Community GIS

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Projections

Learning Objectives

  • explain how projections and datums relate
  • demonstrate the process of projection using tangible objects
  • draw or diagram some common types of distortions that map projections introduce
  • define projection in terms of geographic features and mapping
  • name three common map projections
  • classify three map projections by the type of projected geometry and the spatial accuracy (i.e. preserved features)
  • summarize your general understanding of map projections in two to three paragraphs

 

Task Outline

  • Distance around earth
    • polar
    • equatorial
  • ellipsoid (oblate ellipsoid, spheroid)
  • datum
  • Clarke 1866 ellipsoid
    • 6,356,538.8 meters
    • flattening 1/294.9
  • NAD (19)27
  • NAD (19)83
  • GRS 80
  • WGS 84
  • geodesy
    • local variations
    • geoid

Task Discussion