GIS

• Geographical Information System (GIS)


  A system for capturing, analyzing and displaying geographic data
• Components of GIS


  • Software/Programme
  • Hardware/Computer
  • User/People
  • Data
  • Application
• Hardware


  • Hardware/Computer
  • Software
• Vector data


  Information is shown by point, line and polygon (area)
• Raster data


  Information is shown by pictures or pixel
• Reality is indicated as

  • Vector
  • Raster
• Geographical Information System (GIS)


  A system for capturing, analyzing and displaying geographic data
• Components of GIS


  • Software/Programme
  • Hardware/Computer
  • User/People
  • Data
  • Application
• Hardware


  • Hardware
  • Software
• Vector data


  Information is shown by point, line and polygon (area)
• Raster data


  Information is shown by pictures or pixel
• Reality is indicated as

  • Vector
  • Raster
• HOW DATA IS STORED IN A GIS

  1. Vector data

  2. Raster data
• Advantages of Vector data format


  • Point, line, and area data is shown perfectly
  • Needs less disk storage space for data
  • Lines (like roads) and areas fit together correctly
  • Graphics look more like hand-drawn maps
• Disadvantages of Vector data format

  • More complex data structure
  • Inefficient for remotely-sensed data
  • Some GIS procedures are more complex and slower
  • Overlaying multiple vector maps is time-consuming
• Advantages of Raster data format


  • Simple data structure
  • Efficient for remotely-sensed or scanned data
  • Simple GIS analysis
• Disadvantages of Raster data format

  • Needs more storage space on computer
  • Less pleasing if pixels are big
  • Lines and areas don't fit together well
• Spatial data


  Data linked to the location of geographical features using coordinates e.g. roads
• Attributes data


  Data that describes spatial data or features e.g. roads have 4 lanes or are tarred
• Data types


  • Primary data
  • Secondary data
• Digitising


  The technique to transform map data into vector format
• Scanning


  The technique to transform map data into raster format
• Global Positioning System (GPS)


  Satellite-based navigational system which captures and sends data to a receiver on earth
• Resolution


  The degree of detail and clarity of an image
• Spatial resolution


  The size of an object that can be shown clearly in a photograph or image
• Spectral resolution


  The range of radiation that a remote sensing device is sensitive to
• Temporal resolution/Repeat cycle/Orbital cycle


  The frequency with which images of the same area are collected
• Data integration


  The process of sharing and combining data from different sources
• Data output


  Data that is produced by a computer, device, program, or process
• Data input (Input data)


  Data that is put into a computer, device, program, or process
• Proximity analysis


  An analysis in which geographic features are selected based on their distances from other features/cells
• Remote sensing


  Involves capturing data of objects on earth from a distance e.g. Landsat and Meteosat