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| − | Geographical Information System (GIS) is a tool for analysis and presentation of spatial data. It is a collection of computer hardware, software and geographic data for capturing, managing, analysing and displaying all forms of geographically referenced information.
| + | #Redirect[[Geographical Information System (GIS)]] |
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| − | ==What is GIS?==
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| − | [[Image:GISdefinition.jpg|thumb]] | |
| − | ;Simple definition : A Geographic Information System organizes large volumes of raw data into a map form for easy comprehension.
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| − | :GIS divides raw data into layers so it can give you a better understanding for the whole world.
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| − | A GIS is designed for the collection, storage, and analysis of objects and phenomena where geographic location is an important characteristic or critical to the analysis - this definition is broad and applies to a wide variety of methods for storing, accessing, and manipulating geographic information; it does not limit GIS to the computer environment<ref>Cox, A., Gifford, F. An overview to geographic information systems. The Journal of Academic Librarianship, Volume 23, Issue 6, November 1997, Pages 449-461</ref> .
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| − | ===Characteristics of a GIS===
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| − | GIS stores:
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| − | *geographic coordinate data (spatial data)
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| − | *attribute data
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| − | '''Spatial data:'''
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| − | *represent features having known locations on earth
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| − | *one of: points (0D), lines (1D) or areas (2D)
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| − | '''Attribute data:'''
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| − | *non-graphic information linked to the geographical features (spatial data) describing features eg type of road, name, history.
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| − | ===Data layers and objects===
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| − | *map data separated and stored in layers usually based on common geographical themes or data type
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| − | *alternative: objected-oriented GIS: geographical and all other information regarding a feature stored as an object
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| − | ==Formats==
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| − | Two basic formats for storing and processing coordinate data: Vector and Raster
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| − | '''Vector:'''
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| − | *uses point locations (X,Y coordinate)
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| − | *advantage: less storage space
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| − | *disadvantage: may be more difficult to perform certain overlay functions
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| − | '''Raster:'''
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| − | *data stored as a matrix of pixels, representing points.
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| − | *to analyse or overlay multiple data layers, the layers must share a common projection and coordinate system, and layers must have topology established
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| − | *Disadvantage: it is necessary to store the entire matrix
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| − | *Advantage: can perform neighbourhood analysis easily
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| − | ==Why is GIS unique?==
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| − | *GIS handles SPATIAL information
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| − | **Information referenced by its location in space
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| − | [[Image:Spatialinfo.jpg|400px|centre]]
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| − | ==GIS functions==
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| − | *Data input
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| − | *Storage
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| − | *Management
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| − | *Analysis
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| − | *Output
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| − | ===Data input:===
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| − | *keyboard entry, digitize maps; digital scanning (like a photocopy)
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| − | ===Storing data using Geodatabase===
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| − | *Geodatabase is a container for spatial and non- spatial data that can be organized in a certain structure.
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| − | *Advantages:
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| − | **provide a single, consolidated data storage for field measurements and all types of data used.
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| − | **Controlling data entry by applying validation rule on the attributes.
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| − | [[Image:Geodatabase.jpg|400px|centre]]
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| − | ===Data management:===
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| − | *database management system controls the way data are stored and retrieved
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| − | *includes verifying geographic coordinates and examining for accuracy
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| − | ===GIS analysis:===
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| − | *create new data by manipulating existing data or analyzing relationships between sets of data
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| − | *basic operations: retriecal, map generalization, map abstractions, map sheet manipulation, map abstractions, map sheet manipulation, buffer generation, polgygon overlay and dissolve, measurements, digital terrain analysis and network analysis (Cox and wotshisface, 1997).
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| − | ===Output:===
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| − | *display of output through printers and computer screens
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| − | ==CZM and GIS==
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| − | *GIS stores all data relevant for the [[CZM]]
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| − | *GIS handles data on all spatial scales (North Egypt coast vs. a single harbour)
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| − | *GIS is a powerful analysis tool.
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| − | **Comparison of measurements from different years
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| − | **Overlay analysis of measurements and modelling results
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| − | [[Image:GISCZM.jpg|350px|left]][[Image:GISCZM3.jpg|350px|right|Coastal Zone management: GIS perspective]]
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| − | ==Data types==
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| − | [[Image:Mike21data.jpg|thumb|right|Dfs1 Data MIKE 21]]
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| − | *DFS2 Data MIKE 21
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| − | *Dfs1 Data MIKE 21
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| − | *XYZ Data
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| − | *Wave time series & Rose
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| − | *Scanned Maps
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| − | *CAD drawing
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| − | [[Image:CADdrawing.jpg|thumb|right|CAD drawing]]
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| − | '''Additional Data'''
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| − | *Land use
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| − | *Sediment classification
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| − | *Satellite images
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| − | *Geographical maps
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| − | *Reports (design, licenses, Site investigation)
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| − | *….etc.
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| − | ==External links==
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| − | [http://en.wikipedia.org/wiki/Geographic_information_system Wikipedia: GIS]
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| − | [http://www.geo.ed.ac.uk/home/giswww.html GIS WWWW resource list] of servers likely to be of interest to the GIS community
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| − | [http://support.esri.com/index.cfm?fa=knowledgebase.gisDictionary.gateway GIS dictionary]
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| − | ''8th January, Ulrik Lumborg and Caitlin Pilkington (caitlin.pilkington@gmail.com), DHI.''
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