Reading Discussion

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Reading Discussion

• http//www.ngdc.noaa.gov/mgg/global/relief/ETOPO5/
  IMAGES/GIF/GLOBE.GIF

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Computer Language

• Computers understand strings of zeros and ones,
  making it difficult to comprehend how maps and
  other geographical images are able to be
  represented in digital form.
• It is important to understand that digital
  representation of geography is not equal to
  geography itself, and always involves a certain
  degree of approximation or estimation.
• Without getting too detailed, what kind of
  techniques or methods could be used to process
  geographical information in a beneficial way?

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Methods created for processing geographical
information

• Since the mid-1970s
• Techniques to input geographical information,
  converting the information to digital form
• Techniques for storing such information in
  compact format on computer disks, compact disks,
  and other digital storage media
• Methods for automated analysis of geographical
  data, to search for patterns, combine different
  kinds of data, make measurements, find optimum
  sites or routes , and a host of other tasks
• Methods to predict the outcome of various
  scenarios, such as the effects of climate change
  on vegetation
• Techniques for display of data in the form of
  maps, images, and other kinds of displays
• Capabilities for output of results in the form of
  numbers and tables

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Geographical Information Systems

• Also known as GISs
• Encompasses wide range of geographical data
  includes GIS data, GIS decisions, and GIS systems
• Complex systems that can take months or years to
  set up
• How do they work?

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GIS Pyramid

• The decision-making pyramid is one technique used
  to analyze and simplify data
• Uses a layered method of projecting data
• One layer superimposed over the existing layer
  below
• GIS are now in the process of filling the upper
  half of the pyramid

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GIS Chain

• GISs are complex systems made up of several
  interconnecting parts
• GISs cannot be bought of the shelf but rather
  must be built within an organization
• Careful attention must be paid to all links of
  the chain
• There is a distinct difference between GPS
  (global positioning systems) and GIS, but do you
  think that a hand-held GPS/navigation device can
  be considered a GIS? After all it can be bought
  off the shelf.

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Maps

• Traditionally geographical data was presented on
  maps
• A legend would be present on the map describing
  the meaning of the symbols used on the mapped
  area
• Effective in storing and presenting geographical
  data
• Ineffective in manipulating data and altering the
  presentation
• Usually made for a particular purpose

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Advantages of GIS over maps

• Data storage and data presentation are separate
• Allows data to be presented and viewed in various
  ways
• Once data is stored we can
• Zoom in or out
• Display selected areas
• Make calculations and correlations
• Create and present tables displaying desired
  details on the map
• Superimpose the map on other information
• Search demographics for best location for retail
  stores!
• Anything else?

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Components

• There are many definitions of geographical
  information system, for now consider a GIS to be
  any computer-based capability for the
  manipulation of geographical data
• Includes hardware, software, special devices used
  to input maps and create map products, and
  communication systems needed to link various
  elements

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• Hardware and software functions include
• Acquisition and verification
• Compilation
• Storage
• Updating and changing
• Management and exchange
• Manipulation
• Retrieval and presentation
• Analysis and combination
• Now do you consider a GPS device a GIS?

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Georeferencing

• All data in a GIS are georeferenced to a specific
  location on the surface of the Earth through a
  coordinate system
• Common coordinate system is that of longitude and
  latitude, however many other systems exist
• GIS must be capable of transforming georeferences
  from one system to another
• Can a GPS fulfill this criteria?

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More about GIS

• Has the ability to attach a variety of qualities
  and characteristics to geographical areas
• Qualities can be physical parameters (ie.
  Elevation and temperature), vegetation, ownership
  of land, zoning, etc.
• Qualities may be attached to points, but often
  are assigned to more complex features such as
  lines or areas

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• Visualize data stored as theme layers with each
  layer linked to a common georeferencing system
• Layers may represent different attributes for
  particular purposes
• Market research
• Layers ? postal codes, reports on demographics,
  purchasing habits, etc.
• Firefighters
• Layers ? connections of a water supply pipe
  network (critical to know which valves to close
  in order to increase water pressure)
• State and local governments
• Layers ? property lines, properties bordering a
  road if owners are affected by roadwork.
• Can you think of any other applications where
  the several layers in a GIS would be important?

