Understanding Heights and Vertical Datums

Understanding Heights and Vertical Datums
  1. Describe how heights and vertical datums are used in surveying.
    • Define height as used in the context of surveying and mapping.
    • Define vertical datum.
    • Provide reasons for choosing different vertical datums.
  2. Identify types of vertical datums and their associated heights
    • Define an ellipsoidal datum.
      • Define an ellipsoid.
      • Describe the global nature of ellipsoidal datums.
      • Define an ellipsoidal height.
      • Describe strengths and weakness of ellipsoidal datums.
    • Define a geopotential datum.
      • Describe earth’s gravity field.
      • Explain why geopotential datums help describe water flow.
      • Define the geoid.
      • Recognize NAVD 88 as the current geopotential datum in the U.S.
      • Define orthometric height, geoid height/geoid undulation, and dynamic height.
      • Describe strengths and weakness of geopotential datums.
    • Define a tidal datum.
      • Describe the local nature of tidal datums.
      • Explain why tidal datums are important and what they are used for.
      • Describe strengths and weakness of tidal datums.