Page 111 - DCAP208_Management Support Systems

Management Support Systems

Notes GIS therefore refers to a set of three aspects of our modern world, and offers new ways to deal
with them. Geographical Information Systems (GIS) are computer-based systems that enable
users to collect, store, process, analyze and present spatial data.
It provides an electronic representation of information, called spatial data, about the Earth’s
natural and man-made features. A GIS references these real-world spatial data elements to a
coordinate system. These features can be separated into different layers. A GIS system stores
each category of information in a separate “layer” for ease of maintenance, analysis, and
visualization.

Example: Layers can represent terrain characteristics, census data, demographics
information, environmental and ecological data, roads, land use, river drainage and flood plains,
and rare wildlife habitats. Different applications create and use different layers.
A GIS can also store attribute data, which is descriptive information of the map features. This
attribute information is placed in a database separate from the graphics data but is linked to
them.
A GIS allows the examination of both spatial and attribute data at the same time. Also, a GIS lets
users search the attribute data and relate it to the spatial data. Therefore, a GIS can combine
geographic and other types of data to generate maps and reports, enabling users to collect,
manage, and interpret location-based information in a planned and systematic way.

Notes In short, a GIS can be defined as a computer system capable of assembling, storing,
manipulating, and displaying geographically referenced information.

GIS is used to display and analyze spatial data which are tied to a relational database. This
connection is what gives GIS its power: maps can be drawn from the database and data can be
referenced from the maps. When a database is updated, the associated map can be dynamically
updated as well. GIS databases include a wide variety of information: geographic, social, political,
environmental, and demographic.
GIS uses layers, called “themes,” to overlay different types of information, much as some static
maps use mylar overlays to add tiers of information to a geographic background. Each theme
represents a category of information, such as roads or forest cover.

!
Caution As with the old mylar maps, the layers which are underneath remain visible
while additional themes are placed above.
Figure 7.4: GIS Themes

Source: http://www.mohaminfo.com/ITServices/Services/gis.aspx

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