Geographic Information Systems Geographic Information SystemsGIS is a System of computer software, hardwareand data, and personnel to help manipulate,analyze and present information that is tied to aspatial location – • spatial location – usually a geographic location • information – visualization of analysis of data • system – linking software, hardware, data • personnel – a thinking explorer who is key to the power of GIS
What is GIS?• There are probably as many definitions of GIS as there are authors on GIS but there are certain fundamental components that remain the same throughout:1. Geographic locations also called geographically referenced or spatial data2. Information about the locations also called Attributes or Non-Spatial data3. Software for storing and processing the data4. Hardware to facilitate the storage, processing and distribution of data5. The people who operate the systems
GIS Definitions• An organized collection of computer hardware, software, geographic data and personnel designed to efficiently capture, store, update, manipulate, analyze and display all forms of geographically referenced information.• In summary, Demers describes GIS as consisting of 4 sub-systems1. A Data Input subsystem that collects and preprocesses spatial data2. A data storage and retrieval subsystem that organizes the spatial data3. A data manipulation and analysis subsystem that performs tasks on the data4. A reporting subsystem that displays the data in tabular, graphic or map form.
• A method to visualize, manipulate, analyze, and display spatial data• “Smart Maps” linking a database to the map
• GPS – Global Positioning System• A static map – paper or digital – Maps are often a “product” of a GIS – A way to visualize the analysis• A software package
History• Pre-computer – Early maps• CGIS• Harvard• No books till around 1990 (Star & Estes) that dealt with GIS by computer• Theory books – Burroughs – Ian McHarg’s History of CAD Graphics
Contributing Sciences• Geography - generally concerned with man and his environment.• Cartography - for the display of spatial information in the form of maps. Maps are graphic representations of the real world.• Computer Science - Provides the hardware, software and techniques for accomplishing the essential functions of a GIS• Surveying and Photogrammetry - Provides the geographic locations• Remote Sensing - A source of data from satellite images and aerial photography• Global Positioning System (GPS) - A source of highly accurate locational data and navigation tool.• Database Technology - Handles large volumes of data in tabular form, making it easy to store, access and manipulate data.• Mathematics - The use of geometry, statistics are integrated in a GIS• CAD (Computer Aided Design) - A tool for accurately designing maps digitally.
How does a GIS differ from CAD or Database Systems1. The ability to construct topology in a GIS and therefore to perform complex spatial analysis2. The ability to link the traditional cartographic-type of map to a database and perform complex queries, interacting with both.
What is it used for?1. Can you map that?2. Where is what?3. Where has it changed?4. What relationships exist?5. Where is it best?6. What affects what?7. What if...?
• Estimates are that 80% of all data has a spatial component – Data from most sciences can be analyzed “spatially”
Database Database“Not Easy to Interpret”“Not Easy to Interpret”
Visualization Visualization“Worth a Thousand Words”“Worth a Thousand Words”
Two Ways to Input and Visualize Data Two Ways to Input and Visualize Data The World in GIS The World in GIS • Raster – Grid – “pixels” – a location and value – Satellite images and aerial photos are already in this formatReal world • Vector – Linear – Points, lines & polygons – “Features” (house, lake, etc.) – Attributes – size, type, length, etc.
• Digitized and Scanned Maps – purchased, donated, free (Internet) – created by user• Data Bases – Tables of data• GPS – Global Positioning System – accurate locations• Field Sampling of Attributes• Remote Sensing & Aerial Photography
Five Data Layers Five Data Layers “Alike” Features “Alike” FeaturesRivers CapitalsRoads States Lakes
Turning Data Into InformationTurning Data Into Information “Spatial Analysis” – not just a map
Asking A Question – InteractionAsking A Question – Interaction
Maps and Database areMaps and Database are “Interactive” “Interactive”
Multiple Databases can beMultiple Databases can be Linked and Related Linked and Related
• Emergency Services – Fire & Police• Environmental – Monitoring & Modeling• Business – Site Location, Delivery Systems• Industry – Transportation, Communication, Mining, Pipelines, Healthcare• Government – Local, State, Federal, Military• Education – Research, Teaching Tool, Administration Wherever Spatial Data Analysis is Needed