What is GIS? A technology ± hardwa hardware re & sof softwa tware re tool toolss
An info inform rmat atio ion n hand handli ling ng stra strate tegy gy The The obje objectiv ctive: e: to impro improve ve over overall all decisi decision on making 2
GIS: a formal definition ³A system for capturing, storing, checking, integrating, manipulating, analysing and displaying data which are spatially referenced to the Earth. This is normally considered to involve a spatially referenced computer database and appropriate applications software´ 3
GIS definition ³« a special case of information system where the database consists of observation son spatially distributed features, activities or events, which are definable in space as points, lines or area. A geographic information systems manipulates data about these points, lines and areas to retrieve data for ad hoc queries and analyses´
Why is GIS unique? GIS GIS han handl dles es SPA SPATI TIAL AL info inform rmat atio ion n ± Informat Information ion referen referenced ced by by its location location in in space
GIS makes makes connec connection tionss betwee between n activ activitie itiess based on spatial proximity
GIS concepts are not new! Lond London on chol choler eraa epi epide dem mic 18 1854
+ Cholera death Water pump
GIS: historical background This technology has developed from: ± Digita Digitall cartogr cartograph aphy y and and CAD ± Data Data Base Manage Manageme ment nt Syste Systems ms ID 1 2
Data Base Management System 7
Digital Digital Mapping Mapping Computer Aided Aided Design esign
Surveying urveying Remote Sensing
Cross-di Cross-disc sciiplin plinary ary nature of GIS GIS
GIS components Spati patial data
GI Computer Comput Computer er hardw hardware are / software tools
Speci pecif ic appli applicati cations / deci decision making making objecti objectives 9
What makes data spatial? Gr id coco-ordin -ord ordin inate ate
Place lacen name
Lat atiitude / Longi ngitude tude Postcode Descr ipt ptiion
Dista Di stan nce & bear ing ing
Characteristics of spatial data Location
Kingsto ingston n Univers Universiity,P ty,Pe enrhynR rhynRo oad
The shape of a building or county The course of a ri river, the route of a road The shape of th the landscape, landscape, relief
Characteristics of spatial data
North of . . .
W ithin ithin
the Royal Borough of Kingston-upon-Thames King ston-upon-Thames
Opposite the Surrey County Council building
North of Surbiton station
Adjacent to Penrhyn Road
Spatial Data: examples Socio ocio-e -eccono onomic data ata ± Region Regional al health health data data ± Consume Consumerr / lifest lifestyle yle profiles profiles ± Geode Geodemo mogr grap aphic hicss
Env Environ ironm mental ntal data data ± Topog Topogra raph phic ic dat dataa ± Themati Thematicc data, data, soils, soils, geolog geology y 14
Data Modelling Modelling - step 1 Features
± Building ldings s ± Road cen centrelin trelines es ± Lamp column columns ± Gas p ipes ± CTV A TV Access ccess covers ± Road surfaces
Data Data Mode Modell llin ing g - step step 2 Poin intt Line Lin e Poly olyg gon
Data ata Mod Model elli ling ng - step step 3
Object: Enttity: En
Build lding ing Poly olyg gon Tour ist Informat In formatiion Bureau 17
Name : Address: A ddress: Tow own n: Owner: Tel el.. No: Floor space
Next 5 Market Place King ingsto ston n Ms J Shore 0181 547 1245 1300 sq m
Spatial data storage 7,10 5,9
as geometric objects: points, lines, polygons
as image files composed of grid-cells (pixels)
Spatial data storage model import important ant in in determ determini ining ng the the poten potential tial applica applicatio tions ns of of the sys system tem model model may also also affec affectt the type type of analys analysis is work work that can be achieved hybri hybrid d approach approach to stor storing ing grap graphic hical al and and attrib attribute ute inform informatio ation n Attrib Attribute ute inform informatio ation n often often stor stored ed with within in stand standard ard relat relation ional al database Graphi Graphical cal inform informatio ation n is stored stored in a propri proprietar etary y file file sys system tem ± optim optimis ised ed tool toolss for for data data handl handling ing ± although although non-st non-standar andard d proprieta proprietary ry system system will will be difficul difficultt to integrate with other systems, it will tend to be very efficient at handling large graphics files.
Vector data model
advantag advantagee of of the vector vector data data format: format: allows allows precise precise represent representati ation on of points, boundaries, and linear features. ± useful useful for for analys analysis is tasks tasks that require require accur accurate ate positio positioning ning,, ± for defining defining spatial relationship relationship (ie the the connectivi connectivity ty and and adjacency adjacency)) between coverage features (topology), important for such purposes as network analysis (for example to find an optimal op timal path between two nodes in a complex transport network)
main main disad disadvant vantage age of vector vector data is that that the boundaries boundaries of the the result resulting ing map polygons are discrete (enclosed by well-defined boundary lines), whereas in reality the map polygons may represent continuous gradation or gradual change, as in soil maps.
