Introduction to Geographical Information Systems

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Introduction to Geographical Information Systems

• Definition GIS is a System of computer software,
  hardware and data, and personnel to help
  manipulate, analyze and present information that
  is tied to a spatial location
• spatial location usually a geographic location
• information visualization of analysis of data
• system linking software, hardware, data
• personnel the most critical key to the
  successful use of a GIS
• 
  http//www.gis.com/

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Types of data that can be included in a GIS

• Cadastral information
• Images
• Land Uses
• Inventory of Natural Resources
• Market Analysis and Trends
• Planning Schemes
• Risk Analyses
• Analytical Models and Simulations

In summary if the information has any spatial
component it can be presented within a GIS.
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History of GIS

• 1960s Restricted to paper-based systems Maps
• 1970s First Digital Mapping
• Early 1980s first Computer Aided Design or CAD
  packages
• Mid 1980s First GIS using Workstations
• Late 1980s Desktop Mapping, Integration of CAD
  with Databases, birth of PC-based systems
• Early 1990s Desktop GIS with full integration
  of data
• Mid 1990s GIS became more accessible with
  Windows based destop GIS
• Late 1990s GIS became functional over the
  Internet
• Early 2000s full integration of GIS into
  applications e.g. In Vehicle Navigation Systems

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How does GIS vary from other Graphics Programs ?

• Computer-aid design (CAD), computer cartography,
  database management and remote-sensing were all
  important in the development of GIS, however,
• AA GIS allows information to be linked to an
  object, such as point, line or polygons.
  Consequently information can be calculated from
  the topography of the object or information can
  be attached to the object and stored in a
  separate table.
• A GIS has the ability to shade various land
  parcels (districts) according to ranges of
  specified variables. This makes identification
  of spatial relations within the data set easy to
  identify.

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DIFFERENCE BETWEEN A GIS AND MAPS/ATLASES

• Maps have to be printed and in relatively large
  formats
• Although maps can be compiled into an Atlas, they
  are not seamless and you have to compare one page
  with another
• Maps have to be printed at fixed scales
• Maps cannot provide all the annotation you might
  require with respect to shading and place names
• Although Maps should always include a scale bar
  it is still not easy to calculate the lengths of
  features represented on the map and is almost
  impossible to determine areas with any reasonable
  accuracy.

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GIS Maps are Customizable

• With a GIS you can combine information that you
  wish to use and ignore information that is
  redundant to your needs
• Each feature of a Map is stored in a GIS as a
  series of files that collectively are referred to
  as a layer or coverage. You can add different
  coverages onto each other
• A GIS allows the different representation and
  colour of points, the colour and style of lines,
  the colour and shading properties of polygons,
  the colour, font, size and orientation of labels
  to be changed
• One of the most important aspects of a GIS is the
  displaying of information attached to the
  coverage which can also be represent by colour
  gradients or by unique colours according to
  attributes with a linked table of information

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GIS Maps are Searchable

• Any of the data whether it be within the
  associated table or be a measurement of the
  object and whether its numerical or text can be
  searched and identified.
• Searches can be simple such as find all estuaries
  which are always open to compound searches such
  as find all estuaries that are always open and
  have a mangrove population.
• Searches can be based on features based on the
  parameters of map features - e.g. the length of
  sandy beaches along a coastline that are longer
  than 5km

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GIS Maps are Updatable

• Since the information is stored electronically
  information is easily updated without require
  republishing.
• This information ca be writen to CD and can
  dispatched to offices or made available via a
  network
• More recently advance in GIS applications allow
  information to be updated and available to the
  entire users of the World Wide Web.
• Consequently information can be maintained in its
  most current form and optimizes decision-making.

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What Computers Would You Need To Run A GIS?

• A typical GIS is fairly complex and the databases
  and images are usually large - they consequently
  take up considerable disk space.
• Needing to handle so much data requires a fair
  amount of memory and processing power.
• Backups of data can be undertaken using tapes or
  re-writable CDs
• Often GIS software is graded into being able to
  view data, to minor alterations, to full
  customizing and programming (usually BASIC) and
  finally through to a full centrally managing
  large or corporate application.

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Getting Maps and Data into a GIS

• Geocoding one Table against an already existing
  GIS table and feature list
• Using a Digitizing Board
• Scan a pre-existing map and then geo-reference it
  within the GIS
• Using a GPS to field map features

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• Purchase data from government and commercial
  vendors.
• Data supplied via internet services, or via
  online viewing and downloading of files, e.g.
  Western Cape Nature Conservation Board is
  starting this.
• Meta databases which can be maps which provide
  information on suppliers of spatial information.
• With high bandwidths you can even log into
  different servers and mix data from different
  sources, and first system now exists where you
  can can upload your data to a map service for
  distribution via the world-wide web.

Where Can You Get Data?
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Who Produces Digital Maps?

• North America - USGS provide togographical maps,
  satellite imagery, correct orthophotos, scanned
  copies of paper maps, etc.
• South Africa Chief Directorate Surveys and
  Mapping provide the above products and charge
  only the cost of CD cutting.
• Increasingly in South Africa, private companies
  are providing more of the data. Consequently
  Computamaps in Cape Town has developed and
  markets very high resolution (20m) Digital
  Terrain Model for SouthAfrica that are
  extensively used in the mobile telecommunications
  industry. The Knowledge Factor has map of all
  land parcels in South Africa and records of
  ownership as reflected in the Deeds Office.

