April 18, 2007
What is GIS?
A system for capturing, storing,
analyzing and managing data and
associated attributes which are
spatially referenced to the earth.
Why use GIS?
Businesses can use GIS for
demographic reasons such as
• Locating likely customer populations.
• Where to establish new branches, sales
divisions and storage facilities.
Governments use GIS for
• Planning and organizing geographic data
• Keep track of public works and roads
• Computing the locational consequences
ESRI - ARCGIS
Clark Labs - IDRISI
Who uses GIS?
Pepsi and Coke
The Technology Behind GIS
Vector – GIS application that uses
points to store and plot lines and
polygons for infinite precision of
Raster – GIS application that uses
pixels to store and plot geographic
• Measures type, length and time of geographic region
• Used most often in transportation, utility and marketing applications.
• Compact data structure • Complex data structure
• Low storage cost • Difficult to compute
• Best for map output • Cannot store image data
• Can overlay displays easily • Less efficiently stored
• Transfers a spatial area into pixels and
gives them a value
• Resolution of images depends upon pixel
• Measures land
• Easy to create • Must pre-define
• Efficient storage spatial resolution
of dense data • Requires large
• Easy to compute storage space
with. • Can be inefficient
•Great for image • Harder to overlay
data. •Poor with linear
Most GIS systems support both
vector and raster systems but not
• 3D Intergraph