What is the specific measurement method of altitude?

1. Traditional geometric leveling method: it refers to setting a datum point every 35 meters from the national elevation datum point 1985 located in Qingdao, and calculating the elevation changes on both sides with a level. Altitude, also called altitude, is the height difference between a place and sea level.

2.GPS height fitting method: strengthen the integrated construction of a national network through Beidou base; Build an open platform for location services, providing real-time high-precision location services from meter level to centimeter level.

3. Geoid refinement method: 1956 Establish the leveling origin in Qingdao, and calculate the absolute elevation of other control points according to the Qingdao leveling origin.