Geography Reference
In-Depth Information
7. It must have considerable accuracy and integrity; if the product lets decision makers down, a long
time will elapse before they depend on such information again.
Classification of GIS Products
Products from a GIS might be classified in several ways. I will use the terms media, format, purpose, and
audience.
Media
: I use the term “media” to denote the physical carriers of the information presented to the decision
maker. Common media are paper, photographic materials (opaque ones like photographs and translucent
ones like slides and films), and electronic visual devices like computer monitors. Three-dimensional
electric displays activated by laser beams—called holograms—may be available in the future, but more
conventional products are now available that can meet more important, if less exotic, criteria. Almost all
products of existing GIS are designed to respond to the sense of vision in some manner.
Format
: While the number of visual media that carry information is limited, the number of forms or
formats that information can assume is without limit. An (almost) infinite variety can be obtained with
characters—the 26 letters of the alphabet, Arabic number symbols, and some special symbols. This type
of information is called character-based.
Character-based information can appear in the form of text, tables, lists, formulae, and so on. The way in
which information is organized has a tremendous impact on whether or not it will be useful. Character-
based information can be processed by an individual in serial fashion (like a reader “processing” this line
of text) or in search mode—a procedure in which a person examines unconnected groups of characters in
order to find desired information. Looking up a number in a telephone directory exemplifies use of the
search mode—a procedure in which a person examines unconnected groups of characters in order to find
desired information—followed, of course, by serial mode.
For purposes of mental model building, the best products allow a user of character-based information
to quickly grasp two things: the overall scheme of organization of the information (revealed by tables of
contents, materials on “how to use this information,” executive summaries, etc.) and the subject of the
information itself (illustrated by introductions, table titles, lists of parameters relating to the information,
etc.). Development of products that can meet these criteria is an art and a science.
Graphic information—pictures, photographs, drawings, maps, displays, graphs, diagrams, and so on—is
also as versatile as character-based information.
Simplistically, character-based information is read, while graphic information is viewed. Both can help
a decision maker form a more complete mental model of an issue, but each provides information in
different ways.
It is rare that any information is either totally character-based or graphic. Combinations of the two are
the most effective (graphs have descriptive headings and designations; reports have diagrams and
illustrations), though the process of “marrying” the two is not always straightforward, particularly when
computers are used.
Purpose
: Another classification that might be considered during design of a product from a GIS are the
purposes of that product or information. Some of the possible purposes include the following:
Search WWH ::
Custom Search