Introduction to

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Introduction to Geographic Information Systems
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Definition
Geographic Information Systems are computer
systems for the
Capture Storage Retrieval Analysis Display
of Spatial Information
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Spatial Information
Everything on the Earth's Surface has a location
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Geographic Information may be referenced by
Latitude and Longitude Metric Coordinates
(AMG) Street Address Parcel (property
boundaries) Spatial relationship to other map data
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Maps in Geographic Information Systemsare
represented thematically
Map data is separated into THEMES or OVERLAYS of
discrete information. Hydrologic data is mapped
on a separate overlay from soils or geology.
Geographic Information Systems are
sometimes referred to as Thematic Mapping Systems
or Map Overlay Systems
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THEMES
Mapped themes
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Spatial Query

• The organisation of mapped data by themes allows
  flexible and powerful methods of searching mapped
  data for specific combinations of factors.
• "Locate and Display all playgrounds downstream of
  landfills within 100 year floodplain"

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Query by Attribute

• GIS systems link mapped data to tabular (text)
  data bases. This allows one to query by
  attributes in the database and have the GIS
  display their location as a map.
• "Display all water mains installed before 1950
  with a diameter less than 12 inches"

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Corresponding map feature
Attribute table
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Spatial Information

• In addition to organising spatial data by themes,
  mapped information is also structured as points,
  lines and polygons.

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Point Data

• Examples of point data include location of wells,
  post office, man holes, stream gauges, bird
  nesting sites or control points.

Nesting Sites
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Line Data

• Examples of line data include road networks,
  utility lines, stream drainages, and fault lines.

Stream Drainage
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Polygon Data

• Examples of polygon data include land use,
  vegetation cover, enumeration districts, soil
  types, and zoning.

Land Use
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GIS packages store spatial data in two basic
forms Vector and Raster
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GIS Data Structures Vector

• GIS systems which store map features in vector
  format store points, lines and polygons with
  high accuracy. They are preferred in urban
  applications where legal boundaries and the
  analysis of networks are important.

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GIS Data Structures Raster or Grid

• GIS systems which store map features in raster or
  grid format generalise the location of features
  to a regular matrix of cells. Raster GIS data
  structures are preferred for digital elevation
  modelling, statistical analysis, remotely sensed
  data, simulation modelling and natural resource
  applications.

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GIS Data Integration

• Many GIS systems handle both vector and raster
  data from a wide variety of sources including
  satellite imagery, cadastral information, hand
  digitised maps and scanned images.

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Vector to Raster Conversion
The quality of the result depends on the chosen
cell size
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Geo-referencing

• In order to ensure that all maps in a GIS
  database overlay accurately, the data set is
  "geo-referenced" to a common coordinate system.
  In Australia the Australian Metric Grid is used
  to geo-reference all map data bases.

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Setting Technical Standards

• By setting technical standards for
  geo-referencing, data may be shared by different
  organisations producing GIS data bases.

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Spatial Analysis

• Spatial Analysis is a set of analytical
  procedures applied to GIS data to describe,
  predict, or assess environmental or social
  issues.

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Spatial Analysis Techniques

• Spatial analysis techniques include methods for
• Measuring Distance, and Area
• Interpolating values
• Reclassifying Map Features
• Identifying the co-occurence of values on
  different map themes (overlay analysis)

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Digital Elevation Modelling (DEM)

• There are also specific methods for analysing
  terrain including
• Calculating slope
• Solar aspect
• Viewshed Analysis
• Runoff Analysis

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Automated Cartography and Data Visualisation

• GIS systems also have reasonably sophisticated
  graphic capabilities for map production and data
  visualisation in plan and perspective.

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GIS Applications

• Because GIS systems are designed as a generic
  system for handling any kind of spatial data,
  they are applied in a wide range of applications
  in urban and rural environments.

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Urban GIS Applications - Utilities

• Utilities management - Water, gas, electricity,
  sewer
• Flow demand/analysis - Hydrologic performance of
  utility networks
• Storm water management - Modelling
  surface/subsurface flows, effects of
  retention/detention basins on peak flows

See also http//www.esri.com/library/userconf/pro
c99/proceed/track.htm
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Urban GIS Applications - Health and Safety

• Building Codes - Permit Information, code
  enforcement, permit processing, building
  inspection
• Emergency Services Planning - Location and
  allocation of critical facilities, hazardous
  materials mapping, risk management, flood
  control, evacuation routes, fire incident
  analysis, emergency response analysis
• Health Services - Patient distribution analysis,
  water quality monitoring, disease outbreak
  patterns, medical facilities planning

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Urban GIS Applications - Health and Safety

• Police Services - Crime pattern analysis,
  computer-aided dispatch, response time analysis,
  resource allocation
• Sanitation - Waste collection routing/balancing,
  solid landfill site selection, hazardous waste
  disposal siting.
• Transportation - Traffic incident analysis,
  parking facilities planning, route analysis, road
  maintenance scheduling, traffic engineering,
  traffic zone analysis, traffic management, road
  improvements planning, bus routing/scheduling,
  car pooling services

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Urban GIS Applications - Planning

• Land Use Analysis - Land Use Suitability, Land
  Use mix, area analysis
• Strategic Planning - Land Use trends analysis,
  population projections/distribution, land
  availability, land rent.
• Zoning - Conformance, performance analysis

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Natural Resource GIS Applications

• Agricultural Planning/Conservation - Agricultural
  capability analysis, market analysis, whole farm
  planning
• Forestry - Timber assessment and management,
  Harvest scheduling and planning, environmental
  impact assessment, pest management
• Wildlife - Habitat assessment and management,
  identification of rare/endangered species and
  habitats, impact assessment

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Natural Resource GIS Applications

• Catchment Management - Runoff and erosion
  modelling, sedimentation and water quality
  studies, evaluation of management alternatives,
  integrated catchment management.
• Archaeological Site Conservation - Mapping and
  prediction of prehistoric sites, site vandalism
  studies, site management studies.
• Geology and Mining - Oil, gas and minerals
  exploration. Geologic mapping and terrain
  analysis, open pit mine design and reclamation,
  geologic hazard mapping