gis
TRANSCRIPT
Contents
1. Definition 2. Uniqueness 3. Background 4. GIS components 5. Characteristics of spatial data 6. Spatial Data Modelling 7. Spatial data storage and Comperison 8. Modelling in real world 9. Database and GIS10. Benefits and Applications of GIS
GIS: a formal definition
“A system for capturing, storing, capturing, storing, checking, integrating, manipulating, checking, integrating, manipulating, analysinganalysing and displayingdisplaying data which are spatially referenced to the Earth.”
This is normally considered to involve a spatially referenced computer database and appropriate applications software.
Why is GIS unique?
➲ GIS handles SPATIAL information Information referenced by its location in space
➲ GIS makes connections between activities based on spatial proximity
GIS concepts are not new!➲ London cholera epidemic 1854
Cholera deathCholera death
Water pumpWater pump
GIS: background
This technology has developed from: Digital cartography and CAD Data Base Management Systems
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ATTRIBID X,Y123
ID123
CAD SystemCAD System Data Base Management SystemData Base Management System
DigitalDigitalMappingMapping
Photo-Photo-grammetrygrammetry
ComputerComputerAidedAided
DesignDesign
SurveyingSurveying
RemoteRemoteSensingSensing
DatabasesDatabases
GISGIS
Cross-disciplinary nature of GIS
Relation between GIS components
Specific applications / decision making objectives
G I SG I S
Spatial data
Computer Computer hardware / / software toolssoftware tools
What makes data spatial?
PlacenamePlacenameAddressAddress
PostalCodePostalCode
DistanceDistanceDescriptionDescription
Latitude/Longitude Latitude/Longitude
Characteristics of spatial data
Geometry➲ The shape of a
building or county➲ The course of a river➲ The route of a road➲ The shape of the
landscape
Characteristics of spatial data
➲ Topology• Connected to . . .
• Within . . .
• Adjacent to . . .
• Opposite of . . .
• North of . . .
• Opposite of the Main Hostel building
• Adjacent to M.G. Road
• North of HOWRAH station
Characteristics of spatial data
➲ Location with Attributes
Name : Samhati Soor Address: 5 Market Place Town: Contai Tel. No: 03220-287871 Floor space: 1300 sq ft Postal Code: 721401 Latitude: 21.78° N Longitude: 87.75° E
• Features
– Buildings– Road centrelines
– Lamp columns
– Gas pipes– CTV Access covers– Road surfaces
Spatial Data Modelling - step 1
Spatial data storage
➲ Vector model
➲ Raster model
point
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2,5
5,4
4,1
7,105,9
4,7
6,68,6
9,8
line
polygon
2,2
5 10
5
10
as geometric objects: points, lines, polygons
as image files composed of grid-cells (pixels)
Comparison between vector model and raster model
VECTOR
Advantages:1.Good representation of reality2.Compact data structure3.Topology can be described in
a network4.Accurate graphics
RASTER
Advantages:1.Simple data structure2.Easy overlay3.Various kinds of spatial
analysis4.Uniform size and shape5.Cheaper technology
Disadvantages:1.Large amount of data2.Less “pretty”3.Projection transformation is difficult4.Different scales between layers can be a nightmare5.May lose information due to generalization
Disadvantages:1.Complex data structures2.Simulation may be difficult3.Some spatial analysis is difficult or impossible to perform
Modelling in real world
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1 2 24 45
1 3 52 55
2 1 0 45 46 40
...
0 0 0 0 0 0 0 2 0 0 0 0 0 0 1 0 0 0 0 2 0 0 1 0 0 0 0 0 0 0 0 2 0 0 0 0 2 2 2 0 1 ...
x
y
Databases & GIS
• At a simple level a GIS may just form the graphical interface to a database
• The majority of GIS applications follow this example Linked database tableLinked database table
Spatial datSpatial dataa
SQL Query ManagerSQL Query Manager
MapInfoMapInfo
The benefits of GIS include:
➲ Better information management
➲ Higher quality analysis
➲ Ability to carry out “what if?” scenarios
➲ Improve project efficiency
GIS Applications
➲ Facilities management➲ Marketing and retailing➲ Environmental➲ Transport/vehicle routing➲ Health➲ Insurance
and many more . . .
References
1.https://www.llnl.gov/str/September02/pdfs/09_02.2.pdf 2.Geographic information system - Wikipedia, the free
encyclopedia 3.http://www.gim-
international.com/download/whitepaper_uploadfile_3.pdf 4.GIS (geographic information system) - National Geographic
Education 5.OECD Glossary of Statistical Terms - Geographic
information Definition 6.What is GIS (Geographic Information Systems)? A Word
Definition From Webopedia 7.http://www.nwgis.com/gisdefn.htm 8.GIS OUTLINE www.grossmont.edu 9.What Is GIS? | Geographic Information Systems www.esri.com10.http://unstats.un.org/unsd/publication/SeriesF/SeriesF_79
E.pdf