BRAE 239 Lecture Notes - Lecture 3: Geodetic Datum, North American Vertical Datum Of 1988, Sea Level Datum Of 1929
15 Oct 2016
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A level surface taken as a surface of reference. Ngvd29 - national geodetic vertical datum of 1929. Navd88 - north american vertical datum of 1988. Tidal - sea level (should always be at gravity field) Use tidal datum to come up with a method to find vertical datum (need 30 years of observations) Datum is like an o (a reference point. Benchmark: a permanent object, having a marked point whose elevation relative to a spec. The process in leveling of completing a loop by always starting on a point of known terminating on a point with a known elevation. Often can be the same point for both the start and end. Back sight: first rod reading after each set up. On a monument already leveled to or starting benchmark. Fore sight: all rod readings except the first. Once the loop is completed you need to:
