Audio Cartography: Visual Encoding of Acoustic Parameters - Advances in Cartography and GIScience - page 24

spectrum generates a low ratio of texture units whereas a broad spectrum
produces a high ratio of texture units (Caivano 1990).
Figure 6: Irregular point textures display width of narrow, medium, and broad frequency
spectrum
5.7 Spatial Reach
Spatial reach implies the auditory perception of a sound and is usually
specified by geographic coordinates. As the parameter relies on subjective
perception, we consider uncertainties in the underlying information and
need a modifiable visualization concerning its clarity. Therefore, we
encode spatial reach with the variables size and crispness (Bertin 1974,
MacEachren 1992). A possible realization adopts color hue from a specific
sound source to qualitatively determine the source and to geographically
describe its spatial reach or extent ( Fig. 7 ) . The color hue is varied in
crispness to selectively filter edges or fills of an object.
Figure 7: Variations of size and crispness mark the spatial reach of a perceived sound
5.8 Noise Limit Value
The parameter noise limit value requires a conspicuous encoding to
underline the relevance of the underlying information. Blur immediately
directs visual attention to relevant areas (Kosara 2001). Thus, we consider
blur as a possible encoding technique to generate sharp areas exceeding
critical noise levels while blurring the irrelevant areas. As blurring relies
on context to create focus, the visualization requires the embedding of the
parameter into a spatial setting ( Fig. 8 ) .