The Elevation of a terrain surface whether land based or bathymetric in nature described the Earth s morphology The Elevation data theme includes digital elevation models for land ice and ocean surfaces both for terrestrial elevation and bathymetry as well as shorelines

The main purpose of a Digital Elevation Model is to provide an elevation property with reference to a specified origin vertical reference or datum This property may be height when the value is measured opposite to the gravity field of the Earth or depth when the value is measured in the direction of the gravity field In line with existing technologies three spatial representation methods have been provided grid vector and triangulated irregular network TIN Regarding provision of data the grid spatial representation type is mandatory for the description of land elevation whereas the other ones are optional Finally either the grid or the vector spatial representation type is mandatory for the provision of data describing the bathymetry whereas the other ones are optional