Community GIS

This course will become read-only in the near future. Tell us at community.p2pu.org if that is a problem.

Projections [Jan. 24, 2012, 1:48 a.m.]

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