GEOGRAPHIC INFORMATION SYSTEMS
Exercise 2: Geographic Information Systems (GIS)
1. This lab manual.
edition, 2004, by R. Christopherson.
3. GIS database for Calvert County, MD--provided in computer laboratory.
4. Workstation running ArcGIS software--provided in computer laboratory.
1. This exercise—be familiar with all terms in
2. Pages 25-32 in
In the ArcGIS software, different data layers are called
. The themes in the
Calvert County database include county boundary, roads, water, major soils, elevation and land
use. The object of the exercise will be to comprehend the basics of a GIS including the concepts
of georeferencing, overlaying of the various themes, and spatial analysis of theme attributes.
Each of the themes has an associated spreadsheet table that contains columns of information such
as ownership, location, and size (area).
Geographic Information Systems
“Geographical information systems should be thought of as being very much more than a
means of coding, storing, and retrieving data about aspects of the earth's surface. In a
very real sense the data in a geographical information system .
.. should be thought of as
representing a model of the real world. Because these data can be accessed, transformed,
and manipulated interactively in a geographical information system, they can serve as a
test bed for studying environmental processes or for analyzing the results of trends, or of
anticipating the possible results of planning decisions. By using the GIS in a similar way
that a trainee pilot uses a flight simulator, it is, in principle, possible for planners and
decision-makers to explore a range of possible scenarios and to obtain an idea of the
consequences of a course of action before the mistakes have been irrevocably made in the
-- From Burrough, P.A. (1986).
Principles of Geographical Information Systems
Oxford: Clarendon Press, page 6.
A Geographic Information System (
) is a “computer-based, data-processing tool for
gathering, manipulating and analyzing geographic information” (
, p.31). Geographic
information systems are capable of assembling, storing, manipulating and displaying data
according to their locations. They differ from digital cartography, spreadsheets, or other database
management systems in that all data in a GIS is likely to be connected to real world coordinates.