What is GIS?


    What is a GIS? 
    • a particular form of Information System applied to geographical data
    • a System is a group of connected entities and activities which interact for a common purpose
      • a car is a system in which all the components operate together to provide transportation
    • an Information System is a set of processes, executed on raw data, to produce information which will be useful in decision-making
      • a chain of steps leads from observation and collection of data through analysis
      • an information system must have a full range of functions to achieve its purpose, including observation, measurement, description, explanation, forecasting, decision-making
    • a Geographic Information System uses geographically referenced data as well as non-spatial data and includes operations which support spatial analysis
      • in GIS, the common purpose is decision-making, for managing use of land, resources, transportation, retailing, oceans or any spatially distributed entities
      • the connection between the elements of the system is geography, e.g. location, proximity, spatial distribution
    • in this context GIS can be seen as a system of hardware, software and procedures designed to support the capture,

    • management, manipulation, analysis, modeling and display of spatially-referenced data for solving complex planning and management problems

      • although many other computer programs can use spatial data (e.g. AutoCAD and statistics packages), GISs include the additional ability to perform spatial operations
    Alternative names 
    • alternative names which people have used over the years illustrate the range of applications and emphasis
    Why is GIS important? 
    • "GIS technology is to geographical analysis what the microscope, the telescope, and computers have been to other sciences.... (It) could therefore be the catalyst needed to dissolve the regional-systematic and human- physical dichotomies that have long plagued geography" and other disciplines which use spatial information.1
    • GIS integrates spatial and other kinds of information within a single system - it offers a consistent framework for analyzing geographical data
    • by putting maps and other kinds of spatial information into digital form, GIS allows us to manipulate and display geographical knowledge in new and exciting ways
    • GIS makes connections between activities based on geographic proximity
      • looking at data geographically can often suggest new insights, explanations
      • these connections are often unrecognized without GIS, but can be vital to understanding and managing activities and resources
      • e.g. we can link toxic waste records with school locations through geographic proximity
    • GIS allows access to administrative records - property ownership, tax files, utility cables and pipes - via their geographical positions
    Why is GIS so hot? 
    • high level of interest in new developments in computing

    • ____________________ 1Abler, R.F., 1988. "Awards, rewards and excellence: keeping geography alive and well," Professional Geographer, 40:135-40.
    • GIS gives a "high tech" feel to geographic information
    • maps are fascinating and so are maps in computers
    • there is increasing interest in geography and geographic education
    • GIS is an important tool in understanding and managing the environment
    Market value of GIS 
    • Fortune Magazine, April 24, 1989 published a major, general-interest article on the significance of GIS to business:
    • GIS is described as a geographical equivalent of a spreadsheet, i.e. allows answers to "what if" questions with spatial dimensions
    • an example of the value of GIS given in the article is the Potlatch Corporation, Idaho
      • controls 600,000 ac of timberland in Idaho - 4,900 separate timber stands
      • old method of inventory using hand-drawn maps meant that inventory was "hopelessly out of date"
      • $180,000/year now being spent on GIS-based inventory "a bargain"
      • GIS "gives Potlatch up-to-the-minute information on the status of timber.... A forest manager sitting at a terminal can check land ownership changes in a few minutes by zooming in on a map"
      • $650,000 on hardware and software produces more than 27% annual return on investment
    • GIS market
      • Dataquest projected a market of $288 million in 1988, $590 million in 1992 for GIS, growing at 35% per year
      • ESRI of Redlands, CA, developers of ARC/INFO, had 350 employees and sales of $40 million in 1988 and a reported 42% increase in sales in 1989
      • Intergraph had 1988 sales of $800 million in a more diverse but GIS-dominated market
      • the 1989 edition of GIS Sourcebook listed over 60 different "GIS" programs (though not all of these have complete GIS functionality) and over 100 GIS consultants (US)
    • GIS is a convergence of technological fields and traditional disciplines
    • GIS has been called an "enabling technology" because of the potential it offers for the wide variety of disciplines which must deal with spatial data
    • each related field provides some of the techniques which make up GIS
      • many of these related fields emphasize data collection - GIS brings them together by emphasizing integration, modeling and analysis
    • as the integrating field, GIS often claims to be the science of spatial information
    • broadly concerned with understanding the world and man's place in it
    • long tradition in spatial analysis
    • provides techniques for conducting spatial analysis and a spatial perspective on research
    • concerned with the display of spatial information
    • currently the main source of input data for GIS is maps
    • provides long tradition in the design of maps which is an important form of output from GIS
    • computer cartography (also called "digital cartography", "automated cartography") provides methods for digital

