Lecture
This lecture covers the definition of the geoid as a zero equipotential gravity field related to the earth's physical surface and gravity conditions. It explains the geoid elevation, variations in mean sea level, and the geoid's deformable nature. The relation between gravity intensity, masses, and topography is discussed, along with the mathematical approximation of the geoid as a regular surface. The lecture also addresses geodetic reference surfaces, coordinate conversions, and the global and local ellipsoids. Various reference systems like WGS84 and CH1903 are explained, along with the Swiss local geoid and its variations.