Title: Introduction to
1Introduction to Geographic Information Systems
2Definition
Geographic Information Systems are computer
systems for the
Capture Storage Retrieval Analysis Display
of Spatial Information
3Spatial Information
Everything on the Earth's Surface has a location
4Geographic Information may be referenced by
Latitude and Longitude Metric Coordinates
(AMG) Street Address Parcel (property
boundaries) Spatial relationship to other map data
5Maps 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
6THEMES
Mapped themes
7Spatial 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"
8Query 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"
9Corresponding map feature
Attribute table
10Spatial Information
- In addition to organising spatial data by themes,
mapped information is also structured as points,
lines and polygons.
11Point Data
- Examples of point data include location of wells,
post office, man holes, stream gauges, bird
nesting sites or control points.
Nesting Sites
12Line Data
- Examples of line data include road networks,
utility lines, stream drainages, and fault lines.
Stream Drainage
13Polygon Data
- Examples of polygon data include land use,
vegetation cover, enumeration districts, soil
types, and zoning.
Land Use
14GIS packages store spatial data in two basic
forms Vector and Raster
15GIS 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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17GIS 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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19GIS 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.
20Vector to Raster Conversion
The quality of the result depends on the chosen
cell size
21Geo-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.
22Setting Technical Standards
- By setting technical standards for
geo-referencing, data may be shared by different
organisations producing GIS data bases.
23Spatial Analysis
- Spatial Analysis is a set of analytical
procedures applied to GIS data to describe,
predict, or assess environmental or social
issues.
24Spatial 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)
25Digital Elevation Modelling (DEM)
- There are also specific methods for analysing
terrain including - Calculating slope
- Solar aspect
- Viewshed Analysis
- Runoff Analysis
26Automated Cartography and Data Visualisation
- GIS systems also have reasonably sophisticated
graphic capabilities for map production and data
visualisation in plan and perspective.
27GIS 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.
28Urban 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
29Urban 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
30Urban 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
31Urban 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
32Natural 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
33Natural 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