etc Size

End Type none/serif/dot/etc width, depth

Notch/Bump v/half-round/etc width, depth

Mark/Whisker exist/slope/etc density, slope, length

Holes primary shape size, number

Intersection three/four/five number of spokes

Local Warp shear, twist, bulge warp factor

Table 3.2. List of shape-based visual attributes with examples for categorical and
quantitative tasks.

Experiments and Lessons

Exploration of shapes through various experimental visualizations is
ongoing. At this point, using more than one shape attribute to convey more
than one to three data variables within a singular glyph has largely been
limited to experimental visualizations. These experiments, done to “see
what's possible”, have not been rigorously tested, and it is acknowledged