Vertical datums

average level for the surface of one or more of Earth's oceans

thumb|upright=1.5|Map of the undulation of the geoid in meters (based on the EGM96 gravity model and the [[WGS84 reference ellipsoid).]]

elevation of a location in reference to a historic mean sea level taken as a vertical datum

thumb|Present-day altimetry and [[bathymetry. Data from the National Geophysical Data Center's TerrainBase Digital Terrain Model.]] thumb|Relief map of Sierra Nevada (Spain)|Sierra Nevada, Spain upright|thumb|A shaded and colored image (i.e. terrain is enhanced) of varied terrain from the Shuttle Radar Topography Mission. This shows an elevation model of New Zealand's [[Alpine Fault, running about long. The escarpment is flanked by a vast chain of hills between the fault and the mountains of the Southern Alps. Northeast is towards the top.]]

vertical datum in use in large parts of Western Europe, originally created for use in the Netherlands

thumb|Sign referring to ' ("standard zero") or (short N. N. or NN') is an outdated official vertical datum used in Germany. Elevations using this reference system were to be marked (“meters above standard zero”). has been replaced by (NHN).

level of water that charted depths displayed on a nautical chart are measured from

reference surface for vertical positions

elevation measure

boulder in Lake Geneva and reference point of altimetry in Switzerland

thumb|right|NHN height sign in the Harz mountains of Germany on the Brocken road

vertical datum for orthometric heights

vertical datum used in Switzerland