Difference between revisions of "Geographical Information System"

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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.  
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This article provides a description of [[Geographic Information System (GIS)]], what it is, what it does and how it is used in coastal management. There are links to the wider GIS community.
  
 
==What is GIS?==
 
==What is GIS?==
 
[[Image:GISdefinition.jpg|thumb]]
 
[[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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A Geographic Information System organizes large volumes of raw data into a map form for easy comprehension. It divides raw data into layers so it can give you a better understanding for the whole world.
:GIS divides raw data into layers so it can give you a better understanding for the whole world.
 
  
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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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 name="Cox">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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GIS handles SPATIAL information - i.e. information referenced by its location in space.
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[[Image:Spatialinfo.jpg|400px|center]]
  
  
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GIS technology can be utilised in all areas dealing with georeferenced information, including:
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*scientific research/investigations
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*resource and asset management
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*[[Environmental Impact Assessment (EIA)]]
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*urban planning
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*cartography
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*and many other areas.
  
 
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==GIS Data==
==Why is GIS unique?==
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GIS stores ''geographic coordinate data'' (spatial data) and ''attribute data''. ''Spatial data'' represents features having known locations on earth. Can be one of points (0-Dimensional), lines (1-Dimensional) or areas (2-Dimensional), while ''attribute data'' is non-graphic information linked to the geographical features (spatial data) describing features eg type of road, name, history. Attribute data are stored in an attribute table that is connected to the spatial data.
*GIS handles SPATIAL information
 
**Information referenced by its location in space
 
[[Image:Spatialinfo.jpg|400px|centre]]
 
 
 
 
 
==Characteristics of a GIS==
 
GIS stores ''geographic coordinate data'' (spatial data) and ''attribute data''.
 
 
 
'''Spatial data:'''  
 
*represent features having known locations on earth
 
*one of: points (0D), lines (1D) or areas (2D)
 
 
 
'''Attribute data:'''
 
*non-graphic information linked to the geographical features (spatial data) describing features eg type of road, name, history.  
 
  
  
 
===Data formats===
 
===Data formats===
Two basic formats for storing and processing coordinate data: Vector and Raster
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Discrete and continuous data can be represented, and two basic formats are used for storing and processing coordinate data: Vector and Raster.
  
 
'''Vector:'''
 
'''Vector:'''
*uses point locations (X,Y coordinate)
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Vector data type uses point locations (X,Y coordinate), or polyline/polygons, as representation. An advantage this has is that less storage space is used and can be easier to combine different vector layers, while a disadvantage is that it may be more difficult to perform certain overlay functions.
*advantage: less storage space
 
*disadvantage: may be more difficult to perform certain overlay functions
 
  
 
'''Raster:'''
 
'''Raster:'''
*data stored as a matrix of pixels, representing points.  
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Data is stored as a matrix of pixels. To analyse or overlay multiple data layers, the layers must share a common projection and coordinate system, and layers must have topology established. An advantage is that neighbourhood analysis can be performed easily, and a disadvantage is that it is necessary to store the entire matrix.
*to analyse or overlay multiple data layers, the layers must share a common projection and coordinate system, and layers must have topology established
 
*Disadvantage: it is necessary to store the entire matrix
 
*Advantage: can perform neighbourhood analysis easily
 
  
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===Data types===
  
 
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Some types of data used in GIS are listed below:
==Data types==
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*Satellite images
[[Image:Mike21data.jpg|thumb|right|Dfs1 Data MIKE 21]]
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*Geographical maps
*DFS2 Data MIKE 21
 
*Dfs1 Data MIKE 21
 
*XYZ Data
 
 
*Wave time series & Rose
 
*Wave time series & Rose
 
*Scanned Maps
 
*Scanned Maps
*CAD drawing
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*CAD drawing   [[Image:CADdrawing.jpg|thumb|right|CAD drawing]]
[[Image:CADdrawing.jpg|thumb|right|CAD drawing]]
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Additional data include:
'''Additional Data'''
 
 
*Land use
 
*Land use
 
*Sediment classification
 
*Sediment classification
*Satellite images
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*DFS2 Data [http://www.dhigroup.com/Software/Marine/MIKE21.aspx MIKE 21]
*Geographical maps
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*Dfs1 Data MIKE 21
*Reports (design, licenses, Site investigation)
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*XYZ Data
*….etc.
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*Reports (design, licenses, Site investigation), etc.
 +
[[Image:Mike21data.jpg|thumb|right|Dfs2 Data MIKE 21]]
  
 
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Map data is separated and stored in layers usually based on common geographical themes or data type. An alternative is objected-oriented GIS, where geographical and all other information regarding a feature stored as an object.
 