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• GIS can link information from widely scattered
  sources
• Data can be easily represented in several
  different ways (graphical, tabular, etc.)
• Correlations can be made i.e.. It is possible to
  relate quality of groundwater at a site with the
  health of inhabitants, predict vegetation growth
  with respect to climate change, compare
  development proposals with restrictions of land
  use
• Where may this information be helpful?
• Do you know of any examples of GISs and how they
  benefit us?

http//www.novaregion.org/4MileRun/images/4mr_gis_
model.gif
http//www.gis.com/implementing_gis/graphics/comop
t1.gif
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Data Integration

• GISs have the capability of obtaining data from a
  variety of sources, including but not only maps,
  images from satellites, videofilm taken from
  aircraft, statistical data, photographs, data
  from computer-assisted design (CAD) systems and
  several other media
• As GISs advance their definition changes, and
  becomes more challenging to convey for now we
  can consider GIS to be in the process of becoming
  a typical data integration machine
• Storage capacity of these systems is minuet in
  comparison with the complexity of the entire
  Earth

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Storage

• 100,000 words can be digitally stored in
  approximately 1 million bytes (1byte8bits)
• Information from a topographic map may take 100
  megabytes (1megabyte just over 1million bytes)
  to digitally capture
• One scene from a satellite can take over 300
  megabytes, the equivalent space needed to store
  300 books
• What is the relevance of this? What does it mean?

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• On a map symbols are used to signify attributes
  such as roads and power lines, in a geographical
  database a road or power line would be
  represented with a series of points connected
  with straight lines
• This allows the database to save space and
  implement the symbolization when the map is
  displayed

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• Databases are vital in GISs because they allow
  the storing of geographical data in a structured
  manner
• Some GISs are imposing more structure by
  implementing database management systems (DBMS)
  to store part or all of the data in a largely
  independent subsystem under the GIS
• How does a DBMS help a GIS?

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database vs. traditional filing cabinets

• Database
• Stores and maintains data in one place
• Stores in a uniform, structured, and controlled
  manner
• Ensures that data are accessible to many users at
  once, each of whom has the same understanding of
  the databases contents
• Easily updated with new data

• Paper in filing cabinets
• Data often stored in ways that are understandable
  to one person only
• Data easily corrupted by use, or edited in ways
  that are meaningful only to the editor
• Inaccessible to anyone other than the creator of
  the system
• Data stored in formats and at scales that are so
  diverse that they cannot be compared or collated
• Difficult to update data

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GIS diversity

• The diversity of GIS has caused various
  definitions, typically users contrive working
  definitions suited to their own specific uses
• Views of GIS include
• A data processing system designed for map
  production or visualization
• A data analysis system for examining conflicts
  over plans or optimizing the design of transport
  systems
• An information system for responding to queries
  about land ownership or soil type
• A management system to support the operations of
  a utility company, helping it to maintain its
  distribution network of pipes or cables
• A planning system to aid the design of road
  systems, excavations, or forest harvest
  operations
• An electronic navigation system for use in land
  or sea transport

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Definition ?

• Can we come up with one definition?
• GIS is now accepted internationally as an
  umbrella term for all digital systems designed to
  process geographical data.

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Disciplines, applications, types of data and end
users encompassed by GIS

• Disciplines computer sciences, cartography,
  photogrammetry, surveying, remote sensing,
  geography, hydrography, statistics, information
  sciences, planning
• Applications operation and maintenance of
  networks and other facilities, management of
  natural resources, real estate management, road
  planning, map production
• Data digital maps, digital imaging of scanned
  maps and photos, satellite data, ground truth
  data, video images, tabular data, text data
• Users water supply and sewage engineers,
  planners, biologists and cartographers, surveyors

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• CAD ? computer assisted design. Image processing
  system designed to perform a wide range of
  operations on images.
• As images become a more important part of GIS the
  distinction between image processing and GIS is
  becoming increasingly blurred
• Key terms for distinction
• GIS ? analysis ? process
• CAD ? extraction ? design

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• Forest fires ravaging southern California,
  foot-and-mouth disease devastating the British
  livestock industry, the recent outbreak of severe
  acute respiratory syndrome (SARS)all of these
  disasters have at least one thing in common the
  role played by geospatial analysts, mining
  satellite images for information to help
  authorities make crucial decisions.
• It is for reasons like this that geotechnology is
  one of the three most important emerging and
  evolving fields, along with nanotechnology and
  biotechnology.

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Questions/comments?
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