General Information


What is GIS?

    GIS stands for 'geographic information system', a special kind of information system using
    computers to work with information special information about what is where on the Earth's surface

    There are many kinds of information:

    • numbers:
      computers are used to add, multiply, divide, ...

    • text:
      computers are used as word processors to create, edit, send, and receive text
    • pictures:
      computers are used as image processors
    • lists or tables:
      in spreadsheets
    • sounds:
      in music synthesizers
    • maps and images of the Earth's surface:
      in GIS

    why use computers to handle information?

    easy to store, retrieve, query, manipulate, send, receive, copy, display...

    Most of these things can be done by hand, but only slowly.

    Paper maps are difficult to handle, store, send, receive, copy...

    GIS makes all of these operations easier.

    Today, all kinds of information are being handled in computers. It is good to have one place to go for all kinds of information. One system, the Internet, is used to send, receive all kinds of information.

    What Does a GIS Look Like:
    How Would I Know One if I Saw One?

    There are two distinct meanings of the question "is this a GIS?"

    1. a real application, including the hardware, data, and software needed to solve a problem

    2. a type of software sold by a software developer (compare Microsoft Word)

    focus on (1) first

    • like any other computer (nothing special about the hardware) keyboard, display monitor (screen), cables, Internet connection

    • some extra bits perhaps
      • maps come in big bits of paper
      • need specially big printers, plotters to make map output from GIS
      • need specially big devices to scan, input data from maps to GIS digitizers, scanners
    • not all GISs will need these.
    • what's important is the kind of information that's stored
      • information about what is where
      • the contents of maps and images
      • you'd know a computer was being used for GIS because the data stored in it would include maps and images>/p>

      • but in addition, a GIS includes the tools to do things with this information (special software) special functions that work on geographic information functions to:

        • display on the screen
        • edit, change, or transform data
        • measure distances, areas
        • combine maps of the same area together


          those were simple, but functions can be much more sophisticated

        • keep inventories of what is where
        • manage properties, facilities
        • judge the suitability of areas for different purposes
        • help users make decisions about places, plane
        • make predictions about the future


    The functions that a GIS can perform are part of its software.

    • Now we're into the second meaning above - A GIS is a type of software. This software will probably have been supplied by a company that specializes in GIS. The user will have combined the software with his or her data.

      The price of the software may be anywhere from $50 to $50,000. There are many different GIS software vendors: some specialize in GIS, for others, GIS is one of many markets for their products.

    • why go to all this trouble and expense?<
    • who needs to know what is where?
    • these are just a few of the most important uses:
      • utility companies gas, phone, electric, water, cable TV a single company may have hundreds of thousands of customers each with a connection to the network: thousands of miles of wires, underground pipes, transformers, switches, manholes, poles... billions of dollars of installed infrastructure.

        thousands of maintenance calls per day

        • need to keep track of all this
        • need to maintain accurate information about what is where
        • need to keep records up to date
        • need to make daily work assignments to crews
        • need to provide information to others - e.g. another company wishing to dig up a street


          what are they likely to need to avoid?

      • transportation

        a state department of transportation may:

        • need to store information on the state of pavement everywhere on the state highway network
        • need to maintain an inventory of all highway signs
        • need to analyze data on accidents, look for 'black spots'
      • a traveling salesperson
        needs a system in the car for finding locations, routes
      • a delivery company, e.g. Federal Express, UPS
        • need to keep track of shipments, know where they are
        • need to plan efficient delivery routes
      • a school bus operator
        need to plan efficient collection routes
      • a transit authority


        need to know where transit vehicles are at all times. Studies have shown substantial savings when routes and schedules are managed using GIS

      • farmers
        increasingly use detailed maps, images to:

        • plan crops
        • analyze yields
        • plan efficient application of fertilizers, chemicals
        these techniques are known as 'precision agriculture'
      • forestry
        • need to keep track of what timber is growing where
        • need to be able to plan timber harvest
        • how to provide for timber needs now, but maintain a healthy forest resource for the future
        • need to plan locations of roads, methods of cutting and removing logs, to comply with environmental regulations
        • need to manage forests for many purposes, including recreation


    What is There to Learn About GIS?

    • what will it take to be an effective user of GIS?

    defining a GIS project

    • what data will I need?
      • how detailed must the data be?
      • how will the data be manipulated?
    • where will the data come from?
      • off the Internet
      • how to search for geographic data
      • creating data from paper maps by digitizing or scanning
    • how to build a database
      • there are many different ways
      • data come in different formats
    • how to operate a GIS
      • what kinds of GIS are there?
      • finding the right functions
      • how to make a good display or map
    • understanding the results
      • what do they tell me about the real world?