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Obtaining New Data

• The USGS develops from aerial photography,
  digital, geo-corrected orthophotographs of pan
  imagery at 1 metre resolution for the entire
  country every 5 years.
• In South Africa many parts have never had any
  orthophotographs prepared. The most accurate
  digital elevation model which records height data
  was for a resolution of 200 metre raster grid
  cells from the Surveyor General for South Africa.
• More Accurate Digital Terrain Information can be
  acquired using the LIDAR (look this up) and
  Digital Elevation Models with centimeter
  resolution for small areas are being prepared.
• Virtually all new maps being prepared nowadays
  are done through a GIS and hand drawing is very
  much a thing of the past.

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Types Of GIS

• There are two types of GIS which store the
  information in very different format. These are
  known as vector-based and raster-based.
• Originally there was little cross functionality
  between the two systems, however, most current
  software has the ability to present both systems
• Some software such as TNT Mips has extensive
  functionality in both systems.

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Raster Grids
Uses pixels for location and value attributes
and includes satellite-images and digital aerial
photos are already in this format.
Each grid will have a value that corresponds to
some feature, for example water might have a
value of 6 and there fore all grids which have a
value of 6 represents water. Raster-based GIS
systems are not strong on the data-base
functionality, but are good for spatial
analysis, modeling and visualizations.
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Vector Linear Points, Lines Polygons
Vector GIS use points, lines and polygons to
represent features. Since such features are
precisely define by geographical co-ordinates,
they are useful for accurate calculation of
measurements and are easily attached to tabulated
data for querying. Vector-based GIS are used
extensively for management such as municipal
offices would require
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Environmental Sensitivity Index Atlas
Application of GIS to Pollution Management

• For pollution control you will normally use
  Environmental Sensitivity Index Maps developed by
  NOAA. These are used by coastal managers for all
  forms of oil/chemical pollution and contain three
  types of information, namely-
• Coastline Information
• Sensitive Biological Resources
• Human Use Features

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Thematic Mapping - for Sensitivity Atlases
Coastline Information that is colour coded with
respect to either type of coastal and/or its
vulnerability to pollution which ranges from
Exposed Rocky Headlands which are the least
vulnerable and will be coloured with cold colours
such blue/green to estuarine environment (marshes
and mangroves) which are the most vulnerable to
the effects of pollution and are coloured warm
colours such as red/orange.
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Intertidal

• Intertidal
• Exposed Rocky Shores
• Exposed, Solid Man-Made Structures
• Exposed, Wave-Cut Platforms
• Sandy Beaches
• Mixed Sand and Gravel Beaches
• Gravel Beaches
• Exposed Tidal Flats
• Sheltered Rocky Shores and Scarps
• Sheltered, Solid Man-Made Structures
• Peat Shores
• Sheltered Tidal Flats
• Salt to Brackish Marshes
• Mangroves Inundated

• Subtidal
• Coral Reefs
• Seagrasses
• Kelp
• Soft Bottom
• Mixed Hard Bottom
• On-Water
• Off shore
• Bays and Estuaries

Subtidal
On-Water
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Sensitive Biological Featuresused in USA (NOAA)

• Marine Mammal, Dolphin, Manatee, Seals, Otters,
  Whale,
• Terrestrial Mammal Primate, Canine, Feline,
• Small Mammal Hyrax and threatened, endangered,
  or rare species.
• Bird Diving Bird, Gull/Tern, Pelagic, Raptor,
  Shorebird, Wading Bird, Waterfowl
• Reptile/Amphibian Alligator/Crocodile, Turtle,
  other rare species, especially aquatic/wetland
  concentration areas.
• Fish Diadromous, Nursery Estuarine Fish,
  Resident Estuarine Fish, Freshwater Fish, Benthic
  Marine Fish, Pelagic Marine Fish.
• Shellfish/Insect Bivalve, Cephalopod, Crab,
  Echinoderm, Gastropod, Lobster/Crayfish, Shrimp,
  Insect
• Habitat/Rare Plant Coral Reef, Floating Aquatic
  Vegetation, Hardbottom Reef, Kelp Bed, Rare,
  Submerged Aquatic Vegetation, Worm Bed

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Sensitive Human Resources
Human Use Resources that are depicted as both
shading and symbols

• Protected marine sites (reserves/sanctuaries),
• Recreational sites including swimming beaches,
  angling spots, mariculture sites
• Commercial and subsistance gathering of marine
  resources (mussels, bait, crayfish), coastal
  developments such as harbours and marinas, power
  plants including nuclear, mining and marine
  intakes and discharges (e.g. a fish factor will
  take in clean water for processing and discharge
  this water with discharges of fish oil which are
  potential pollutants).

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Sensitive Human Resources - continued
Recreation/Access Access - Vehicular access to
the shoreline, Beach - High-use recreational
beaches, Boat Ramp, Diving Site, High-use
recreational areas, Marina, Recreational Fishing,
High-use recreational areas Management Areas
Reservation, Marine Sanctuary, National Park,
Park - State and regional parks, Special
Management Areas - Usually water-associated,Wildli
fe Refuge, Preserve, Reserve Resource Extraction
Site Aquaculture Site - Hatcheries, ponds, and
pens, Commercial Fishery, Log Storage Area,
Mining - Intertidal/subtidal mining leases,
Subsistence - Designated harvest sites, Water
Intake - Industrial drinking water cooling
water, aquaculture Cultural Resource
Archaeological Site - Water-, coastal-, or
wetland-associated, Historical Site - Water-,
coastal-, or wetland-associated
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All of these features are put onto maps using an
ICON-based