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Lesson Objectives
Understand how a GIS functions
Understand what a GIS is
Look at some GIS applications
Understand how spatial data isrepresented in a GIS
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Data vs.Information
Data, by itself, generally differs frominformation.
Data is of little use unless it is transformedinto information.
Information is an answer to a questionbased on raw data.
We transform data into informationthrough the use of an Information System.
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INFORMATION SYSTEMOVERVIEW
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What is an InformationSystem?
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What is an InformationSystem?
Information systems can be very simple,
such as a telephone directory.
Data
Storage
Information System
Query
Information
Wh i I f i
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What is an InformationSystem?
In the digital environment we use software to
create complex information systems.
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What is a GIS?
A means of storing,
retrieving, sorting,
and comparing
spatial data
to support some
analytic process.
+
Information System
Geographic Position
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GIS links graphical features (entities) to tabular data(attributes)
What is a GIS?
GEOGRAPHIC Information System
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A GIS is a system (hardware + databaseengine) that is designed to efficiently,
assemble, store, update, analyze, manipulate,and display geographically referencedinformation (data identified by theirlocations).
A GIS also includes the people
operating the system and the datathat go into the system.
GIS Definition
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Data can be:
1. Positioned by its known spatialcoordinates.
2. Input and organized (generally inlayers).
3. Stored and retrieved.
4. Analyzed (usually via a RelationalDBMS).
5. Modified and displayed
Key Functions of a GIS
Geographic Information
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Decision
GISProcessOutput
GIS
analysis
Import or
build datasets
Define GIS
criteria
Define
problemDecision
GISProcessOutput
GIS
analysis
Import or
build datasets
Define GIS
criteria
Define
problem
Geographic InformationSystems
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MODELLING AND
STRUCTURING DATA
(How we represent features or spatialelements)
Representing Spatial
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Representing SpatialElements
RASTER
VECTOR
Real World
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Entity Representations
Points - simplestelement
Lines (arcs) - set ofconnected points
Polygons - set ofconnected lines
We typically represent objects in space as three
distinct spatial elements:
We use these three spatial elements to represent real world features andattach locational information to them.
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Raster vs. Vector
RasterAdvantagesThe most common data format
Easy to perform mathematical and overlay operations
Satellite information is easily incorporated
Better represents continuous- type data
VectorAdvantages
Accurate positional information that is best for storing discretethematic features (e.g., roads, shorelines, sea-bed features.
Compact data storage requirements
Can associate unlimited numbers of attributes with specific features
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GIS FUNCTIONALITY
(What do they do?)
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Data Assembly
Data Storage
Spatial Data Analysis andManipulation
Spatial Data Output
GIS Functions
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GIS Functions
Data Assembly
Maps RSI
Intel Database Direct Entry
Keyboard
GPS
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Data Input/Creation
GIS F i
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Spatial data(ARC functions)
Attribute data(INFO or TABLES functions)
1 (Universe polygon)
2 3
4 5
GIS Storage
3
COV# ZONE ZIP
1 02 C-19 22060
3 A-4 22061
4 C-22 22060
5 A-5 22057
GIS Functions
3 A-4 22061
GIS F ti
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Common Manipulation
Reclassification
Map Projection changes
Common Analysis
Buffering
Overlay
Network
Spatial Data Manipulation and Analysis
GIS Functions
Spatial Anal sis
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Spatial Analysis
Overlay function creates new
layers to solve spatial problems
GIS F ti
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Tables
Maps
Interactive Displays
3-D Perspective View
Spatial Data Output
GIS Functions
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SOME EXAMPLES
AND APPLICATIONS
Amphibious Assault
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Amphibious AssaultPlanning
S ti l A l i
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Spatial Analysis
Proximity Analysis (Buffers)
1000 Meter Buffer of Railroads
Fli ht Pl i
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Flight Planning
Flight Planning/Flythroughs
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Flight Planning/Flythroughs
Other GIS Applications
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Other GIS Applications
Cross country movement
Route planning Intervisibility study
Facilities management
Airfield assessment
Road network analysis (convoys)
Propagation coverages
Observation post siting analysis
Perspective views
Facilities Management
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Facilities Management
Airfields
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Airfields
Network Analysis
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Network Analysis
A t P ti C
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Antenna Propagation Coverages
Perspective Views
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Perspective Views
SUMMARY
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SUMMARY
Key Concepts
Data representation
Applications