What is an Enhanced Digital Terrain Model?
An Enhanced Digital Terrain Model (DTM) is a digital file consisting of break-lines and spot heights providing a highly detailed representation of the topographical variations in the Earth's surface. Break-lines represent linear features such as banks, ditches and rock faces.
Enhanced DTMs are revised within the same three year cycle as the orthophotography.
- Version1: March 2003 to July 2006
- Version2: July 2006 to April 2010
- Version3: April 2010 to October 2012
- Version4: April 2012 to Present
- The Enhanced DTM consists of a point file of heights, along with break-lines showing definite changes in height, giving a highly detailed representation of the Earth's surface.
- Random spot heights are generated depending on gradient. An Enhanced DTM therefore carries a higher density of data where it is most needed.
- The Enhanced DTM can be used in the electronic process of representing topography in 3 dimensions e.g. in a Geographical Information or CAD system.
- Derived from OSNI's Orthophotography dataset, the Enhanced DTM is generated using photogrammetric methods of data acquisition.
- All height measurements refer to elevation in metres above mean sea level at Belfast Lough.
- Enhanced DTMs can be used to generate 3D Triangular Irregular Networks (TIN).
- 95% of the data is within +/- 1.0m accuracy.
- Height Analysis
- Environmental Impact Analysis
- Sight Lines
- Wind flow and pollution dispersion
- Soil erosion modelling
- Flow direction and accumulation
- Watershed delineation
Enhanced DTMs in Action
Enhanced Digital Terrain Models (DTM) are utilised by a number of organisations and businesses. One such organisation is the Rivers Agency within Department of Agriculture and Regional Development (DARD). The Agency is using Enhanced DTM information to produce a series of National Flood Map products for Northern Ireland catchments. As part of the modelling process, the enhanced DTM is used to derive river catchment boundaries; these are subsequently processed in accordance with the latest Flood Estimation methods to produce a flood flow grid product. Both the flood flow grid and the Enhanced DTM are then applied within a flood modelling package to predict the extent of flooding. The accuracy of the Enhanced DTM is +/- 1m, which makes it suitable for this type of modelling at a strategic level.
For detailed information about this product please click on the links below:
Alternatively you can email us at firstname.lastname@example.org