`visualize': to form a
mental vision, image, or picture of
(something not visible or present to the
sight, or of an abstraction); to make
visible to the mind or imagination. Oxford
English Dictionary, 2nd edition, 1989
In science often large and/or complex
collections of data have to be processed. Usually it is not
suitable for human researchers to investigate such data-sets
by reading lists of numbers or other textual representations.
The mapping of information into graphs or images, i.e.,
visualization, was identified as a powerful tool for data
investigation already a long time ago.
Two examples of early flow visualization by
Leonardo da Vinci (images out of ``Frontiers of Scientific
Visualization'' by Pickover and
Leonardo da Vinci (1452-1519),
for example, already used drawings to communicate scientific
results. Fig. 1.1 shows two examples of his work.
recently, the extensive use of computers for data processing
generated a new need for elaborated visualization techniques.
In the early 1990s annual-conference series, solely focusing on
visualization, e.g., the ``EUROGRAPHICS Workshop on
Visualization in Scientific Computing'' or the ``IEEE
Conference on Visualization'', were established. Ten years later
already a few compendia on visualization
are available as comprehensive text books, for example,
``Scientific Visualization'' by Gregory Nielson, Hans Hagen, and
Heinrich Müller .
To illustrate the role visualization is playing at the end of the
first millennium, some of the most important application fields
are listed below:
Medical data visualization -
(anatomic) data is acquired through measurement devices,
e.g., MRI or CT, which is then presented using volume
visualization techniques, e.g., direct volume rendering or
Flow visualization -
vector data, either computed by flow simulation, or
measured data using experimental setups, is plotted for the
purpose of data investigation. For example, the design of
new aircrafts can be checked using simulation and
visualization without constructing
Geographic information systems (GIS) and visualization -
for hundrets of years up to now maps are used as visualization of
geographic data. Techniques like color coding, height
fields, iso-lines, and icons, are used to show topographic
information like mountains, rivers, etc., together with additional
information, for example, temperature.
Information visualization -
big databases, multi-modal data, and abstract data (usually
increasingly require appropriate visualization
techniques. Business data visualization
(charts, diagrams, and graphs) is already widly used to
illustrate economic data and relationships.
Visualization of microscopic data -
molecules and/or atomic structures investigated in biology,
chemistry, and physics, increasingly are visualized for
analysis. Also data acquired by non-optical microscopes
usually needs to be visualized before investigation can
Large-scale data and visualization -
astronomy, for instance, deals with data that is simulated
or measured at a scale that prohibits direct investigation
in most cases. Again, visualization can help to ``fit'',
for example, the entire universe into the study room of an
Architectural visualization -
Planning of urban regions as well as buildings is enhanced
by visualization methods. New buildings, are
visualized on the basis of computer aided design (CAD)
data together with existing context. This allows to
evaluate plans before actual
Archeology and visualization -
to investigate archaic cultures, for instance, visualization
enables researchers to imagine life, habits, rites, etc.,
in former ages. Reconstruction of historic buildings using
visualization is an area of increasing importance.
Visualization aims to maximally exploit the
visual channel to the human user for information communication.
Visual resolution, spatial as well as temporal, and `resolution'
of the human perceptional capabilities restrict the
content of information that can be conveyed to the human user