 
 
 
Map data is separated and stored in layers usually based on common geographical themes or data type. And alternative is objected-oriented GIS, where geographical and all other information regarding a feature stored as an object.
 
  
 
==GIS functions==
 
==GIS functions==
Line 79: Line 63:
  
 
===Data input===
 
===Data input===
*keyboard entry, digitize maps; digital scanning (like a photocopy)
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Data input can be via:
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*Import of raw data (ASCII)
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*keyboard entry  
 +
*digitising maps
 +
*digital scanning
 +
 
  
 
===Storing data using Geodatabase===
 
===Storing data using Geodatabase===
*Geodatabase is a container for spatial and non- spatial data that can be organized in a certain structure.
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[[Image:Geodatabase.jpg|400px|right]]
*Advantages:
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A geodatabase is a container for spatial and non-spatial data that can be organized in a certain structure. It has the advantages of providing a single, consolidated data storage for field measurements and all types of data used, and the ability of controlling data entry by applying validation rule on the attributes.
**provide a single, consolidated data storage for field measurements and all types of data used.
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<br style="clear:both;"/>
**Controlling data entry by applying validation rule on the attributes.
 
 
 
[[Image:Geodatabase.jpg|400px|centre]]
 
 
 
  
 
===Data management===
 
===Data management===
*database management system controls the way data are stored and retrieved
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Database management system controls the way data are stored and retrieved. This includes verifying geographic coordinates and examining for accuracy.
*includes verifying geographic coordinates and examining for accuracy
 
  
 
===GIS analysis===
 
===GIS analysis===
*create new data by manipulating existing data or analyzing relationships between sets of data
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GIS analysis creates new data by manipulating existing data or analyzing relationships between sets of data. It's basic operations include:
*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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*retrieval
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*map generalization
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*map abstractions
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*map sheet manipulation
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*map abstractions
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*map sheet manipulation
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*buffer generation
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*polgygon overlay and dissolve
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*measurements
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*digital terrain analysis, and  
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*network analysis<ref name="Cox"/>
  
 
===Output===
 
===Output===
*display of output through printers and computer screens
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The display of output is achieved through printers and computer screens. Data might also be exported to formats supported by other tools.
  
 
==Benefits of GIS==
 
==Benefits of GIS==
*ability to integrate different databases into one environment
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GIS has many benefits, which include:
*ability to display and manage spatial data in a spatial contect
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*Analysis of spatial data in a complex environment
*rapid production of specialized map and graphic products
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*Ability to integrate different databases into one environment
*performs complex spatial analysis
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*Ability to display and manage spatial data in a spatial context
 +
*Rapid production of specialized maps and graphic products
 +
*Performs complex spatial analysis
  
==CZM and GIS==
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==Coastal Zone Management and GIS==
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[[Image:GISCZM3.jpg|350px|left|Coastal Zone management: GIS perspective]]
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GIS stores all data relevant for [[Integrated Coastal Zone Management (ICZM)|ICZM]]. It handles data on all spatial scales (Entire regional coast vs. a single harbour) and is a powerful analysis tool, allowing the comparison of measurements from different years, as well as overlay analysis of measurements and modelling results.
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<br style="clear:both;"/>
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:<small>Fig: Coastal Zone Management: GIS perspective</small>
  
*GIS stores all data relevant for the [[CZM]]
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==External links==
*GIS handles data on all spatial scales (North Egypt coast vs. a single harbour)
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:[http://www.gisig.it/ GISIG] –-- Geographical Information Systems International Group
*GIS is a powerful analysis tool.
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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
**Comparison of measurements from different years
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:[http://support.esri.com/index.cfm?fa=knowledgebase.gisDictionary.gateway GIS dictionary]
**Overlay analysis of measurements and modelling results
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:[http://en.wikipedia.org/wiki/Geographic_information_system Wikipedia: GIS]
  
  
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==See also==
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[[ICZM and Information Systems]]
  
[[Image:GISCZM3.jpg|500px|centre|Coastal Zone management: GIS perspective]]
 
  
==External links==
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==References==
[http://en.wikipedia.org/wiki/Geographic_information_system Wikipedia: GIS]
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<references/>
 
 
[http://www.geo.ed.ac.uk/home/giswww.html GIS WWWW resource list] of servers likely to be of interest to the GIS community
 
  
[http://support.esri.com/index.cfm?fa=knowledgebase.gisDictionary.gateway GIS dictionary]
 
  
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{{author
  
==References==
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|AuthorID=12941
<references/>
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|AuthorFullName=Ulrik Lumborg
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|AuthorName=UlrikLumborg}}
  
''8th January, Ulrik Lumborg and Caitlin Pilkington (caitlin.pilkington@gmail.com), DHI.''
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[[Category:Coastal and marine observation and monitoring]]
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[[Category:Information systems]]

Latest revision as of 17:54, 29 June 2019

This article provides a description of Geographic Information System (GIS), what it is, what it does and how it is used in coastal management. There are links to the wider GIS community.