Raster data model
good good for for rep repre rese sent ntin ing g indi indist stin inct ct bou bounda ndari ries es ± thematic thematic informa information tion on soil types, types, soil moisture, moisture, vegeta vegetation, tion, ground ground temperatures
as reconnais reconnaissanc sancee satell satellite itess and and aerial aerial surveys surveys use rasterraster-base based d scanners, the information (ie scanned images) can be directly incorporated into GIS
the the highe higherr the the grid grid resolu resoluti tion, on, the the large largerr the data data file file is goin going g to be
Manipulation and analysis What hat wou would happ happen en if . . . A chemical leaked into a river? Where does . . . The Green Belt exist in relation to the City? Has . . . Population changed over the last ten years? Is the there re a spa spati tial al patt patter ern n rel relat ated ed to . . . Car ownership in our area? 26
Databases & GIS Spatial data
At a simple le level a GIS may just form the graphical interface to a database The The majority of GI GIS applications follow this example
MapIn Map Info fo
Linked database table
SQL Query Manager
Geo-relational Data Models Linked Linked tables tables bas based ed on on the the relati relationa onall mode model, l, but storing geographical information such as: ± Geom eometry etry ± Topol opolo ogy ± Attr Attrib ibut utes es
GIS & Analysis In the context of GIS, analysis is... ³ Deriving new information from existing data´ It is also the manipulation of data to solve a problem within n 500m of a lake e.g. identify all areas withi Increasing use is made of the analytical capabilities of GIS, BUT many GIS projects only use the software to store and manage geographical data Yet analysis often relies on many simple basic GIS techniques
Simple Query The identi identific ficatio ation n of objects objects and their their attrib attribute utess either by location or attribute query.
MapIn Map Info fo
Buffering Crea Creati tion on of an are areaa of inte intere rest st arou around nd an an objec objectt ± proximi proximity ty analys analysis is and environm environmenta entall impact impact assess assessmen ment. t.
MapIn Map Info fo
Cookie Cutting Overla Overlay y of datase datasets ts usin using g one one datase datasett as a siev sievee or cookie cutter to select a subset of the other dataset.
MapIn Map Info fo
Overlays Layer: ayer: A them themati aticc plan planee of GIS GIS feat featur ures es cont contain ainin ing g geographically and logically related data
Overlay Overlaying ing involve involvess superim superimposin posing g two two or or more map layers layers to produce produce a new map layer.
Examp Example: le: a new gene genetic ticall ally y enginee engineered red vari variety ety of of wheat wheat grow growss well well in dry dry environments, with long growing seasons and alkaline soils. Given the availability of data on the length len gth of the growing season, moisture regime and soil alkalinity, where is the best place to plant the wheat? ± overlay overlaying ing (superimpo (superimposing) sing) several several maps maps showing showing (separa (separately tely)) water-budge water-budget, t, growing season length, soil pH, sodium content, and so on. The GIS analysis can establish the locations where all the favorable soil conditions coincide, as the places where the wheat will grow best.
its The benef its
of GIS include:
Bette Betterr inf infor orm matio ation n man manag agem emen entt High Higher er qual qualit ity y anal analys ysis is Abili Ability ty to to carr carry y out out ³wha ³whatt if?´ if?´ scen scenar ario ioss Impr Improv ovee proj projec ectt effi effici cien ency cy 36
GIS Applications Faci Facili liti ties es manag anagem emen entt Marke arketi ting ng and and reta retail ilin ing g Environmental Tran Transp spor ort/ t/ve vehi hicl clee rout routin ing g Health Insurance and many more . . . 37
Function of GIS Point-in-polygon Queries
Proximity Queries Questions involves proximity: ³what objects are within a certain distance of this tower?´ These questions can be answered by the means of µBuffer¶ A region surrounding the area of interest for a given distance.
Network Queries Defining Network: A set of linear features that are all interconnected, whose primary purpose is to direct the movement movement of some commodity from one point to another. Example: Highways, Streets, Railways, etc.
Route Optimization Defines the what is is the best way to get from A to B with the conditions of shortest time to travel and distance. Such queries could be commonly used by emergency service like fire, police or delivery vehicles, salesperson, etc. Network load Queries Involve predictions of the response of a network n etwork to an event. Example: How a sewer network will respond to a heavy rainfall. Effect of construction on a given stretch of road on traffic flow
Thematic Mapping Allow the user to present the data in a way that allows for quick and easy recognition of pattern that could not be seen by just looking at a table of numbers. Superimposing Superimposing two two different thematic maps allows the viewer to visually find any relationship between two variables