Fundamentals of Geodesy Pt VII – Vertical Datums & Geoid Models 2

Course Description

The development of a geodetic vertical datum for the United States traces its history to 1877.  Since that time the U.S. Coast & Geodetic Survey, now called the National Geodetic Survey has conducted high accuracy leveling across the country including the island areas of Hawaii, American Samoa, Guam, Northern Marians, Puerto Rico and the U.S. Virgin Islands.  This presentation will discuss the historical development of those efforts along with the evolution of the computation of increasingly more accurate geoid models to support GPS-derived heights.  The class will also briefly discuss some of the limitations of GPS-derived heights.

Learning Objectives

• Historical development of leveling networks in the United States
• Specific differences between NGVD 29 and NAVD 88
• Examples of NGS computed geoid models
• Limitations of GPS-derived orthometric heights