What is GIS?

GISdefinition.jpg

A Geographic Information System organizes large volumes of raw data into a map form for easy comprehension. It divides raw data into layers so it can give you a better understanding for the whole world.


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[1] .


GIS handles SPATIAL information - i.e. information referenced by its location in space.

Spatialinfo.jpg


GIS technology can be utilised in all areas dealing with georeferenced information, including:

GIS Data

GIS stores geographic coordinate data (spatial data) and attribute data. Spatial data represents features having known locations on earth. Can be one of points (0-Dimensional), lines (1-Dimensional) or areas (2-Dimensional), while attribute data is non-graphic information linked to the geographical features (spatial data) describing features eg type of road, name, history. Attribute data are stored in an attribute table that is connected to the spatial data.


Data formats

Discrete and continuous data can be represented, and two basic formats are used for storing and processing coordinate data: Vector and Raster.

Vector: Vector data type uses point locations (X,Y coordinate), or polyline/polygons, as representation. An advantage this has is that less storage space is used and can be easier to combine different vector layers, while a disadvantage is that it may be more difficult to perform certain overlay functions.

Raster: Data is stored as a matrix of pixels. To analyse or overlay multiple data layers, the layers must share a common projection and coordinate system, and layers must have topology established. An advantage is that neighbourhood analysis can be performed easily, and a disadvantage is that it is necessary to store the entire matrix.

Data types

Some types of data used in GIS are listed below:

  • Satellite images
  • Geographical maps
  • Wave time series & Rose
  • Scanned Maps
  • CAD drawing
    CAD drawing

Additional data include:

  • Land use
  • Sediment classification
  • DFS2 Data MIKE 21
  • Dfs1 Data MIKE 21
  • XYZ Data
  • Reports (design, licenses, Site investigation), etc.
Dfs2 Data MIKE 21

Map data is separated and stored in layers usually based on common geographical themes or data type. An alternative is objected-oriented GIS, where geographical and all other information regarding a feature stored as an object.

GIS functions

  • Data input
  • Storage
  • Management
  • Analysis
  • Output


Data input

Data input can be via:

  • Import of raw data (ASCII)
  • keyboard entry
  • digitising maps
  • digital scanning


Storing data using Geodatabase

Geodatabase.jpg

A geodatabase is a container for spatial and non-spatial data that can be organized in a certain structure. It has the advantages of providing a single, consolidated data storage for field measurements and all types of data used, and the ability of controlling data entry by applying validation rule on the attributes.

Data management

Database management system controls the way data are stored and retrieved. This includes verifying geographic coordinates and examining for accuracy.

GIS analysis

GIS analysis creates new data by manipulating existing data or analyzing relationships between sets of data. It's basic operations include:

  • retrieval
  • 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[1]

Output

The display of output is achieved through printers and computer screens. Data might also be exported to formats supported by other tools.

Benefits of GIS

GIS has many benefits, which include:

  • Analysis of spatial data in a complex environment
  • Ability to integrate different databases into one environment
  • Ability to display and manage spatial data in a spatial context
  • Rapid production of specialized maps and graphic products
  • Performs complex spatial analysis

Coastal Zone Management and GIS

Coastal Zone management: GIS perspective

GIS stores all data relevant for ICZM. It handles data on all spatial scales (Entire regional coast vs. a single harbour) and is a powerful analysis tool, allowing the comparison of measurements from different years, as well as overlay analysis of measurements and modelling results.

Fig: Coastal Zone Management: GIS perspective

External links

GISIG –-- Geographical Information Systems International Group
GIS WWWW resource list of servers likely to be of interest to the GIS community
GIS dictionary
Wikipedia: GIS


See also

ICZM and Information Systems


References

  1. 1.0 1.1 Cox, A., Gifford, F. An overview to geographic information systems. The Journal of Academic Librarianship, Volume 23, Issue 6, November 1997, Pages 449-461


The main author of this article is Ulrik Lumborg
Please note that others may also have edited the contents of this article.

Citation: Ulrik Lumborg (2019): Geographical Information System. Available from http://www.coastalwiki.org/wiki/Geographical_Information_System [accessed on 25-05-2020]