Characteristics and Examples of Spatial Data - Introducing Geographic Information Systems with ArcGIS - page 102

An information system , in the context of this material, is a set of steps, or set of processes that is executed
by a “device” to produce information. We choose to call the symbols that are input to the process by two
names: data and parameters. “Data” we have discussed along with its formation into bases. “Parameters”
we consider to be information, which the user of an information system supplies at the time of use of the
system. Such parameters might specify which data in the base are to be used, how they are to be combined,
what the format of the resulting information—output—is to be, and other specifications and/or constraints.

For an example, a professor may assign a student the task of compiling a bibliography of the works
of Shakespeare. The database might be a library catalog; the parameters are such descriptive terms as
“bibliography.” “Shakespeare,” “word-processed”; the device is the student, who, with his eyes,
pencil, word processor, and so on produces the information. Figure 2-4 is a diagram of a generic
information system.

A Garden-Variety Information System

Inputs Processing Outputs

Parameters :

Supplied by system
user to deine a
particular request
for information

Device : Information:

Equipment with
capacity to combine
or manipulate inputs
so they become outputs

To aid human
understanding
and decision
making

Database :

Data gathered
together over time
to support requests
of users

FIGURE 2-4 Schematic of a general information system

In Summary

Based on the preceding discussion of spatial data, databases, and information systems, we can offer
yet another definition of a GIS: A geographic information system is an information system that has
its primary source of input a base composed of data referenced by spatial (or land, or geographic)
coordinates. The system accepts parameters, examines its database, and provides information for
decision making and resource management. In an automated spatial information system, a major part
of the device that does the processing is an electronic digital computer. Much of the database it uses is
stored on computer hard drives in servers or PCs.