Glyph-Based Multi-field Visualization - Scientific Visualization: Uncertainty, Multifield, Biomedical, and Scalable Visualization - page 126

Fig. 13.1 Visualization of the flow in an engine using composite glyphs that depict the range of
vector magnitude and direction in each cluster by Peng et al. [ 16 ]
13.3 Critical Design Aspects of Glyph-Based Visualization
It was a wide-spread opinion for a long time that “just” knowing the basic principles
of glyph-based visualization would suffice to its successful usage. More recently,
however, it has been understood that only well designed glyphs, where different glyph
properties are carefully chosen and combined, are actually useful. In this section, we
discuss critical design aspects and guidelines for glyph-based visualization.
In the context of information visualization, Ward [ 24 ] discusses glyph place-
ment strategies such as data- or structure-driven placement. Ropinski and Preim [ 19 ]
propose a perception-based glyph taxonomy for medical visualization. The authors
categorize glyphs according to (1) preattentive visual stimuli such as glyph shape,
color and placement, and (2) attentive visual processing, which is mainly related to
the interactive exploration phase (e.g., changing the position or parameter mapping
of a glyph). Additional usage guidelines are proposed, for instance, that parameter
mappings should focus the user's attention and emphasize important variates in the
visualization. Also, glyph shapes should be unambiguous when viewed from differ-
ent viewing directions. Kindlmann [ 9 ], for example, uses superquadric glyph shapes
that fulfill the latter criterion.
Inspired by the work of Ropinski and Preim, Lie et al. [ 14 ] propose further guide-
lines for glyph-based 3D visualization. Aligned with the visualization pipeline [ 4 ], the
task of creating a glyph-based 3D visualization is divided into three stages as shown
in Fig. 13.2 : (1) during data mapping , the data variates are remapped (to achieve, for
example, some contrast enhancement) and mapped to the different glyph properties;
(2) glyph instantiation creates the individual glyphs, properly arranged across the
domain; and (3) during rendering , the glyphs are placed in the visualization, where
one has to cope with issues such as visual cluttering or occlusion. In the following,
we discuss critical design aspects for each of these steps.