    • representation and manipulation of cartographic features and methods of visualization
    Remote Sensing 
    • images from space and the air are major source of geographical data
    • remote sensing includes techniques for data acquisition and processing anywhere on the globe at low cost, consistent update potential
    • many image analysis systems contain sophisticated analytical functions
    • interpreted data from a remote sensing system can be merged with other data layers in a GIS
    • using aerial photographs and techniques for making accurate measurements from them, photogrammetry is the source of most data on topography (ground surface elevations) used for input to GIS
    • provides high quality data on positions of land boundaries, buildings, etc.
    • source of high accuracy positional control for GIS
    • many models built using GIS are statistical in nature, many statistical techniques used for analysis
    • statistics is important in understanding issues of error and uncertainty in GIS data
    Operations Research 
    • many applications of GIS require use of optimizing techniques for decision-making
    Computer Science 
    • computer-aided design (CAD) provides software, techniques for data input, display and visualization, representation, particularly in 3 dimensions
    • advances in computer graphics provide hardware, software for handling and displaying graphic objects, techniques of visualization
    • database management systems (DBMS) contribute methods for representing data in digital form, procedures for system design and handling large volumes of data, particularly access and update
    • artificial intelligence (AI) uses the computer to make choices based on available data in a way that is seen to emulate human intelligence and decision-making - computer can act as an "expert" in such functions as designing maps, generalizing map features
      • although GIS has yet to take full advantage of AI, AI already provides methods and techniques for system design
    • several branches of mathematics, especially geometry and graph theory, are used in GIS system design and analysis of spatial data
    Civil Engineering 
    • GIS has many applications in transportation, urban engineering
    • address matching - finding locations given street addresses
    • vehicle routing and scheduling
    • location analysis, site selection
    • development of evacuation plans
    Natural resource-based 
    • management of wild and scenic rivers, recreation resources, floodplains, wetlands, agricultural lands, aquifers, forests, wildlife
    • Environmental impact analysis (EIA)
    • viewshed analysis
    • hazardous or toxic facility siting
    • groundwater modeling and contamination tracking
    • wildlife habitat analysis, migration routes planning
    Land parcel-based 
    • zoning, subdivision plan review
    • land acquisition
    • environmental impact statements
    • water quality management
    • maintenance of ownership
    Facilities management 
    • locating underground pipes, cables
    • balancing loads in electrical networks
    • planning facility maintenance
    • tracking energy use
    • data acquisition - from maps, images or field surveys
    • data input - data must be input from source material to the digital database
    • data storage - how often is it used, how should it be updated, is it confidential?
    Data Analysis Subsystem 
    • retrieval and analysis - may be simple responses to queries, or complex statistical analyses of large sets of data
    • information output - how to display the results? as maps or tables? Or will the information be fed into some other digital system?
    Information Use Subsystem 
    • users may be researchers, planners, managers
    • interaction needed between GIS group and users to plan analytical procedures and data structures
    Management Subsystem 
    • organizational role - GIS section is often organized as a separate unit within a resource management agency (cf. the Computer Center at many universities) offering spatial database and analysis services
    • staff - include System Manager, Database Manager, System Operator, System Analysts, Digitizer Operators - a typical resource management agency GIS center might have a staff of 5-7
    • procedures - extensive interaction is needed between the GIS group and the rest of the organization if the system is to function effectively

    • In this course all of these subsystems will be examined. 

1 comment:

  1. GIS definitions by prof .kvk-s2 (A) ,PH.D researcher S.M.alsubari 24-12-2013