Envisioning information - The Visualization of Spatial Social Structure - page 16

green) 13 . However, in this topic I suggest that the most intuitively appealing
combination is the painter's red, blue and yellow - which fortunately also
coincide with Britain's major political parties' symbols and also with national
colours, and have many other useful associations.

1.5 Perspective and detail

Generalization, if you wish to call it that, occurs spontaneously in all
perception. Complex though a map may be, the mind derives from it
a simplified pattern.

(Arnheim, 1976, p. 9)

The most powerful ability of the eye - brain working in combination is gen-
eralization. 14 The brain only ever sees through the constantly changing light
intensities, which are measured by the retina. These are analysed by the brain to
allow instant assumptions to be made, before more careful inspection is under-
taken (Figures 1.9, 1.10 and 1.11). Such ability is essential to our survival in
everyday life; it was even more so in the past. Through visualization we are
utilizing one of the most finely tuned pieces of evolutionary good fortune.
We live in a three-dimensional world, despite having as near to two-
dimensional vision as often makes little difference. Perspective is the name
given to the effect of projecting a three-dimensional scene on to our two-
dimensional retinas; we use it to try to reconstruct three-dimensional form.
Although we do have binocular vision, if you close one eye you lose little
feel for the three-dimensional reality. For the most part we move about in two
dimensions and, in fact, have a far weaker grasp of the real three-dimensional
world than we may imagine (as illustrated here in Chapter 9).
It is often claimed that expensive equipment which allows volumes (commer-
cially known as '3D') to be created and seen is at the forefront of visualization.
Stereoscopic vision, though, might not be as great an asset to visualization as it is
often thought to be in seeing the real world. Stereo vision works well at gauging
position when nothing is moving behind or in front of anything else. Once things
begin to move, though, it can become a confusing irrelevancy. In visualization,
if we want things to move, then it is usually through animation that they move.
Animation can be used for much more than understanding three-dimensional
form. As the creation of a changing or moving image, it can add another level of
sophistication to two-dimensional visualization. However, like colour, animation
(employing time) is not the same type of dimension as the spatial. In animation

13 'It is possible to express a trivariate distribution by mapping each variable onto one of the
dimensions of (red, green and blue) color space' (Sibert J.L. 1980, p. 214).
14 See Tobler (1968, 1969, 1989b), Rhind (1975c), Lavin (1986) and Herzog (1989).