geographical information system (GIS) is a system of hardware, data, people, organizations, and institutional arrangements for storing, analyzing, and disseminating spatially-linked information
in other words, GIS is a computer based set of procedures for assembling, storing, manipulating, analyzing and displaying geographically referenced information.
it is the system that uses geographical data for purposes such as providing information that can be used for making decisions. it is a complex computer system that can hold and use data that describes places on the earth’s surface
components of geographical information system
- hardware: these include CPU, screen, keyboard, mouse, scanner, printer, digitizing tablet
- software: these include application programme such as arcview
- data: thses include maps, aerial photos, setellite images, adminstrative records etc,
- people: include data captures. data users, GIS analyst etc
- Methods: GIS design according to user’s needs
The characteristics that make a Geographical Information System (GIS) unique:
GIS applications are built around the notion that location matters. The question of where things are, or spatial distribution of subject matters is crucial to making informed decision in disaster management, environmental monitoring, marine biology research, facilities management, community development, marketing, and campaign just to name a few.
GIS is often seen as a special case of information system. Information system is intended to induce the effective use of data by organizing data in some way or another. What distinguishes GIS from other information systems is that data is organized spatially.
For instance, library information system may store literature with no regard to its location. Hurricane tracking system stores “where, when, and what” of hurricanes. This multidimensionality makes GIS data management distinct and complex from a standpoint of general IT professionals. This all originates from the notion of geography that encompasses space, time, and attributes of problems concerned.
Like other information systems, GIS is digital. These days, most of GIS store some information about places as computerized databases, retrieve that information by means of software functions, and share that information through distributed network like internet.
The digital nature of GIS poses both opportunities and challenges. It is hardly easy to manage geographic problems (e.g., finding ways, monitoring air quality, managing natural resources, and tackling climate change) given the scale beyond mundane human cognition.
If we can digitize what was/is going on in the village and community, and connect digital villages through the network, human civilization will be able to do science and business in an entirely different way in few decades. Challenges arise from the very nature of computerization. Computational constructs are finite whereas the world is not. GIS or Digital Earth is never equated with the Earth.
Computerization like virtual reality might augment human sensory inputs, but has virtually no control over creativity and ethics of human mind put into GIS. GIS is never value-free. Technological optimism needs to be exercised with caution.
The field of GIS is hard to define. The truth is that no single discipline can claim the ownership of GIS. Many fields of science and technology shape the making of GIS (e.g., mathematics, computer science, geodesy, cartography, and operations research). Many disciplines and industries participate in the remaking of GIS by contributing applications (e.g., public policy, marketing, civil engineering, and environmental science).
GIS is founded on science, is driven by technology that evolves quickly, and is activated by applications that range widely. Moreover, GIS allows users to see how things are related by gluing different subjects to the geographic frame of reference (picture a layer cake model!). GIS, by putting all things together, gives rise to a new way of understanding and problem-solving.
Aside from the synergy of integrating knowledge directed at a certain purpose, it remains to be seen how well the seam between intellectually contributory patches of GIS can be tied together from knowledge engineering perspectives