diepteas

Diepteas is a term used in Dutch-language technical literature to denote the vertical axis that represents depth in a three-dimensional coordinate system. The diepteas corresponds to the dimension along which depth values are measured, typically extending downward from a defined reference surface such as the land surface or mean sea level. In many contexts this axis aligns with the z-axis of Cartesian coordinates, or with the bathymetric axis in oceanographic data, though naming and conventions can vary by discipline.

In oceanography and bathymetry, depth is measured below a reference surface, most commonly mean sea level, and depth values increase with increasing distance below the surface. In geology, geotechnical engineering, and mining, the diepteas often represents depth below the terrain surface or rock formation. In geographic information systems (GIS) and 3D modeling, the diepteas is treated as a vertical coordinate distinct from horizontal coordinates, and it is tied to a vertical datum and a sign convention.

Coordinate conventions for the diepteas differ: some systems treat depth as a positive downward value, while others use depth as negative elevation. The zero point of the diepteas is defined by a vertical datum, such as mean sea level, the geoid, or an ellipsoid, depending on the application. The term is more common in Dutch-language sources; English equivalents include depth axis or vertical axis.

See also: vertical coordinate system; z-axis; bathymetry; bathymetric data; vertical datum.