Elevation Data

Different forms of elevation data

DEM - The representation of continuous elevation values over a topographic surface by a regular array of sampled z-values, referenced to a common datum. To be expressed as a grid or raster data set. The DEM is ground only representation and excludes vegetation such as trees and shrubs and human constructed features such as sheds and houses.

DSM - surface including ground, vegetation, building and structures defined by either random points or regular grid of spot heights and may include breaklines. Can be in point (ASCII), vector or raster format.

DTM - A topographic model of the earth's surface in digital format represented by mass points and may include breaklines. The DTM is a filtered version of a DSM that represents only bare earth surfaces. The DTM representation of ground includes works such as levees, banks and roads.

What is included in our elevation data?

Our elevation data models are derived from a range of capture technologies. DSMs are generated from ortho-mosaics created during the processing of aerial imagery. DTMs derived by stereoscopic photogrammetric processes and semi-automated building and vegetation filtering to achieve a smoother result with remaining some non-ground features. Elevation models available reflect the technology and imagery resolution available at the time of capture and processing.

Typically, Landgate has not edited the DEMs to support hydrological studies.

What options are available? 

• DEM Index
• South West DTM Index
• LiDAR Index

Supply format

ASCII or BIL (Band Interleaved by Line)

How to access our elevation data

Access options

Contact the Data Delivery team. Data will be supplied under a transactional licence.