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Multivariate data (also called multidimensional or n-dimensional) consists
of some number of points, m, each of which is defined by an n-vector of
values.
Such data can be viewed as an mxn matrix, where each row
represents a data point and each column represents an observation (also called
a variable or dimension).
An
observation may be nominal or ordinal, and may or may not have a distance
metric, ordering relation, or absolute zero.
Each variable/dimension may be independent or dependent.
A glyph consists of a graphical entity with p components, each of
which may have r geometric attributes and s appearance attributes.
Typical geometric attributes include shape, size, orientation, position, and
direction/magnitude of motion, while appearance attributes include color,
texture, and transparency.
Attributes can be discrete or continuous, scalar
or vector, and may or may not have a distance metric, ordering relation, or
absolute zero.
The list below (and Figure) give examples of glyphs from the literature
and attributes controlled by the multivariate data point.
Figure 1:
Examples of glyphs: variations on profiles; stars/metroglyphs;
stick figure icons and trees; autoglyphs and boxes; faces; arrows and
weathervanes.
![\begin{figure*}
\centerline{\hbox{ %
\psfig{figure=profile.eps,width=1.75in}
\hs...
....75in}
\hspace*{.5in}
\psfig{figure=arrow.eps,width=1.75in}
}}
\par\end{figure*}](img1.gif) |
- profiles [17]: height and color of bars.
- stars [45]: length of evenly spaced rays emanating from
center.
- Anderson/metroglyphs [1,20]: length of
rays.
- stick figure icons [39]: length, angle, color of limbs.
- trees [29]: length, thickness, angles of branches; branch
structure derived from analyzing relations between dimensions.
- autoglyph [4]: color of boxes.
- boxes [21]: height, width, depth of first box; height of
successive boxes.
- faces [6]: size and position of eyes, nose, mouth;
curvature of mouth; angle of eyebrows.
- arrows[48]: length, width, taper, and color of
base and head.
- weathervanes [18]: level in bulb, length of flags.
- circular profiles [37]: distance from center to vertices
at equal angles.
- bugs [9]: wing shapes controlled by time series; length
of head spikes (antennae); size and color of tail; size of body markings.
- wheels [9]: time wheels create ring of time series plots,
value controls distance from base ring; 3D wheel maps time to height,
variable value to radius.
- Glyphmaker [40]: user-controlled mappings.
Next: Glyph Limitations
Up: A Taxonomy of Glyph
Previous: Introduction
Matthew Ward
1999-02-08