"sistem informasi geografi"
Geographic Information Systems (GIS) an overview Topic structure • GIS defined • GIS applications • GIS development • GIS components 2 Geographical Information System (GIS) … defined – A GIS is a computer based system for the management of geographic data. – Geographic data is any data that is geographically referenced i.e. location known. – Information implies that data are organized to yield useful knowledge – System implies GIS is made up of several inter-related and linked components with different functions 3 Geographic information is ... Everything happens somewhere Geographic Information and Computers – Why store it in the computer • the “modern” way of doing things • utilize the benefits of information technology – compact storage – access by many users – better organization of data » consistency, access formats etc – faster execution of existing tasks – newer kinds of operations possible 5 Compact storage Limited access Data access by many users Doing newer things … data integration Newer kinds of operations are possible … industrial accident scenario Newer kinds of operations … computer rendering of the landscape 3D Visualisation … PCE Pollution Levels GIS vs manual operations PROCEDURE GIS MANUAL Display: seconds few minutes 300-400 properties Query: search for a seconds few minutes property by address Map Analysis: find seconds few hours freehold owners Modelling: shortest path .. street network Example: manipulating a typical cadastral map sheet 13 New opportunities … and dangers The need for caution and disciplinary expertise: an example The task: LOCATE A SUITABLE LANDFILL SITE 14 Selected applications of GIS • (i) Primary Industries and Agriculture: – Irrigation Management, Land Development and Management, Soil Conservation, Resource Management, Forestry Inventory Management, Timber Industry • Environmental Management: – Conservation, Flora and Fauna, Wildlife, National Parks, Pollution Control and Monitoring, Ecological Modelling 19 AGRICULTURAL NON-POINT POLLUTION POTENTIAL Watersheds Slopes Soils Land Use Animal Loading Selected applications of GIS • Disaster Planning: (ii) – Emergency Services, Hazards Monitoring, modelling flood impacts • Facilities Management: – Electricity Utilities, Water Utilities, Gas Utilities, Fire Authorities, Roads Inventory, Telecommunications 23 Selected applications of GIS • Urban GISs: (iii) – Local Government, Urban Planning, Crime Analysis, Cadastral and Land Tax, Housing Development • Marketing Analysis: – Customers, branches, competitors etc 28 GIS for Market Analyses Selected applications of GIS (iv) • Scope of applications … It appears that the application possibility is there for any operation or organisation which uses and depends on geographic information 30 Stages in the development of GIS – inventory applications – data gathering and conversion – analysis applications – project oriented applications – management applications – day to day running of organisations (Crain & MacDonald 1984) 31 GIS development … contributing disciplines (i) – disciplines that have developed concepts for dealing with space – fields that develop geographic data acquisition tools – disciplines that provide theories fundamental to our working with space and automation 32 GIS development … contributing disciplines (ii) – fields making substantial use of automated spatial information systems – fields that provide guidance about information The strength and intellectual interest of the subject … derives from cross-fertilisation among these many fields 33 GIS development ... contributing disciplines (iii) – Geography: – geographical analysis, computer cartography, remote sensing – Surveying: – geodesy, photogrammetry – Computer Science – computer-aided design, database management, AI/expert systems – Others – Statistics, Mathematics, Civil Engineering 34 GIS development … related terms – LIS Land information systems – AM/FM Automated mapping/facilities management – FIS Facilities information systems – NRIS Natural resources information systems – others … share common core technology 35 GIS components Real User GIS database World Software Hardware Applications 36 GIS components 5 key components Hardware Software Data People Methods 37 GIS components … data (i) – GIS Database is the heart of the system • stored data relates to geographic features/objects (location and attributes) • formal design methodology – user needs/requirements – conceptual design – physical design – implementation 38 GIS components … data (ii) Data models – Data reduction/simplification • Stages of reduction » real world » GIS representation/data model » computer storage – Common data models – vector models – raster models 39 Geographic information is ... GIS components … data (iii) Vector and Raster models – Vector models – points, lines, polygons – more complex objects Real World – Raster models – grid cell – Vector vs raster – extended debate Vector Raster 41 GIS components … data (iv) • for further consideration ... • data model to be used • geographic and temporal scales • primary / secondary data • sources • metrics 42 GIS components … software • hardware support (i) » making the machinery work – data input/conversion ... – data management functions ... – mapping, analysis and modelling functions ... 43 GIS components … software (ii) – data input/conversion • for loading data into and out of package • map digitising and editing capability • coordinate projection and transformation functions • edgematching capabilities • ... 44 GIS components … software (iii) – data management functions • manage attribute and graphic data and their links • database functions on attribute data » data definition and entry » update, change, query, sort etc » statistical calculations 45 GIS components … software (iv) – mapping, analysis and modelling functions • support for display/mapping functions • analytical operations » map overlay, buffering, nearest neighbour analysis etc • “what if” capabilities • modelling (DEMs, watersheds etc ...) 46 Stored as discrete elements Displayed as integrated data Queries … in either direction using whatever data that is available GIS components … software (v) – Application differences in terms of • purposes • themes of information • types of data • particular tools • specific processing requirements • specific forms of data organisation 52 GIS components … software (vi) – “close relatives”… software handling geographic data • Computer aided drawing (CAD) • Desktop mapping systems • 3D GIS • Contouring and surface mapping packages • Image processing systems (IP) • DBMSs 53 GIS components …hardware INPUT DEVICES CENTRAL OUTPUT DEVICES digitisers, scanners... PROCESSING UNIT VDUs, plotters... CPU STORAGE DEVICES harddisks, CD-ROMs.. 54 GIS Hardware CPUs Creating graphic data for GIS applications GIS components … people aspects (i) – organisational issues – to deal with the introduction and management of new technology – methodological issues – not always purely technical issues – user interfaces – the management of individual’s interaction with the system 59 GIS components … people aspects (ii) organisational issues – implementation a complex process – management of technological change – restructuring of work methods – various organisational impacts: data handling, staffing, funding etc. – “little empires” ... integration may make people less important – ... 60 GIS components … people aspects (iii) methodological issues – new staffing requirements – “someone” to make decisions: – data model used – map scale etc – entity selection and information filtering – interaction between users – interfaces – types of users – types of interfaces 61 GIS ... some misconceptions • that a manual system can be quickly transformed into a GIS • that GIS has the ability to turn poor quality data into good quality data • that the user does not need to be competent in the application he/she is seeking to develop • that the problem/issue is always a technical one rather than one that may involve organisational matters 62