Graphics Reference
In-Depth Information
Overview
Zoom and filter
Details-on-demand
First, the user needs to get an overview of the data. In the overview phase, the user
identifies interesting patterns and subsets and focuses on one or more of them. Fo-
cusing consists in a distortion of the overview visualization or in using another vi-
sualization technique (Buja et al.,
). Analyzing the patterns, the user highlights
the most important information, using the drill-down functionality. Finally, access-
ing the (selected) data subsets, the user can retrieve interesting patterns and subsets
in order to perform further detailed exploration (Antoch,
).
According to Shneiderman's (
) proposal for designing advanced graphical
user interfaces, four more tasks supplement the previous list, namely:
Overview: the user gains an overview of the data.
Zoom: the user zooms in on items of interest.
Filter: the user filters out uninteresting items, by dynamic queries. By allowing
users to control the contents of the display, they can quickly concentrate on in-
teresting patterns. At this aim, the sotware should offer both controls and rapid
display update.
Details-on-demand: the user selects an item or a group of items in order to get
details.
Relate: the user views relationships among data items.
History: undoand replay supportallows the userto progressively refine the explo-
ration; the run actionŠs history is stored to retrace the followed steps.
Extraction: allows the user to extract subsets through query parameter setting.
he analysis approach in an exploratory framework mainly focuses on the results
of direct visualization. hese results can be made dynamic offering user interaction
capabilities on the graphical representation. he incorporation of interactive tech-
niquesimpliesthat to any action on a screen corresponds a reaction either in numerical
analysis or in visualization (VITAMIN-S FSR,
).
The Use of Visual Variables
for Designing Useful Representations
4.7.1
In an interview, Bertin (
) stressed the idea that the use of computers for visual-
ization should not ignore the real objectives of graphics, namely, treating data to get
information and communicating, when necessary, the information obtained.
According to the definition of an image as a sign's structured set in a visual field,
Bertin identifies three dimensions: X and Y define the sign's position in
-D space,
and Z, the third dimension, specifies the informative content. In order to measure
the usefulness of any given construction or graphical invention and to avoid useless
graphics, Bertin warns us to answer the following three questions:
Which are the X, Y, and Z components of the data table? (What is it all about?)
What are the groups in X and Y that Z builds? (What is the information at the
general level?)
